includes/db/Database.php

   1 <?php
   2 /**
   3  * @defgroup Database Database
   4  *
   5  * This file deals with database interface functions
   6  * and query specifics/optimisations.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along
  19  * with this program; if not, write to the Free Software Foundation, Inc.,
  20  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  21  * http://www.gnu.org/copyleft/gpl.html
  22  *
  23  * @file
  24  * @ingroup Database
  25  */
  26
  27 /**
  28  * Base interface for all DBMS-specific code. At a bare minimum, all of the
  29  * following must be implemented to support MediaWiki
  30  *
  31  * @file
  32  * @ingroup Database
  33  */
  34 interface DatabaseType {
  35         /**
  36          * Get the type of the DBMS, as it appears in $wgDBtype.
  37          *
  38          * @return string
  39          */
  40         function getType();
  41
  42         /**
  43          * Open a connection to the database. Usually aborts on failure
  44          *
  45          * @param string $server database server host
  46          * @param string $user database user name
  47          * @param string $password database user password
  48          * @param string $dbName database name
  49          * @return bool
  50          * @throws DBConnectionError
  51          */
  52         function open( $server, $user, $password, $dbName );
  53
  54         /**
  55          * Fetch the next row from the given result object, in object form.
  56          * Fields can be retrieved with $row->fieldname, with fields acting like
  57          * member variables.
  58          * If no more rows are available, false is returned.
  59          *
  60          * @param $res ResultWrapper|object as returned from DatabaseBase::query(), etc.
  61          * @return object|bool
  62          * @throws DBUnexpectedError Thrown if the database returns an error
  63          */
  64         function fetchObject( $res );
  65
  66         /**
  67          * Fetch the next row from the given result object, in associative array
  68          * form.  Fields are retrieved with $row['fieldname'].
  69          * If no more rows are available, false is returned.
  70          *
  71          * @param $res ResultWrapper result object as returned from DatabaseBase::query(), etc.
  72          * @return array|bool
  73          * @throws DBUnexpectedError Thrown if the database returns an error
  74          */
  75         function fetchRow( $res );
  76
  77         /**
  78          * Get the number of rows in a result object
  79          *
  80          * @param $res Mixed: A SQL result
  81          * @return int
  82          */
  83         function numRows( $res );
  84
  85         /**
  86          * Get the number of fields in a result object
  87          * @see http://www.php.net/mysql_num_fields
  88          *
  89          * @param $res Mixed: A SQL result
  90          * @return int
  91          */
  92         function numFields( $res );
  93
  94         /**
  95          * Get a field name in a result object
  96          * @see http://www.php.net/mysql_field_name
  97          *
  98          * @param $res Mixed: A SQL result
  99          * @param $n Integer
 100          * @return string
 101          */
 102         function fieldName( $res, $n );
 103
 104         /**
 105          * Get the inserted value of an auto-increment row
 106          *
 107          * The value inserted should be fetched from nextSequenceValue()
 108          *
 109          * Example:
 110          * $id = $dbw->nextSequenceValue( 'page_page_id_seq' );
 111          * $dbw->insert( 'page', array( 'page_id' => $id ) );
 112          * $id = $dbw->insertId();
 113          *
 114          * @return int
 115          */
 116         function insertId();
 117
 118         /**
 119          * Change the position of the cursor in a result object
 120          * @see http://www.php.net/mysql_data_seek
 121          *
 122          * @param $res Mixed: A SQL result
 123          * @param $row Mixed: Either MySQL row or ResultWrapper
 124          */
 125         function dataSeek( $res, $row );
 126
 127         /**
 128          * Get the last error number
 129          * @see http://www.php.net/mysql_errno
 130          *
 131          * @return int
 132          */
 133         function lastErrno();
 134
 135         /**
 136          * Get a description of the last error
 137          * @see http://www.php.net/mysql_error
 138          *
 139          * @return string
 140          */
 141         function lastError();
 142
 143         /**
 144          * mysql_fetch_field() wrapper
 145          * Returns false if the field doesn't exist
 146          *
 147          * @param string $table table name
 148          * @param string $field field name
 149          *
 150          * @return Field
 151          */
 152         function fieldInfo( $table, $field );
 153
 154         /**
 155          * Get information about an index into an object
 156          * @param string $table Table name
 157          * @param string $index Index name
 158          * @param string $fname Calling function name
 159          * @return Mixed: Database-specific index description class or false if the index does not exist
 160          */
 161         function indexInfo( $table, $index, $fname = __METHOD__ );
 162
 163         /**
 164          * Get the number of rows affected by the last write query
 165          * @see http://www.php.net/mysql_affected_rows
 166          *
 167          * @return int
 168          */
 169         function affectedRows();
 170
 171         /**
 172          * Wrapper for addslashes()
 173          *
 174          * @param string $s to be slashed.
 175          * @return string: slashed string.
 176          */
 177         function strencode( $s );
 178
 179         /**
 180          * Returns a wikitext link to the DB's website, e.g.,
 181          *     return "[http://www.mysql.com/ MySQL]";
 182          * Should at least contain plain text, if for some reason
 183          * your database has no website.
 184          *
 185          * @return string: wikitext of a link to the server software's web site
 186          */
 187         function getSoftwareLink();
 188
 189         /**
 190          * A string describing the current software version, like from
 191          * mysql_get_server_info().
 192          *
 193          * @return string: Version information from the database server.
 194          */
 195         function getServerVersion();
 196
 197         /**
 198          * A string describing the current software version, and possibly
 199          * other details in a user-friendly way.  Will be listed on Special:Version, etc.
 200          * Use getServerVersion() to get machine-friendly information.
 201          *
 202          * @return string: Version information from the database server
 203          */
 204         function getServerInfo();
 205 }
 206
 207 /**
 208  * Interface for classes that implement or wrap DatabaseBase
 209  * @ingroup Database
 210  */
 211 interface IDatabase {}
 212
 213 /**
 214  * Database abstraction object
 215  * @ingroup Database
 216  */
 217 abstract class DatabaseBase implements IDatabase, DatabaseType {
 218         /** Number of times to re-try an operation in case of deadlock */
 219         const DEADLOCK_TRIES = 4;
 220         /** Minimum time to wait before retry, in microseconds */
 221         const DEADLOCK_DELAY_MIN = 500000;
 222         /** Maximum time to wait before retry */
 223         const DEADLOCK_DELAY_MAX = 1500000;
 224
 225 # ------------------------------------------------------------------------------
 226 # Variables
 227 # ------------------------------------------------------------------------------
 228
 229         protected $mLastQuery = '';
 230         protected $mDoneWrites = false;
 231         protected $mPHPError = false;
 232
 233         protected $mServer, $mUser, $mPassword, $mDBname;
 234
 235         protected $mConn = null;
 236         protected $mOpened = false;
 237
 238         /** @var callable[] */
 239         protected $mTrxIdleCallbacks = array();
 240         /** @var callable[] */
 241         protected $mTrxPreCommitCallbacks = array();
 242
 243         protected $mTablePrefix;
 244         protected $mFlags;
 245         protected $mForeign;
 246         protected $mTrxLevel = 0;
 247         protected $mErrorCount = 0;
 248         protected $mLBInfo = array();
 249         protected $mFakeSlaveLag = null, $mFakeMaster = false;
 250         protected $mDefaultBigSelects = null;
 251         protected $mSchemaVars = false;
 252
 253         protected $preparedArgs;
 254
 255         protected $htmlErrors;
 256
 257         protected $delimiter = ';';
 258
 259         /**
 260          * Remembers the function name given for starting the most recent transaction via begin().
 261          * Used to provide additional context for error reporting.
 262          *
 263          * @var String
 264          * @see DatabaseBase::mTrxLevel
 265          */
 266         private $mTrxFname = null;
 267
 268         /**
 269          * Record if possible write queries were done in the last transaction started
 270          *
 271          * @var Bool
 272          * @see DatabaseBase::mTrxLevel
 273          */
 274         private $mTrxDoneWrites = false;
 275
 276         /**
 277          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 278          *
 279          * @var Bool
 280          * @see DatabaseBase::mTrxLevel
 281          */
 282         private $mTrxAutomatic = false;
 283
 284         /**
 285          * @since 1.21
 286          * @var file handle for upgrade
 287          */
 288         protected $fileHandle = null;
 289
 290 # ------------------------------------------------------------------------------
 291 # Accessors
 292 # ------------------------------------------------------------------------------
 293         # These optionally set a variable and return the previous state
 294
 295         /**
 296          * A string describing the current software version, and possibly
 297          * other details in a user-friendly way.  Will be listed on Special:Version, etc.
 298          * Use getServerVersion() to get machine-friendly information.
 299          *
 300          * @return string: Version information from the database server
 301          */
 302         public function getServerInfo() {
 303                 return $this->getServerVersion();
 304         }
 305
 306         /**
 307          * @return string: command delimiter used by this database engine
 308          */
 309         public function getDelimiter() {
 310                 return $this->delimiter;
 311         }
 312
 313         /**
 314          * Boolean, controls output of large amounts of debug information.
 315          * @param $debug bool|null
 316          *   - true to enable debugging
 317          *   - false to disable debugging
 318          *   - omitted or null to do nothing
 319          *
 320          * @return bool|null previous value of the flag
 321          */
 322         public function debug( $debug = null ) {
 323                 return wfSetBit( $this->mFlags, DBO_DEBUG, $debug );
 324         }
 325
 326         /**
 327          * Turns buffering of SQL result sets on (true) or off (false). Default is
 328          * "on".
 329          *
 330          * Unbuffered queries are very troublesome in MySQL:
 331          *
 332          *   - If another query is executed while the first query is being read
 333          *     out, the first query is killed. This means you can't call normal
 334          *     MediaWiki functions while you are reading an unbuffered query result
 335          *     from a normal wfGetDB() connection.
 336          *
 337          *   - Unbuffered queries cause the MySQL server to use large amounts of
 338          *     memory and to hold broad locks which block other queries.
 339          *
 340          * If you want to limit client-side memory, it's almost always better to
 341          * split up queries into batches using a LIMIT clause than to switch off
 342          * buffering.
 343          *
 344          * @param $buffer null|bool
 345          *
 346          * @return null|bool The previous value of the flag
 347          */
 348         public function bufferResults( $buffer = null ) {
 349                 if ( is_null( $buffer ) ) {
 350                         return !(bool)( $this->mFlags & DBO_NOBUFFER );
 351                 } else {
 352                         return !wfSetBit( $this->mFlags, DBO_NOBUFFER, !$buffer );
 353                 }
 354         }
 355
 356         /**
 357          * Turns on (false) or off (true) the automatic generation and sending
 358          * of a "we're sorry, but there has been a database error" page on
 359          * database errors. Default is on (false). When turned off, the
 360          * code should use lastErrno() and lastError() to handle the
 361          * situation as appropriate.
 362          *
 363          * @param $ignoreErrors bool|null
 364          *
 365          * @return bool The previous value of the flag.
 366          */
 367         public function ignoreErrors( $ignoreErrors = null ) {
 368                 return wfSetBit( $this->mFlags, DBO_IGNORE, $ignoreErrors );
 369         }
 370
 371         /**
 372          * Gets or sets the current transaction level.
 373          *
 374          * Historically, transactions were allowed to be "nested". This is no
 375          * longer supported, so this function really only returns a boolean.
 376          *
 377          * @param int $level An integer (0 or 1), or omitted to leave it unchanged.
 378          * @return int The previous value
 379          */
 380         public function trxLevel( $level = null ) {
 381                 return wfSetVar( $this->mTrxLevel, $level );
 382         }
 383
 384         /**
 385          * Get/set the number of errors logged. Only useful when errors are ignored
 386          * @param int $count The count to set, or omitted to leave it unchanged.
 387          * @return int The error count
 388          */
 389         public function errorCount( $count = null ) {
 390                 return wfSetVar( $this->mErrorCount, $count );
 391         }
 392
 393         /**
 394          * Get/set the table prefix.
 395          * @param string $prefix The table prefix to set, or omitted to leave it unchanged.
 396          * @return string The previous table prefix.
 397          */
 398         public function tablePrefix( $prefix = null ) {
 399                 return wfSetVar( $this->mTablePrefix, $prefix );
 400         }
 401
 402         /**
 403          * Set the filehandle to copy write statements to.
 404          *
 405          * @param $fh filehandle
 406          */
 407         public function setFileHandle( $fh ) {
 408                 $this->fileHandle = $fh;
 409         }
 410
 411         /**
 412          * Get properties passed down from the server info array of the load
 413          * balancer.
 414          *
 415          * @param string $name The entry of the info array to get, or null to get the
 416          *   whole array
 417          *
 418          * @return LoadBalancer|null
 419          */
 420         public function getLBInfo( $name = null ) {
 421                 if ( is_null( $name ) ) {
 422                         return $this->mLBInfo;
 423                 } else {
 424                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 425                                 return $this->mLBInfo[$name];
 426                         } else {
 427                                 return null;
 428                         }
 429                 }
 430         }
 431
 432         /**
 433          * Set the LB info array, or a member of it. If called with one parameter,
 434          * the LB info array is set to that parameter. If it is called with two
 435          * parameters, the member with the given name is set to the given value.
 436          *
 437          * @param $name
 438          * @param $value
 439          */
 440         public function setLBInfo( $name, $value = null ) {
 441                 if ( is_null( $value ) ) {
 442                         $this->mLBInfo = $name;
 443                 } else {
 444                         $this->mLBInfo[$name] = $value;
 445                 }
 446         }
 447
 448         /**
 449          * Set lag time in seconds for a fake slave
 450          *
 451          * @param $lag int
 452          */
 453         public function setFakeSlaveLag( $lag ) {
 454                 $this->mFakeSlaveLag = $lag;
 455         }
 456
 457         /**
 458          * Make this connection a fake master
 459          *
 460          * @param $enabled bool
 461          */
 462         public function setFakeMaster( $enabled = true ) {
 463                 $this->mFakeMaster = $enabled;
 464         }
 465
 466         /**
 467          * Returns true if this database supports (and uses) cascading deletes
 468          *
 469          * @return bool
 470          */
 471         public function cascadingDeletes() {
 472                 return false;
 473         }
 474
 475         /**
 476          * Returns true if this database supports (and uses) triggers (e.g. on the page table)
 477          *
 478          * @return bool
 479          */
 480         public function cleanupTriggers() {
 481                 return false;
 482         }
 483
 484         /**
 485          * Returns true if this database is strict about what can be put into an IP field.
 486          * Specifically, it uses a NULL value instead of an empty string.
 487          *
 488          * @return bool
 489          */
 490         public function strictIPs() {
 491                 return false;
 492         }
 493
 494         /**
 495          * Returns true if this database uses timestamps rather than integers
 496          *
 497          * @return bool
 498          */
 499         public function realTimestamps() {
 500                 return false;
 501         }
 502
 503         /**
 504          * Returns true if this database does an implicit sort when doing GROUP BY
 505          *
 506          * @return bool
 507          */
 508         public function implicitGroupby() {
 509                 return true;
 510         }
 511
 512         /**
 513          * Returns true if this database does an implicit order by when the column has an index
 514          * For example: SELECT page_title FROM page LIMIT 1
 515          *
 516          * @return bool
 517          */
 518         public function implicitOrderby() {
 519                 return true;
 520         }
 521
 522         /**
 523          * Returns true if this database can do a native search on IP columns
 524          * e.g. this works as expected: .. WHERE rc_ip = '127.42.12.102/32';
 525          *
 526          * @return bool
 527          */
 528         public function searchableIPs() {
 529                 return false;
 530         }
 531
 532         /**
 533          * Returns true if this database can use functional indexes
 534          *
 535          * @return bool
 536          */
 537         public function functionalIndexes() {
 538                 return false;
 539         }
 540
 541         /**
 542          * Return the last query that went through DatabaseBase::query()
 543          * @return String
 544          */
 545         public function lastQuery() {
 546                 return $this->mLastQuery;
 547         }
 548
 549         /**
 550          * Returns true if the connection may have been used for write queries.
 551          * Should return true if unsure.
 552          *
 553          * @return bool
 554          */
 555         public function doneWrites() {
 556                 return $this->mDoneWrites;
 557         }
 558
 559         /**
 560          * Returns true if there is a transaction open with possible write
 561          * queries or transaction pre-commit/idle callbacks waiting on it to finish.
 562          *
 563          * @return bool
 564          */
 565         public function writesOrCallbacksPending() {
 566                 return $this->mTrxLevel && (
 567                         $this->mTrxDoneWrites || $this->mTrxIdleCallbacks || $this->mTrxPreCommitCallbacks
 568                 );
 569         }
 570
 571         /**
 572          * Is a connection to the database open?
 573          * @return Boolean
 574          */
 575         public function isOpen() {
 576                 return $this->mOpened;
 577         }
 578
 579         /**
 580          * Set a flag for this connection
 581          *
 582          * @param $flag Integer: DBO_* constants from Defines.php:
 583          *   - DBO_DEBUG: output some debug info (same as debug())
 584          *   - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
 585          *   - DBO_IGNORE: ignore errors (same as ignoreErrors())
 586          *   - DBO_TRX: automatically start transactions
 587          *   - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
 588          *       and removes it in command line mode
 589          *   - DBO_PERSISTENT: use persistant database connection
 590          */
 591         public function setFlag( $flag ) {
 592                 global $wgDebugDBTransactions;
 593                 $this->mFlags |= $flag;
 594                 if ( ( $flag & DBO_TRX ) & $wgDebugDBTransactions ) {
 595                         wfDebug( "Implicit transactions are now  disabled.\n" );
 596                 }
 597         }
 598
 599         /**
 600          * Clear a flag for this connection
 601          *
 602          * @param $flag: same as setFlag()'s $flag param
 603          */
 604         public function clearFlag( $flag ) {
 605                 global $wgDebugDBTransactions;
 606                 $this->mFlags &= ~$flag;
 607                 if ( ( $flag & DBO_TRX ) && $wgDebugDBTransactions ) {
 608                         wfDebug( "Implicit transactions are now disabled.\n" );
 609                 }
 610         }
 611
 612         /**
 613          * Returns a boolean whether the flag $flag is set for this connection
 614          *
 615          * @param $flag: same as setFlag()'s $flag param
 616          * @return Boolean
 617          */
 618         public function getFlag( $flag ) {
 619                 return !!( $this->mFlags & $flag );
 620         }
 621
 622         /**
 623          * General read-only accessor
 624          *
 625          * @param $name string
 626          *
 627          * @return string
 628          */
 629         public function getProperty( $name ) {
 630                 return $this->$name;
 631         }
 632
 633         /**
 634          * @return string
 635          */
 636         public function getWikiID() {
 637                 if ( $this->mTablePrefix ) {
 638                         return "{$this->mDBname}-{$this->mTablePrefix}";
 639                 } else {
 640                         return $this->mDBname;
 641                 }
 642         }
 643
 644         /**
 645          * Return a path to the DBMS-specific schema file, otherwise default to tables.sql
 646          *
 647          * @return string
 648          */
 649         public function getSchemaPath() {
 650                 global $IP;
 651                 if ( file_exists( "$IP/maintenance/" . $this->getType() . "/tables.sql" ) ) {
 652                         return "$IP/maintenance/" . $this->getType() . "/tables.sql";
 653                 } else {
 654                         return "$IP/maintenance/tables.sql";
 655                 }
 656         }
 657
 658 # ------------------------------------------------------------------------------
 659 # Other functions
 660 # ------------------------------------------------------------------------------
 661
 662         /**
 663          * Constructor.
 664          * @param string $server database server host
 665          * @param string $user database user name
 666          * @param string $password database user password
 667          * @param string $dbName database name
 668          * @param $flags
 669          * @param string $tablePrefix database table prefixes. By default use the prefix gave in LocalSettings.php
 670          * @param bool $foreign disable some operations specific to local databases
 671          */
 672         function __construct( $server = false, $user = false, $password = false, $dbName = false,
 673                 $flags = 0, $tablePrefix = 'get from global', $foreign = false
 674         ) {
 675                 global $wgDBprefix, $wgCommandLineMode, $wgDebugDBTransactions;
 676
 677                 $this->mFlags = $flags;
 678
 679                 if ( $this->mFlags & DBO_DEFAULT ) {
 680                         if ( $wgCommandLineMode ) {
 681                                 $this->mFlags &= ~DBO_TRX;
 682                                 if ( $wgDebugDBTransactions ) {
 683                                         wfDebug( "Implicit transaction open disabled.\n" );
 684                                 }
 685                         } else {
 686                                 $this->mFlags |= DBO_TRX;
 687                                 if ( $wgDebugDBTransactions ) {
 688                                         wfDebug( "Implicit transaction open enabled.\n" );
 689                                 }
 690                         }
 691                 }
 692
 693                 /** Get the default table prefix*/
 694                 if ( $tablePrefix == 'get from global' ) {
 695                         $this->mTablePrefix = $wgDBprefix;
 696                 } else {
 697                         $this->mTablePrefix = $tablePrefix;
 698                 }
 699
 700                 $this->mForeign = $foreign;
 701
 702                 if ( $user ) {
 703                         $this->open( $server, $user, $password, $dbName );
 704                 }
 705         }
 706
 707         /**
 708          * Called by serialize. Throw an exception when DB connection is serialized.
 709          * This causes problems on some database engines because the connection is
 710          * not restored on unserialize.
 711          */
 712         public function __sleep() {
 713                 throw new MWException( 'Database serialization may cause problems, since the connection is not restored on wakeup.' );
 714         }
 715
 716         /**
 717          * Given a DB type, construct the name of the appropriate child class of
 718          * DatabaseBase. This is designed to replace all of the manual stuff like:
 719          *      $class = 'Database' . ucfirst( strtolower( $type ) );
 720          * as well as validate against the canonical list of DB types we have
 721          *
 722          * This factory function is mostly useful for when you need to connect to a
 723          * database other than the MediaWiki default (such as for external auth,
 724          * an extension, et cetera). Do not use this to connect to the MediaWiki
 725          * database. Example uses in core:
 726          * @see LoadBalancer::reallyOpenConnection()
 727          * @see ForeignDBRepo::getMasterDB()
 728          * @see WebInstaller_DBConnect::execute()
 729          *
 730          * @since 1.18
 731          *
 732          * @param string $dbType A possible DB type
 733          * @param array $p An array of options to pass to the constructor.
 734          *    Valid options are: host, user, password, dbname, flags, tablePrefix
 735          * @return DatabaseBase subclass or null
 736          */
 737         final public static function factory( $dbType, $p = array() ) {
 738                 $canonicalDBTypes = array(
 739                         'mysql', 'postgres', 'sqlite', 'oracle', 'mssql'
 740                 );
 741                 $dbType = strtolower( $dbType );
 742                 $class = 'Database' . ucfirst( $dbType );
 743
 744                 if ( in_array( $dbType, $canonicalDBTypes ) || ( class_exists( $class ) && is_subclass_of( $class, 'DatabaseBase' ) ) ) {
 745                         return new $class(
 746                                 isset( $p['host'] ) ? $p['host'] : false,
 747                                 isset( $p['user'] ) ? $p['user'] : false,
 748                                 isset( $p['password'] ) ? $p['password'] : false,
 749                                 isset( $p['dbname'] ) ? $p['dbname'] : false,
 750                                 isset( $p['flags'] ) ? $p['flags'] : 0,
 751                                 isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : 'get from global',
 752                                 isset( $p['foreign'] ) ? $p['foreign'] : false
 753                         );
 754                 } else {
 755                         return null;
 756                 }
 757         }
 758
 759         protected function installErrorHandler() {
 760                 $this->mPHPError = false;
 761                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 762                 set_error_handler( array( $this, 'connectionErrorHandler' ) );
 763         }
 764
 765         /**
 766          * @return bool|string
 767          */
 768         protected function restoreErrorHandler() {
 769                 restore_error_handler();
 770                 if ( $this->htmlErrors !== false ) {
 771                         ini_set( 'html_errors', $this->htmlErrors );
 772                 }
 773                 if ( $this->mPHPError ) {
 774                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 775                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 776                         return $error;
 777                 } else {
 778                         return false;
 779                 }
 780         }
 781
 782         /**
 783          * @param $errno
 784          * @param $errstr
 785          * @access private
 786          */
 787         public function connectionErrorHandler( $errno, $errstr ) {
 788                 $this->mPHPError = $errstr;
 789         }
 790
 791         /**
 792          * Closes a database connection.
 793          * if it is open : commits any open transactions
 794          *
 795          * @throws MWException
 796          * @return Bool operation success. true if already closed.
 797          */
 798         public function close() {
 799                 if ( count( $this->mTrxIdleCallbacks ) ) { // sanity
 800                         throw new MWException( "Transaction idle callbacks still pending." );
 801                 }
 802                 $this->mOpened = false;
 803                 if ( $this->mConn ) {
 804                         if ( $this->trxLevel() ) {
 805                                 if ( !$this->mTrxAutomatic ) {
 806                                         wfWarn( "Transaction still in progress (from {$this->mTrxFname}), " .
 807                                                 " performing implicit commit before closing connection!" );
 808                                 }
 809
 810                                 $this->commit( __METHOD__, 'flush' );
 811                         }
 812
 813                         $ret = $this->closeConnection();
 814                         $this->mConn = false;
 815                         return $ret;
 816                 } else {
 817                         return true;
 818                 }
 819         }
 820
 821         /**
 822          * Closes underlying database connection
 823          * @since 1.20
 824          * @return bool: Whether connection was closed successfully
 825          */
 826         abstract protected function closeConnection();
 827
 828         /**
 829          * @param string $error fallback error message, used if none is given by DB
 830          * @throws DBConnectionError
 831          */
 832         function reportConnectionError( $error = 'Unknown error' ) {
 833                 $myError = $this->lastError();
 834                 if ( $myError ) {
 835                         $error = $myError;
 836                 }
 837
 838                 # New method
 839                 throw new DBConnectionError( $this, $error );
 840         }
 841
 842         /**
 843          * The DBMS-dependent part of query()
 844          *
 845          * @param  $sql String: SQL query.
 846          * @return ResultWrapper Result object to feed to fetchObject, fetchRow, ...; or false on failure
 847          */
 848         abstract protected function doQuery( $sql );
 849
 850         /**
 851          * Determine whether a query writes to the DB.
 852          * Should return true if unsure.
 853          *
 854          * @param $sql string
 855          *
 856          * @return bool
 857          */
 858         public function isWriteQuery( $sql ) {
 859                 return !preg_match( '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 860         }
 861
 862         /**
 863          * Run an SQL query and return the result. Normally throws a DBQueryError
 864          * on failure. If errors are ignored, returns false instead.
 865          *
 866          * In new code, the query wrappers select(), insert(), update(), delete(),
 867          * etc. should be used where possible, since they give much better DBMS
 868          * independence and automatically quote or validate user input in a variety
 869          * of contexts. This function is generally only useful for queries which are
 870          * explicitly DBMS-dependent and are unsupported by the query wrappers, such
 871          * as CREATE TABLE.
 872          *
 873          * However, the query wrappers themselves should call this function.
 874          *
 875          * @param  $sql        String: SQL query
 876          * @param  $fname      String: Name of the calling function, for profiling/SHOW PROCESSLIST
 877          *     comment (you can use __METHOD__ or add some extra info)
 878          * @param  $tempIgnore Boolean:   Whether to avoid throwing an exception on errors...
 879          *     maybe best to catch the exception instead?
 880          * @throws MWException
 881          * @return boolean|ResultWrapper. true for a successful write query, ResultWrapper object
 882          *     for a successful read query, or false on failure if $tempIgnore set
 883          */
 884         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 885                 global $wgUser, $wgDebugDBTransactions;
 886
 887                 $this->mLastQuery = $sql;
 888                 if ( !$this->mDoneWrites && $this->isWriteQuery( $sql ) ) {
 889                         # Set a flag indicating that writes have been done
 890                         wfDebug( __METHOD__ . ": Writes done: $sql\n" );
 891                         $this->mDoneWrites = true;
 892                 }
 893
 894                 # Add a comment for easy SHOW PROCESSLIST interpretation
 895                 if ( is_object( $wgUser ) && $wgUser->isItemLoaded( 'name' ) ) {
 896                         $userName = $wgUser->getName();
 897                         if ( mb_strlen( $userName ) > 15 ) {
 898                                 $userName = mb_substr( $userName, 0, 15 ) . '...';
 899                         }
 900                         $userName = str_replace( '/', '', $userName );
 901                 } else {
 902                         $userName = '';
 903                 }
 904
 905                 // Add trace comment to the begin of the sql string, right after the operator.
 906                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (bug 42598)
 907                 $commentedSql = preg_replace( '/\s|$/', " /* $fname $userName */ ", $sql, 1 );
 908
 909                 # If DBO_TRX is set, start a transaction
 910                 if ( ( $this->mFlags & DBO_TRX ) && !$this->mTrxLevel &&
 911                         $sql != 'BEGIN' && $sql != 'COMMIT' && $sql != 'ROLLBACK' )
 912                 {
 913                         # Avoid establishing transactions for SHOW and SET statements too -
 914                         # that would delay transaction initializations to once connection
 915                         # is really used by application
 916                         $sqlstart = substr( $sql, 0, 10 ); // very much worth it, benchmark certified(tm)
 917                         if ( strpos( $sqlstart, "SHOW " ) !== 0 && strpos( $sqlstart, "SET " ) !== 0 ) {
 918                                 if ( $wgDebugDBTransactions ) {
 919                                         wfDebug( "Implicit transaction start.\n" );
 920                                 }
 921                                 $this->begin( __METHOD__ . " ($fname)" );
 922                                 $this->mTrxAutomatic = true;
 923                         }
 924                 }
 925
 926                 # Keep track of whether the transaction has write queries pending
 927                 if ( $this->mTrxLevel && !$this->mTrxDoneWrites && $this->isWriteQuery( $sql ) ) {
 928                         $this->mTrxDoneWrites = true;
 929                         Profiler::instance()->transactionWritingIn( $this->mServer, $this->mDBname );
 930                 }
 931
 932                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 933                 if ( !Profiler::instance()->isStub() ) {
 934                         # generalizeSQL will probably cut down the query to reasonable
 935                         # logging size most of the time. The substr is really just a sanity check.
 936                         if ( $isMaster ) {
 937                                 $queryProf = 'query-m: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
 938                                 $totalProf = 'DatabaseBase::query-master';
 939                         } else {
 940                                 $queryProf = 'query: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
 941                                 $totalProf = 'DatabaseBase::query';
 942                         }
 943                         wfProfileIn( $totalProf );
 944                         wfProfileIn( $queryProf );
 945                 }
 946
 947                 if ( $this->debug() ) {
 948                         static $cnt = 0;
 949
 950                         $cnt++;
 951                         $sqlx = substr( $commentedSql, 0, 500 );
 952                         $sqlx = strtr( $sqlx, "\t\n", '  ' );
 953
 954                         $master = $isMaster ? 'master' : 'slave';
 955                         wfDebug( "Query {$this->mDBname} ($cnt) ($master): $sqlx\n" );
 956                 }
 957
 958                 $queryId = MWDebug::query( $sql, $fname, $isMaster );
 959
 960                 # Do the query and handle errors
 961                 $ret = $this->doQuery( $commentedSql );
 962
 963                 MWDebug::queryTime( $queryId );
 964
 965                 # Try reconnecting if the connection was lost
 966                 if ( false === $ret && $this->wasErrorReissuable() ) {
 967                         # Transaction is gone, like it or not
 968                         $this->mTrxLevel = 0;
 969                         $this->mTrxIdleCallbacks = array(); // cancel
 970                         $this->mTrxPreCommitCallbacks = array(); // cancel
 971                         wfDebug( "Connection lost, reconnecting...\n" );
 972
 973                         if ( $this->ping() ) {
 974                                 wfDebug( "Reconnected\n" );
 975                                 $sqlx = substr( $commentedSql, 0, 500 );
 976                                 $sqlx = strtr( $sqlx, "\t\n", '  ' );
 977                                 global $wgRequestTime;
 978                                 $elapsed = round( microtime( true ) - $wgRequestTime, 3 );
 979                                 if ( $elapsed < 300 ) {
 980                                         # Not a database error to lose a transaction after a minute or two
 981                                         wfLogDBError( "Connection lost and reconnected after {$elapsed}s, query: $sqlx\n" );
 982                                 }
 983                                 $ret = $this->doQuery( $commentedSql );
 984                         } else {
 985                                 wfDebug( "Failed\n" );
 986                         }
 987                 }
 988
 989                 if ( false === $ret ) {
 990                         $this->reportQueryError( $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 991                 }
 992
 993                 if ( !Profiler::instance()->isStub() ) {
 994                         wfProfileOut( $queryProf );
 995                         wfProfileOut( $totalProf );
 996                 }
 997
 998                 return $this->resultObject( $ret );
 999         }
1000
1001         /**
1002          * Report a query error. Log the error, and if neither the object ignore
1003          * flag nor the $tempIgnore flag is set, throw a DBQueryError.
1004          *
1005          * @param $error String
1006          * @param $errno Integer
1007          * @param $sql String
1008          * @param $fname String
1009          * @param $tempIgnore Boolean
1010          * @throws DBQueryError
1011          */
1012         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1013                 # Ignore errors during error handling to avoid infinite recursion
1014                 $ignore = $this->ignoreErrors( true );
1015                 ++$this->mErrorCount;
1016
1017                 if ( $ignore || $tempIgnore ) {
1018                         wfDebug( "SQL ERROR (ignored): $error\n" );
1019                         $this->ignoreErrors( $ignore );
1020                 } else {
1021                         $sql1line = str_replace( "\n", "\\n", $sql );
1022                         wfLogDBError( "$fname\t{$this->mServer}\t$errno\t$error\t$sql1line\n" );
1023                         wfDebug( "SQL ERROR: " . $error . "\n" );
1024                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1025                 }
1026         }
1027
1028         /**
1029          * Intended to be compatible with the PEAR::DB wrapper functions.
1030          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
1031          *
1032          * ? = scalar value, quoted as necessary
1033          * ! = raw SQL bit (a function for instance)
1034          * & = filename; reads the file and inserts as a blob
1035          *     (we don't use this though...)
1036          *
1037          * @param $sql string
1038          * @param $func string
1039          *
1040          * @return array
1041          */
1042         protected function prepare( $sql, $func = 'DatabaseBase::prepare' ) {
1043                 /* MySQL doesn't support prepared statements (yet), so just
1044                    pack up the query for reference. We'll manually replace
1045                    the bits later. */
1046                 return array( 'query' => $sql, 'func' => $func );
1047         }
1048
1049         /**
1050          * Free a prepared query, generated by prepare().
1051          * @param $prepared
1052          */
1053         protected function freePrepared( $prepared ) {
1054                 /* No-op by default */
1055         }
1056
1057         /**
1058          * Execute a prepared query with the various arguments
1059          * @param string $prepared the prepared sql
1060          * @param $args Mixed: Either an array here, or put scalars as varargs
1061          *
1062          * @return ResultWrapper
1063          */
1064         public function execute( $prepared, $args = null ) {
1065                 if ( !is_array( $args ) ) {
1066                         # Pull the var args
1067                         $args = func_get_args();
1068                         array_shift( $args );
1069                 }
1070
1071                 $sql = $this->fillPrepared( $prepared['query'], $args );
1072
1073                 return $this->query( $sql, $prepared['func'] );
1074         }
1075
1076         /**
1077          * For faking prepared SQL statements on DBs that don't support it directly.
1078          *
1079          * @param string $preparedQuery a 'preparable' SQL statement
1080          * @param array $args of arguments to fill it with
1081          * @return string executable SQL
1082          */
1083         public function fillPrepared( $preparedQuery, $args ) {
1084                 reset( $args );
1085                 $this->preparedArgs =& $args;
1086
1087                 return preg_replace_callback( '/(\\\\[?!&]|[?!&])/',
1088                         array( &$this, 'fillPreparedArg' ), $preparedQuery );
1089         }
1090
1091         /**
1092          * preg_callback func for fillPrepared()
1093          * The arguments should be in $this->preparedArgs and must not be touched
1094          * while we're doing this.
1095          *
1096          * @param $matches Array
1097          * @throws DBUnexpectedError
1098          * @return String
1099          */
1100         protected function fillPreparedArg( $matches ) {
1101                 switch ( $matches[1] ) {
1102                         case '\\?':
1103                                 return '?';
1104                         case '\\!':
1105                                 return '!';
1106                         case '\\&':
1107                                 return '&';
1108                 }
1109
1110                 list( /* $n */, $arg ) = each( $this->preparedArgs );
1111
1112                 switch ( $matches[1] ) {
1113                         case '?':
1114                                 return $this->addQuotes( $arg );
1115                         case '!':
1116                                 return $arg;
1117                         case '&':
1118                                 # return $this->addQuotes( file_get_contents( $arg ) );
1119                                 throw new DBUnexpectedError( $this, '& mode is not implemented. If it\'s really needed, uncomment the line above.' );
1120                         default:
1121                                 throw new DBUnexpectedError( $this, 'Received invalid match. This should never happen!' );
1122                 }
1123         }
1124
1125         /**
1126          * Free a result object returned by query() or select(). It's usually not
1127          * necessary to call this, just use unset() or let the variable holding
1128          * the result object go out of scope.
1129          *
1130          * @param $res Mixed: A SQL result
1131          */
1132         public function freeResult( $res ) {
1133         }
1134
1135         /**
1136          * A SELECT wrapper which returns a single field from a single result row.
1137          *
1138          * Usually throws a DBQueryError on failure. If errors are explicitly
1139          * ignored, returns false on failure.
1140          *
1141          * If no result rows are returned from the query, false is returned.
1142          *
1143          * @param string|array $table Table name. See DatabaseBase::select() for details.
1144          * @param string $var The field name to select. This must be a valid SQL
1145          *   fragment: do not use unvalidated user input.
1146          * @param string|array $cond The condition array. See DatabaseBase::select() for details.
1147          * @param string $fname The function name of the caller.
1148          * @param string|array $options The query options. See DatabaseBase::select() for details.
1149          *
1150          * @return bool|mixed The value from the field, or false on failure.
1151          */
1152         public function selectField( $table, $var, $cond = '', $fname = __METHOD__,
1153                 $options = array()
1154         ) {
1155                 if ( !is_array( $options ) ) {
1156                         $options = array( $options );
1157                 }
1158
1159                 $options['LIMIT'] = 1;
1160
1161                 $res = $this->select( $table, $var, $cond, $fname, $options );
1162
1163                 if ( $res === false || !$this->numRows( $res ) ) {
1164                         return false;
1165                 }
1166
1167                 $row = $this->fetchRow( $res );
1168
1169                 if ( $row !== false ) {
1170                         return reset( $row );
1171                 } else {
1172                         return false;
1173                 }
1174         }
1175
1176         /**
1177          * Returns an optional USE INDEX clause to go after the table, and a
1178          * string to go at the end of the query.
1179          *
1180          * @param array $options associative array of options to be turned into
1181          *              an SQL query, valid keys are listed in the function.
1182          * @return Array
1183          * @see DatabaseBase::select()
1184          */
1185         public function makeSelectOptions( $options ) {
1186                 $preLimitTail = $postLimitTail = '';
1187                 $startOpts = '';
1188
1189                 $noKeyOptions = array();
1190
1191                 foreach ( $options as $key => $option ) {
1192                         if ( is_numeric( $key ) ) {
1193                                 $noKeyOptions[$option] = true;
1194                         }
1195                 }
1196
1197                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1198
1199                 $preLimitTail .= $this->makeOrderBy( $options );
1200
1201                 // if (isset($options['LIMIT'])) {
1202                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
1203                 //              isset($options['OFFSET']) ? $options['OFFSET']
1204                 //              : false);
1205                 // }
1206
1207                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1208                         $postLimitTail .= ' FOR UPDATE';
1209                 }
1210
1211                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1212                         $postLimitTail .= ' LOCK IN SHARE MODE';
1213                 }
1214
1215                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1216                         $startOpts .= 'DISTINCT';
1217                 }
1218
1219                 # Various MySQL extensions
1220                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1221                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1222                 }
1223
1224                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1225                         $startOpts .= ' HIGH_PRIORITY';
1226                 }
1227
1228                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1229                         $startOpts .= ' SQL_BIG_RESULT';
1230                 }
1231
1232                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1233                         $startOpts .= ' SQL_BUFFER_RESULT';
1234                 }
1235
1236                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1237                         $startOpts .= ' SQL_SMALL_RESULT';
1238                 }
1239
1240                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1241                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1242                 }
1243
1244                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1245                         $startOpts .= ' SQL_CACHE';
1246                 }
1247
1248                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1249                         $startOpts .= ' SQL_NO_CACHE';
1250                 }
1251
1252                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1253                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1254                 } else {
1255                         $useIndex = '';
1256                 }
1257
1258                 return array( $startOpts, $useIndex, $preLimitTail, $postLimitTail );
1259         }
1260
1261         /**
1262          * Returns an optional GROUP BY with an optional HAVING
1263          *
1264          * @param array $options associative array of options
1265          * @return string
1266          * @see DatabaseBase::select()
1267          * @since 1.21
1268          */
1269         public function makeGroupByWithHaving( $options ) {
1270                 $sql = '';
1271                 if ( isset( $options['GROUP BY'] ) ) {
1272                         $gb = is_array( $options['GROUP BY'] )
1273                                 ? implode( ',', $options['GROUP BY'] )
1274                                 : $options['GROUP BY'];
1275                         $sql .= ' GROUP BY ' . $gb;
1276                 }
1277                 if ( isset( $options['HAVING'] ) ) {
1278                         $having = is_array( $options['HAVING'] )
1279                                 ? $this->makeList( $options['HAVING'], LIST_AND )
1280                                 : $options['HAVING'];
1281                         $sql .= ' HAVING ' . $having;
1282                 }
1283                 return $sql;
1284         }
1285
1286         /**
1287          * Returns an optional ORDER BY
1288          *
1289          * @param array $options associative array of options
1290          * @return string
1291          * @see DatabaseBase::select()
1292          * @since 1.21
1293          */
1294         public function makeOrderBy( $options ) {
1295                 if ( isset( $options['ORDER BY'] ) ) {
1296                         $ob = is_array( $options['ORDER BY'] )
1297                                 ? implode( ',', $options['ORDER BY'] )
1298                                 : $options['ORDER BY'];
1299                         return ' ORDER BY ' . $ob;
1300                 }
1301                 return '';
1302         }
1303
1304         /**
1305          * Execute a SELECT query constructed using the various parameters provided.
1306          * See below for full details of the parameters.
1307          *
1308          * @param string|array $table Table name
1309          * @param string|array $vars Field names
1310          * @param string|array $conds Conditions
1311          * @param string $fname Caller function name
1312          * @param array $options Query options
1313          * @param $join_conds Array Join conditions
1314          *
1315          * @param $table string|array
1316          *
1317          * May be either an array of table names, or a single string holding a table
1318          * name. If an array is given, table aliases can be specified, for example:
1319          *
1320          *    array( 'a' => 'user' )
1321          *
1322          * This includes the user table in the query, with the alias "a" available
1323          * for use in field names (e.g. a.user_name).
1324          *
1325          * All of the table names given here are automatically run through
1326          * DatabaseBase::tableName(), which causes the table prefix (if any) to be
1327          * added, and various other table name mappings to be performed.
1328          *
1329          *
1330          * @param $vars string|array
1331          *
1332          * May be either a field name or an array of field names. The field names
1333          * can be complete fragments of SQL, for direct inclusion into the SELECT
1334          * query. If an array is given, field aliases can be specified, for example:
1335          *
1336          *   array( 'maxrev' => 'MAX(rev_id)' )
1337          *
1338          * This includes an expression with the alias "maxrev" in the query.
1339          *
1340          * If an expression is given, care must be taken to ensure that it is
1341          * DBMS-independent.
1342          *
1343          *
1344          * @param $conds string|array
1345          *
1346          * May be either a string containing a single condition, or an array of
1347          * conditions. If an array is given, the conditions constructed from each
1348          * element are combined with AND.
1349          *
1350          * Array elements may take one of two forms:
1351          *
1352          *   - Elements with a numeric key are interpreted as raw SQL fragments.
1353          *   - Elements with a string key are interpreted as equality conditions,
1354          *     where the key is the field name.
1355          *     - If the value of such an array element is a scalar (such as a
1356          *       string), it will be treated as data and thus quoted appropriately.
1357          *       If it is null, an IS NULL clause will be added.
1358          *     - If the value is an array, an IN(...) clause will be constructed,
1359          *       such that the field name may match any of the elements in the
1360          *       array. The elements of the array will be quoted.
1361          *
1362          * Note that expressions are often DBMS-dependent in their syntax.
1363          * DBMS-independent wrappers are provided for constructing several types of
1364          * expression commonly used in condition queries. See:
1365          *    - DatabaseBase::buildLike()
1366          *    - DatabaseBase::conditional()
1367          *
1368          *
1369          * @param $options string|array
1370          *
1371          * Optional: Array of query options. Boolean options are specified by
1372          * including them in the array as a string value with a numeric key, for
1373          * example:
1374          *
1375          *    array( 'FOR UPDATE' )
1376          *
1377          * The supported options are:
1378          *
1379          *   - OFFSET: Skip this many rows at the start of the result set. OFFSET
1380          *     with LIMIT can theoretically be used for paging through a result set,
1381          *     but this is discouraged in MediaWiki for performance reasons.
1382          *
1383          *   - LIMIT: Integer: return at most this many rows. The rows are sorted
1384          *     and then the first rows are taken until the limit is reached. LIMIT
1385          *     is applied to a result set after OFFSET.
1386          *
1387          *   - FOR UPDATE: Boolean: lock the returned rows so that they can't be
1388          *     changed until the next COMMIT.
1389          *
1390          *   - DISTINCT: Boolean: return only unique result rows.
1391          *
1392          *   - GROUP BY: May be either an SQL fragment string naming a field or
1393          *     expression to group by, or an array of such SQL fragments.
1394          *
1395          *   - HAVING: May be either an string containing a HAVING clause or an array of
1396          *     conditions building the HAVING clause. If an array is given, the conditions
1397          *     constructed from each element are combined with AND.
1398          *
1399          *   - ORDER BY: May be either an SQL fragment giving a field name or
1400          *     expression to order by, or an array of such SQL fragments.
1401          *
1402          *   - USE INDEX: This may be either a string giving the index name to use
1403          *     for the query, or an array. If it is an associative array, each key
1404          *     gives the table name (or alias), each value gives the index name to
1405          *     use for that table. All strings are SQL fragments and so should be
1406          *     validated by the caller.
1407          *
1408          *   - EXPLAIN: In MySQL, this causes an EXPLAIN SELECT query to be run,
1409          *     instead of SELECT.
1410          *
1411          * And also the following boolean MySQL extensions, see the MySQL manual
1412          * for documentation:
1413          *
1414          *    - LOCK IN SHARE MODE
1415          *    - STRAIGHT_JOIN
1416          *    - HIGH_PRIORITY
1417          *    - SQL_BIG_RESULT
1418          *    - SQL_BUFFER_RESULT
1419          *    - SQL_SMALL_RESULT
1420          *    - SQL_CALC_FOUND_ROWS
1421          *    - SQL_CACHE
1422          *    - SQL_NO_CACHE
1423          *
1424          *
1425          * @param $join_conds string|array
1426          *
1427          * Optional associative array of table-specific join conditions. In the
1428          * most common case, this is unnecessary, since the join condition can be
1429          * in $conds. However, it is useful for doing a LEFT JOIN.
1430          *
1431          * The key of the array contains the table name or alias. The value is an
1432          * array with two elements, numbered 0 and 1. The first gives the type of
1433          * join, the second is an SQL fragment giving the join condition for that
1434          * table. For example:
1435          *
1436          *    array( 'page' => array( 'LEFT JOIN', 'page_latest=rev_id' ) )
1437          *
1438          * @return ResultWrapper. If the query returned no rows, a ResultWrapper
1439          *   with no rows in it will be returned. If there was a query error, a
1440          *   DBQueryError exception will be thrown, except if the "ignore errors"
1441          *   option was set, in which case false will be returned.
1442          */
1443         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1444                 $options = array(), $join_conds = array() ) {
1445                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1446
1447                 return $this->query( $sql, $fname );
1448         }
1449
1450         /**
1451          * The equivalent of DatabaseBase::select() except that the constructed SQL
1452          * is returned, instead of being immediately executed. This can be useful for
1453          * doing UNION queries, where the SQL text of each query is needed. In general,
1454          * however, callers outside of Database classes should just use select().
1455          *
1456          * @param string|array $table Table name
1457          * @param string|array $vars Field names
1458          * @param string|array $conds Conditions
1459          * @param string $fname Caller function name
1460          * @param string|array $options Query options
1461          * @param $join_conds string|array Join conditions
1462          *
1463          * @return string SQL query string.
1464          * @see DatabaseBase::select()
1465          */
1466         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1467                 $options = array(), $join_conds = array() )
1468         {
1469                 if ( is_array( $vars ) ) {
1470                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1471                 }
1472
1473                 $options = (array)$options;
1474                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1475                         ? $options['USE INDEX']
1476                         : array();
1477
1478                 if ( is_array( $table ) ) {
1479                         $from = ' FROM ' .
1480                                 $this->tableNamesWithUseIndexOrJOIN( $table, $useIndexes, $join_conds );
1481                 } elseif ( $table != '' ) {
1482                         if ( $table[0] == ' ' ) {
1483                                 $from = ' FROM ' . $table;
1484                         } else {
1485                                 $from = ' FROM ' .
1486                                         $this->tableNamesWithUseIndexOrJOIN( array( $table ), $useIndexes, array() );
1487                         }
1488                 } else {
1489                         $from = '';
1490                 }
1491
1492                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail ) =
1493                         $this->makeSelectOptions( $options );
1494
1495                 if ( !empty( $conds ) ) {
1496                         if ( is_array( $conds ) ) {
1497                                 $conds = $this->makeList( $conds, LIST_AND );
1498                         }
1499                         $sql = "SELECT $startOpts $vars $from $useIndex WHERE $conds $preLimitTail";
1500                 } else {
1501                         $sql = "SELECT $startOpts $vars $from $useIndex $preLimitTail";
1502                 }
1503
1504                 if ( isset( $options['LIMIT'] ) ) {
1505                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1506                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1507                 }
1508                 $sql = "$sql $postLimitTail";
1509
1510                 if ( isset( $options['EXPLAIN'] ) ) {
1511                         $sql = 'EXPLAIN ' . $sql;
1512                 }
1513
1514                 return $sql;
1515         }
1516
1517         /**
1518          * Single row SELECT wrapper. Equivalent to DatabaseBase::select(), except
1519          * that a single row object is returned. If the query returns no rows,
1520          * false is returned.
1521          *
1522          * @param string|array $table Table name
1523          * @param string|array $vars Field names
1524          * @param array $conds Conditions
1525          * @param string $fname Caller function name
1526          * @param string|array $options Query options
1527          * @param $join_conds array|string Join conditions
1528          *
1529          * @return object|bool
1530          */
1531         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1532                 $options = array(), $join_conds = array() )
1533         {
1534                 $options = (array)$options;
1535                 $options['LIMIT'] = 1;
1536                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1537
1538                 if ( $res === false ) {
1539                         return false;
1540                 }
1541
1542                 if ( !$this->numRows( $res ) ) {
1543                         return false;
1544                 }
1545
1546                 $obj = $this->fetchObject( $res );
1547
1548                 return $obj;
1549         }
1550
1551         /**
1552          * Estimate rows in dataset.
1553          *
1554          * MySQL allows you to estimate the number of rows that would be returned
1555          * by a SELECT query, using EXPLAIN SELECT. The estimate is provided using
1556          * index cardinality statistics, and is notoriously inaccurate, especially
1557          * when large numbers of rows have recently been added or deleted.
1558          *
1559          * For DBMSs that don't support fast result size estimation, this function
1560          * will actually perform the SELECT COUNT(*).
1561          *
1562          * Takes the same arguments as DatabaseBase::select().
1563          *
1564          * @param string $table table name
1565          * @param array|string $vars : unused
1566          * @param array|string $conds : filters on the table
1567          * @param string $fname function name for profiling
1568          * @param array $options options for select
1569          * @return Integer: row count
1570          */
1571         public function estimateRowCount( $table, $vars = '*', $conds = '',
1572                 $fname = __METHOD__, $options = array() )
1573         {
1574                 $rows = 0;
1575                 $res = $this->select( $table, array( 'rowcount' => 'COUNT(*)' ), $conds, $fname, $options );
1576
1577                 if ( $res ) {
1578                         $row = $this->fetchRow( $res );
1579                         $rows = ( isset( $row['rowcount'] ) ) ? $row['rowcount'] : 0;
1580                 }
1581
1582                 return $rows;
1583         }
1584
1585         /**
1586          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1587          * It's only slightly flawed. Don't use for anything important.
1588          *
1589          * @param string $sql A SQL Query
1590          *
1591          * @return string
1592          */
1593         static function generalizeSQL( $sql ) {
1594                 # This does the same as the regexp below would do, but in such a way
1595                 # as to avoid crashing php on some large strings.
1596                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1597
1598                 $sql = str_replace( "\\\\", '', $sql );
1599                 $sql = str_replace( "\\'", '', $sql );
1600                 $sql = str_replace( "\\\"", '', $sql );
1601                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1602                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1603
1604                 # All newlines, tabs, etc replaced by single space
1605                 $sql = preg_replace( '/\s+/', ' ', $sql );
1606
1607                 # All numbers => N
1608                 $sql = preg_replace( '/-?[0-9]+/s', 'N', $sql );
1609
1610                 return $sql;
1611         }
1612
1613         /**
1614          * Determines whether a field exists in a table
1615          *
1616          * @param string $table table name
1617          * @param string $field filed to check on that table
1618          * @param string $fname calling function name (optional)
1619          * @return Boolean: whether $table has filed $field
1620          */
1621         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1622                 $info = $this->fieldInfo( $table, $field );
1623
1624                 return (bool)$info;
1625         }
1626
1627         /**
1628          * Determines whether an index exists
1629          * Usually throws a DBQueryError on failure
1630          * If errors are explicitly ignored, returns NULL on failure
1631          *
1632          * @param $table
1633          * @param $index
1634          * @param $fname string
1635          *
1636          * @return bool|null
1637          */
1638         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1639                 if ( !$this->tableExists( $table ) ) {
1640                         return null;
1641                 }
1642
1643                 $info = $this->indexInfo( $table, $index, $fname );
1644                 if ( is_null( $info ) ) {
1645                         return null;
1646                 } else {
1647                         return $info !== false;
1648                 }
1649         }
1650
1651         /**
1652          * Query whether a given table exists
1653          *
1654          * @param $table string
1655          * @param $fname string
1656          *
1657          * @return bool
1658          */
1659         public function tableExists( $table, $fname = __METHOD__ ) {
1660                 $table = $this->tableName( $table );
1661                 $old = $this->ignoreErrors( true );
1662                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname );
1663                 $this->ignoreErrors( $old );
1664
1665                 return (bool)$res;
1666         }
1667
1668         /**
1669          * mysql_field_type() wrapper
1670          * @param $res
1671          * @param $index
1672          * @return string
1673          */
1674         public function fieldType( $res, $index ) {
1675                 if ( $res instanceof ResultWrapper ) {
1676                         $res = $res->result;
1677                 }
1678
1679                 return mysql_field_type( $res, $index );
1680         }
1681
1682         /**
1683          * Determines if a given index is unique
1684          *
1685          * @param $table string
1686          * @param $index string
1687          *
1688          * @return bool
1689          */
1690         public function indexUnique( $table, $index ) {
1691                 $indexInfo = $this->indexInfo( $table, $index );
1692
1693                 if ( !$indexInfo ) {
1694                         return null;
1695                 }
1696
1697                 return !$indexInfo[0]->Non_unique;
1698         }
1699
1700         /**
1701          * Helper for DatabaseBase::insert().
1702          *
1703          * @param $options array
1704          * @return string
1705          */
1706         protected function makeInsertOptions( $options ) {
1707                 return implode( ' ', $options );
1708         }
1709
1710         /**
1711          * INSERT wrapper, inserts an array into a table.
1712          *
1713          * $a may be either:
1714          *
1715          *   - A single associative array. The array keys are the field names, and
1716          *     the values are the values to insert. The values are treated as data
1717          *     and will be quoted appropriately. If NULL is inserted, this will be
1718          *     converted to a database NULL.
1719          *   - An array with numeric keys, holding a list of associative arrays.
1720          *     This causes a multi-row INSERT on DBMSs that support it. The keys in
1721          *     each subarray must be identical to each other, and in the same order.
1722          *
1723          * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
1724          * returns success.
1725          *
1726          * $options is an array of options, with boolean options encoded as values
1727          * with numeric keys, in the same style as $options in
1728          * DatabaseBase::select(). Supported options are:
1729          *
1730          *   - IGNORE: Boolean: if present, duplicate key errors are ignored, and
1731          *     any rows which cause duplicate key errors are not inserted. It's
1732          *     possible to determine how many rows were successfully inserted using
1733          *     DatabaseBase::affectedRows().
1734          *
1735          * @param $table   String Table name. This will be passed through
1736          *                 DatabaseBase::tableName().
1737          * @param $a       Array of rows to insert
1738          * @param $fname   String Calling function name (use __METHOD__) for logs/profiling
1739          * @param array $options of options
1740          *
1741          * @return bool
1742          */
1743         public function insert( $table, $a, $fname = __METHOD__, $options = array() ) {
1744                 # No rows to insert, easy just return now
1745                 if ( !count( $a ) ) {
1746                         return true;
1747                 }
1748
1749                 $table = $this->tableName( $table );
1750
1751                 if ( !is_array( $options ) ) {
1752                         $options = array( $options );
1753                 }
1754
1755                 $fh = null;
1756                 if ( isset( $options['fileHandle'] ) ) {
1757                         $fh = $options['fileHandle'];
1758                 }
1759                 $options = $this->makeInsertOptions( $options );
1760
1761                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1762                         $multi = true;
1763                         $keys = array_keys( $a[0] );
1764                 } else {
1765                         $multi = false;
1766                         $keys = array_keys( $a );
1767                 }
1768
1769                 $sql = 'INSERT ' . $options .
1770                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1771
1772                 if ( $multi ) {
1773                         $first = true;
1774                         foreach ( $a as $row ) {
1775                                 if ( $first ) {
1776                                         $first = false;
1777                                 } else {
1778                                         $sql .= ',';
1779                                 }
1780                                 $sql .= '(' . $this->makeList( $row ) . ')';
1781                         }
1782                 } else {
1783                         $sql .= '(' . $this->makeList( $a ) . ')';
1784                 }
1785
1786                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1787                         return false;
1788                 } elseif ( $fh !== null ) {
1789                         return true;
1790                 }
1791
1792                 return (bool)$this->query( $sql, $fname );
1793         }
1794
1795         /**
1796          * Make UPDATE options for the DatabaseBase::update function
1797          *
1798          * @param array $options The options passed to DatabaseBase::update
1799          * @return string
1800          */
1801         protected function makeUpdateOptions( $options ) {
1802                 if ( !is_array( $options ) ) {
1803                         $options = array( $options );
1804                 }
1805
1806                 $opts = array();
1807
1808                 if ( in_array( 'LOW_PRIORITY', $options ) ) {
1809                         $opts[] = $this->lowPriorityOption();
1810                 }
1811
1812                 if ( in_array( 'IGNORE', $options ) ) {
1813                         $opts[] = 'IGNORE';
1814                 }
1815
1816                 return implode( ' ', $opts );
1817         }
1818
1819         /**
1820          * UPDATE wrapper. Takes a condition array and a SET array.
1821          *
1822          * @param $table  String name of the table to UPDATE. This will be passed through
1823          *                DatabaseBase::tableName().
1824          *
1825          * @param array $values  An array of values to SET. For each array element,
1826          *                the key gives the field name, and the value gives the data
1827          *                to set that field to. The data will be quoted by
1828          *                DatabaseBase::addQuotes().
1829          *
1830          * @param $conds  Array:  An array of conditions (WHERE). See
1831          *                DatabaseBase::select() for the details of the format of
1832          *                condition arrays. Use '*' to update all rows.
1833          *
1834          * @param $fname  String: The function name of the caller (from __METHOD__),
1835          *                for logging and profiling.
1836          *
1837          * @param array $options An array of UPDATE options, can be:
1838          *                   - IGNORE: Ignore unique key conflicts
1839          *                   - LOW_PRIORITY: MySQL-specific, see MySQL manual.
1840          * @return Boolean
1841          */
1842         function update( $table, $values, $conds, $fname = __METHOD__, $options = array() ) {
1843                 $table = $this->tableName( $table );
1844                 $opts = $this->makeUpdateOptions( $options );
1845                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET );
1846
1847                 if ( $conds !== array() && $conds !== '*' ) {
1848                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1849                 }
1850
1851                 return $this->query( $sql, $fname );
1852         }
1853
1854         /**
1855          * Makes an encoded list of strings from an array
1856          * @param array $a containing the data
1857          * @param int $mode Constant
1858          *      - LIST_COMMA:          comma separated, no field names
1859          *      - LIST_AND:            ANDed WHERE clause (without the WHERE). See
1860          *        the documentation for $conds in DatabaseBase::select().
1861          *      - LIST_OR:             ORed WHERE clause (without the WHERE)
1862          *      - LIST_SET:            comma separated with field names, like a SET clause
1863          *      - LIST_NAMES:          comma separated field names
1864          *
1865          * @throws MWException|DBUnexpectedError
1866          * @return string
1867          */
1868         public function makeList( $a, $mode = LIST_COMMA ) {
1869                 if ( !is_array( $a ) ) {
1870                         throw new DBUnexpectedError( $this, 'DatabaseBase::makeList called with incorrect parameters' );
1871                 }
1872
1873                 $first = true;
1874                 $list = '';
1875
1876                 foreach ( $a as $field => $value ) {
1877                         if ( !$first ) {
1878                                 if ( $mode == LIST_AND ) {
1879                                         $list .= ' AND ';
1880                                 } elseif ( $mode == LIST_OR ) {
1881                                         $list .= ' OR ';
1882                                 } else {
1883                                         $list .= ',';
1884                                 }
1885                         } else {
1886                                 $first = false;
1887                         }
1888
1889                         if ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_numeric( $field ) ) {
1890                                 $list .= "($value)";
1891                         } elseif ( ( $mode == LIST_SET ) && is_numeric( $field ) ) {
1892                                 $list .= "$value";
1893                         } elseif ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_array( $value ) ) {
1894                                 if ( count( $value ) == 0 ) {
1895                                         throw new MWException( __METHOD__ . ": empty input for field $field" );
1896                                 } elseif ( count( $value ) == 1 ) {
1897                                         // Special-case single values, as IN isn't terribly efficient
1898                                         // Don't necessarily assume the single key is 0; we don't
1899                                         // enforce linear numeric ordering on other arrays here.
1900                                         $value = array_values( $value );
1901                                         $list .= $field . " = " . $this->addQuotes( $value[0] );
1902                                 } else {
1903                                         $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1904                                 }
1905                         } elseif ( $value === null ) {
1906                                 if ( $mode == LIST_AND || $mode == LIST_OR ) {
1907                                         $list .= "$field IS ";
1908                                 } elseif ( $mode == LIST_SET ) {
1909                                         $list .= "$field = ";
1910                                 }
1911                                 $list .= 'NULL';
1912                         } else {
1913                                 if ( $mode == LIST_AND || $mode == LIST_OR || $mode == LIST_SET ) {
1914                                         $list .= "$field = ";
1915                                 }
1916                                 $list .= $mode == LIST_NAMES ? $value : $this->addQuotes( $value );
1917                         }
1918                 }
1919
1920                 return $list;
1921         }
1922
1923         /**
1924          * Build a partial where clause from a 2-d array such as used for LinkBatch.
1925          * The keys on each level may be either integers or strings.
1926          *
1927          * @param array $data organized as 2-d
1928          *              array(baseKeyVal => array(subKeyVal => [ignored], ...), ...)
1929          * @param string $baseKey field name to match the base-level keys to (eg 'pl_namespace')
1930          * @param string $subKey field name to match the sub-level keys to (eg 'pl_title')
1931          * @return Mixed: string SQL fragment, or false if no items in array.
1932          */
1933         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1934                 $conds = array();
1935
1936                 foreach ( $data as $base => $sub ) {
1937                         if ( count( $sub ) ) {
1938                                 $conds[] = $this->makeList(
1939                                         array( $baseKey => $base, $subKey => array_keys( $sub ) ),
1940                                         LIST_AND );
1941                         }
1942                 }
1943
1944                 if ( $conds ) {
1945                         return $this->makeList( $conds, LIST_OR );
1946                 } else {
1947                         // Nothing to search for...
1948                         return false;
1949                 }
1950         }
1951
1952         /**
1953          * Return aggregated value alias
1954          *
1955          * @param $valuedata
1956          * @param $valuename string
1957          *
1958          * @return string
1959          */
1960         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1961                 return $valuename;
1962         }
1963
1964         /**
1965          * @param $field
1966          * @return string
1967          */
1968         public function bitNot( $field ) {
1969                 return "(~$field)";
1970         }
1971
1972         /**
1973          * @param $fieldLeft
1974          * @param $fieldRight
1975          * @return string
1976          */
1977         public function bitAnd( $fieldLeft, $fieldRight ) {
1978                 return "($fieldLeft & $fieldRight)";
1979         }
1980
1981         /**
1982          * @param  $fieldLeft
1983          * @param  $fieldRight
1984          * @return string
1985          */
1986         public function bitOr( $fieldLeft, $fieldRight ) {
1987                 return "($fieldLeft | $fieldRight)";
1988         }
1989
1990         /**
1991          * Build a concatenation list to feed into a SQL query
1992          * @param array $stringList list of raw SQL expressions; caller is responsible for any quoting
1993          * @return String
1994          */
1995         public function buildConcat( $stringList ) {
1996                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
1997         }
1998
1999         /**
2000          * Change the current database
2001          *
2002          * @todo Explain what exactly will fail if this is not overridden.
2003          *
2004          * @param $db
2005          *
2006          * @return bool Success or failure
2007          */
2008         public function selectDB( $db ) {
2009                 # Stub.  Shouldn't cause serious problems if it's not overridden, but
2010                 # if your database engine supports a concept similar to MySQL's
2011                 # databases you may as well.
2012                 $this->mDBname = $db;
2013                 return true;
2014         }
2015
2016         /**
2017          * Get the current DB name
2018          */
2019         public function getDBname() {
2020                 return $this->mDBname;
2021         }
2022
2023         /**
2024          * Get the server hostname or IP address
2025          */
2026         public function getServer() {
2027                 return $this->mServer;
2028         }
2029
2030         /**
2031          * Format a table name ready for use in constructing an SQL query
2032          *
2033          * This does two important things: it quotes the table names to clean them up,
2034          * and it adds a table prefix if only given a table name with no quotes.
2035          *
2036          * All functions of this object which require a table name call this function
2037          * themselves. Pass the canonical name to such functions. This is only needed
2038          * when calling query() directly.
2039          *
2040          * @param string $name database table name
2041          * @param string $format One of:
2042          *   quoted - Automatically pass the table name through addIdentifierQuotes()
2043          *            so that it can be used in a query.
2044          *   raw - Do not add identifier quotes to the table name
2045          * @return String: full database name
2046          */
2047         public function tableName( $name, $format = 'quoted' ) {
2048                 global $wgSharedDB, $wgSharedPrefix, $wgSharedTables;
2049                 # Skip the entire process when we have a string quoted on both ends.
2050                 # Note that we check the end so that we will still quote any use of
2051                 # use of `database`.table. But won't break things if someone wants
2052                 # to query a database table with a dot in the name.
2053                 if ( $this->isQuotedIdentifier( $name ) ) {
2054                         return $name;
2055                 }
2056
2057                 # Lets test for any bits of text that should never show up in a table
2058                 # name. Basically anything like JOIN or ON which are actually part of
2059                 # SQL queries, but may end up inside of the table value to combine
2060                 # sql. Such as how the API is doing.
2061                 # Note that we use a whitespace test rather than a \b test to avoid
2062                 # any remote case where a word like on may be inside of a table name
2063                 # surrounded by symbols which may be considered word breaks.
2064                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
2065                         return $name;
2066                 }
2067
2068                 # Split database and table into proper variables.
2069                 # We reverse the explode so that database.table and table both output
2070                 # the correct table.
2071                 $dbDetails = explode( '.', $name, 2 );
2072                 if ( count( $dbDetails ) == 2 ) {
2073                         list( $database, $table ) = $dbDetails;
2074                         # We don't want any prefix added in this case
2075                         $prefix = '';
2076                 } else {
2077                         list( $table ) = $dbDetails;
2078                         if ( $wgSharedDB !== null # We have a shared database
2079                                 && $this->mForeign == false # We're not working on a foreign database
2080                                 && !$this->isQuotedIdentifier( $table ) # Paranoia check to prevent shared tables listing '`table`'
2081                                 && in_array( $table, $wgSharedTables ) # A shared table is selected
2082                         ) {
2083                                 $database = $wgSharedDB;
2084                                 $prefix = $wgSharedPrefix === null ? $this->mTablePrefix : $wgSharedPrefix;
2085                         } else {
2086                                 $database = null;
2087                                 $prefix = $this->mTablePrefix; # Default prefix
2088                         }
2089                 }
2090
2091                 # Quote $table and apply the prefix if not quoted.
2092                 $tableName = "{$prefix}{$table}";
2093                 if ( $format == 'quoted' && !$this->isQuotedIdentifier( $tableName ) ) {
2094                         $tableName = $this->addIdentifierQuotes( $tableName );
2095                 }
2096
2097                 # Quote $database and merge it with the table name if needed
2098                 if ( $database !== null ) {
2099                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $database ) ) {
2100                                 $database = $this->addIdentifierQuotes( $database );
2101                         }
2102                         $tableName = $database . '.' . $tableName;
2103                 }
2104
2105                 return $tableName;
2106         }
2107
2108         /**
2109          * Fetch a number of table names into an array
2110          * This is handy when you need to construct SQL for joins
2111          *
2112          * Example:
2113          * extract( $dbr->tableNames( 'user', 'watchlist' ) );
2114          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
2115          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
2116          *
2117          * @return array
2118          */
2119         public function tableNames() {
2120                 $inArray = func_get_args();
2121                 $retVal = array();
2122
2123                 foreach ( $inArray as $name ) {
2124                         $retVal[$name] = $this->tableName( $name );
2125                 }
2126
2127                 return $retVal;
2128         }
2129
2130         /**
2131          * Fetch a number of table names into an zero-indexed numerical array
2132          * This is handy when you need to construct SQL for joins
2133          *
2134          * Example:
2135          * list( $user, $watchlist ) = $dbr->tableNamesN( 'user', 'watchlist' );
2136          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
2137          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
2138          *
2139          * @return array
2140          */
2141         public function tableNamesN() {
2142                 $inArray = func_get_args();
2143                 $retVal = array();
2144
2145                 foreach ( $inArray as $name ) {
2146                         $retVal[] = $this->tableName( $name );
2147                 }
2148
2149                 return $retVal;
2150         }
2151
2152         /**
2153          * Get an aliased table name
2154          * e.g. tableName AS newTableName
2155          *
2156          * @param string $name Table name, see tableName()
2157          * @param string|bool $alias Alias (optional)
2158          * @return string SQL name for aliased table. Will not alias a table to its own name
2159          */
2160         public function tableNameWithAlias( $name, $alias = false ) {
2161                 if ( !$alias || $alias == $name ) {
2162                         return $this->tableName( $name );
2163                 } else {
2164                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
2165                 }
2166         }
2167
2168         /**
2169          * Gets an array of aliased table names
2170          *
2171          * @param $tables array( [alias] => table )
2172          * @return array of strings, see tableNameWithAlias()
2173          */
2174         public function tableNamesWithAlias( $tables ) {
2175                 $retval = array();
2176                 foreach ( $tables as $alias => $table ) {
2177                         if ( is_numeric( $alias ) ) {
2178                                 $alias = $table;
2179                         }
2180                         $retval[] = $this->tableNameWithAlias( $table, $alias );
2181                 }
2182                 return $retval;
2183         }
2184
2185         /**
2186          * Get an aliased field name
2187          * e.g. fieldName AS newFieldName
2188          *
2189          * @param string $name Field name
2190          * @param string|bool $alias Alias (optional)
2191          * @return string SQL name for aliased field. Will not alias a field to its own name
2192          */
2193         public function fieldNameWithAlias( $name, $alias = false ) {
2194                 if ( !$alias || (string)$alias === (string)$name ) {
2195                         return $name;
2196                 } else {
2197                         return $name . ' AS ' . $alias; //PostgreSQL needs AS
2198                 }
2199         }
2200
2201         /**
2202          * Gets an array of aliased field names
2203          *
2204          * @param $fields array( [alias] => field )
2205          * @return array of strings, see fieldNameWithAlias()
2206          */
2207         public function fieldNamesWithAlias( $fields ) {
2208                 $retval = array();
2209                 foreach ( $fields as $alias => $field ) {
2210                         if ( is_numeric( $alias ) ) {
2211                                 $alias = $field;
2212                         }
2213                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
2214                 }
2215                 return $retval;
2216         }
2217
2218         /**
2219          * Get the aliased table name clause for a FROM clause
2220          * which might have a JOIN and/or USE INDEX clause
2221          *
2222          * @param array $tables ( [alias] => table )
2223          * @param $use_index array Same as for select()
2224          * @param $join_conds array Same as for select()
2225          * @return string
2226          */
2227         protected function tableNamesWithUseIndexOrJOIN(
2228                 $tables, $use_index = array(), $join_conds = array()
2229         ) {
2230                 $ret = array();
2231                 $retJOIN = array();
2232                 $use_index = (array)$use_index;
2233                 $join_conds = (array)$join_conds;
2234
2235                 foreach ( $tables as $alias => $table ) {
2236                         if ( !is_string( $alias ) ) {
2237                                 // No alias? Set it equal to the table name
2238                                 $alias = $table;
2239                         }
2240                         // Is there a JOIN clause for this table?
2241                         if ( isset( $join_conds[$alias] ) ) {
2242                                 list( $joinType, $conds ) = $join_conds[$alias];
2243                                 $tableClause = $joinType;
2244                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
2245                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2246                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2247                                         if ( $use != '' ) {
2248                                                 $tableClause .= ' ' . $use;
2249                                         }
2250                                 }
2251                                 $on = $this->makeList( (array)$conds, LIST_AND );
2252                                 if ( $on != '' ) {
2253                                         $tableClause .= ' ON (' . $on . ')';
2254                                 }
2255
2256                                 $retJOIN[] = $tableClause;
2257                         // Is there an INDEX clause for this table?
2258                         } elseif ( isset( $use_index[$alias] ) ) {
2259                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2260                                 $tableClause .= ' ' . $this->useIndexClause(
2261                                         implode( ',', (array)$use_index[$alias] ) );
2262
2263                                 $ret[] = $tableClause;
2264                         } else {
2265                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2266
2267                                 $ret[] = $tableClause;
2268                         }
2269                 }
2270
2271                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2272                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
2273                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
2274
2275                 // Compile our final table clause
2276                 return implode( ' ', array( $implicitJoins, $explicitJoins ) );
2277         }
2278
2279         /**
2280          * Get the name of an index in a given table
2281          *
2282          * @param $index
2283          *
2284          * @return string
2285          */
2286         protected function indexName( $index ) {
2287                 // Backwards-compatibility hack
2288                 $renamed = array(
2289                         'ar_usertext_timestamp' => 'usertext_timestamp',
2290                         'un_user_id' => 'user_id',
2291                         'un_user_ip' => 'user_ip',
2292                 );
2293
2294                 if ( isset( $renamed[$index] ) ) {
2295                         return $renamed[$index];
2296                 } else {
2297                         return $index;
2298                 }
2299         }
2300
2301         /**
2302          * If it's a string, adds quotes and backslashes
2303          * Otherwise returns as-is
2304          *
2305          * @param $s string
2306          *
2307          * @return string
2308          */
2309         public function addQuotes( $s ) {
2310                 if ( $s === null ) {
2311                         return 'NULL';
2312                 } else {
2313                         # This will also quote numeric values. This should be harmless,
2314                         # and protects against weird problems that occur when they really
2315                         # _are_ strings such as article titles and string->number->string
2316                         # conversion is not 1:1.
2317                         return "'" . $this->strencode( $s ) . "'";
2318                 }
2319         }
2320
2321         /**
2322          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
2323          * MySQL uses `backticks` while basically everything else uses double quotes.
2324          * Since MySQL is the odd one out here the double quotes are our generic
2325          * and we implement backticks in DatabaseMysql.
2326          *
2327          * @param $s string
2328          *
2329          * @return string
2330          */
2331         public function addIdentifierQuotes( $s ) {
2332                 return '"' . str_replace( '"', '""', $s ) . '"';
2333         }
2334
2335         /**
2336          * Returns if the given identifier looks quoted or not according to
2337          * the database convention for quoting identifiers .
2338          *
2339          * @param $name string
2340          *
2341          * @return boolean
2342          */
2343         public function isQuotedIdentifier( $name ) {
2344                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2345         }
2346
2347         /**
2348          * @param $s string
2349          * @return string
2350          */
2351         protected function escapeLikeInternal( $s ) {
2352                 $s = str_replace( '\\', '\\\\', $s );
2353                 $s = $this->strencode( $s );
2354                 $s = str_replace( array( '%', '_' ), array( '\%', '\_' ), $s );
2355
2356                 return $s;
2357         }
2358
2359         /**
2360          * LIKE statement wrapper, receives a variable-length argument list with parts of pattern to match
2361          * containing either string literals that will be escaped or tokens returned by anyChar() or anyString().
2362          * Alternatively, the function could be provided with an array of aforementioned parameters.
2363          *
2364          * Example: $dbr->buildLike( 'My_page_title/', $dbr->anyString() ) returns a LIKE clause that searches
2365          * for subpages of 'My page title'.
2366          * Alternatively: $pattern = array( 'My_page_title/', $dbr->anyString() ); $query .= $dbr->buildLike( $pattern );
2367          *
2368          * @since 1.16
2369          * @return String: fully built LIKE statement
2370          */
2371         public function buildLike() {
2372                 $params = func_get_args();
2373
2374                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2375                         $params = $params[0];
2376                 }
2377
2378                 $s = '';
2379
2380                 foreach ( $params as $value ) {
2381                         if ( $value instanceof LikeMatch ) {
2382                                 $s .= $value->toString();
2383                         } else {
2384                                 $s .= $this->escapeLikeInternal( $value );
2385                         }
2386                 }
2387
2388                 return " LIKE '" . $s . "' ";
2389         }
2390
2391         /**
2392          * Returns a token for buildLike() that denotes a '_' to be used in a LIKE query
2393          *
2394          * @return LikeMatch
2395          */
2396         public function anyChar() {
2397                 return new LikeMatch( '_' );
2398         }
2399
2400         /**
2401          * Returns a token for buildLike() that denotes a '%' to be used in a LIKE query
2402          *
2403          * @return LikeMatch
2404          */
2405         public function anyString() {
2406                 return new LikeMatch( '%' );
2407         }
2408
2409         /**
2410          * Returns an appropriately quoted sequence value for inserting a new row.
2411          * MySQL has autoincrement fields, so this is just NULL. But the PostgreSQL
2412          * subclass will return an integer, and save the value for insertId()
2413          *
2414          * Any implementation of this function should *not* involve reusing
2415          * sequence numbers created for rolled-back transactions.
2416          * See http://bugs.mysql.com/bug.php?id=30767 for details.
2417          * @param $seqName string
2418          * @return null
2419          */
2420         public function nextSequenceValue( $seqName ) {
2421                 return null;
2422         }
2423
2424         /**
2425          * USE INDEX clause.  Unlikely to be useful for anything but MySQL.  This
2426          * is only needed because a) MySQL must be as efficient as possible due to
2427          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2428          * which index to pick.  Anyway, other databases might have different
2429          * indexes on a given table.  So don't bother overriding this unless you're
2430          * MySQL.
2431          * @param $index
2432          * @return string
2433          */
2434         public function useIndexClause( $index ) {
2435                 return '';
2436         }
2437
2438         /**
2439          * REPLACE query wrapper.
2440          *
2441          * REPLACE is a very handy MySQL extension, which functions like an INSERT
2442          * except that when there is a duplicate key error, the old row is deleted
2443          * and the new row is inserted in its place.
2444          *
2445          * We simulate this with standard SQL with a DELETE followed by INSERT. To
2446          * perform the delete, we need to know what the unique indexes are so that
2447          * we know how to find the conflicting rows.
2448          *
2449          * It may be more efficient to leave off unique indexes which are unlikely
2450          * to collide. However if you do this, you run the risk of encountering
2451          * errors which wouldn't have occurred in MySQL.
2452          *
2453          * @param string $table The table to replace the row(s) in.
2454          * @param array $rows Can be either a single row to insert, or multiple rows,
2455          *    in the same format as for DatabaseBase::insert()
2456          * @param array $uniqueIndexes is an array of indexes. Each element may be either
2457          *    a field name or an array of field names
2458          * @param string $fname Calling function name (use __METHOD__) for logs/profiling
2459          */
2460         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2461                 $quotedTable = $this->tableName( $table );
2462
2463                 if ( count( $rows ) == 0 ) {
2464                         return;
2465                 }
2466
2467                 # Single row case
2468                 if ( !is_array( reset( $rows ) ) ) {
2469                         $rows = array( $rows );
2470                 }
2471
2472                 foreach ( $rows as $row ) {
2473                         # Delete rows which collide
2474                         if ( $uniqueIndexes ) {
2475                                 $sql = "DELETE FROM $quotedTable WHERE ";
2476                                 $first = true;
2477                                 foreach ( $uniqueIndexes as $index ) {
2478                                         if ( $first ) {
2479                                                 $first = false;
2480                                                 $sql .= '( ';
2481                                         } else {
2482                                                 $sql .= ' ) OR ( ';
2483                                         }
2484                                         if ( is_array( $index ) ) {
2485                                                 $first2 = true;
2486                                                 foreach ( $index as $col ) {
2487                                                         if ( $first2 ) {
2488                                                                 $first2 = false;
2489                                                         } else {
2490                                                                 $sql .= ' AND ';
2491                                                         }
2492                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2493                                                 }
2494                                         } else {
2495                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2496                                         }
2497                                 }
2498                                 $sql .= ' )';
2499                                 $this->query( $sql, $fname );
2500                         }
2501
2502                         # Now insert the row
2503                         $this->insert( $table, $row, $fname );
2504                 }
2505         }
2506
2507         /**
2508          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2509          * statement.
2510          *
2511          * @param string $table Table name
2512          * @param array $rows Rows to insert
2513          * @param string $fname Caller function name
2514          *
2515          * @return ResultWrapper
2516          */
2517         protected function nativeReplace( $table, $rows, $fname ) {
2518                 $table = $this->tableName( $table );
2519
2520                 # Single row case
2521                 if ( !is_array( reset( $rows ) ) ) {
2522                         $rows = array( $rows );
2523                 }
2524
2525                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2526                 $first = true;
2527
2528                 foreach ( $rows as $row ) {
2529                         if ( $first ) {
2530                                 $first = false;
2531                         } else {
2532                                 $sql .= ',';
2533                         }
2534
2535                         $sql .= '(' . $this->makeList( $row ) . ')';
2536                 }
2537
2538                 return $this->query( $sql, $fname );
2539         }
2540
2541         /**
2542          * INSERT ON DUPLICATE KEY UPDATE wrapper, upserts an array into a table.
2543          *
2544          * This updates any conflicting rows (according to the unique indexes) using
2545          * the provided SET clause and inserts any remaining (non-conflicted) rows.
2546          *
2547          * $rows may be either:
2548          *   - A single associative array. The array keys are the field names, and
2549          *     the values are the values to insert. The values are treated as data
2550          *     and will be quoted appropriately. If NULL is inserted, this will be
2551          *     converted to a database NULL.
2552          *   - An array with numeric keys, holding a list of associative arrays.
2553          *     This causes a multi-row INSERT on DBMSs that support it. The keys in
2554          *     each subarray must be identical to each other, and in the same order.
2555          *
2556          * It may be more efficient to leave off unique indexes which are unlikely
2557          * to collide. However if you do this, you run the risk of encountering
2558          * errors which wouldn't have occurred in MySQL.
2559          *
2560          * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
2561          * returns success.
2562          *
2563          * @param string $table Table name. This will be passed through DatabaseBase::tableName().
2564          * @param array $rows A single row or list of rows to insert
2565          * @param array $uniqueIndexes List of single field names or field name tuples
2566          * @param array $set An array of values to SET. For each array element,
2567          *                the key gives the field name, and the value gives the data
2568          *                to set that field to. The data will be quoted by
2569          *                DatabaseBase::addQuotes().
2570          * @param string $fname Calling function name (use __METHOD__) for logs/profiling
2571          * @param array $options of options
2572          *
2573          * @return bool
2574          * @since 1.22
2575          */
2576         public function upsert(
2577                 $table, array $rows, array $uniqueIndexes, array $set, $fname = __METHOD__
2578         ) {
2579                 if ( !count( $rows ) ) {
2580                         return true; // nothing to do
2581                 }
2582                 $rows = is_array( reset( $rows ) ) ? $rows : array( $rows );
2583
2584                 if ( count( $uniqueIndexes ) ) {
2585                         $clauses = array(); // list WHERE clauses that each identify a single row
2586                         foreach ( $rows as $row ) {
2587                                 foreach ( $uniqueIndexes as $index ) {
2588                                         $index = is_array( $index ) ? $index : array( $index ); // columns
2589                                         $rowKey = array(); // unique key to this row
2590                                         foreach ( $index as $column ) {
2591                                                 $rowKey[$column] = $row[$column];
2592                                         }
2593                                         $clauses[] = $this->makeList( $rowKey, LIST_AND );
2594                                 }
2595                         }
2596                         $where = array( $this->makeList( $clauses, LIST_OR ) );
2597                 } else {
2598                         $where = false;
2599                 }
2600
2601                 $useTrx = !$this->mTrxLevel;
2602                 if ( $useTrx ) {
2603                         $this->begin( $fname );
2604                 }
2605                 try {
2606                         # Update any existing conflicting row(s)
2607                         if ( $where !== false ) {
2608                                 $ok = $this->update( $table, $set, $where, $fname );
2609                         } else {
2610                                 $ok = true;
2611                         }
2612                         # Now insert any non-conflicting row(s)
2613                         $ok = $this->insert( $table, $rows, $fname, array( 'IGNORE' ) ) && $ok;
2614                 } catch ( Exception $e ) {
2615                         if ( $useTrx ) {
2616                                 $this->rollback( $fname );
2617                         }
2618                         throw $e;
2619                 }
2620                 if ( $useTrx ) {
2621                         $this->commit( $fname );
2622                 }
2623
2624                 return $ok;
2625         }
2626
2627         /**
2628          * DELETE where the condition is a join.
2629          *
2630          * MySQL overrides this to use a multi-table DELETE syntax, in other databases
2631          * we use sub-selects
2632          *
2633          * For safety, an empty $conds will not delete everything. If you want to
2634          * delete all rows where the join condition matches, set $conds='*'.
2635          *
2636          * DO NOT put the join condition in $conds.
2637          *
2638          * @param $delTable   String: The table to delete from.
2639          * @param $joinTable  String: The other table.
2640          * @param $delVar     String: The variable to join on, in the first table.
2641          * @param $joinVar    String: The variable to join on, in the second table.
2642          * @param $conds      Array: Condition array of field names mapped to variables,
2643          *                    ANDed together in the WHERE clause
2644          * @param $fname      String: Calling function name (use __METHOD__) for
2645          *                    logs/profiling
2646          * @throws DBUnexpectedError
2647          */
2648         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2649                 $fname = __METHOD__ )
2650         {
2651                 if ( !$conds ) {
2652                         throw new DBUnexpectedError( $this,
2653                                 'DatabaseBase::deleteJoin() called with empty $conds' );
2654                 }
2655
2656                 $delTable = $this->tableName( $delTable );
2657                 $joinTable = $this->tableName( $joinTable );
2658                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2659                 if ( $conds != '*' ) {
2660                         $sql .= 'WHERE ' . $this->makeList( $conds, LIST_AND );
2661                 }
2662                 $sql .= ')';
2663
2664                 $this->query( $sql, $fname );
2665         }
2666
2667         /**
2668          * Returns the size of a text field, or -1 for "unlimited"
2669          *
2670          * @param $table string
2671          * @param $field string
2672          *
2673          * @return int
2674          */
2675         public function textFieldSize( $table, $field ) {
2676                 $table = $this->tableName( $table );
2677                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2678                 $res = $this->query( $sql, 'DatabaseBase::textFieldSize' );
2679                 $row = $this->fetchObject( $res );
2680
2681                 $m = array();
2682
2683                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2684                         $size = $m[1];
2685                 } else {
2686                         $size = -1;
2687                 }
2688
2689                 return $size;
2690         }
2691
2692         /**
2693          * A string to insert into queries to show that they're low-priority, like
2694          * MySQL's LOW_PRIORITY.  If no such feature exists, return an empty
2695          * string and nothing bad should happen.
2696          *
2697          * @return string Returns the text of the low priority option if it is
2698          *   supported, or a blank string otherwise
2699          */
2700         public function lowPriorityOption() {
2701                 return '';
2702         }
2703
2704         /**
2705          * DELETE query wrapper.
2706          *
2707          * @param array $table Table name
2708          * @param string|array $conds of conditions. See $conds in DatabaseBase::select() for
2709          *               the format. Use $conds == "*" to delete all rows
2710          * @param string $fname name of the calling function
2711          *
2712          * @throws DBUnexpectedError
2713          * @return bool|ResultWrapper
2714          */
2715         public function delete( $table, $conds, $fname = __METHOD__ ) {
2716                 if ( !$conds ) {
2717                         throw new DBUnexpectedError( $this, 'DatabaseBase::delete() called with no conditions' );
2718                 }
2719
2720                 $table = $this->tableName( $table );
2721                 $sql = "DELETE FROM $table";
2722
2723                 if ( $conds != '*' ) {
2724                         if ( is_array( $conds ) ) {
2725                                 $conds = $this->makeList( $conds, LIST_AND );
2726                         }
2727                         $sql .= ' WHERE ' . $conds;
2728                 }
2729
2730                 return $this->query( $sql, $fname );
2731         }
2732
2733         /**
2734          * INSERT SELECT wrapper. Takes data from a SELECT query and inserts it
2735          * into another table.
2736          *
2737          * @param string $destTable The table name to insert into
2738          * @param string|array $srcTable May be either a table name, or an array of table names
2739          *    to include in a join.
2740          *
2741          * @param array $varMap must be an associative array of the form
2742          *    array( 'dest1' => 'source1', ...). Source items may be literals
2743          *    rather than field names, but strings should be quoted with
2744          *    DatabaseBase::addQuotes()
2745          *
2746          * @param array $conds Condition array. See $conds in DatabaseBase::select() for
2747          *    the details of the format of condition arrays. May be "*" to copy the
2748          *    whole table.
2749          *
2750          * @param string $fname The function name of the caller, from __METHOD__
2751          *
2752          * @param array $insertOptions Options for the INSERT part of the query, see
2753          *    DatabaseBase::insert() for details.
2754          * @param array $selectOptions Options for the SELECT part of the query, see
2755          *    DatabaseBase::select() for details.
2756          *
2757          * @return ResultWrapper
2758          */
2759         public function insertSelect( $destTable, $srcTable, $varMap, $conds,
2760                 $fname = __METHOD__,
2761                 $insertOptions = array(), $selectOptions = array() )
2762         {
2763                 $destTable = $this->tableName( $destTable );
2764
2765                 if ( is_array( $insertOptions ) ) {
2766                         $insertOptions = implode( ' ', $insertOptions );
2767                 }
2768
2769                 if ( !is_array( $selectOptions ) ) {
2770                         $selectOptions = array( $selectOptions );
2771                 }
2772
2773                 list( $startOpts, $useIndex, $tailOpts ) = $this->makeSelectOptions( $selectOptions );
2774
2775                 if ( is_array( $srcTable ) ) {
2776                         $srcTable = implode( ',', array_map( array( &$this, 'tableName' ), $srcTable ) );
2777                 } else {
2778                         $srcTable = $this->tableName( $srcTable );
2779                 }
2780
2781                 $sql = "INSERT $insertOptions INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2782                         " SELECT $startOpts " . implode( ',', $varMap ) .
2783                         " FROM $srcTable $useIndex ";
2784
2785                 if ( $conds != '*' ) {
2786                         if ( is_array( $conds ) ) {
2787                                 $conds = $this->makeList( $conds, LIST_AND );
2788                         }
2789                         $sql .= " WHERE $conds";
2790                 }
2791
2792                 $sql .= " $tailOpts";
2793
2794                 return $this->query( $sql, $fname );
2795         }
2796
2797         /**
2798          * Construct a LIMIT query with optional offset.  This is used for query
2799          * pages.  The SQL should be adjusted so that only the first $limit rows
2800          * are returned.  If $offset is provided as well, then the first $offset
2801          * rows should be discarded, and the next $limit rows should be returned.
2802          * If the result of the query is not ordered, then the rows to be returned
2803          * are theoretically arbitrary.
2804          *
2805          * $sql is expected to be a SELECT, if that makes a difference.
2806          *
2807          * The version provided by default works in MySQL and SQLite.  It will very
2808          * likely need to be overridden for most other DBMSes.
2809          *
2810          * @param string $sql SQL query we will append the limit too
2811          * @param $limit Integer the SQL limit
2812          * @param $offset Integer|bool the SQL offset (default false)
2813          *
2814          * @throws DBUnexpectedError
2815          * @return string
2816          */
2817         public function limitResult( $sql, $limit, $offset = false ) {
2818                 if ( !is_numeric( $limit ) ) {
2819                         throw new DBUnexpectedError( $this, "Invalid non-numeric limit passed to limitResult()\n" );
2820                 }
2821                 return "$sql LIMIT "
2822                         . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2823                         . "{$limit} ";
2824         }
2825
2826         /**
2827          * Returns true if current database backend supports ORDER BY or LIMIT for separate subqueries
2828          * within the UNION construct.
2829          * @return Boolean
2830          */
2831         public function unionSupportsOrderAndLimit() {
2832                 return true; // True for almost every DB supported
2833         }
2834
2835         /**
2836          * Construct a UNION query
2837          * This is used for providing overload point for other DB abstractions
2838          * not compatible with the MySQL syntax.
2839          * @param array $sqls SQL statements to combine
2840          * @param $all Boolean: use UNION ALL
2841          * @return String: SQL fragment
2842          */
2843         public function unionQueries( $sqls, $all ) {
2844                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2845                 return '(' . implode( $glue, $sqls ) . ')';
2846         }
2847
2848         /**
2849          * Returns an SQL expression for a simple conditional.  This doesn't need
2850          * to be overridden unless CASE isn't supported in your DBMS.
2851          *
2852          * @param string|array $cond SQL expression which will result in a boolean value
2853          * @param string $trueVal SQL expression to return if true
2854          * @param string $falseVal SQL expression to return if false
2855          * @return String: SQL fragment
2856          */
2857         public function conditional( $cond, $trueVal, $falseVal ) {
2858                 if ( is_array( $cond ) ) {
2859                         $cond = $this->makeList( $cond, LIST_AND );
2860                 }
2861                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2862         }
2863
2864         /**
2865          * Returns a comand for str_replace function in SQL query.
2866          * Uses REPLACE() in MySQL
2867          *
2868          * @param string $orig column to modify
2869          * @param string $old column to seek
2870          * @param string $new column to replace with
2871          *
2872          * @return string
2873          */
2874         public function strreplace( $orig, $old, $new ) {
2875                 return "REPLACE({$orig}, {$old}, {$new})";
2876         }
2877
2878         /**
2879          * Determines how long the server has been up
2880          * STUB
2881          *
2882          * @return int
2883          */
2884         public function getServerUptime() {
2885                 return 0;
2886         }
2887
2888         /**
2889          * Determines if the last failure was due to a deadlock
2890          * STUB
2891          *
2892          * @return bool
2893          */
2894         public function wasDeadlock() {
2895                 return false;
2896         }
2897
2898         /**
2899          * Determines if the last failure was due to a lock timeout
2900          * STUB
2901          *
2902          * @return bool
2903          */
2904         public function wasLockTimeout() {
2905                 return false;
2906         }
2907
2908         /**
2909          * Determines if the last query error was something that should be dealt
2910          * with by pinging the connection and reissuing the query.
2911          * STUB
2912          *
2913          * @return bool
2914          */
2915         public function wasErrorReissuable() {
2916                 return false;
2917         }
2918
2919         /**
2920          * Determines if the last failure was due to the database being read-only.
2921          * STUB
2922          *
2923          * @return bool
2924          */
2925         public function wasReadOnlyError() {
2926                 return false;
2927         }
2928
2929         /**
2930          * Perform a deadlock-prone transaction.
2931          *
2932          * This function invokes a callback function to perform a set of write
2933          * queries. If a deadlock occurs during the processing, the transaction
2934          * will be rolled back and the callback function will be called again.
2935          *
2936          * Usage:
2937          *   $dbw->deadlockLoop( callback, ... );
2938          *
2939          * Extra arguments are passed through to the specified callback function.
2940          *
2941          * Returns whatever the callback function returned on its successful,
2942          * iteration, or false on error, for example if the retry limit was
2943          * reached.
2944          *
2945          * @return bool
2946          */
2947         public function deadlockLoop() {
2948                 $this->begin( __METHOD__ );
2949                 $args = func_get_args();
2950                 $function = array_shift( $args );
2951                 $oldIgnore = $this->ignoreErrors( true );
2952                 $tries = self::DEADLOCK_TRIES;
2953
2954                 if ( is_array( $function ) ) {
2955                         $fname = $function[0];
2956                 } else {
2957                         $fname = $function;
2958                 }
2959
2960                 do {
2961                         $retVal = call_user_func_array( $function, $args );
2962                         $error = $this->lastError();
2963                         $errno = $this->lastErrno();
2964                         $sql = $this->lastQuery();
2965
2966                         if ( $errno ) {
2967                                 if ( $this->wasDeadlock() ) {
2968                                         # Retry
2969                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
2970                                 } else {
2971                                         $this->reportQueryError( $error, $errno, $sql, $fname );
2972                                 }
2973                         }
2974                 } while ( $this->wasDeadlock() && --$tries > 0 );
2975
2976                 $this->ignoreErrors( $oldIgnore );
2977
2978                 if ( $tries <= 0 ) {
2979                         $this->rollback( __METHOD__ );
2980                         $this->reportQueryError( $error, $errno, $sql, $fname );
2981                         return false;
2982                 } else {
2983                         $this->commit( __METHOD__ );
2984                         return $retVal;
2985                 }
2986         }
2987
2988         /**
2989          * Wait for the slave to catch up to a given master position.
2990          *
2991          * @param $pos DBMasterPos object
2992          * @param $timeout Integer: the maximum number of seconds to wait for
2993          *   synchronisation
2994          *
2995          * @return integer: zero if the slave was past that position already,
2996          *   greater than zero if we waited for some period of time, less than
2997          *   zero if we timed out.
2998          */
2999         public function masterPosWait( DBMasterPos $pos, $timeout ) {
3000                 wfProfileIn( __METHOD__ );
3001
3002                 if ( !is_null( $this->mFakeSlaveLag ) ) {
3003                         $wait = intval( ( $pos->pos - microtime( true ) + $this->mFakeSlaveLag ) * 1e6 );
3004
3005                         if ( $wait > $timeout * 1e6 ) {
3006                                 wfDebug( "Fake slave timed out waiting for $pos ($wait us)\n" );
3007                                 wfProfileOut( __METHOD__ );
3008                                 return -1;
3009                         } elseif ( $wait > 0 ) {
3010                                 wfDebug( "Fake slave waiting $wait us\n" );
3011                                 usleep( $wait );
3012                                 wfProfileOut( __METHOD__ );
3013                                 return 1;
3014                         } else {
3015                                 wfDebug( "Fake slave up to date ($wait us)\n" );
3016                                 wfProfileOut( __METHOD__ );
3017                                 return 0;
3018                         }
3019                 }
3020
3021                 wfProfileOut( __METHOD__ );
3022
3023                 # Real waits are implemented in the subclass.
3024                 return 0;
3025         }
3026
3027         /**
3028          * Get the replication position of this slave
3029          *
3030          * @return DBMasterPos, or false if this is not a slave.
3031          */
3032         public function getSlavePos() {
3033                 if ( !is_null( $this->mFakeSlaveLag ) ) {
3034                         $pos = new MySQLMasterPos( 'fake', microtime( true ) - $this->mFakeSlaveLag );
3035                         wfDebug( __METHOD__ . ": fake slave pos = $pos\n" );
3036                         return $pos;
3037                 } else {
3038                         # Stub
3039                         return false;
3040                 }
3041         }
3042
3043         /**
3044          * Get the position of this master
3045          *
3046          * @return DBMasterPos, or false if this is not a master
3047          */
3048         public function getMasterPos() {
3049                 if ( $this->mFakeMaster ) {
3050                         return new MySQLMasterPos( 'fake', microtime( true ) );
3051                 } else {
3052                         return false;
3053                 }
3054         }
3055
3056         /**
3057          * Run an anonymous function as soon as there is no transaction pending.
3058          * If there is a transaction and it is rolled back, then the callback is cancelled.
3059          * Queries in the function will run in AUTO-COMMIT mode unless there are begin() calls.
3060          * Callbacks must commit any transactions that they begin.
3061          *
3062          * This is useful for updates to different systems or when separate transactions are needed.
3063          * For example, one might want to enqueue jobs into a system outside the database, but only
3064          * after the database is updated so that the jobs will see the data when they actually run.
3065          * It can also be used for updates that easily cause deadlocks if locks are held too long.
3066          *
3067          * @param callable $callback
3068          * @since 1.20
3069          */
3070         final public function onTransactionIdle( $callback ) {
3071                 $this->mTrxIdleCallbacks[] = $callback;
3072                 if ( !$this->mTrxLevel ) {
3073                         $this->runOnTransactionIdleCallbacks();
3074                 }
3075         }
3076
3077         /**
3078          * Run an anonymous function before the current transaction commits or now if there is none.
3079          * If there is a transaction and it is rolled back, then the callback is cancelled.
3080          * Callbacks must not start nor commit any transactions.
3081          *
3082          * This is useful for updates that easily cause deadlocks if locks are held too long
3083          * but where atomicity is strongly desired for these updates and some related updates.
3084          *
3085          * @param callable $callback
3086          * @since 1.22
3087          */
3088         final public function onTransactionPreCommitOrIdle( $callback ) {
3089                 if ( $this->mTrxLevel ) {
3090                         $this->mTrxPreCommitCallbacks[] = $callback;
3091                 } else {
3092                         $this->onTransactionIdle( $callback ); // this will trigger immediately
3093                 }
3094         }
3095
3096         /**
3097          * Actually any "on transaction idle" callbacks.
3098          *
3099          * @since 1.20
3100          */
3101         protected function runOnTransactionIdleCallbacks() {
3102                 $autoTrx = $this->getFlag( DBO_TRX ); // automatic begin() enabled?
3103
3104                 $e = null; // last exception
3105                 do { // callbacks may add callbacks :)
3106                         $callbacks = $this->mTrxIdleCallbacks;
3107                         $this->mTrxIdleCallbacks = array(); // recursion guard
3108                         foreach ( $callbacks as $callback ) {
3109                                 try {
3110                                         $this->clearFlag( DBO_TRX ); // make each query its own transaction
3111                                         call_user_func( $callback );
3112                                         $this->setFlag( $autoTrx ? DBO_TRX : 0 ); // restore automatic begin()
3113                                 } catch ( Exception $e ) {}
3114                         }
3115                 } while ( count( $this->mTrxIdleCallbacks ) );
3116
3117                 if ( $e instanceof Exception ) {
3118                         throw $e; // re-throw any last exception
3119                 }
3120         }
3121
3122         /**
3123          * Actually any "on transaction pre-commit" callbacks.
3124          *
3125          * @since 1.22
3126          */
3127         protected function runOnTransactionPreCommitCallbacks() {
3128                 $e = null; // last exception
3129                 do { // callbacks may add callbacks :)
3130                         $callbacks = $this->mTrxPreCommitCallbacks;
3131                         $this->mTrxPreCommitCallbacks = array(); // recursion guard
3132                         foreach ( $callbacks as $callback ) {
3133                                 try {
3134                                         call_user_func( $callback );
3135                                 } catch ( Exception $e ) {}
3136                         }
3137                 } while ( count( $this->mTrxPreCommitCallbacks ) );
3138
3139                 if ( $e instanceof Exception ) {
3140                         throw $e; // re-throw any last exception
3141                 }
3142         }
3143
3144         /**
3145          * Begin a transaction. If a transaction is already in progress, that transaction will be committed before the
3146          * new transaction is started.
3147          *
3148          * Note that when the DBO_TRX flag is set (which is usually the case for web requests, but not for maintenance scripts),
3149          * any previous database query will have started a transaction automatically.
3150          *
3151          * Nesting of transactions is not supported. Attempts to nest transactions will cause a warning, unless the current
3152          * transaction was started automatically because of the DBO_TRX flag.
3153          *
3154          * @param $fname string
3155          */
3156         final public function begin( $fname = __METHOD__ ) {
3157                 global $wgDebugDBTransactions;
3158
3159                 if ( $this->mTrxLevel ) { // implicit commit
3160                         if ( !$this->mTrxAutomatic ) {
3161                                 // We want to warn about inadvertently nested begin/commit pairs, but not about
3162                                 // auto-committing implicit transactions that were started by query() via DBO_TRX
3163                                 $msg = "$fname: Transaction already in progress (from {$this->mTrxFname}), " .
3164                                         " performing implicit commit!";
3165                                 wfWarn( $msg );
3166                                 wfLogDBError( $msg );
3167                         } else {
3168                                 // if the transaction was automatic and has done write operations,
3169                                 // log it if $wgDebugDBTransactions is enabled.
3170                                 if ( $this->mTrxDoneWrites && $wgDebugDBTransactions ) {
3171                                         wfDebug( "$fname: Automatic transaction with writes in progress" .
3172                                                 " (from {$this->mTrxFname}), performing implicit commit!\n"
3173                                         );
3174                                 }
3175                         }
3176
3177                         $this->runOnTransactionPreCommitCallbacks();
3178                         $this->doCommit( $fname );
3179                         if ( $this->mTrxDoneWrites ) {
3180                                 Profiler::instance()->transactionWritingOut( $this->mServer, $this->mDBname );
3181                         }
3182                         $this->runOnTransactionIdleCallbacks();
3183                 }
3184
3185                 $this->doBegin( $fname );
3186                 $this->mTrxFname = $fname;
3187                 $this->mTrxDoneWrites = false;
3188                 $this->mTrxAutomatic = false;
3189         }
3190
3191         /**
3192          * Issues the BEGIN command to the database server.
3193          *
3194          * @see DatabaseBase::begin()
3195          * @param type $fname
3196          */
3197         protected function doBegin( $fname ) {
3198                 $this->query( 'BEGIN', $fname );
3199                 $this->mTrxLevel = 1;
3200         }
3201
3202         /**
3203          * Commits a transaction previously started using begin().
3204          * If no transaction is in progress, a warning is issued.
3205          *
3206          * Nesting of transactions is not supported.
3207          *
3208          * @param $fname string
3209          * @param string $flush Flush flag, set to 'flush' to disable warnings about explicitly committing implicit
3210          *        transactions, or calling commit when no transaction is in progress.
3211          *        This will silently break any ongoing explicit transaction. Only set the flush flag if you are sure
3212          *        that it is safe to ignore these warnings in your context.
3213          */
3214         final public function commit( $fname = __METHOD__, $flush = '' ) {
3215                 if ( $flush != 'flush' ) {
3216                         if ( !$this->mTrxLevel ) {
3217                                 wfWarn( "$fname: No transaction to commit, something got out of sync!" );
3218                         } elseif ( $this->mTrxAutomatic ) {
3219                                 wfWarn( "$fname: Explicit commit of implicit transaction. Something may be out of sync!" );
3220                         }
3221                 } else {
3222                         if ( !$this->mTrxLevel ) {
3223                                 return; // nothing to do
3224                         } elseif ( !$this->mTrxAutomatic ) {
3225                                 wfWarn( "$fname: Flushing an explicit transaction, getting out of sync!" );
3226                         }
3227                 }
3228
3229                 $this->runOnTransactionPreCommitCallbacks();
3230                 $this->doCommit( $fname );
3231                 if ( $this->mTrxDoneWrites ) {
3232                         Profiler::instance()->transactionWritingOut( $this->mServer, $this->mDBname );
3233                 }
3234                 $this->runOnTransactionIdleCallbacks();
3235         }
3236
3237         /**
3238          * Issues the COMMIT command to the database server.
3239          *
3240          * @see DatabaseBase::commit()
3241          * @param type $fname
3242          */
3243         protected function doCommit( $fname ) {
3244                 if ( $this->mTrxLevel ) {
3245                         $this->query( 'COMMIT', $fname );
3246                         $this->mTrxLevel = 0;
3247                 }
3248         }
3249
3250         /**
3251          * Rollback a transaction previously started using begin().
3252          * If no transaction is in progress, a warning is issued.
3253          *
3254          * No-op on non-transactional databases.
3255          *
3256          * @param $fname string
3257          */
3258         final public function rollback( $fname = __METHOD__ ) {
3259                 if ( !$this->mTrxLevel ) {
3260                         wfWarn( "$fname: No transaction to rollback, something got out of sync!" );
3261                 }
3262                 $this->doRollback( $fname );
3263                 $this->mTrxIdleCallbacks = array(); // cancel
3264                 $this->mTrxPreCommitCallbacks = array(); // cancel
3265                 if ( $this->mTrxDoneWrites ) {
3266                         Profiler::instance()->transactionWritingOut( $this->mServer, $this->mDBname );
3267                 }
3268         }
3269
3270         /**
3271          * Issues the ROLLBACK command to the database server.
3272          *
3273          * @see DatabaseBase::rollback()
3274          * @param type $fname
3275          */
3276         protected function doRollback( $fname ) {
3277                 if ( $this->mTrxLevel ) {
3278                         $this->query( 'ROLLBACK', $fname, true );
3279                         $this->mTrxLevel = 0;
3280                 }
3281         }
3282
3283         /**
3284          * Creates a new table with structure copied from existing table
3285          * Note that unlike most database abstraction functions, this function does not
3286          * automatically append database prefix, because it works at a lower
3287          * abstraction level.
3288          * The table names passed to this function shall not be quoted (this
3289          * function calls addIdentifierQuotes when needed).
3290          *
3291          * @param string $oldName name of table whose structure should be copied
3292          * @param string $newName name of table to be created
3293          * @param $temporary Boolean: whether the new table should be temporary
3294          * @param string $fname calling function name
3295          * @throws MWException
3296          * @return Boolean: true if operation was successful
3297          */
3298         public function duplicateTableStructure( $oldName, $newName, $temporary = false,
3299                 $fname = __METHOD__
3300         ) {
3301                 throw new MWException(
3302                         'DatabaseBase::duplicateTableStructure is not implemented in descendant class' );
3303         }
3304
3305         /**
3306          * List all tables on the database
3307          *
3308          * @param string $prefix Only show tables with this prefix, e.g. mw_
3309          * @param string $fname calling function name
3310          * @throws MWException
3311          */
3312         function listTables( $prefix = null, $fname = __METHOD__ ) {
3313                 throw new MWException( 'DatabaseBase::listTables is not implemented in descendant class' );
3314         }
3315
3316         /**
3317          * Convert a timestamp in one of the formats accepted by wfTimestamp()
3318          * to the format used for inserting into timestamp fields in this DBMS.
3319          *
3320          * The result is unquoted, and needs to be passed through addQuotes()
3321          * before it can be included in raw SQL.
3322          *
3323          * @param $ts string|int
3324          *
3325          * @return string
3326          */
3327         public function timestamp( $ts = 0 ) {
3328                 return wfTimestamp( TS_MW, $ts );
3329         }
3330
3331         /**
3332          * Convert a timestamp in one of the formats accepted by wfTimestamp()
3333          * to the format used for inserting into timestamp fields in this DBMS. If
3334          * NULL is input, it is passed through, allowing NULL values to be inserted
3335          * into timestamp fields.
3336          *
3337          * The result is unquoted, and needs to be passed through addQuotes()
3338          * before it can be included in raw SQL.
3339          *
3340          * @param $ts string|int
3341          *
3342          * @return string
3343          */
3344         public function timestampOrNull( $ts = null ) {
3345                 if ( is_null( $ts ) ) {
3346                         return null;
3347                 } else {
3348                         return $this->timestamp( $ts );
3349                 }
3350         }
3351
3352         /**
3353          * Take the result from a query, and wrap it in a ResultWrapper if
3354          * necessary. Boolean values are passed through as is, to indicate success
3355          * of write queries or failure.
3356          *
3357          * Once upon a time, DatabaseBase::query() returned a bare MySQL result
3358          * resource, and it was necessary to call this function to convert it to
3359          * a wrapper. Nowadays, raw database objects are never exposed to external
3360          * callers, so this is unnecessary in external code. For compatibility with
3361          * old code, ResultWrapper objects are passed through unaltered.
3362          *
3363          * @param $result bool|ResultWrapper
3364          *
3365          * @return bool|ResultWrapper
3366          */
3367         public function resultObject( $result ) {
3368                 if ( empty( $result ) ) {
3369                         return false;
3370                 } elseif ( $result instanceof ResultWrapper ) {
3371                         return $result;
3372                 } elseif ( $result === true ) {
3373                         // Successful write query
3374                         return $result;
3375                 } else {
3376                         return new ResultWrapper( $this, $result );
3377                 }
3378         }
3379
3380         /**
3381          * Ping the server and try to reconnect if it there is no connection
3382          *
3383          * @return bool Success or failure
3384          */
3385         public function ping() {
3386                 # Stub.  Not essential to override.
3387                 return true;
3388         }
3389
3390         /**
3391          * Get slave lag. Currently supported only by MySQL.
3392          *
3393          * Note that this function will generate a fatal error on many
3394          * installations. Most callers should use LoadBalancer::safeGetLag()
3395          * instead.
3396          *
3397          * @return int Database replication lag in seconds
3398          */
3399         public function getLag() {
3400                 return intval( $this->mFakeSlaveLag );
3401         }
3402
3403         /**
3404          * Return the maximum number of items allowed in a list, or 0 for unlimited.
3405          *
3406          * @return int
3407          */
3408         function maxListLen() {
3409                 return 0;
3410         }
3411
3412         /**
3413          * Some DBMSs have a special format for inserting into blob fields, they
3414          * don't allow simple quoted strings to be inserted. To insert into such
3415          * a field, pass the data through this function before passing it to
3416          * DatabaseBase::insert().
3417          * @param $b string
3418          * @return string
3419          */
3420         public function encodeBlob( $b ) {
3421                 return $b;
3422         }
3423
3424         /**
3425          * Some DBMSs return a special placeholder object representing blob fields
3426          * in result objects. Pass the object through this function to return the
3427          * original string.
3428          * @param $b string
3429          * @return string
3430          */
3431         public function decodeBlob( $b ) {
3432                 return $b;
3433         }
3434
3435         /**
3436          * Override database's default behavior. $options include:
3437          *     'connTimeout' : Set the connection timeout value in seconds.
3438          *                     May be useful for very long batch queries such as
3439          *                     full-wiki dumps, where a single query reads out over
3440          *                     hours or days.
3441          *
3442          * @param $options Array
3443          * @return void
3444          */
3445         public function setSessionOptions( array $options ) {
3446         }
3447
3448         /**
3449          * Read and execute SQL commands from a file.
3450          *
3451          * Returns true on success, error string or exception on failure (depending
3452          * on object's error ignore settings).
3453          *
3454          * @param string $filename File name to open
3455          * @param bool|callable $lineCallback Optional function called before reading each line
3456          * @param bool|callable $resultCallback Optional function called for each MySQL result
3457          * @param bool|string $fname Calling function name or false if name should be
3458          *      generated dynamically using $filename
3459          * @param bool|callable $inputCallback Callback: Optional function called for each complete line sent
3460          * @throws MWException
3461          * @throws Exception|MWException
3462          * @return bool|string
3463          */
3464         public function sourceFile(
3465                 $filename, $lineCallback = false, $resultCallback = false, $fname = false, $inputCallback = false
3466         ) {
3467                 wfSuppressWarnings();
3468                 $fp = fopen( $filename, 'r' );
3469                 wfRestoreWarnings();
3470
3471                 if ( false === $fp ) {
3472                         throw new MWException( "Could not open \"{$filename}\".\n" );
3473                 }
3474
3475                 if ( !$fname ) {
3476                         $fname = __METHOD__ . "( $filename )";
3477                 }
3478
3479                 try {
3480                         $error = $this->sourceStream( $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3481                 }
3482                 catch ( MWException $e ) {
3483                         fclose( $fp );
3484                         throw $e;
3485                 }
3486
3487                 fclose( $fp );
3488
3489                 return $error;
3490         }
3491
3492         /**
3493          * Get the full path of a patch file. Originally based on archive()
3494          * from updaters.inc. Keep in mind this always returns a patch, as
3495          * it fails back to MySQL if no DB-specific patch can be found
3496          *
3497          * @param string $patch The name of the patch, like patch-something.sql
3498          * @return String Full path to patch file
3499          */
3500         public function patchPath( $patch ) {
3501                 global $IP;
3502
3503                 $dbType = $this->getType();
3504                 if ( file_exists( "$IP/maintenance/$dbType/archives/$patch" ) ) {
3505                         return "$IP/maintenance/$dbType/archives/$patch";
3506                 } else {
3507                         return "$IP/maintenance/archives/$patch";
3508                 }
3509         }
3510
3511         /**
3512          * Set variables to be used in sourceFile/sourceStream, in preference to the
3513          * ones in $GLOBALS. If an array is set here, $GLOBALS will not be used at
3514          * all. If it's set to false, $GLOBALS will be used.
3515          *
3516          * @param bool|array $vars mapping variable name to value.
3517          */
3518         public function setSchemaVars( $vars ) {
3519                 $this->mSchemaVars = $vars;
3520         }
3521
3522         /**
3523          * Read and execute commands from an open file handle.
3524          *
3525          * Returns true on success, error string or exception on failure (depending
3526          * on object's error ignore settings).
3527          *
3528          * @param $fp Resource: File handle
3529          * @param $lineCallback Callback: Optional function called before reading each query
3530          * @param $resultCallback Callback: Optional function called for each MySQL result
3531          * @param string $fname Calling function name
3532          * @param $inputCallback Callback: Optional function called for each complete query sent
3533          * @return bool|string
3534          */
3535         public function sourceStream( $fp, $lineCallback = false, $resultCallback = false,
3536                 $fname = __METHOD__, $inputCallback = false )
3537         {
3538                 $cmd = '';
3539
3540                 while ( !feof( $fp ) ) {
3541                         if ( $lineCallback ) {
3542                                 call_user_func( $lineCallback );
3543                         }
3544
3545                         $line = trim( fgets( $fp ) );
3546
3547                         if ( $line == '' ) {
3548                                 continue;
3549                         }
3550
3551                         if ( '-' == $line[0] && '-' == $line[1] ) {
3552                                 continue;
3553                         }
3554
3555                         if ( $cmd != '' ) {
3556                                 $cmd .= ' ';
3557                         }
3558
3559                         $done = $this->streamStatementEnd( $cmd, $line );
3560
3561                         $cmd .= "$line\n";
3562
3563                         if ( $done || feof( $fp ) ) {
3564                                 $cmd = $this->replaceVars( $cmd );
3565
3566                                 if ( ( $inputCallback && call_user_func( $inputCallback, $cmd ) ) || !$inputCallback ) {
3567                                         $res = $this->query( $cmd, $fname );
3568
3569                                         if ( $resultCallback ) {
3570                                                 call_user_func( $resultCallback, $res, $this );
3571                                         }
3572
3573                                         if ( false === $res ) {
3574                                                 $err = $this->lastError();
3575                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3576                                         }
3577                                 }
3578                                 $cmd = '';
3579                         }
3580                 }
3581
3582                 return true;
3583         }
3584
3585         /**
3586          * Called by sourceStream() to check if we've reached a statement end
3587          *
3588          * @param string $sql SQL assembled so far
3589          * @param string $newLine New line about to be added to $sql
3590          * @return Bool Whether $newLine contains end of the statement
3591          */
3592         public function streamStatementEnd( &$sql, &$newLine ) {
3593                 if ( $this->delimiter ) {
3594                         $prev = $newLine;
3595                         $newLine = preg_replace( '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3596                         if ( $newLine != $prev ) {
3597                                 return true;
3598                         }
3599                 }
3600                 return false;
3601         }
3602
3603         /**
3604          * Database independent variable replacement. Replaces a set of variables
3605          * in an SQL statement with their contents as given by $this->getSchemaVars().
3606          *
3607          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3608          *
3609          * - '{$var}' should be used for text and is passed through the database's
3610          *   addQuotes method.
3611          * - `{$var}` should be used for identifiers (eg: table and database names),
3612          *   it is passed through the database's addIdentifierQuotes method which
3613          *   can be overridden if the database uses something other than backticks.
3614          * - / *$var* / is just encoded, besides traditional table prefix and
3615          *   table options its use should be avoided.
3616          *
3617          * @param string $ins SQL statement to replace variables in
3618          * @return String The new SQL statement with variables replaced
3619          */
3620         protected function replaceSchemaVars( $ins ) {
3621                 $vars = $this->getSchemaVars();
3622                 foreach ( $vars as $var => $value ) {
3623                         // replace '{$var}'
3624                         $ins = str_replace( '\'{$' . $var . '}\'', $this->addQuotes( $value ), $ins );
3625                         // replace `{$var}`
3626                         $ins = str_replace( '`{$' . $var . '}`', $this->addIdentifierQuotes( $value ), $ins );
3627                         // replace /*$var*/
3628                         $ins = str_replace( '/*$' . $var . '*/', $this->strencode( $value ), $ins );
3629                 }
3630                 return $ins;
3631         }
3632
3633         /**
3634          * Replace variables in sourced SQL
3635          *
3636          * @param $ins string
3637          *
3638          * @return string
3639          */
3640         protected function replaceVars( $ins ) {
3641                 $ins = $this->replaceSchemaVars( $ins );
3642
3643                 // Table prefixes
3644                 $ins = preg_replace_callback( '!/\*(?:\$wgDBprefix|_)\*/([a-zA-Z_0-9]*)!',
3645                         array( $this, 'tableNameCallback' ), $ins );
3646
3647                 // Index names
3648                 $ins = preg_replace_callback( '!/\*i\*/([a-zA-Z_0-9]*)!',
3649                         array( $this, 'indexNameCallback' ), $ins );
3650
3651                 return $ins;
3652         }
3653
3654         /**
3655          * Get schema variables. If none have been set via setSchemaVars(), then
3656          * use some defaults from the current object.
3657          *
3658          * @return array
3659          */
3660         protected function getSchemaVars() {
3661                 if ( $this->mSchemaVars ) {
3662                         return $this->mSchemaVars;
3663                 } else {
3664                         return $this->getDefaultSchemaVars();
3665                 }
3666         }
3667
3668         /**
3669          * Get schema variables to use if none have been set via setSchemaVars().
3670          *
3671          * Override this in derived classes to provide variables for tables.sql
3672          * and SQL patch files.
3673          *
3674          * @return array
3675          */
3676         protected function getDefaultSchemaVars() {
3677                 return array();
3678         }
3679
3680         /**
3681          * Table name callback
3682          *
3683          * @param $matches array
3684          *
3685          * @return string
3686          */
3687         protected function tableNameCallback( $matches ) {
3688                 return $this->tableName( $matches[1] );
3689         }
3690
3691         /**
3692          * Index name callback
3693          *
3694          * @param $matches array
3695          *
3696          * @return string
3697          */
3698         protected function indexNameCallback( $matches ) {
3699                 return $this->indexName( $matches[1] );
3700         }
3701
3702         /**
3703          * Check to see if a named lock is available. This is non-blocking.
3704          *
3705          * @param string $lockName name of lock to poll
3706          * @param string $method name of method calling us
3707          * @return Boolean
3708          * @since 1.20
3709          */
3710         public function lockIsFree( $lockName, $method ) {
3711                 return true;
3712         }
3713
3714         /**
3715          * Acquire a named lock
3716          *
3717          * Abstracted from Filestore::lock() so child classes can implement for
3718          * their own needs.
3719          *
3720          * @param string $lockName name of lock to aquire
3721          * @param string $method name of method calling us
3722          * @param $timeout Integer: timeout
3723          * @return Boolean
3724          */
3725         public function lock( $lockName, $method, $timeout = 5 ) {
3726                 return true;
3727         }
3728
3729         /**
3730          * Release a lock.
3731          *
3732          * @param string $lockName Name of lock to release
3733          * @param string $method Name of method calling us
3734          *
3735          * @return int Returns 1 if the lock was released, 0 if the lock was not established
3736          * by this thread (in which case the lock is not released), and NULL if the named
3737          * lock did not exist
3738          */
3739         public function unlock( $lockName, $method ) {
3740                 return true;
3741         }
3742
3743         /**
3744          * Lock specific tables
3745          *
3746          * @param array $read of tables to lock for read access
3747          * @param array $write of tables to lock for write access
3748          * @param string $method name of caller
3749          * @param bool $lowPriority Whether to indicate writes to be LOW PRIORITY
3750          *
3751          * @return bool
3752          */
3753         public function lockTables( $read, $write, $method, $lowPriority = true ) {
3754                 return true;
3755         }
3756
3757         /**
3758          * Unlock specific tables
3759          *
3760          * @param string $method the caller
3761          *
3762          * @return bool
3763          */
3764         public function unlockTables( $method ) {
3765                 return true;
3766         }
3767
3768         /**
3769          * Delete a table
3770          * @param $tableName string
3771          * @param $fName string
3772          * @return bool|ResultWrapper
3773          * @since 1.18
3774          */
3775         public function dropTable( $tableName, $fName = __METHOD__ ) {
3776                 if ( !$this->tableExists( $tableName, $fName ) ) {
3777                         return false;
3778                 }
3779                 $sql = "DROP TABLE " . $this->tableName( $tableName );
3780                 if ( $this->cascadingDeletes() ) {
3781                         $sql .= " CASCADE";
3782                 }
3783                 return $this->query( $sql, $fName );
3784         }
3785
3786         /**
3787          * Get search engine class. All subclasses of this need to implement this
3788          * if they wish to use searching.
3789          *
3790          * @return String
3791          */
3792         public function getSearchEngine() {
3793                 return 'SearchEngineDummy';
3794         }
3795
3796         /**
3797          * Find out when 'infinity' is. Most DBMSes support this. This is a special
3798          * keyword for timestamps in PostgreSQL, and works with CHAR(14) as well
3799          * because "i" sorts after all numbers.
3800          *
3801          * @return String
3802          */
3803         public function getInfinity() {
3804                 return 'infinity';
3805         }
3806
3807         /**
3808          * Encode an expiry time into the DBMS dependent format
3809          *
3810          * @param string $expiry timestamp for expiry, or the 'infinity' string
3811          * @return String
3812          */
3813         public function encodeExpiry( $expiry ) {
3814                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3815                         ? $this->getInfinity()
3816                         : $this->timestamp( $expiry );
3817         }
3818
3819         /**
3820          * Decode an expiry time into a DBMS independent format
3821          *
3822          * @param string $expiry DB timestamp field value for expiry
3823          * @param $format integer: TS_* constant, defaults to TS_MW
3824          * @return String
3825          */
3826         public function decodeExpiry( $expiry, $format = TS_MW ) {
3827                 return ( $expiry == '' || $expiry == $this->getInfinity() )
3828                         ? 'infinity'
3829                         : wfTimestamp( $format, $expiry );
3830         }
3831
3832         /**
3833          * Allow or deny "big selects" for this session only. This is done by setting
3834          * the sql_big_selects session variable.
3835          *
3836          * This is a MySQL-specific feature.
3837          *
3838          * @param $value Mixed: true for allow, false for deny, or "default" to
3839          *   restore the initial value
3840          */
3841         public function setBigSelects( $value = true ) {
3842                 // no-op
3843         }
3844
3845         /**
3846          * @since 1.19
3847          */
3848         public function __toString() {
3849                 return (string)$this->mConn;
3850         }
3851
3852         public function __destruct() {
3853                 if ( count( $this->mTrxIdleCallbacks ) || count( $this->mTrxPreCommitCallbacks ) ) {
3854                         trigger_error( "Transaction idle or pre-commit callbacks still pending." ); // sanity
3855                 }
3856         }
3857 }