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