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 /** Number of times to re-try an operation in case of deadlock */
  28 define( 'DEADLOCK_TRIES', 4 );
  29 /** Minimum time to wait before retry, in microseconds */
  30 define( 'DEADLOCK_DELAY_MIN', 500000 );
  31 /** Maximum time to wait before retry */
  32 define( 'DEADLOCK_DELAY_MAX', 1500000 );
  33
  34 /**
  35  * Base interface for all DBMS-specific code. At a bare minimum, all of the
  36  * following must be implemented to support MediaWiki
  37  *
  38  * @file
  39  * @ingroup Database
  40  */
  41 interface DatabaseType {
  42         /**
  43          * Get the type of the DBMS, as it appears in $wgDBtype.
  44          *
  45          * @return string
  46          */
  47         function getType();
  48
  49         /**
  50          * Open a connection to the database. Usually aborts on failure
  51          *
  52          * @param $server String: database server host
  53          * @param $user String: database user name
  54          * @param $password String: database user password
  55          * @param $dbName String: database name
  56          * @return bool
  57          * @throws DBConnectionError
  58          */
  59         function open( $server, $user, $password, $dbName );
  60
  61         /**
  62          * Fetch the next row from the given result object, in object form.
  63          * Fields can be retrieved with $row->fieldname, with fields acting like
  64          * member variables.
  65          *
  66          * @param $res ResultWrapper|object as returned from DatabaseBase::query(), etc.
  67          * @return Row object
  68          * @throws DBUnexpectedError Thrown if the database returns an error
  69          */
  70         function fetchObject( $res );
  71
  72         /**
  73          * Fetch the next row from the given result object, in associative array
  74          * form.  Fields are retrieved with $row['fieldname'].
  75          *
  76          * @param $res ResultWrapper result object as returned from DatabaseBase::query(), etc.
  77          * @return Row object
  78          * @throws DBUnexpectedError Thrown if the database returns an error
  79          */
  80         function fetchRow( $res );
  81
  82         /**
  83          * Get the number of rows in a result object
  84          *
  85          * @param $res Mixed: A SQL result
  86          * @return int
  87          */
  88         function numRows( $res );
  89
  90         /**
  91          * Get the number of fields in a result object
  92          * @see http://www.php.net/mysql_num_fields
  93          *
  94          * @param $res Mixed: A SQL result
  95          * @return int
  96          */
  97         function numFields( $res );
  98
  99         /**
 100          * Get a field name in a result object
 101          * @see http://www.php.net/mysql_field_name
 102          *
 103          * @param $res Mixed: A SQL result
 104          * @param $n Integer
 105          * @return string
 106          */
 107         function fieldName( $res, $n );
 108
 109         /**
 110          * Get the inserted value of an auto-increment row
 111          *
 112          * The value inserted should be fetched from nextSequenceValue()
 113          *
 114          * Example:
 115          * $id = $dbw->nextSequenceValue('page_page_id_seq');
 116          * $dbw->insert('page',array('page_id' => $id));
 117          * $id = $dbw->insertId();
 118          *
 119          * @return int
 120          */
 121         function insertId();
 122
 123         /**
 124          * Change the position of the cursor in a result object
 125          * @see http://www.php.net/mysql_data_seek
 126          *
 127          * @param $res Mixed: A SQL result
 128          * @param $row Mixed: Either MySQL row or ResultWrapper
 129          */
 130         function dataSeek( $res, $row );
 131
 132         /**
 133          * Get the last error number
 134          * @see http://www.php.net/mysql_errno
 135          *
 136          * @return int
 137          */
 138         function lastErrno();
 139
 140         /**
 141          * Get a description of the last error
 142          * @see http://www.php.net/mysql_error
 143          *
 144          * @return string
 145          */
 146         function lastError();
 147
 148         /**
 149          * mysql_fetch_field() wrapper
 150          * Returns false if the field doesn't exist
 151          *
 152          * @param $table string: table name
 153          * @param $field string: field name
 154          *
 155          * @return Field
 156          */
 157         function fieldInfo( $table, $field );
 158
 159         /**
 160          * Get information about an index into an object
 161          * @param $table string: Table name
 162          * @param $index string: Index name
 163          * @param $fname string: Calling function name
 164          * @return Mixed: Database-specific index description class or false if the index does not exist
 165          */
 166         function indexInfo( $table, $index, $fname = 'Database::indexInfo' );
 167
 168         /**
 169          * Get the number of rows affected by the last write query
 170          * @see http://www.php.net/mysql_affected_rows
 171          *
 172          * @return int
 173          */
 174         function affectedRows();
 175
 176         /**
 177          * Wrapper for addslashes()
 178          *
 179          * @param $s string: to be slashed.
 180          * @return string: slashed string.
 181          */
 182         function strencode( $s );
 183
 184         /**
 185          * Returns a wikitext link to the DB's website, e.g.,
 186          *     return "[http://www.mysql.com/ MySQL]";
 187          * Should at least contain plain text, if for some reason
 188          * your database has no website.
 189          *
 190          * @return string: wikitext of a link to the server software's web site
 191          */
 192         static function getSoftwareLink();
 193
 194         /**
 195          * A string describing the current software version, like from
 196          * mysql_get_server_info().
 197          *
 198          * @return string: Version information from the database server.
 199          */
 200         function getServerVersion();
 201
 202         /**
 203          * A string describing the current software version, and possibly
 204          * other details in a user-friendly way.  Will be listed on Special:Version, etc.
 205          * Use getServerVersion() to get machine-friendly information.
 206          *
 207          * @return string: Version information from the database server
 208          */
 209         function getServerInfo();
 210 }
 211
 212 /**
 213  * Database abstraction object
 214  * @ingroup Database
 215  */
 216 abstract class DatabaseBase implements DatabaseType {
 217
 218 # ------------------------------------------------------------------------------
 219 # Variables
 220 # ------------------------------------------------------------------------------
 221
 222         protected $mLastQuery = '';
 223         protected $mDoneWrites = false;
 224         protected $mPHPError = false;
 225
 226         protected $mServer, $mUser, $mPassword, $mDBname;
 227
 228         /**
 229          * @var DatabaseBase
 230          */
 231         protected $mConn = null;
 232         protected $mOpened = false;
 233
 234         protected $mTablePrefix;
 235         protected $mFlags;
 236         protected $mTrxLevel = 0;
 237         protected $mErrorCount = 0;
 238         protected $mLBInfo = array();
 239         protected $mFakeSlaveLag = null, $mFakeMaster = false;
 240         protected $mDefaultBigSelects = null;
 241         protected $mSchemaVars = false;
 242
 243         protected $preparedArgs;
 244
 245         protected $htmlErrors;
 246
 247         protected $delimiter = ';';
 248
 249 # ------------------------------------------------------------------------------
 250 # Accessors
 251 # ------------------------------------------------------------------------------
 252         # These optionally set a variable and return the previous state
 253
 254         /**
 255          * A string describing the current software version, and possibly
 256          * other details in a user-friendly way.  Will be listed on Special:Version, etc.
 257          * Use getServerVersion() to get machine-friendly information.
 258          *
 259          * @return string: Version information from the database server
 260          */
 261         public function getServerInfo() {
 262                 return $this->getServerVersion();
 263         }
 264
 265         /**
 266          * Boolean, controls output of large amounts of debug information.
 267          * @param $debug bool|null
 268          *   - true to enable debugging
 269          *   - false to disable debugging
 270          *   - omitted or null to do nothing
 271          *
 272          * @return bool|null previous value of the flag
 273          */
 274         function debug( $debug = null ) {
 275                 return wfSetBit( $this->mFlags, DBO_DEBUG, $debug );
 276         }
 277
 278         /**
 279          * Turns buffering of SQL result sets on (true) or off (false). Default is
 280          * "on".
 281          *
 282          * Unbuffered queries are very troublesome in MySQL:
 283          *
 284          *   - If another query is executed while the first query is being read
 285          *     out, the first query is killed. This means you can't call normal
 286          *     MediaWiki functions while you are reading an unbuffered query result
 287          *     from a normal wfGetDB() connection.
 288          *
 289          *   - Unbuffered queries cause the MySQL server to use large amounts of
 290          *     memory and to hold broad locks which block other queries.
 291          *
 292          * If you want to limit client-side memory, it's almost always better to
 293          * split up queries into batches using a LIMIT clause than to switch off
 294          * buffering.
 295          *
 296          * @param $buffer null|bool
 297          *
 298          * @return null|bool The previous value of the flag
 299          */
 300         function bufferResults( $buffer = null ) {
 301                 if ( is_null( $buffer ) ) {
 302                         return !(bool)( $this->mFlags & DBO_NOBUFFER );
 303                 } else {
 304                         return !wfSetBit( $this->mFlags, DBO_NOBUFFER, !$buffer );
 305                 }
 306         }
 307
 308         /**
 309          * Turns on (false) or off (true) the automatic generation and sending
 310          * of a "we're sorry, but there has been a database error" page on
 311          * database errors. Default is on (false). When turned off, the
 312          * code should use lastErrno() and lastError() to handle the
 313          * situation as appropriate.
 314          *
 315          * @param $ignoreErrors bool|null
 316          *
 317          * @return bool The previous value of the flag.
 318          */
 319         function ignoreErrors( $ignoreErrors = null ) {
 320                 return wfSetBit( $this->mFlags, DBO_IGNORE, $ignoreErrors );
 321         }
 322
 323         /**
 324          * Gets or sets the current transaction level.
 325          *
 326          * Historically, transactions were allowed to be "nested". This is no
 327          * longer supported, so this function really only returns a boolean.
 328          *
 329          * @param $level int An integer (0 or 1), or omitted to leave it unchanged.
 330          * @return int The previous value
 331          */
 332         function trxLevel( $level = null ) {
 333                 return wfSetVar( $this->mTrxLevel, $level );
 334         }
 335
 336         /**
 337          * Get/set the number of errors logged. Only useful when errors are ignored
 338          * @param $count int The count to set, or omitted to leave it unchanged.
 339          * @return int The error count
 340          */
 341         function errorCount( $count = null ) {
 342                 return wfSetVar( $this->mErrorCount, $count );
 343         }
 344
 345         /**
 346          * Get/set the table prefix.
 347          * @param $prefix string The table prefix to set, or omitted to leave it unchanged.
 348          * @return string The previous table prefix.
 349          */
 350         function tablePrefix( $prefix = null ) {
 351                 return wfSetVar( $this->mTablePrefix, $prefix );
 352         }
 353
 354         /**
 355          * Get properties passed down from the server info array of the load
 356          * balancer.
 357          *
 358          * @param $name string The entry of the info array to get, or null to get the
 359          *   whole array
 360          *
 361          * @return LoadBalancer|null
 362          */
 363         function getLBInfo( $name = null ) {
 364                 if ( is_null( $name ) ) {
 365                         return $this->mLBInfo;
 366                 } else {
 367                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 368                                 return $this->mLBInfo[$name];
 369                         } else {
 370                                 return null;
 371                         }
 372                 }
 373         }
 374
 375         /**
 376          * Set the LB info array, or a member of it. If called with one parameter,
 377          * the LB info array is set to that parameter. If it is called with two
 378          * parameters, the member with the given name is set to the given value.
 379          *
 380          * @param $name
 381          * @param $value
 382          */
 383         function setLBInfo( $name, $value = null ) {
 384                 if ( is_null( $value ) ) {
 385                         $this->mLBInfo = $name;
 386                 } else {
 387                         $this->mLBInfo[$name] = $value;
 388                 }
 389         }
 390
 391         /**
 392          * Set lag time in seconds for a fake slave
 393          *
 394          * @param $lag int
 395          */
 396         function setFakeSlaveLag( $lag ) {
 397                 $this->mFakeSlaveLag = $lag;
 398         }
 399
 400         /**
 401          * Make this connection a fake master
 402          *
 403          * @param $enabled bool
 404          */
 405         function setFakeMaster( $enabled = true ) {
 406                 $this->mFakeMaster = $enabled;
 407         }
 408
 409         /**
 410          * Returns true if this database supports (and uses) cascading deletes
 411          *
 412          * @return bool
 413          */
 414         function cascadingDeletes() {
 415                 return false;
 416         }
 417
 418         /**
 419          * Returns true if this database supports (and uses) triggers (e.g. on the page table)
 420          *
 421          * @return bool
 422          */
 423         function cleanupTriggers() {
 424                 return false;
 425         }
 426
 427         /**
 428          * Returns true if this database is strict about what can be put into an IP field.
 429          * Specifically, it uses a NULL value instead of an empty string.
 430          *
 431          * @return bool
 432          */
 433         function strictIPs() {
 434                 return false;
 435         }
 436
 437         /**
 438          * Returns true if this database uses timestamps rather than integers
 439          *
 440          * @return bool
 441         */
 442         function realTimestamps() {
 443                 return false;
 444         }
 445
 446         /**
 447          * Returns true if this database does an implicit sort when doing GROUP BY
 448          *
 449          * @return bool
 450          */
 451         function implicitGroupby() {
 452                 return true;
 453         }
 454
 455         /**
 456          * Returns true if this database does an implicit order by when the column has an index
 457          * For example: SELECT page_title FROM page LIMIT 1
 458          *
 459          * @return bool
 460          */
 461         function implicitOrderby() {
 462                 return true;
 463         }
 464
 465         /**
 466          * Returns true if this database requires that SELECT DISTINCT queries require that all
 467            ORDER BY expressions occur in the SELECT list per the SQL92 standard
 468          *
 469          * @return bool
 470          */
 471         function standardSelectDistinct() {
 472                 return true;
 473         }
 474
 475         /**
 476          * Returns true if this database can do a native search on IP columns
 477          * e.g. this works as expected: .. WHERE rc_ip = '127.42.12.102/32';
 478          *
 479          * @return bool
 480          */
 481         function searchableIPs() {
 482                 return false;
 483         }
 484
 485         /**
 486          * Returns true if this database can use functional indexes
 487          *
 488          * @return bool
 489          */
 490         function functionalIndexes() {
 491                 return false;
 492         }
 493
 494         /**
 495          * Return the last query that went through DatabaseBase::query()
 496          * @return String
 497          */
 498         function lastQuery() {
 499                 return $this->mLastQuery;
 500         }
 501
 502         /**
 503          * Returns true if the connection may have been used for write queries.
 504          * Should return true if unsure.
 505          *
 506          * @return bool
 507          */
 508         function doneWrites() {
 509                 return $this->mDoneWrites;
 510         }
 511
 512         /**
 513          * Is a connection to the database open?
 514          * @return Boolean
 515          */
 516         function isOpen() {
 517                 return $this->mOpened;
 518         }
 519
 520         /**
 521          * Set a flag for this connection
 522          *
 523          * @param $flag Integer: DBO_* constants from Defines.php:
 524          *   - DBO_DEBUG: output some debug info (same as debug())
 525          *   - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
 526          *   - DBO_IGNORE: ignore errors (same as ignoreErrors())
 527          *   - DBO_TRX: automatically start transactions
 528          *   - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
 529          *       and removes it in command line mode
 530          *   - DBO_PERSISTENT: use persistant database connection
 531          */
 532         function setFlag( $flag ) {
 533                 $this->mFlags |= $flag;
 534         }
 535
 536         /**
 537          * Clear a flag for this connection
 538          *
 539          * @param $flag: same as setFlag()'s $flag param
 540          */
 541         function clearFlag( $flag ) {
 542                 $this->mFlags &= ~$flag;
 543         }
 544
 545         /**
 546          * Returns a boolean whether the flag $flag is set for this connection
 547          *
 548          * @param $flag: same as setFlag()'s $flag param
 549          * @return Boolean
 550          */
 551         function getFlag( $flag ) {
 552                 return !!( $this->mFlags & $flag );
 553         }
 554
 555         /**
 556          * General read-only accessor
 557          *
 558          * @param $name string
 559          *
 560          * @return string
 561          */
 562         function getProperty( $name ) {
 563                 return $this->$name;
 564         }
 565
 566         /**
 567          * @return string
 568          */
 569         function getWikiID() {
 570                 if ( $this->mTablePrefix ) {
 571                         return "{$this->mDBname}-{$this->mTablePrefix}";
 572                 } else {
 573                         return $this->mDBname;
 574                 }
 575         }
 576
 577         /**
 578          * Return a path to the DBMS-specific schema file, otherwise default to tables.sql
 579          *
 580          * @return string
 581          */
 582         public function getSchemaPath() {
 583                 global $IP;
 584                 if ( file_exists( "$IP/maintenance/" . $this->getType() . "/tables.sql" ) ) {
 585                         return "$IP/maintenance/" . $this->getType() . "/tables.sql";
 586                 } else {
 587                         return "$IP/maintenance/tables.sql";
 588                 }
 589         }
 590
 591 # ------------------------------------------------------------------------------
 592 # Other functions
 593 # ------------------------------------------------------------------------------
 594
 595         /**
 596          * Constructor.
 597          * @param $server String: database server host
 598          * @param $user String: database user name
 599          * @param $password String: database user password
 600          * @param $dbName String: database name
 601          * @param $flags
 602          * @param $tablePrefix String: database table prefixes. By default use the prefix gave in LocalSettings.php
 603          */
 604         function __construct( $server = false, $user = false, $password = false, $dbName = false,
 605                 $flags = 0, $tablePrefix = 'get from global'
 606         ) {
 607                 global $wgDBprefix, $wgCommandLineMode;
 608
 609                 $this->mFlags = $flags;
 610
 611                 if ( $this->mFlags & DBO_DEFAULT ) {
 612                         if ( $wgCommandLineMode ) {
 613                                 $this->mFlags &= ~DBO_TRX;
 614                         } else {
 615                                 $this->mFlags |= DBO_TRX;
 616                         }
 617                 }
 618
 619                 /** Get the default table prefix*/
 620                 if ( $tablePrefix == 'get from global' ) {
 621                         $this->mTablePrefix = $wgDBprefix;
 622                 } else {
 623                         $this->mTablePrefix = $tablePrefix;
 624                 }
 625
 626                 if ( $user ) {
 627                         $this->open( $server, $user, $password, $dbName );
 628                 }
 629         }
 630
 631         /**
 632          * Called by serialize. Throw an exception when DB connection is serialized.
 633          * This causes problems on some database engines because the connection is
 634          * not restored on unserialize.
 635          */
 636         public function __sleep() {
 637                 throw new MWException( 'Database serialization may cause problems, since the connection is not restored on wakeup.' );
 638         }
 639
 640         /**
 641          * Same as new DatabaseMysql( ... ), kept for backward compatibility
 642          * @deprecated since 1.17
 643          *
 644          * @param $server
 645          * @param $user
 646          * @param $password
 647          * @param $dbName
 648          * @param $flags int
 649          * @return DatabaseMysql
 650          */
 651         static function newFromParams( $server, $user, $password, $dbName, $flags = 0 ) {
 652                 wfDeprecated( __METHOD__, '1.17' );
 653                 return new DatabaseMysql( $server, $user, $password, $dbName, $flags );
 654         }
 655
 656         /**
 657          * Same as new factory( ... ), kept for backward compatibility
 658          * @deprecated since 1.18
 659          * @see Database::factory()
 660          * @return DatabaseBase
 661          */
 662         public final static function newFromType( $dbType, $p = array() ) {
 663                 wfDeprecated( __METHOD__, '1.18' );
 664                 if ( isset( $p['tableprefix'] ) ) {
 665                         $p['tablePrefix'] = $p['tableprefix'];
 666                 }
 667                 return self::factory( $dbType, $p );
 668         }
 669
 670         /**
 671          * Given a DB type, construct the name of the appropriate child class of
 672          * DatabaseBase. This is designed to replace all of the manual stuff like:
 673          *      $class = 'Database' . ucfirst( strtolower( $type ) );
 674          * as well as validate against the canonical list of DB types we have
 675          *
 676          * This factory function is mostly useful for when you need to connect to a
 677          * database other than the MediaWiki default (such as for external auth,
 678          * an extension, et cetera). Do not use this to connect to the MediaWiki
 679          * database. Example uses in core:
 680          * @see LoadBalancer::reallyOpenConnection()
 681          * @see ExternalUser_MediaWiki::initFromCond()
 682          * @see ForeignDBRepo::getMasterDB()
 683          * @see WebInstaller_DBConnect::execute()
 684          *
 685          * @since 1.18
 686          *
 687          * @param $dbType String A possible DB type
 688          * @param $p Array An array of options to pass to the constructor.
 689          *    Valid options are: host, user, password, dbname, flags, tablePrefix
 690          * @return DatabaseBase subclass or null
 691          */
 692         public final static function factory( $dbType, $p = array() ) {
 693                 $canonicalDBTypes = array(
 694                         'mysql', 'postgres', 'sqlite', 'oracle', 'mssql', 'ibm_db2'
 695                 );
 696                 $dbType = strtolower( $dbType );
 697                 $class = 'Database' . ucfirst( $dbType );
 698
 699                 if( in_array( $dbType, $canonicalDBTypes ) || ( class_exists( $class ) && is_subclass_of( $class, 'DatabaseBase' ) ) ) {
 700                         return new $class(
 701                                 isset( $p['host'] ) ? $p['host'] : false,
 702                                 isset( $p['user'] ) ? $p['user'] : false,
 703                                 isset( $p['password'] ) ? $p['password'] : false,
 704                                 isset( $p['dbname'] ) ? $p['dbname'] : false,
 705                                 isset( $p['flags'] ) ? $p['flags'] : 0,
 706                                 isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : 'get from global'
 707                         );
 708                 } else {
 709                         return null;
 710                 }
 711         }
 712
 713         protected function installErrorHandler() {
 714                 $this->mPHPError = false;
 715                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 716                 set_error_handler( array( $this, 'connectionErrorHandler' ) );
 717         }
 718
 719         /**
 720          * @return bool|string
 721          */
 722         protected function restoreErrorHandler() {
 723                 restore_error_handler();
 724                 if ( $this->htmlErrors !== false ) {
 725                         ini_set( 'html_errors', $this->htmlErrors );
 726                 }
 727                 if ( $this->mPHPError ) {
 728                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 729                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 730                         return $error;
 731                 } else {
 732                         return false;
 733                 }
 734         }
 735
 736         /**
 737          * @param $errno
 738          * @param $errstr
 739          */
 740         protected function connectionErrorHandler( $errno,  $errstr ) {
 741                 $this->mPHPError = $errstr;
 742         }
 743
 744         /**
 745          * Closes a database connection.
 746          * if it is open : commits any open transactions
 747          *
 748          * @return Bool operation success. true if already closed.
 749          */
 750         public function close() {
 751                 $this->mOpened = false;
 752                 if ( $this->mConn ) {
 753                         if ( $this->trxLevel() ) {
 754                                 $this->commit( __METHOD__ );
 755                         }
 756                         $ret = $this->closeConnection();
 757                         $this->mConn = false;
 758                         return $ret;
 759                 } else {
 760                         return true;
 761                 }
 762         }
 763
 764         /**
 765          * Closes underlying database connection
 766          * @since 1.20
 767          * @return bool: Whether connection was closed successfully
 768          */
 769         protected abstract function closeConnection();
 770
 771         /**
 772          * @param $error String: fallback error message, used if none is given by DB
 773          */
 774         function reportConnectionError( $error = 'Unknown error' ) {
 775                 $myError = $this->lastError();
 776                 if ( $myError ) {
 777                         $error = $myError;
 778                 }
 779
 780                 # New method
 781                 throw new DBConnectionError( $this, $error );
 782         }
 783
 784         /**
 785          * The DBMS-dependent part of query()
 786          *
 787          * @param  $sql String: SQL query.
 788          * @return ResultWrapper Result object to feed to fetchObject, fetchRow, ...; or false on failure
 789          */
 790         protected abstract function doQuery( $sql );
 791
 792         /**
 793          * Determine whether a query writes to the DB.
 794          * Should return true if unsure.
 795          *
 796          * @param $sql string
 797          *
 798          * @return bool
 799          */
 800         function isWriteQuery( $sql ) {
 801                 return !preg_match( '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 802         }
 803
 804         /**
 805          * Run an SQL query and return the result. Normally throws a DBQueryError
 806          * on failure. If errors are ignored, returns false instead.
 807          *
 808          * In new code, the query wrappers select(), insert(), update(), delete(),
 809          * etc. should be used where possible, since they give much better DBMS
 810          * independence and automatically quote or validate user input in a variety
 811          * of contexts. This function is generally only useful for queries which are
 812          * explicitly DBMS-dependent and are unsupported by the query wrappers, such
 813          * as CREATE TABLE.
 814          *
 815          * However, the query wrappers themselves should call this function.
 816          *
 817          * @param  $sql        String: SQL query
 818          * @param  $fname      String: Name of the calling function, for profiling/SHOW PROCESSLIST
 819          *     comment (you can use __METHOD__ or add some extra info)
 820          * @param  $tempIgnore Boolean:   Whether to avoid throwing an exception on errors...
 821          *     maybe best to catch the exception instead?
 822          * @return boolean|ResultWrapper. true for a successful write query, ResultWrapper object
 823          *     for a successful read query, or false on failure if $tempIgnore set
 824          * @throws DBQueryError Thrown when the database returns an error of any kind
 825          */
 826         public function query( $sql, $fname = '', $tempIgnore = false ) {
 827                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 828                 if ( !Profiler::instance()->isStub() ) {
 829                         # generalizeSQL will probably cut down the query to reasonable
 830                         # logging size most of the time. The substr is really just a sanity check.
 831
 832                         if ( $isMaster ) {
 833                                 $queryProf = 'query-m: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
 834                                 $totalProf = 'DatabaseBase::query-master';
 835                         } else {
 836                                 $queryProf = 'query: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
 837                                 $totalProf = 'DatabaseBase::query';
 838                         }
 839
 840                         wfProfileIn( $totalProf );
 841                         wfProfileIn( $queryProf );
 842                 }
 843
 844                 $this->mLastQuery = $sql;
 845                 if ( !$this->mDoneWrites && $this->isWriteQuery( $sql ) ) {
 846                         # Set a flag indicating that writes have been done
 847                         wfDebug( __METHOD__ . ": Writes done: $sql\n" );
 848                         $this->mDoneWrites = true;
 849                 }
 850
 851                 # Add a comment for easy SHOW PROCESSLIST interpretation
 852                 global $wgUser;
 853                 if ( is_object( $wgUser ) && $wgUser->isItemLoaded( 'name' ) ) {
 854                         $userName = $wgUser->getName();
 855                         if ( mb_strlen( $userName ) > 15 ) {
 856                                 $userName = mb_substr( $userName, 0, 15 ) . '...';
 857                         }
 858                         $userName = str_replace( '/', '', $userName );
 859                 } else {
 860                         $userName = '';
 861                 }
 862                 $commentedSql = preg_replace( '/\s/', " /* $fname $userName */ ", $sql, 1 );
 863
 864                 # If DBO_TRX is set, start a transaction
 865                 if ( ( $this->mFlags & DBO_TRX ) && !$this->trxLevel() &&
 866                         $sql != 'BEGIN' && $sql != 'COMMIT' && $sql != 'ROLLBACK' ) {
 867                         # avoid establishing transactions for SHOW and SET statements too -
 868                         # that would delay transaction initializations to once connection
 869                         # is really used by application
 870                         $sqlstart = substr( $sql, 0, 10 ); // very much worth it, benchmark certified(tm)
 871                         if ( strpos( $sqlstart, "SHOW " ) !== 0 && strpos( $sqlstart, "SET " ) !== 0 )
 872                                 $this->begin( __METHOD__ . " ($fname)" );
 873                 }
 874
 875                 if ( $this->debug() ) {
 876                         static $cnt = 0;
 877
 878                         $cnt++;
 879                         $sqlx = substr( $commentedSql, 0, 500 );
 880                         $sqlx = strtr( $sqlx, "\t\n", '  ' );
 881
 882                         $master = $isMaster ? 'master' : 'slave';
 883                         wfDebug( "Query {$this->mDBname} ($cnt) ($master): $sqlx\n" );
 884                 }
 885
 886                 if ( istainted( $sql ) & TC_MYSQL ) {
 887                         throw new MWException( 'Tainted query found' );
 888                 }
 889
 890                 $queryId = MWDebug::query( $sql, $fname, $isMaster );
 891
 892                 # Do the query and handle errors
 893                 $ret = $this->doQuery( $commentedSql );
 894
 895                 MWDebug::queryTime( $queryId );
 896
 897                 # Try reconnecting if the connection was lost
 898                 if ( false === $ret && $this->wasErrorReissuable() ) {
 899                         # Transaction is gone, like it or not
 900                         $this->mTrxLevel = 0;
 901                         wfDebug( "Connection lost, reconnecting...\n" );
 902
 903                         if ( $this->ping() ) {
 904                                 wfDebug( "Reconnected\n" );
 905                                 $sqlx = substr( $commentedSql, 0, 500 );
 906                                 $sqlx = strtr( $sqlx, "\t\n", '  ' );
 907                                 global $wgRequestTime;
 908                                 $elapsed = round( microtime( true ) - $wgRequestTime, 3 );
 909                                 if ( $elapsed < 300 ) {
 910                                         # Not a database error to lose a transaction after a minute or two
 911                                         wfLogDBError( "Connection lost and reconnected after {$elapsed}s, query: $sqlx\n" );
 912                                 }
 913                                 $ret = $this->doQuery( $commentedSql );
 914                         } else {
 915                                 wfDebug( "Failed\n" );
 916                         }
 917                 }
 918
 919                 if ( false === $ret ) {
 920                         $this->reportQueryError( $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 921                 }
 922
 923                 if ( !Profiler::instance()->isStub() ) {
 924                         wfProfileOut( $queryProf );
 925                         wfProfileOut( $totalProf );
 926                 }
 927
 928                 return $this->resultObject( $ret );
 929         }
 930
 931         /**
 932          * Report a query error. Log the error, and if neither the object ignore
 933          * flag nor the $tempIgnore flag is set, throw a DBQueryError.
 934          *
 935          * @param $error String
 936          * @param $errno Integer
 937          * @param $sql String
 938          * @param $fname String
 939          * @param $tempIgnore Boolean
 940          */
 941         function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
 942                 # Ignore errors during error handling to avoid infinite recursion
 943                 $ignore = $this->ignoreErrors( true );
 944                 ++$this->mErrorCount;
 945
 946                 if ( $ignore || $tempIgnore ) {
 947                         wfDebug( "SQL ERROR (ignored): $error\n" );
 948                         $this->ignoreErrors( $ignore );
 949                 } else {
 950                         $sql1line = str_replace( "\n", "\\n", $sql );
 951                         wfLogDBError( "$fname\t{$this->mServer}\t$errno\t$error\t$sql1line\n" );
 952                         wfDebug( "SQL ERROR: " . $error . "\n" );
 953                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
 954                 }
 955         }
 956
 957         /**
 958          * Intended to be compatible with the PEAR::DB wrapper functions.
 959          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
 960          *
 961          * ? = scalar value, quoted as necessary
 962          * ! = raw SQL bit (a function for instance)
 963          * & = filename; reads the file and inserts as a blob
 964          *     (we don't use this though...)
 965          *
 966          * This function should not be used directly by new code outside of the
 967          * database classes. The query wrapper functions (select() etc.) should be
 968          * used instead.
 969          *
 970          * @param $sql string
 971          * @param $func string
 972          *
 973          * @return array
 974          */
 975         function prepare( $sql, $func = 'DatabaseBase::prepare' ) {
 976                 /* MySQL doesn't support prepared statements (yet), so just
 977                    pack up the query for reference. We'll manually replace
 978                    the bits later. */
 979                 return array( 'query' => $sql, 'func' => $func );
 980         }
 981
 982         /**
 983          * Free a prepared query, generated by prepare().
 984          * @param $prepared
 985          */
 986         function freePrepared( $prepared ) {
 987                 /* No-op by default */
 988         }
 989
 990         /**
 991          * Execute a prepared query with the various arguments
 992          * @param $prepared String: the prepared sql
 993          * @param $args Mixed: Either an array here, or put scalars as varargs
 994          *
 995          * @return ResultWrapper
 996          */
 997         function execute( $prepared, $args = null ) {
 998                 if ( !is_array( $args ) ) {
 999                         # Pull the var args
1000                         $args = func_get_args();
1001                         array_shift( $args );
1002                 }
1003
1004                 $sql = $this->fillPrepared( $prepared['query'], $args );
1005
1006                 return $this->query( $sql, $prepared['func'] );
1007         }
1008
1009         /**
1010          * Prepare & execute an SQL statement, quoting and inserting arguments
1011          * in the appropriate places.
1012          *
1013          * This function should not be used directly by new code outside of the
1014          * database classes. The query wrapper functions (select() etc.) should be
1015          * used instead.
1016          *
1017          * @param $query String
1018          * @param $args ...
1019          *
1020          * @return ResultWrapper
1021          */
1022         function safeQuery( $query, $args = null ) {
1023                 $prepared = $this->prepare( $query, 'DatabaseBase::safeQuery' );
1024
1025                 if ( !is_array( $args ) ) {
1026                         # Pull the var args
1027                         $args = func_get_args();
1028                         array_shift( $args );
1029                 }
1030
1031                 $retval = $this->execute( $prepared, $args );
1032                 $this->freePrepared( $prepared );
1033
1034                 return $retval;
1035         }
1036
1037         /**
1038          * For faking prepared SQL statements on DBs that don't support
1039          * it directly.
1040          * @param $preparedQuery String: a 'preparable' SQL statement
1041          * @param $args Array of arguments to fill it with
1042          * @return string executable SQL
1043          */
1044         function fillPrepared( $preparedQuery, $args ) {
1045                 reset( $args );
1046                 $this->preparedArgs =& $args;
1047
1048                 return preg_replace_callback( '/(\\\\[?!&]|[?!&])/',
1049                         array( &$this, 'fillPreparedArg' ), $preparedQuery );
1050         }
1051
1052         /**
1053          * preg_callback func for fillPrepared()
1054          * The arguments should be in $this->preparedArgs and must not be touched
1055          * while we're doing this.
1056          *
1057          * @param $matches Array
1058          * @return String
1059          */
1060         function fillPreparedArg( $matches ) {
1061                 switch( $matches[1] ) {
1062                         case '\\?': return '?';
1063                         case '\\!': return '!';
1064                         case '\\&': return '&';
1065                 }
1066
1067                 list( /* $n */ , $arg ) = each( $this->preparedArgs );
1068
1069                 switch( $matches[1] ) {
1070                         case '?': return $this->addQuotes( $arg );
1071                         case '!': return $arg;
1072                         case '&':
1073                                 # return $this->addQuotes( file_get_contents( $arg ) );
1074                                 throw new DBUnexpectedError( $this, '& mode is not implemented. If it\'s really needed, uncomment the line above.' );
1075                         default:
1076                                 throw new DBUnexpectedError( $this, 'Received invalid match. This should never happen!' );
1077                 }
1078         }
1079
1080         /**
1081          * Free a result object returned by query() or select(). It's usually not
1082          * necessary to call this, just use unset() or let the variable holding
1083          * the result object go out of scope.
1084          *
1085          * @param $res Mixed: A SQL result
1086          */
1087         function freeResult( $res ) {
1088         }
1089
1090         /**
1091          * Simple UPDATE wrapper.
1092          * Usually throws a DBQueryError on failure.
1093          * If errors are explicitly ignored, returns success
1094          *
1095          * This function exists for historical reasons, DatabaseBase::update() has a more standard
1096          * calling convention and feature set
1097          *
1098          * @param $table string
1099          * @param $var
1100          * @param $value
1101          * @param $cond
1102          * @param $fname string
1103          *
1104          * @return bool
1105          */
1106         function set( $table, $var, $value, $cond, $fname = 'DatabaseBase::set' ) {
1107                 $table = $this->tableName( $table );
1108                 $sql = "UPDATE $table SET $var = '" .
1109                   $this->strencode( $value ) . "' WHERE ($cond)";
1110
1111                 return (bool)$this->query( $sql, $fname );
1112         }
1113
1114         /**
1115          * A SELECT wrapper which returns a single field from a single result row.
1116          *
1117          * Usually throws a DBQueryError on failure. If errors are explicitly
1118          * ignored, returns false on failure.
1119          *
1120          * If no result rows are returned from the query, false is returned.
1121          *
1122          * @param $table string|array Table name. See DatabaseBase::select() for details.
1123          * @param $var string The field name to select. This must be a valid SQL
1124          *   fragment: do not use unvalidated user input.
1125          * @param $cond string|array The condition array. See DatabaseBase::select() for details.
1126          * @param $fname string The function name of the caller.
1127          * @param $options string|array The query options. See DatabaseBase::select() for details.
1128          *
1129          * @return bool|mixed The value from the field, or false on failure.
1130          */
1131         function selectField( $table, $var, $cond = '', $fname = 'DatabaseBase::selectField',
1132                 $options = array() )
1133         {
1134                 if ( !is_array( $options ) ) {
1135                         $options = array( $options );
1136                 }
1137
1138                 $options['LIMIT'] = 1;
1139
1140                 $res = $this->select( $table, $var, $cond, $fname, $options );
1141
1142                 if ( $res === false || !$this->numRows( $res ) ) {
1143                         return false;
1144                 }
1145
1146                 $row = $this->fetchRow( $res );
1147
1148                 if ( $row !== false ) {
1149                         return reset( $row );
1150                 } else {
1151                         return false;
1152                 }
1153         }
1154
1155         /**
1156          * Returns an optional USE INDEX clause to go after the table, and a
1157          * string to go at the end of the query.
1158          *
1159          * @param $options Array: associative array of options to be turned into
1160          *              an SQL query, valid keys are listed in the function.
1161          * @return Array
1162          * @see DatabaseBase::select()
1163          */
1164         function makeSelectOptions( $options ) {
1165                 $preLimitTail = $postLimitTail = '';
1166                 $startOpts = '';
1167
1168                 $noKeyOptions = array();
1169
1170                 foreach ( $options as $key => $option ) {
1171                         if ( is_numeric( $key ) ) {
1172                                 $noKeyOptions[$option] = true;
1173                         }
1174                 }
1175
1176                 if ( isset( $options['GROUP BY'] ) ) {
1177                         $gb = is_array( $options['GROUP BY'] )
1178                                 ? implode( ',', $options['GROUP BY'] )
1179                                 : $options['GROUP BY'];
1180                         $preLimitTail .= " GROUP BY {$gb}";
1181                 }
1182
1183                 if ( isset( $options['HAVING'] ) ) {
1184                         $preLimitTail .= " HAVING {$options['HAVING']}";
1185                 }
1186
1187                 if ( isset( $options['ORDER BY'] ) ) {
1188                         $ob = is_array( $options['ORDER BY'] )
1189                                 ? implode( ',', $options['ORDER BY'] )
1190                                 : $options['ORDER BY'];
1191                         $preLimitTail .= " ORDER BY {$ob}";
1192                 }
1193
1194                 // if (isset($options['LIMIT'])) {
1195                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
1196                 //              isset($options['OFFSET']) ? $options['OFFSET']
1197                 //              : false);
1198                 // }
1199
1200                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1201                         $postLimitTail .= ' FOR UPDATE';
1202                 }
1203
1204                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1205                         $postLimitTail .= ' LOCK IN SHARE MODE';
1206                 }
1207
1208                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1209                         $startOpts .= 'DISTINCT';
1210                 }
1211
1212                 # Various MySQL extensions
1213                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1214                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1215                 }
1216
1217                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1218                         $startOpts .= ' HIGH_PRIORITY';
1219                 }
1220
1221                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1222                         $startOpts .= ' SQL_BIG_RESULT';
1223                 }
1224
1225                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1226                         $startOpts .= ' SQL_BUFFER_RESULT';
1227                 }
1228
1229                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1230                         $startOpts .= ' SQL_SMALL_RESULT';
1231                 }
1232
1233                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1234                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1235                 }
1236
1237                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1238                         $startOpts .= ' SQL_CACHE';
1239                 }
1240
1241                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1242                         $startOpts .= ' SQL_NO_CACHE';
1243                 }
1244
1245                 if ( isset( $options['USE INDEX'] ) && ! is_array( $options['USE INDEX'] ) ) {
1246                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1247                 } else {
1248                         $useIndex = '';
1249                 }
1250
1251                 return array( $startOpts, $useIndex, $preLimitTail, $postLimitTail );
1252         }
1253
1254         /**
1255          * Execute a SELECT query constructed using the various parameters provided.
1256          * See below for full details of the parameters.
1257          *
1258          * @param $table String|Array Table name
1259          * @param $vars String|Array Field names
1260          * @param $conds String|Array Conditions
1261          * @param $fname String Caller function name
1262          * @param $options Array Query options
1263          * @param $join_conds Array Join conditions
1264          *
1265          * @param $table string|array
1266          *
1267          * May be either an array of table names, or a single string holding a table
1268          * name. If an array is given, table aliases can be specified, for example:
1269          *
1270          *    array( 'a' => 'user' )
1271          *
1272          * This includes the user table in the query, with the alias "a" available
1273          * for use in field names (e.g. a.user_name).
1274          *
1275          * All of the table names given here are automatically run through
1276          * DatabaseBase::tableName(), which causes the table prefix (if any) to be
1277          * added, and various other table name mappings to be performed.
1278          *
1279          *
1280          * @param $vars string|array
1281          *
1282          * May be either a field name or an array of field names. The field names
1283          * here are complete fragments of SQL, for direct inclusion into the SELECT
1284          * query. Expressions and aliases may be specified as in SQL, for example:
1285          *
1286          *   array( 'MAX(rev_id) AS maxrev' )
1287          *
1288          * If an expression is given, care must be taken to ensure that it is
1289          * DBMS-independent.
1290          *
1291          *
1292          * @param $conds string|array
1293          *
1294          * May be either a string containing a single condition, or an array of
1295          * conditions. If an array is given, the conditions constructed from each
1296          * element are combined with AND.
1297          *
1298          * Array elements may take one of two forms:
1299          *
1300          *   - Elements with a numeric key are interpreted as raw SQL fragments.
1301          *   - Elements with a string key are interpreted as equality conditions,
1302          *     where the key is the field name.
1303          *     - If the value of such an array element is a scalar (such as a
1304          *       string), it will be treated as data and thus quoted appropriately.
1305          *       If it is null, an IS NULL clause will be added.
1306          *     - If the value is an array, an IN(...) clause will be constructed,
1307          *       such that the field name may match any of the elements in the
1308          *       array. The elements of the array will be quoted.
1309          *
1310          * Note that expressions are often DBMS-dependent in their syntax.
1311          * DBMS-independent wrappers are provided for constructing several types of
1312          * expression commonly used in condition queries. See:
1313          *    - DatabaseBase::buildLike()
1314          *    - DatabaseBase::conditional()
1315          *
1316          *
1317          * @param $options string|array
1318          *
1319          * Optional: Array of query options. Boolean options are specified by
1320          * including them in the array as a string value with a numeric key, for
1321          * example:
1322          *
1323          *    array( 'FOR UPDATE' )
1324          *
1325          * The supported options are:
1326          *
1327          *   - OFFSET: Skip this many rows at the start of the result set. OFFSET
1328          *     with LIMIT can theoretically be used for paging through a result set,
1329          *     but this is discouraged in MediaWiki for performance reasons.
1330          *
1331          *   - LIMIT: Integer: return at most this many rows. The rows are sorted
1332          *     and then the first rows are taken until the limit is reached. LIMIT
1333          *     is applied to a result set after OFFSET.
1334          *
1335          *   - FOR UPDATE: Boolean: lock the returned rows so that they can't be
1336          *     changed until the next COMMIT.
1337          *
1338          *   - DISTINCT: Boolean: return only unique result rows.
1339          *
1340          *   - GROUP BY: May be either an SQL fragment string naming a field or
1341          *     expression to group by, or an array of such SQL fragments.
1342          *
1343          *   - HAVING: A string containing a HAVING clause.
1344          *
1345          *   - ORDER BY: May be either an SQL fragment giving a field name or
1346          *     expression to order by, or an array of such SQL fragments.
1347          *
1348          *   - USE INDEX: This may be either a string giving the index name to use
1349          *     for the query, or an array. If it is an associative array, each key
1350          *     gives the table name (or alias), each value gives the index name to
1351          *     use for that table. All strings are SQL fragments and so should be
1352          *     validated by the caller.
1353          *
1354          *   - EXPLAIN: In MySQL, this causes an EXPLAIN SELECT query to be run,
1355          *     instead of SELECT.
1356          *
1357          * And also the following boolean MySQL extensions, see the MySQL manual
1358          * for documentation:
1359          *
1360          *    - LOCK IN SHARE MODE
1361          *    - STRAIGHT_JOIN
1362          *    - HIGH_PRIORITY
1363          *    - SQL_BIG_RESULT
1364          *    - SQL_BUFFER_RESULT
1365          *    - SQL_SMALL_RESULT
1366          *    - SQL_CALC_FOUND_ROWS
1367          *    - SQL_CACHE
1368          *    - SQL_NO_CACHE
1369          *
1370          *
1371          * @param $join_conds string|array
1372          *
1373          * Optional associative array of table-specific join conditions. In the
1374          * most common case, this is unnecessary, since the join condition can be
1375          * in $conds. However, it is useful for doing a LEFT JOIN.
1376          *
1377          * The key of the array contains the table name or alias. The value is an
1378          * array with two elements, numbered 0 and 1. The first gives the type of
1379          * join, the second is an SQL fragment giving the join condition for that
1380          * table. For example:
1381          *
1382          *    array( 'page' => array('LEFT JOIN','page_latest=rev_id') )
1383          *
1384          * @return ResultWrapper. If the query returned no rows, a ResultWrapper
1385          *   with no rows in it will be returned. If there was a query error, a
1386          *   DBQueryError exception will be thrown, except if the "ignore errors"
1387          *   option was set, in which case false will be returned.
1388          */
1389         function select( $table, $vars, $conds = '', $fname = 'DatabaseBase::select',
1390                 $options = array(), $join_conds = array() ) {
1391                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1392
1393                 return $this->query( $sql, $fname );
1394         }
1395
1396         /**
1397          * The equivalent of DatabaseBase::select() except that the constructed SQL
1398          * is returned, instead of being immediately executed.
1399          *
1400          * @param $table string|array Table name
1401          * @param $vars string|array Field names
1402          * @param $conds string|array Conditions
1403          * @param $fname string Caller function name
1404          * @param $options string|array Query options
1405          * @param $join_conds string|array Join conditions
1406          *
1407          * @return string SQL query string.
1408          * @see DatabaseBase::select()
1409          */
1410         function selectSQLText( $table, $vars, $conds = '', $fname = 'DatabaseBase::select', $options = array(), $join_conds = array() ) {
1411                 if ( is_array( $vars ) ) {
1412                         $vars = implode( ',', $vars );
1413                 }
1414
1415                 $options = (array)$options;
1416
1417                 if ( is_array( $table ) ) {
1418                         $useIndex = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1419                                 ? $options['USE INDEX']
1420                                 : array();
1421                         if ( count( $join_conds ) || count( $useIndex ) ) {
1422                                 $from = ' FROM ' .
1423                                         $this->tableNamesWithUseIndexOrJOIN( $table, $useIndex, $join_conds );
1424                         } else {
1425                                 $from = ' FROM ' . implode( ',', $this->tableNamesWithAlias( $table ) );
1426                         }
1427                 } elseif ( $table != '' ) {
1428                         if ( $table[0] == ' ' ) {
1429                                 $from = ' FROM ' . $table;
1430                         } else {
1431                                 $from = ' FROM ' . $this->tableName( $table );
1432                         }
1433                 } else {
1434                         $from = '';
1435                 }
1436
1437                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail ) = $this->makeSelectOptions( $options );
1438
1439                 if ( !empty( $conds ) ) {
1440                         if ( is_array( $conds ) ) {
1441                                 $conds = $this->makeList( $conds, LIST_AND );
1442                         }
1443                         $sql = "SELECT $startOpts $vars $from $useIndex WHERE $conds $preLimitTail";
1444                 } else {
1445                         $sql = "SELECT $startOpts $vars $from $useIndex $preLimitTail";
1446                 }
1447
1448                 if ( isset( $options['LIMIT'] ) ) {
1449                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1450                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1451                 }
1452                 $sql = "$sql $postLimitTail";
1453
1454                 if ( isset( $options['EXPLAIN'] ) ) {
1455                         $sql = 'EXPLAIN ' . $sql;
1456                 }
1457
1458                 return $sql;
1459         }
1460
1461         /**
1462          * Single row SELECT wrapper. Equivalent to DatabaseBase::select(), except
1463          * that a single row object is returned. If the query returns no rows,
1464          * false is returned.
1465          *
1466          * @param $table string|array Table name
1467          * @param $vars string|array Field names
1468          * @param $conds array Conditions
1469          * @param $fname string Caller function name
1470          * @param $options string|array Query options
1471          * @param $join_conds array|string Join conditions
1472          *
1473          * @return object|bool
1474          */
1475         function selectRow( $table, $vars, $conds, $fname = 'DatabaseBase::selectRow',
1476                 $options = array(), $join_conds = array() )
1477         {
1478                 $options = (array)$options;
1479                 $options['LIMIT'] = 1;
1480                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1481
1482                 if ( $res === false ) {
1483                         return false;
1484                 }
1485
1486                 if ( !$this->numRows( $res ) ) {
1487                         return false;
1488                 }
1489
1490                 $obj = $this->fetchObject( $res );
1491
1492                 return $obj;
1493         }
1494
1495         /**
1496          * Estimate rows in dataset.
1497          *
1498          * MySQL allows you to estimate the number of rows that would be returned
1499          * by a SELECT query, using EXPLAIN SELECT. The estimate is provided using
1500          * index cardinality statistics, and is notoriously inaccurate, especially
1501          * when large numbers of rows have recently been added or deleted.
1502          *
1503          * For DBMSs that don't support fast result size estimation, this function
1504          * will actually perform the SELECT COUNT(*).
1505          *
1506          * Takes the same arguments as DatabaseBase::select().
1507          *
1508          * @param $table String: table name
1509          * @param Array|string $vars : unused
1510          * @param Array|string $conds : filters on the table
1511          * @param $fname String: function name for profiling
1512          * @param $options Array: options for select
1513          * @return Integer: row count
1514          */
1515         public function estimateRowCount( $table, $vars = '*', $conds = '',
1516                 $fname = 'DatabaseBase::estimateRowCount', $options = array() )
1517         {
1518                 $rows = 0;
1519                 $res = $this->select ( $table, 'COUNT(*) AS rowcount', $conds, $fname, $options );
1520
1521                 if ( $res ) {
1522                         $row = $this->fetchRow( $res );
1523                         $rows = ( isset( $row['rowcount'] ) ) ? $row['rowcount'] : 0;
1524                 }
1525
1526                 return $rows;
1527         }
1528
1529         /**
1530          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1531          * It's only slightly flawed. Don't use for anything important.
1532          *
1533          * @param $sql String A SQL Query
1534          *
1535          * @return string
1536          */
1537         static function generalizeSQL( $sql ) {
1538                 # This does the same as the regexp below would do, but in such a way
1539                 # as to avoid crashing php on some large strings.
1540                 # $sql = preg_replace ( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql);
1541
1542                 $sql = str_replace ( "\\\\", '', $sql );
1543                 $sql = str_replace ( "\\'", '', $sql );
1544                 $sql = str_replace ( "\\\"", '', $sql );
1545                 $sql = preg_replace ( "/'.*'/s", "'X'", $sql );
1546                 $sql = preg_replace ( '/".*"/s', "'X'", $sql );
1547
1548                 # All newlines, tabs, etc replaced by single space
1549                 $sql = preg_replace ( '/\s+/', ' ', $sql );
1550
1551                 # All numbers => N
1552                 $sql = preg_replace ( '/-?[0-9]+/s', 'N', $sql );
1553
1554                 return $sql;
1555         }
1556
1557         /**
1558          * Determines whether a field exists in a table
1559          *
1560          * @param $table String: table name
1561          * @param $field String: filed to check on that table
1562          * @param $fname String: calling function name (optional)
1563          * @return Boolean: whether $table has filed $field
1564          */
1565         function fieldExists( $table, $field, $fname = 'DatabaseBase::fieldExists' ) {
1566                 $info = $this->fieldInfo( $table, $field );
1567
1568                 return (bool)$info;
1569         }
1570
1571         /**
1572          * Determines whether an index exists
1573          * Usually throws a DBQueryError on failure
1574          * If errors are explicitly ignored, returns NULL on failure
1575          *
1576          * @param $table
1577          * @param $index
1578          * @param $fname string
1579          *
1580          * @return bool|null
1581          */
1582         function indexExists( $table, $index, $fname = 'DatabaseBase::indexExists' ) {
1583                 $info = $this->indexInfo( $table, $index, $fname );
1584                 if ( is_null( $info ) ) {
1585                         return null;
1586                 } else {
1587                         return $info !== false;
1588                 }
1589         }
1590
1591         /**
1592          * Query whether a given table exists
1593          *
1594          * @param $table string
1595          * @param $fname string
1596          *
1597          * @return bool
1598          */
1599         function tableExists( $table, $fname = __METHOD__ ) {
1600                 $table = $this->tableName( $table );
1601                 $old = $this->ignoreErrors( true );
1602                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname );
1603                 $this->ignoreErrors( $old );
1604
1605                 return (bool)$res;
1606         }
1607
1608         /**
1609          * mysql_field_type() wrapper
1610          * @param $res
1611          * @param $index
1612          * @return string
1613          */
1614         function fieldType( $res, $index ) {
1615                 if ( $res instanceof ResultWrapper ) {
1616                         $res = $res->result;
1617                 }
1618
1619                 return mysql_field_type( $res, $index );
1620         }
1621
1622         /**
1623          * Determines if a given index is unique
1624          *
1625          * @param $table string
1626          * @param $index string
1627          *
1628          * @return bool
1629          */
1630         function indexUnique( $table, $index ) {
1631                 $indexInfo = $this->indexInfo( $table, $index );
1632
1633                 if ( !$indexInfo ) {
1634                         return null;
1635                 }
1636
1637                 return !$indexInfo[0]->Non_unique;
1638         }
1639
1640         /**
1641          * Helper for DatabaseBase::insert().
1642          *
1643          * @param $options array
1644          * @return string
1645          */
1646         function makeInsertOptions( $options ) {
1647                 return implode( ' ', $options );
1648         }
1649
1650         /**
1651          * INSERT wrapper, inserts an array into a table.
1652          *
1653          * $a may be either:
1654          *
1655          *   - A single associative array. The array keys are the field names, and
1656          *     the values are the values to insert. The values are treated as data
1657          *     and will be quoted appropriately. If NULL is inserted, this will be
1658          *     converted to a database NULL.
1659          *   - An array with numeric keys, holding a list of associative arrays.
1660          *     This causes a multi-row INSERT on DBMSs that support it. The keys in
1661          *     each subarray must be identical to each other, and in the same order.
1662          *
1663          * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
1664          * returns success.
1665          *
1666          * $options is an array of options, with boolean options encoded as values
1667          * with numeric keys, in the same style as $options in
1668          * DatabaseBase::select(). Supported options are:
1669          *
1670          *   - IGNORE: Boolean: if present, duplicate key errors are ignored, and
1671          *     any rows which cause duplicate key errors are not inserted. It's
1672          *     possible to determine how many rows were successfully inserted using
1673          *     DatabaseBase::affectedRows().
1674          *
1675          * @param $table   String Table name. This will be passed through
1676          *                 DatabaseBase::tableName().
1677          * @param $a       Array of rows to insert
1678          * @param $fname   String Calling function name (use __METHOD__) for logs/profiling
1679          * @param $options Array of options
1680          *
1681          * @return bool
1682          */
1683         function insert( $table, $a, $fname = 'DatabaseBase::insert', $options = array() ) {
1684                 # No rows to insert, easy just return now
1685                 if ( !count( $a ) ) {
1686                         return true;
1687                 }
1688
1689                 $table = $this->tableName( $table );
1690
1691                 if ( !is_array( $options ) ) {
1692                         $options = array( $options );
1693                 }
1694
1695                 $options = $this->makeInsertOptions( $options );
1696
1697                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1698                         $multi = true;
1699                         $keys = array_keys( $a[0] );
1700                 } else {
1701                         $multi = false;
1702                         $keys = array_keys( $a );
1703                 }
1704
1705                 $sql = 'INSERT ' . $options .
1706                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1707
1708                 if ( $multi ) {
1709                         $first = true;
1710                         foreach ( $a as $row ) {
1711                                 if ( $first ) {
1712                                         $first = false;
1713                                 } else {
1714                                         $sql .= ',';
1715                                 }
1716                                 $sql .= '(' . $this->makeList( $row ) . ')';
1717                         }
1718                 } else {
1719                         $sql .= '(' . $this->makeList( $a ) . ')';
1720                 }
1721
1722                 return (bool)$this->query( $sql, $fname );
1723         }
1724
1725         /**
1726          * Make UPDATE options for the DatabaseBase::update function
1727          *
1728          * @param $options Array: The options passed to DatabaseBase::update
1729          * @return string
1730          */
1731         function makeUpdateOptions( $options ) {
1732                 if ( !is_array( $options ) ) {
1733                         $options = array( $options );
1734                 }
1735
1736                 $opts = array();
1737
1738                 if ( in_array( 'LOW_PRIORITY', $options ) ) {
1739                         $opts[] = $this->lowPriorityOption();
1740                 }
1741
1742                 if ( in_array( 'IGNORE', $options ) ) {
1743                         $opts[] = 'IGNORE';
1744                 }
1745
1746                 return implode( ' ', $opts );
1747         }
1748
1749         /**
1750          * UPDATE wrapper. Takes a condition array and a SET array.
1751          *
1752          * @param $table  String name of the table to UPDATE. This will be passed through
1753          *                DatabaseBase::tableName().
1754          *
1755          * @param $values Array:  An array of values to SET. For each array element,
1756          *                the key gives the field name, and the value gives the data
1757          *                to set that field to. The data will be quoted by
1758          *                DatabaseBase::addQuotes().
1759          *
1760          * @param $conds  Array:  An array of conditions (WHERE). See
1761          *                DatabaseBase::select() for the details of the format of
1762          *                condition arrays. Use '*' to update all rows.
1763          *
1764          * @param $fname  String: The function name of the caller (from __METHOD__),
1765          *                for logging and profiling.
1766          *
1767          * @param $options Array: An array of UPDATE options, can be:
1768          *                   - IGNORE: Ignore unique key conflicts
1769          *                   - LOW_PRIORITY: MySQL-specific, see MySQL manual.
1770          * @return Boolean
1771          */
1772         function update( $table, $values, $conds, $fname = 'DatabaseBase::update', $options = array() ) {
1773                 $table = $this->tableName( $table );
1774                 $opts = $this->makeUpdateOptions( $options );
1775                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET );
1776
1777                 if ( $conds !== array() && $conds !== '*' ) {
1778                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1779                 }
1780
1781                 return $this->query( $sql, $fname );
1782         }
1783
1784         /**
1785          * Makes an encoded list of strings from an array
1786          * @param $a Array containing the data
1787          * @param $mode int Constant
1788          *      - LIST_COMMA:          comma separated, no field names
1789          *      - LIST_AND:            ANDed WHERE clause (without the WHERE). See
1790          *        the documentation for $conds in DatabaseBase::select().
1791          *      - LIST_OR:             ORed WHERE clause (without the WHERE)
1792          *      - LIST_SET:            comma separated with field names, like a SET clause
1793          *      - LIST_NAMES:          comma separated field names
1794          *
1795          * @return string
1796          */
1797         function makeList( $a, $mode = LIST_COMMA ) {
1798                 if ( !is_array( $a ) ) {
1799                         throw new DBUnexpectedError( $this, 'DatabaseBase::makeList called with incorrect parameters' );
1800                 }
1801
1802                 $first = true;
1803                 $list = '';
1804
1805                 foreach ( $a as $field => $value ) {
1806                         if ( !$first ) {
1807                                 if ( $mode == LIST_AND ) {
1808                                         $list .= ' AND ';
1809                                 } elseif ( $mode == LIST_OR ) {
1810                                         $list .= ' OR ';
1811                                 } else {
1812                                         $list .= ',';
1813                                 }
1814                         } else {
1815                                 $first = false;
1816                         }
1817
1818                         if ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_numeric( $field ) ) {
1819                                 $list .= "($value)";
1820                         } elseif ( ( $mode == LIST_SET ) && is_numeric( $field ) ) {
1821                                 $list .= "$value";
1822                         } elseif ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_array( $value ) ) {
1823                                 if ( count( $value ) == 0 ) {
1824                                         throw new MWException( __METHOD__ . ': empty input' );
1825                                 } elseif ( count( $value ) == 1 ) {
1826                                         // Special-case single values, as IN isn't terribly efficient
1827                                         // Don't necessarily assume the single key is 0; we don't
1828                                         // enforce linear numeric ordering on other arrays here.
1829                                         $value = array_values( $value );
1830                                         $list .= $field . " = " . $this->addQuotes( $value[0] );
1831                                 } else {
1832                                         $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1833                                 }
1834                         } elseif ( $value === null ) {
1835                                 if ( $mode == LIST_AND || $mode == LIST_OR ) {
1836                                         $list .= "$field IS ";
1837                                 } elseif ( $mode == LIST_SET ) {
1838                                         $list .= "$field = ";
1839                                 }
1840                                 $list .= 'NULL';
1841                         } else {
1842                                 if ( $mode == LIST_AND || $mode == LIST_OR || $mode == LIST_SET ) {
1843                                         $list .= "$field = ";
1844                                 }
1845                                 $list .= $mode == LIST_NAMES ? $value : $this->addQuotes( $value );
1846                         }
1847                 }
1848
1849                 return $list;
1850         }
1851
1852         /**
1853          * Build a partial where clause from a 2-d array such as used for LinkBatch.
1854          * The keys on each level may be either integers or strings.
1855          *
1856          * @param $data Array: organized as 2-d
1857          *              array(baseKeyVal => array(subKeyVal => <ignored>, ...), ...)
1858          * @param $baseKey String: field name to match the base-level keys to (eg 'pl_namespace')
1859          * @param $subKey String: field name to match the sub-level keys to (eg 'pl_title')
1860          * @return Mixed: string SQL fragment, or false if no items in array.
1861          */
1862         function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1863                 $conds = array();
1864
1865                 foreach ( $data as $base => $sub ) {
1866                         if ( count( $sub ) ) {
1867                                 $conds[] = $this->makeList(
1868                                         array( $baseKey => $base, $subKey => array_keys( $sub ) ),
1869                                         LIST_AND );
1870                         }
1871                 }
1872
1873                 if ( $conds ) {
1874                         return $this->makeList( $conds, LIST_OR );
1875                 } else {
1876                         // Nothing to search for...
1877                         return false;
1878                 }
1879         }
1880
1881         /**
1882          * Bitwise operations
1883          */
1884
1885         /**
1886          * @param $field
1887          * @return string
1888          */
1889         function bitNot( $field ) {
1890                 return "(~$field)";
1891         }
1892
1893         /**
1894          * @param $fieldLeft
1895          * @param $fieldRight
1896          * @return string
1897          */
1898         function bitAnd( $fieldLeft, $fieldRight ) {
1899                 return "($fieldLeft & $fieldRight)";
1900         }
1901
1902         /**
1903          * @param  $fieldLeft
1904          * @param  $fieldRight
1905          * @return string
1906          */
1907         function bitOr( $fieldLeft, $fieldRight ) {
1908                 return "($fieldLeft | $fieldRight)";
1909         }
1910
1911         /**
1912          * Change the current database
1913          *
1914          * @todo Explain what exactly will fail if this is not overridden.
1915          *
1916          * @param $db
1917          *
1918          * @return bool Success or failure
1919          */
1920         function selectDB( $db ) {
1921                 # Stub.  Shouldn't cause serious problems if it's not overridden, but
1922                 # if your database engine supports a concept similar to MySQL's
1923                 # databases you may as well.
1924                 $this->mDBname = $db;
1925                 return true;
1926         }
1927
1928         /**
1929          * Get the current DB name
1930          */
1931         function getDBname() {
1932                 return $this->mDBname;
1933         }
1934
1935         /**
1936          * Get the server hostname or IP address
1937          */
1938         function getServer() {
1939                 return $this->mServer;
1940         }
1941
1942         /**
1943          * Format a table name ready for use in constructing an SQL query
1944          *
1945          * This does two important things: it quotes the table names to clean them up,
1946          * and it adds a table prefix if only given a table name with no quotes.
1947          *
1948          * All functions of this object which require a table name call this function
1949          * themselves. Pass the canonical name to such functions. This is only needed
1950          * when calling query() directly.
1951          *
1952          * @param $name String: database table name
1953          * @param $format String One of:
1954          *   quoted - Automatically pass the table name through addIdentifierQuotes()
1955          *            so that it can be used in a query.
1956          *   raw - Do not add identifier quotes to the table name
1957          * @return String: full database name
1958          */
1959         function tableName( $name, $format = 'quoted' ) {
1960                 global $wgSharedDB, $wgSharedPrefix, $wgSharedTables;
1961                 # Skip the entire process when we have a string quoted on both ends.
1962                 # Note that we check the end so that we will still quote any use of
1963                 # use of `database`.table. But won't break things if someone wants
1964                 # to query a database table with a dot in the name.
1965                 if ( $this->isQuotedIdentifier( $name ) ) {
1966                         return $name;
1967                 }
1968
1969                 # Lets test for any bits of text that should never show up in a table
1970                 # name. Basically anything like JOIN or ON which are actually part of
1971                 # SQL queries, but may end up inside of the table value to combine
1972                 # sql. Such as how the API is doing.
1973                 # Note that we use a whitespace test rather than a \b test to avoid
1974                 # any remote case where a word like on may be inside of a table name
1975                 # surrounded by symbols which may be considered word breaks.
1976                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1977                         return $name;
1978                 }
1979
1980                 # Split database and table into proper variables.
1981                 # We reverse the explode so that database.table and table both output
1982                 # the correct table.
1983                 $dbDetails = array_reverse( explode( '.', $name, 2 ) );
1984                 if ( isset( $dbDetails[1] ) ) {
1985                         list( $table, $database ) = $dbDetails;
1986                 } else {
1987                         list( $table ) = $dbDetails;
1988                 }
1989                 $prefix = $this->mTablePrefix; # Default prefix
1990
1991                 # A database name has been specified in input. We don't want any
1992                 # prefixes added.
1993                 if ( isset( $database ) ) {
1994                         $prefix = '';
1995                 }
1996
1997                 # Note that we use the long format because php will complain in in_array if
1998                 # the input is not an array, and will complain in is_array if it is not set.
1999                 if ( !isset( $database ) # Don't use shared database if pre selected.
2000                  && isset( $wgSharedDB ) # We have a shared database
2001                  && !$this->isQuotedIdentifier( $table ) # Paranoia check to prevent shared tables listing '`table`'
2002                  && isset( $wgSharedTables )
2003                  && is_array( $wgSharedTables )
2004                  && in_array( $table, $wgSharedTables ) ) { # A shared table is selected
2005                         $database = $wgSharedDB;
2006                         $prefix   = isset( $wgSharedPrefix ) ? $wgSharedPrefix : $prefix;
2007                 }
2008
2009                 # Quote the $database and $table and apply the prefix if not quoted.
2010                 if ( isset( $database ) ) {
2011                         $database = ( $format == 'quoted' || $this->isQuotedIdentifier( $database ) ? $database : $this->addIdentifierQuotes( $database ) );
2012                 }
2013
2014                 $table = "{$prefix}{$table}";
2015                 if ( $format == 'quoted' && !$this->isQuotedIdentifier( $table ) ) {
2016                         $table = $this->addIdentifierQuotes( "{$table}" );
2017                 }
2018
2019                 # Merge our database and table into our final table name.
2020                 $tableName = ( isset( $database ) ? "{$database}.{$table}" : "{$table}" );
2021
2022                 return $tableName;
2023         }
2024
2025         /**
2026          * Fetch a number of table names into an array
2027          * This is handy when you need to construct SQL for joins
2028          *
2029          * Example:
2030          * extract($dbr->tableNames('user','watchlist'));
2031          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
2032          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
2033          *
2034          * @return array
2035          */
2036         public function tableNames() {
2037                 $inArray = func_get_args();
2038                 $retVal = array();
2039
2040                 foreach ( $inArray as $name ) {
2041                         $retVal[$name] = $this->tableName( $name );
2042                 }
2043
2044                 return $retVal;
2045         }
2046
2047         /**
2048          * Fetch a number of table names into an zero-indexed numerical array
2049          * This is handy when you need to construct SQL for joins
2050          *
2051          * Example:
2052          * list( $user, $watchlist ) = $dbr->tableNamesN('user','watchlist');
2053          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
2054          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
2055          *
2056          * @return array
2057          */
2058         public function tableNamesN() {
2059                 $inArray = func_get_args();
2060                 $retVal = array();
2061
2062                 foreach ( $inArray as $name ) {
2063                         $retVal[] = $this->tableName( $name );
2064                 }
2065
2066                 return $retVal;
2067         }
2068
2069         /**
2070          * Get an aliased table name
2071          * e.g. tableName AS newTableName
2072          *
2073          * @param $name string Table name, see tableName()
2074          * @param $alias string|bool Alias (optional)
2075          * @return string SQL name for aliased table. Will not alias a table to its own name
2076          */
2077         public function tableNameWithAlias( $name, $alias = false ) {
2078                 if ( !$alias || $alias == $name ) {
2079                         return $this->tableName( $name );
2080                 } else {
2081                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
2082                 }
2083         }
2084
2085         /**
2086          * Gets an array of aliased table names
2087          *
2088          * @param $tables array( [alias] => table )
2089          * @return array of strings, see tableNameWithAlias()
2090          */
2091         public function tableNamesWithAlias( $tables ) {
2092                 $retval = array();
2093                 foreach ( $tables as $alias => $table ) {
2094                         if ( is_numeric( $alias ) ) {
2095                                 $alias = $table;
2096                         }
2097                         $retval[] = $this->tableNameWithAlias( $table, $alias );
2098                 }
2099                 return $retval;
2100         }
2101
2102         /**
2103          * Get the aliased table name clause for a FROM clause
2104          * which might have a JOIN and/or USE INDEX clause
2105          *
2106          * @param $tables array ( [alias] => table )
2107          * @param $use_index array Same as for select()
2108          * @param $join_conds array Same as for select()
2109          * @return string
2110          */
2111         protected function tableNamesWithUseIndexOrJOIN(
2112                 $tables, $use_index = array(), $join_conds = array()
2113         ) {
2114                 $ret = array();
2115                 $retJOIN = array();
2116                 $use_index = (array)$use_index;
2117                 $join_conds = (array)$join_conds;
2118
2119                 foreach ( $tables as $alias => $table ) {
2120                         if ( !is_string( $alias ) ) {
2121                                 // No alias? Set it equal to the table name
2122                                 $alias = $table;
2123                         }
2124                         // Is there a JOIN clause for this table?
2125                         if ( isset( $join_conds[$alias] ) ) {
2126                                 list( $joinType, $conds ) = $join_conds[$alias];
2127                                 $tableClause = $joinType;
2128                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
2129                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2130                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2131                                         if ( $use != '' ) {
2132                                                 $tableClause .= ' ' . $use;
2133                                         }
2134                                 }
2135                                 $on = $this->makeList( (array)$conds, LIST_AND );
2136                                 if ( $on != '' ) {
2137                                         $tableClause .= ' ON (' . $on . ')';
2138                                 }
2139
2140                                 $retJOIN[] = $tableClause;
2141                         // Is there an INDEX clause for this table?
2142                         } elseif ( isset( $use_index[$alias] ) ) {
2143                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2144                                 $tableClause .= ' ' . $this->useIndexClause(
2145                                         implode( ',', (array)$use_index[$alias] ) );
2146
2147                                 $ret[] = $tableClause;
2148                         } else {
2149                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2150
2151                                 $ret[] = $tableClause;
2152                         }
2153                 }
2154
2155                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2156                 $straightJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
2157                 $otherJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
2158
2159                 // Compile our final table clause
2160                 return implode( ' ', array( $straightJoins, $otherJoins ) );
2161         }
2162
2163         /**
2164          * Get the name of an index in a given table
2165          *
2166          * @param $index
2167          *
2168          * @return string
2169          */
2170         function indexName( $index ) {
2171                 // Backwards-compatibility hack
2172                 $renamed = array(
2173                         'ar_usertext_timestamp' => 'usertext_timestamp',
2174                         'un_user_id'            => 'user_id',
2175                         'un_user_ip'            => 'user_ip',
2176                 );
2177
2178                 if ( isset( $renamed[$index] ) ) {
2179                         return $renamed[$index];
2180                 } else {
2181                         return $index;
2182                 }
2183         }
2184
2185         /**
2186          * If it's a string, adds quotes and backslashes
2187          * Otherwise returns as-is
2188          *
2189          * @param $s string
2190          *
2191          * @return string
2192          */
2193         function addQuotes( $s ) {
2194                 if ( $s === null ) {
2195                         return 'NULL';
2196                 } else {
2197                         # This will also quote numeric values. This should be harmless,
2198                         # and protects against weird problems that occur when they really
2199                         # _are_ strings such as article titles and string->number->string
2200                         # conversion is not 1:1.
2201                         return "'" . $this->strencode( $s ) . "'";
2202                 }
2203         }
2204
2205         /**
2206          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
2207          * MySQL uses `backticks` while basically everything else uses double quotes.
2208          * Since MySQL is the odd one out here the double quotes are our generic
2209          * and we implement backticks in DatabaseMysql.
2210          *
2211          * @param $s string
2212          *
2213          * @return string
2214          */
2215         public function addIdentifierQuotes( $s ) {
2216                 return '"' . str_replace( '"', '""', $s ) . '"';
2217         }
2218
2219         /**
2220          * Returns if the given identifier looks quoted or not according to
2221          * the database convention for quoting identifiers .
2222          *
2223          * @param $name string
2224          *
2225          * @return boolean
2226          */
2227         public function isQuotedIdentifier( $name ) {
2228                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2229         }
2230
2231         /**
2232          * Backwards compatibility, identifier quoting originated in DatabasePostgres
2233          * which used quote_ident which does not follow our naming conventions
2234          * was renamed to addIdentifierQuotes.
2235          * @deprecated since 1.18 use addIdentifierQuotes
2236          *
2237          * @param $s string
2238          *
2239          * @return string
2240          */
2241         function quote_ident( $s ) {
2242                 wfDeprecated( __METHOD__, '1.18' );
2243                 return $this->addIdentifierQuotes( $s );
2244         }
2245
2246         /**
2247          * Escape string for safe LIKE usage.
2248          * WARNING: you should almost never use this function directly,
2249          * instead use buildLike() that escapes everything automatically
2250          * @deprecated since 1.17, warnings in 1.17, removed in ???
2251          *
2252          * @param $s string
2253          *
2254          * @return string
2255          */
2256         public function escapeLike( $s ) {
2257                 wfDeprecated( __METHOD__, '1.17' );
2258                 return $this->escapeLikeInternal( $s );
2259         }
2260
2261         /**
2262          * @param $s string
2263          * @return string
2264          */
2265         protected function escapeLikeInternal( $s ) {
2266                 $s = str_replace( '\\', '\\\\', $s );
2267                 $s = $this->strencode( $s );
2268                 $s = str_replace( array( '%', '_' ), array( '\%', '\_' ), $s );
2269
2270                 return $s;
2271         }
2272
2273         /**
2274          * LIKE statement wrapper, receives a variable-length argument list with parts of pattern to match
2275          * containing either string literals that will be escaped or tokens returned by anyChar() or anyString().
2276          * Alternatively, the function could be provided with an array of aforementioned parameters.
2277          *
2278          * Example: $dbr->buildLike( 'My_page_title/', $dbr->anyString() ) returns a LIKE clause that searches
2279          * for subpages of 'My page title'.
2280          * Alternatively: $pattern = array( 'My_page_title/', $dbr->anyString() ); $query .= $dbr->buildLike( $pattern );
2281          *
2282          * @since 1.16
2283          * @return String: fully built LIKE statement
2284          */
2285         function buildLike() {
2286                 $params = func_get_args();
2287
2288                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2289                         $params = $params[0];
2290                 }
2291
2292                 $s = '';
2293
2294                 foreach ( $params as $value ) {
2295                         if ( $value instanceof LikeMatch ) {
2296                                 $s .= $value->toString();
2297                         } else {
2298                                 $s .= $this->escapeLikeInternal( $value );
2299                         }
2300                 }
2301
2302                 return " LIKE '" . $s . "' ";
2303         }
2304
2305         /**
2306          * Returns a token for buildLike() that denotes a '_' to be used in a LIKE query
2307          *
2308          * @return LikeMatch
2309          */
2310         function anyChar() {
2311                 return new LikeMatch( '_' );
2312         }
2313
2314         /**
2315          * Returns a token for buildLike() that denotes a '%' to be used in a LIKE query
2316          *
2317          * @return LikeMatch
2318          */
2319         function anyString() {
2320                 return new LikeMatch( '%' );
2321         }
2322
2323         /**
2324          * Returns an appropriately quoted sequence value for inserting a new row.
2325          * MySQL has autoincrement fields, so this is just NULL. But the PostgreSQL
2326          * subclass will return an integer, and save the value for insertId()
2327          *
2328          * Any implementation of this function should *not* involve reusing
2329          * sequence numbers created for rolled-back transactions.
2330          * See http://bugs.mysql.com/bug.php?id=30767 for details.
2331          * @param $seqName string
2332          * @return null
2333          */
2334         function nextSequenceValue( $seqName ) {
2335                 return null;
2336         }
2337
2338         /**
2339          * USE INDEX clause.  Unlikely to be useful for anything but MySQL.  This
2340          * is only needed because a) MySQL must be as efficient as possible due to
2341          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2342          * which index to pick.  Anyway, other databases might have different
2343          * indexes on a given table.  So don't bother overriding this unless you're
2344          * MySQL.
2345          * @param $index
2346          * @return string
2347          */
2348         function useIndexClause( $index ) {
2349                 return '';
2350         }
2351
2352         /**
2353          * REPLACE query wrapper.
2354          *
2355          * REPLACE is a very handy MySQL extension, which functions like an INSERT
2356          * except that when there is a duplicate key error, the old row is deleted
2357          * and the new row is inserted in its place.
2358          *
2359          * We simulate this with standard SQL with a DELETE followed by INSERT. To
2360          * perform the delete, we need to know what the unique indexes are so that
2361          * we know how to find the conflicting rows.
2362          *
2363          * It may be more efficient to leave off unique indexes which are unlikely
2364          * to collide. However if you do this, you run the risk of encountering
2365          * errors which wouldn't have occurred in MySQL.
2366          *
2367          * @param $table String: The table to replace the row(s) in.
2368          * @param $rows array Can be either a single row to insert, or multiple rows,
2369          *    in the same format as for DatabaseBase::insert()
2370          * @param $uniqueIndexes array is an array of indexes. Each element may be either
2371          *    a field name or an array of field names
2372          * @param $fname String: Calling function name (use __METHOD__) for logs/profiling
2373          */
2374         function replace( $table, $uniqueIndexes, $rows, $fname = 'DatabaseBase::replace' ) {
2375                 $quotedTable = $this->tableName( $table );
2376
2377                 if ( count( $rows ) == 0 ) {
2378                         return;
2379                 }
2380
2381                 # Single row case
2382                 if ( !is_array( reset( $rows ) ) ) {
2383                         $rows = array( $rows );
2384                 }
2385
2386                 foreach( $rows as $row ) {
2387                         # Delete rows which collide
2388                         if ( $uniqueIndexes ) {
2389                                 $sql = "DELETE FROM $quotedTable WHERE ";
2390                                 $first = true;
2391                                 foreach ( $uniqueIndexes as $index ) {
2392                                         if ( $first ) {
2393                                                 $first = false;
2394                                                 $sql .= '( ';
2395                                         } else {
2396                                                 $sql .= ' ) OR ( ';
2397                                         }
2398                                         if ( is_array( $index ) ) {
2399                                                 $first2 = true;
2400                                                 foreach ( $index as $col ) {
2401                                                         if ( $first2 ) {
2402                                                                 $first2 = false;
2403                                                         } else {
2404                                                                 $sql .= ' AND ';
2405                                                         }
2406                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2407                                                 }
2408                                         } else {
2409                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2410                                         }
2411                                 }
2412                                 $sql .= ' )';
2413                                 $this->query( $sql, $fname );
2414                         }
2415
2416                         # Now insert the row
2417                         $this->insert( $table, $row );
2418                 }
2419         }
2420
2421         /**
2422          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2423          * statement.
2424          *
2425          * @param $table string Table name
2426          * @param $rows array Rows to insert
2427          * @param $fname string Caller function name
2428          *
2429          * @return ResultWrapper
2430          */
2431         protected function nativeReplace( $table, $rows, $fname ) {
2432                 $table = $this->tableName( $table );
2433
2434                 # Single row case
2435                 if ( !is_array( reset( $rows ) ) ) {
2436                         $rows = array( $rows );
2437                 }
2438
2439                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2440                 $first = true;
2441
2442                 foreach ( $rows as $row ) {
2443                         if ( $first ) {
2444                                 $first = false;
2445                         } else {
2446                                 $sql .= ',';
2447                         }
2448
2449                         $sql .= '(' . $this->makeList( $row ) . ')';
2450                 }
2451
2452                 return $this->query( $sql, $fname );
2453         }
2454
2455         /**
2456          * DELETE where the condition is a join.
2457          *
2458          * MySQL overrides this to use a multi-table DELETE syntax, in other databases
2459          * we use sub-selects
2460          *
2461          * For safety, an empty $conds will not delete everything. If you want to
2462          * delete all rows where the join condition matches, set $conds='*'.
2463          *
2464          * DO NOT put the join condition in $conds.
2465          *
2466          * @param $delTable   String: The table to delete from.
2467          * @param $joinTable  String: The other table.
2468          * @param $delVar     String: The variable to join on, in the first table.
2469          * @param $joinVar    String: The variable to join on, in the second table.
2470          * @param $conds      Array: Condition array of field names mapped to variables,
2471          *                    ANDed together in the WHERE clause
2472          * @param $fname      String: Calling function name (use __METHOD__) for
2473          *                    logs/profiling
2474          */
2475         function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2476                 $fname = 'DatabaseBase::deleteJoin' )
2477         {
2478                 if ( !$conds ) {
2479                         throw new DBUnexpectedError( $this,
2480                                 'DatabaseBase::deleteJoin() called with empty $conds' );
2481                 }
2482
2483                 $delTable = $this->tableName( $delTable );
2484                 $joinTable = $this->tableName( $joinTable );
2485                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2486                 if ( $conds != '*' ) {
2487                         $sql .= 'WHERE ' . $this->makeList( $conds, LIST_AND );
2488                 }
2489                 $sql .= ')';
2490
2491                 $this->query( $sql, $fname );
2492         }
2493
2494         /**
2495          * Returns the size of a text field, or -1 for "unlimited"
2496          *
2497          * @param $table string
2498          * @param $field string
2499          *
2500          * @return int
2501          */
2502         function textFieldSize( $table, $field ) {
2503                 $table = $this->tableName( $table );
2504                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2505                 $res = $this->query( $sql, 'DatabaseBase::textFieldSize' );
2506                 $row = $this->fetchObject( $res );
2507
2508                 $m = array();
2509
2510                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2511                         $size = $m[1];
2512                 } else {
2513                         $size = -1;
2514                 }
2515
2516                 return $size;
2517         }
2518
2519         /**
2520          * A string to insert into queries to show that they're low-priority, like
2521          * MySQL's LOW_PRIORITY.  If no such feature exists, return an empty
2522          * string and nothing bad should happen.
2523          *
2524          * @return string Returns the text of the low priority option if it is
2525          *   supported, or a blank string otherwise
2526          */
2527         function lowPriorityOption() {
2528                 return '';
2529         }
2530
2531         /**
2532          * DELETE query wrapper.
2533          *
2534          * @param $table Array Table name
2535          * @param $conds String|Array of conditions. See $conds in DatabaseBase::select() for
2536          *               the format. Use $conds == "*" to delete all rows
2537          * @param $fname String name of the calling function
2538          *
2539          * @return bool
2540          */
2541         function delete( $table, $conds, $fname = 'DatabaseBase::delete' ) {
2542                 if ( !$conds ) {
2543                         throw new DBUnexpectedError( $this, 'DatabaseBase::delete() called with no conditions' );
2544                 }
2545
2546                 $table = $this->tableName( $table );
2547                 $sql = "DELETE FROM $table";
2548
2549                 if ( $conds != '*' ) {
2550                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
2551                 }
2552
2553                 return $this->query( $sql, $fname );
2554         }
2555
2556         /**
2557          * INSERT SELECT wrapper. Takes data from a SELECT query and inserts it
2558          * into another table.
2559          *
2560          * @param $destTable string The table name to insert into
2561          * @param $srcTable string|array May be either a table name, or an array of table names
2562          *    to include in a join.
2563          *
2564          * @param $varMap array must be an associative array of the form
2565          *    array( 'dest1' => 'source1', ...). Source items may be literals
2566          *    rather than field names, but strings should be quoted with
2567          *    DatabaseBase::addQuotes()
2568          *
2569          * @param $conds array Condition array. See $conds in DatabaseBase::select() for
2570          *    the details of the format of condition arrays. May be "*" to copy the
2571          *    whole table.
2572          *
2573          * @param $fname string The function name of the caller, from __METHOD__
2574          *
2575          * @param $insertOptions array Options for the INSERT part of the query, see
2576          *    DatabaseBase::insert() for details.
2577          * @param $selectOptions array Options for the SELECT part of the query, see
2578          *    DatabaseBase::select() for details.
2579          *
2580          * @return ResultWrapper
2581          */
2582         function insertSelect( $destTable, $srcTable, $varMap, $conds,
2583                 $fname = 'DatabaseBase::insertSelect',
2584                 $insertOptions = array(), $selectOptions = array() )
2585         {
2586                 $destTable = $this->tableName( $destTable );
2587
2588                 if ( is_array( $insertOptions ) ) {
2589                         $insertOptions = implode( ' ', $insertOptions );
2590                 }
2591
2592                 if ( !is_array( $selectOptions ) ) {
2593                         $selectOptions = array( $selectOptions );
2594                 }
2595
2596                 list( $startOpts, $useIndex, $tailOpts ) = $this->makeSelectOptions( $selectOptions );
2597
2598                 if ( is_array( $srcTable ) ) {
2599                         $srcTable =  implode( ',', array_map( array( &$this, 'tableName' ), $srcTable ) );
2600                 } else {
2601                         $srcTable = $this->tableName( $srcTable );
2602                 }
2603
2604                 $sql = "INSERT $insertOptions INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2605                         " SELECT $startOpts " . implode( ',', $varMap ) .
2606                         " FROM $srcTable $useIndex ";
2607
2608                 if ( $conds != '*' ) {
2609                         if ( is_array( $conds ) ) {
2610                                 $conds = $this->makeList( $conds, LIST_AND );
2611                         }
2612                         $sql .= " WHERE $conds";
2613                 }
2614
2615                 $sql .= " $tailOpts";
2616
2617                 return $this->query( $sql, $fname );
2618         }
2619
2620         /**
2621          * Construct a LIMIT query with optional offset.  This is used for query
2622          * pages.  The SQL should be adjusted so that only the first $limit rows
2623          * are returned.  If $offset is provided as well, then the first $offset
2624          * rows should be discarded, and the next $limit rows should be returned.
2625          * If the result of the query is not ordered, then the rows to be returned
2626          * are theoretically arbitrary.
2627          *
2628          * $sql is expected to be a SELECT, if that makes a difference.  For
2629          * UPDATE, limitResultForUpdate should be used.
2630          *
2631          * The version provided by default works in MySQL and SQLite.  It will very
2632          * likely need to be overridden for most other DBMSes.
2633          *
2634          * @param $sql String SQL query we will append the limit too
2635          * @param $limit Integer the SQL limit
2636          * @param $offset Integer|bool the SQL offset (default false)
2637          *
2638          * @return string
2639          */
2640         function limitResult( $sql, $limit, $offset = false ) {
2641                 if ( !is_numeric( $limit ) ) {
2642                         throw new DBUnexpectedError( $this, "Invalid non-numeric limit passed to limitResult()\n" );
2643                 }
2644
2645                 return "$sql LIMIT "
2646                                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2647                                 . "{$limit} ";
2648         }
2649
2650         /**
2651          * @param $sql
2652          * @param $num
2653          * @return string
2654          */
2655         function limitResultForUpdate( $sql, $num ) {
2656                 return $this->limitResult( $sql, $num, 0 );
2657         }
2658
2659         /**
2660          * Returns true if current database backend supports ORDER BY or LIMIT for separate subqueries
2661          * within the UNION construct.
2662          * @return Boolean
2663          */
2664         function unionSupportsOrderAndLimit() {
2665                 return true; // True for almost every DB supported
2666         }
2667
2668         /**
2669          * Construct a UNION query
2670          * This is used for providing overload point for other DB abstractions
2671          * not compatible with the MySQL syntax.
2672          * @param $sqls Array: SQL statements to combine
2673          * @param $all Boolean: use UNION ALL
2674          * @return String: SQL fragment
2675          */
2676         function unionQueries( $sqls, $all ) {
2677                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2678                 return '(' . implode( $glue, $sqls ) . ')';
2679         }
2680
2681         /**
2682          * Returns an SQL expression for a simple conditional.  This doesn't need
2683          * to be overridden unless CASE isn't supported in your DBMS.
2684          *
2685          * @param $cond String: SQL expression which will result in a boolean value
2686          * @param $trueVal String: SQL expression to return if true
2687          * @param $falseVal String: SQL expression to return if false
2688          * @return String: SQL fragment
2689          */
2690         function conditional( $cond, $trueVal, $falseVal ) {
2691                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2692         }
2693
2694         /**
2695          * Returns a comand for str_replace function in SQL query.
2696          * Uses REPLACE() in MySQL
2697          *
2698          * @param $orig String: column to modify
2699          * @param $old String: column to seek
2700          * @param $new String: column to replace with
2701          *
2702          * @return string
2703          */
2704         function strreplace( $orig, $old, $new ) {
2705                 return "REPLACE({$orig}, {$old}, {$new})";
2706         }
2707
2708         /**
2709          * Determines how long the server has been up
2710          * STUB
2711          *
2712          * @return int
2713          */
2714         function getServerUptime() {
2715                 return 0;
2716         }
2717
2718         /**
2719          * Determines if the last failure was due to a deadlock
2720          * STUB
2721          *
2722          * @return bool
2723          */
2724         function wasDeadlock() {
2725                 return false;
2726         }
2727
2728         /**
2729          * Determines if the last failure was due to a lock timeout
2730          * STUB
2731          *
2732          * @return bool
2733          */
2734         function wasLockTimeout() {
2735                 return false;
2736         }
2737
2738         /**
2739          * Determines if the last query error was something that should be dealt
2740          * with by pinging the connection and reissuing the query.
2741          * STUB
2742          *
2743          * @return bool
2744          */
2745         function wasErrorReissuable() {
2746                 return false;
2747         }
2748
2749         /**
2750          * Determines if the last failure was due to the database being read-only.
2751          * STUB
2752          *
2753          * @return bool
2754          */
2755         function wasReadOnlyError() {
2756                 return false;
2757         }
2758
2759         /**
2760          * Perform a deadlock-prone transaction.
2761          *
2762          * This function invokes a callback function to perform a set of write
2763          * queries. If a deadlock occurs during the processing, the transaction
2764          * will be rolled back and the callback function will be called again.
2765          *
2766          * Usage:
2767          *   $dbw->deadlockLoop( callback, ... );
2768          *
2769          * Extra arguments are passed through to the specified callback function.
2770          *
2771          * Returns whatever the callback function returned on its successful,
2772          * iteration, or false on error, for example if the retry limit was
2773          * reached.
2774          *
2775          * @return bool
2776          */
2777         function deadlockLoop() {
2778
2779                 $this->begin( __METHOD__ );
2780                 $args = func_get_args();
2781                 $function = array_shift( $args );
2782                 $oldIgnore = $this->ignoreErrors( true );
2783                 $tries = DEADLOCK_TRIES;
2784
2785                 if ( is_array( $function ) ) {
2786                         $fname = $function[0];
2787                 } else {
2788                         $fname = $function;
2789                 }
2790
2791                 do {
2792                         $retVal = call_user_func_array( $function, $args );
2793                         $error = $this->lastError();
2794                         $errno = $this->lastErrno();
2795                         $sql = $this->lastQuery();
2796
2797                         if ( $errno ) {
2798                                 if ( $this->wasDeadlock() ) {
2799                                         # Retry
2800                                         usleep( mt_rand( DEADLOCK_DELAY_MIN, DEADLOCK_DELAY_MAX ) );
2801                                 } else {
2802                                         $this->reportQueryError( $error, $errno, $sql, $fname );
2803                                 }
2804                         }
2805                 } while ( $this->wasDeadlock() && --$tries > 0 );
2806
2807                 $this->ignoreErrors( $oldIgnore );
2808
2809                 if ( $tries <= 0 ) {
2810                         $this->rollback( __METHOD__ );
2811                         $this->reportQueryError( $error, $errno, $sql, $fname );
2812                         return false;
2813                 } else {
2814                         $this->commit( __METHOD__ );
2815                         return $retVal;
2816                 }
2817         }
2818
2819         /**
2820          * Wait for the slave to catch up to a given master position.
2821          *
2822          * @param $pos DBMasterPos object
2823          * @param $timeout Integer: the maximum number of seconds to wait for
2824          *   synchronisation
2825          *
2826          * @return integer: zero if the slave was past that position already,
2827          *   greater than zero if we waited for some period of time, less than
2828          *   zero if we timed out.
2829          */
2830         function masterPosWait( DBMasterPos $pos, $timeout ) {
2831                 wfProfileIn( __METHOD__ );
2832
2833                 if ( !is_null( $this->mFakeSlaveLag ) ) {
2834                         $wait = intval( ( $pos->pos - microtime( true ) + $this->mFakeSlaveLag ) * 1e6 );
2835
2836                         if ( $wait > $timeout * 1e6 ) {
2837                                 wfDebug( "Fake slave timed out waiting for $pos ($wait us)\n" );
2838                                 wfProfileOut( __METHOD__ );
2839                                 return -1;
2840                         } elseif ( $wait > 0 ) {
2841                                 wfDebug( "Fake slave waiting $wait us\n" );
2842                                 usleep( $wait );
2843                                 wfProfileOut( __METHOD__ );
2844                                 return 1;
2845                         } else {
2846                                 wfDebug( "Fake slave up to date ($wait us)\n" );
2847                                 wfProfileOut( __METHOD__ );
2848                                 return 0;
2849                         }
2850                 }
2851
2852                 wfProfileOut( __METHOD__ );
2853
2854                 # Real waits are implemented in the subclass.
2855                 return 0;
2856         }
2857
2858         /**
2859          * Get the replication position of this slave
2860          *
2861          * @return DBMasterPos, or false if this is not a slave.
2862          */
2863         function getSlavePos() {
2864                 if ( !is_null( $this->mFakeSlaveLag ) ) {
2865                         $pos = new MySQLMasterPos( 'fake', microtime( true ) - $this->mFakeSlaveLag );
2866                         wfDebug( __METHOD__ . ": fake slave pos = $pos\n" );
2867                         return $pos;
2868                 } else {
2869                         # Stub
2870                         return false;
2871                 }
2872         }
2873
2874         /**
2875          * Get the position of this master
2876          *
2877          * @return DBMasterPos, or false if this is not a master
2878          */
2879         function getMasterPos() {
2880                 if ( $this->mFakeMaster ) {
2881                         return new MySQLMasterPos( 'fake', microtime( true ) );
2882                 } else {
2883                         return false;
2884                 }
2885         }
2886
2887         /**
2888          * Begin a transaction, committing any previously open transaction
2889          *
2890          * @param $fname string
2891          */
2892         function begin( $fname = 'DatabaseBase::begin' ) {
2893                 $this->query( 'BEGIN', $fname );
2894                 $this->mTrxLevel = 1;
2895         }
2896
2897         /**
2898          * End a transaction
2899          *
2900          * @param $fname string
2901          */
2902         function commit( $fname = 'DatabaseBase::commit' ) {
2903                 if ( $this->mTrxLevel ) {
2904                         $this->query( 'COMMIT', $fname );
2905                         $this->mTrxLevel = 0;
2906                 }
2907         }
2908
2909         /**
2910          * Rollback a transaction.
2911          * No-op on non-transactional databases.
2912          *
2913          * @param $fname string
2914          */
2915         function rollback( $fname = 'DatabaseBase::rollback' ) {
2916                 if ( $this->mTrxLevel ) {
2917                         $this->query( 'ROLLBACK', $fname, true );
2918                         $this->mTrxLevel = 0;
2919                 }
2920         }
2921
2922         /**
2923          * Creates a new table with structure copied from existing table
2924          * Note that unlike most database abstraction functions, this function does not
2925          * automatically append database prefix, because it works at a lower
2926          * abstraction level.
2927          * The table names passed to this function shall not be quoted (this
2928          * function calls addIdentifierQuotes when needed).
2929          *
2930          * @param $oldName String: name of table whose structure should be copied
2931          * @param $newName String: name of table to be created
2932          * @param $temporary Boolean: whether the new table should be temporary
2933          * @param $fname String: calling function name
2934          * @return Boolean: true if operation was successful
2935          */
2936         function duplicateTableStructure( $oldName, $newName, $temporary = false,
2937                 $fname = 'DatabaseBase::duplicateTableStructure' )
2938         {
2939                 throw new MWException(
2940                         'DatabaseBase::duplicateTableStructure is not implemented in descendant class' );
2941         }
2942
2943         /**
2944          * List all tables on the database
2945          *
2946          * @param $prefix string Only show tables with this prefix, e.g. mw_
2947          * @param $fname String: calling function name
2948          */
2949         function listTables( $prefix = null, $fname = 'DatabaseBase::listTables' ) {
2950                 throw new MWException( 'DatabaseBase::listTables is not implemented in descendant class' );
2951         }
2952
2953         /**
2954          * Convert a timestamp in one of the formats accepted by wfTimestamp()
2955          * to the format used for inserting into timestamp fields in this DBMS.
2956          *
2957          * The result is unquoted, and needs to be passed through addQuotes()
2958          * before it can be included in raw SQL.
2959          *
2960          * @param $ts string|int
2961          *
2962          * @return string
2963          */
2964         function timestamp( $ts = 0 ) {
2965                 return wfTimestamp( TS_MW, $ts );
2966         }
2967
2968         /**
2969          * Convert a timestamp in one of the formats accepted by wfTimestamp()
2970          * to the format used for inserting into timestamp fields in this DBMS. If
2971          * NULL is input, it is passed through, allowing NULL values to be inserted
2972          * into timestamp fields.
2973          *
2974          * The result is unquoted, and needs to be passed through addQuotes()
2975          * before it can be included in raw SQL.
2976          *
2977          * @param $ts string|int
2978          *
2979          * @return string
2980          */
2981         function timestampOrNull( $ts = null ) {
2982                 if ( is_null( $ts ) ) {
2983                         return null;
2984                 } else {
2985                         return $this->timestamp( $ts );
2986                 }
2987         }
2988
2989         /**
2990          * Take the result from a query, and wrap it in a ResultWrapper if
2991          * necessary. Boolean values are passed through as is, to indicate success
2992          * of write queries or failure.
2993          *
2994          * Once upon a time, DatabaseBase::query() returned a bare MySQL result
2995          * resource, and it was necessary to call this function to convert it to
2996          * a wrapper. Nowadays, raw database objects are never exposed to external
2997          * callers, so this is unnecessary in external code. For compatibility with
2998          * old code, ResultWrapper objects are passed through unaltered.
2999          *
3000          * @param $result bool|ResultWrapper
3001          *
3002          * @return bool|ResultWrapper
3003          */
3004         function resultObject( $result ) {
3005                 if ( empty( $result ) ) {
3006                         return false;
3007                 } elseif ( $result instanceof ResultWrapper ) {
3008                         return $result;
3009                 } elseif ( $result === true ) {
3010                         // Successful write query
3011                         return $result;
3012                 } else {
3013                         return new ResultWrapper( $this, $result );
3014                 }
3015         }
3016
3017         /**
3018          * Return aggregated value alias
3019          *
3020          * @param $valuedata
3021          * @param $valuename string
3022          *
3023          * @return string
3024          */
3025         function aggregateValue ( $valuedata, $valuename = 'value' ) {
3026                 return $valuename;
3027         }
3028
3029         /**
3030          * Ping the server and try to reconnect if it there is no connection
3031          *
3032          * @return bool Success or failure
3033          */
3034         function ping() {
3035                 # Stub.  Not essential to override.
3036                 return true;
3037         }
3038
3039         /**
3040          * Get slave lag. Currently supported only by MySQL.
3041          *
3042          * Note that this function will generate a fatal error on many
3043          * installations. Most callers should use LoadBalancer::safeGetLag()
3044          * instead.
3045          *
3046          * @return int Database replication lag in seconds
3047          */
3048         function getLag() {
3049                 return intval( $this->mFakeSlaveLag );
3050         }
3051
3052         /**
3053          * Return the maximum number of items allowed in a list, or 0 for unlimited.
3054          *
3055          * @return int
3056          */
3057         function maxListLen() {
3058                 return 0;
3059         }
3060
3061         /**
3062          * Some DBMSs have a special format for inserting into blob fields, they
3063          * don't allow simple quoted strings to be inserted. To insert into such
3064          * a field, pass the data through this function before passing it to
3065          * DatabaseBase::insert().
3066          * @param $b string
3067          * @return string
3068          */
3069         function encodeBlob( $b ) {
3070                 return $b;
3071         }
3072
3073         /**
3074          * Some DBMSs return a special placeholder object representing blob fields
3075          * in result objects. Pass the object through this function to return the
3076          * original string.
3077          * @param $b string
3078          * @return string
3079          */
3080         function decodeBlob( $b ) {
3081                 return $b;
3082         }
3083
3084         /**
3085          * Override database's default connection timeout
3086          *
3087          * @param $timeout Integer in seconds
3088          * @return void
3089          * @deprecated since 1.19; use setSessionOptions()
3090          */
3091         public function setTimeout( $timeout ) {
3092                 wfDeprecated( __METHOD__, '1.19' );
3093                 $this->setSessionOptions( array( 'connTimeout' => $timeout ) );
3094         }
3095
3096         /**
3097          * Override database's default behavior. $options include:
3098          *     'connTimeout' : Set the connection timeout value in seconds.
3099          *                     May be useful for very long batch queries such as
3100          *                     full-wiki dumps, where a single query reads out over
3101          *                     hours or days.
3102          *
3103          * @param $options Array
3104          * @return void
3105          */
3106         public function setSessionOptions( array $options ) {}
3107
3108         /**
3109          * Read and execute SQL commands from a file.
3110          *
3111          * Returns true on success, error string or exception on failure (depending
3112          * on object's error ignore settings).
3113          *
3114          * @param $filename String: File name to open
3115          * @param $lineCallback Callback: Optional function called before reading each line
3116          * @param $resultCallback Callback: Optional function called for each MySQL result
3117          * @param $fname String: Calling function name or false if name should be
3118          *      generated dynamically using $filename
3119          * @return bool|string
3120          */
3121         function sourceFile( $filename, $lineCallback = false, $resultCallback = false, $fname = false ) {
3122                 wfSuppressWarnings();
3123                 $fp = fopen( $filename, 'r' );
3124                 wfRestoreWarnings();
3125
3126                 if ( false === $fp ) {
3127                         throw new MWException( "Could not open \"{$filename}\".\n" );
3128                 }
3129
3130                 if ( !$fname ) {
3131                         $fname = __METHOD__ . "( $filename )";
3132                 }
3133
3134                 try {
3135                         $error = $this->sourceStream( $fp, $lineCallback, $resultCallback, $fname );
3136                 }
3137                 catch ( MWException $e ) {
3138                         fclose( $fp );
3139                         throw $e;
3140                 }
3141
3142                 fclose( $fp );
3143
3144                 return $error;
3145         }
3146
3147         /**
3148          * Get the full path of a patch file. Originally based on archive()
3149          * from updaters.inc. Keep in mind this always returns a patch, as
3150          * it fails back to MySQL if no DB-specific patch can be found
3151          *
3152          * @param $patch String The name of the patch, like patch-something.sql
3153          * @return String Full path to patch file
3154          */
3155         public function patchPath( $patch ) {
3156                 global $IP;
3157
3158                 $dbType = $this->getType();
3159                 if ( file_exists( "$IP/maintenance/$dbType/archives/$patch" ) ) {
3160                         return "$IP/maintenance/$dbType/archives/$patch";
3161                 } else {
3162                         return "$IP/maintenance/archives/$patch";
3163                 }
3164         }
3165
3166         /**
3167          * Set variables to be used in sourceFile/sourceStream, in preference to the
3168          * ones in $GLOBALS. If an array is set here, $GLOBALS will not be used at
3169          * all. If it's set to false, $GLOBALS will be used.
3170          *
3171          * @param $vars bool|array mapping variable name to value.
3172          */
3173         function setSchemaVars( $vars ) {
3174                 $this->mSchemaVars = $vars;
3175         }
3176
3177         /**
3178          * Read and execute commands from an open file handle.
3179          *
3180          * Returns true on success, error string or exception on failure (depending
3181          * on object's error ignore settings).
3182          *
3183          * @param $fp Resource: File handle
3184          * @param $lineCallback Callback: Optional function called before reading each line
3185          * @param $resultCallback Callback: Optional function called for each MySQL result
3186          * @param $fname String: Calling function name
3187          * @param $inputCallback Callback: Optional function called for each complete line (ended with ;) sent
3188          * @return bool|string
3189          */
3190         public function sourceStream( $fp, $lineCallback = false, $resultCallback = false,
3191                 $fname = 'DatabaseBase::sourceStream', $inputCallback = false )
3192         {
3193                 $cmd = '';
3194
3195                 while ( !feof( $fp ) ) {
3196                         if ( $lineCallback ) {
3197                                 call_user_func( $lineCallback );
3198                         }
3199
3200                         $line = trim( fgets( $fp ) );
3201
3202                         if ( $line == '' ) {
3203                                 continue;
3204                         }
3205
3206                         if ( '-' == $line[0] && '-' == $line[1] ) {
3207                                 continue;
3208                         }
3209
3210                         if ( $cmd != '' ) {
3211                                 $cmd .= ' ';
3212                         }
3213
3214                         $done = $this->streamStatementEnd( $cmd, $line );
3215
3216                         $cmd .= "$line\n";
3217
3218                         if ( $done || feof( $fp ) ) {
3219                                 $cmd = $this->replaceVars( $cmd );
3220                                 if ( $inputCallback ) {
3221                                         call_user_func( $inputCallback, $cmd );
3222                                 }
3223                                 $res = $this->query( $cmd, $fname );
3224
3225                                 if ( $resultCallback ) {
3226                                         call_user_func( $resultCallback, $res, $this );
3227                                 }
3228
3229                                 if ( false === $res ) {
3230                                         $err = $this->lastError();
3231                                         return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3232                                 }
3233
3234                                 $cmd = '';
3235                         }
3236                 }
3237
3238                 return true;
3239         }
3240
3241         /**
3242          * Called by sourceStream() to check if we've reached a statement end
3243          *
3244          * @param $sql String SQL assembled so far
3245          * @param $newLine String New line about to be added to $sql
3246          * @return Bool Whether $newLine contains end of the statement
3247          */
3248         public function streamStatementEnd( &$sql, &$newLine ) {
3249                 if ( $this->delimiter ) {
3250                         $prev = $newLine;
3251                         $newLine = preg_replace( '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3252                         if ( $newLine != $prev ) {
3253                                 return true;
3254                         }
3255                 }
3256                 return false;
3257         }
3258
3259         /**
3260          * Database independent variable replacement. Replaces a set of variables
3261          * in an SQL statement with their contents as given by $this->getSchemaVars().
3262          *
3263          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3264          *
3265          * - '{$var}' should be used for text and is passed through the database's
3266          *   addQuotes method.
3267          * - `{$var}` should be used for identifiers (eg: table and database names),
3268          *   it is passed through the database's addIdentifierQuotes method which
3269          *   can be overridden if the database uses something other than backticks.
3270          * - / *$var* / is just encoded, besides traditional table prefix and
3271          *   table options its use should be avoided.
3272          *
3273          * @param $ins String: SQL statement to replace variables in
3274          * @return String The new SQL statement with variables replaced
3275          */
3276         protected function replaceSchemaVars( $ins ) {
3277                 $vars = $this->getSchemaVars();
3278                 foreach ( $vars as $var => $value ) {
3279                         // replace '{$var}'
3280                         $ins = str_replace( '\'{$' . $var . '}\'', $this->addQuotes( $value ), $ins );
3281                         // replace `{$var}`
3282                         $ins = str_replace( '`{$' . $var . '}`', $this->addIdentifierQuotes( $value ), $ins );
3283                         // replace /*$var*/
3284                         $ins = str_replace( '/*$' . $var . '*/', $this->strencode( $value ) , $ins );
3285                 }
3286                 return $ins;
3287         }
3288
3289         /**
3290          * Replace variables in sourced SQL
3291          *
3292          * @param $ins string
3293          *
3294          * @return string
3295          */
3296         protected function replaceVars( $ins ) {
3297                 $ins = $this->replaceSchemaVars( $ins );
3298
3299                 // Table prefixes
3300                 $ins = preg_replace_callback( '!/\*(?:\$wgDBprefix|_)\*/([a-zA-Z_0-9]*)!',
3301                         array( $this, 'tableNameCallback' ), $ins );
3302
3303                 // Index names
3304                 $ins = preg_replace_callback( '!/\*i\*/([a-zA-Z_0-9]*)!',
3305                         array( $this, 'indexNameCallback' ), $ins );
3306
3307                 return $ins;
3308         }
3309
3310         /**
3311          * Get schema variables. If none have been set via setSchemaVars(), then
3312          * use some defaults from the current object.
3313          *
3314          * @return array
3315          */
3316         protected function getSchemaVars() {
3317                 if ( $this->mSchemaVars ) {
3318                         return $this->mSchemaVars;
3319                 } else {
3320                         return $this->getDefaultSchemaVars();
3321                 }
3322         }
3323
3324         /**
3325          * Get schema variables to use if none have been set via setSchemaVars().
3326          *
3327          * Override this in derived classes to provide variables for tables.sql
3328          * and SQL patch files.
3329          *
3330          * @return array
3331          */
3332         protected function getDefaultSchemaVars() {
3333                 return array();
3334         }
3335
3336         /**
3337          * Table name callback
3338          *
3339          * @param $matches array
3340          *
3341          * @return string
3342          */
3343         protected function tableNameCallback( $matches ) {
3344                 return $this->tableName( $matches[1] );
3345         }
3346
3347         /**
3348          * Index name callback
3349          *
3350          * @param $matches array
3351          *
3352          * @return string
3353          */
3354         protected function indexNameCallback( $matches ) {
3355                 return $this->indexName( $matches[1] );
3356         }
3357
3358         /**
3359          * Build a concatenation list to feed into a SQL query
3360          * @param $stringList Array: list of raw SQL expressions; caller is responsible for any quoting
3361          * @return String
3362          */
3363         function buildConcat( $stringList ) {
3364                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
3365         }
3366
3367         /**
3368          * Acquire a named lock
3369          *
3370          * Abstracted from Filestore::lock() so child classes can implement for
3371          * their own needs.
3372          *
3373          * @param $lockName String: name of lock to aquire
3374          * @param $method String: name of method calling us
3375          * @param $timeout Integer: timeout
3376          * @return Boolean
3377          */
3378         public function lock( $lockName, $method, $timeout = 5 ) {
3379                 return true;
3380         }
3381
3382         /**
3383          * Release a lock.
3384          *
3385          * @param $lockName String: Name of lock to release
3386          * @param $method String: Name of method calling us
3387          *
3388          * @return int Returns 1 if the lock was released, 0 if the lock was not established
3389          * by this thread (in which case the lock is not released), and NULL if the named
3390          * lock did not exist
3391          */
3392         public function unlock( $lockName, $method ) {
3393                 return true;
3394         }
3395
3396         /**
3397          * Lock specific tables
3398          *
3399          * @param $read Array of tables to lock for read access
3400          * @param $write Array of tables to lock for write access
3401          * @param $method String name of caller
3402          * @param $lowPriority bool Whether to indicate writes to be LOW PRIORITY
3403          *
3404          * @return bool
3405          */
3406         public function lockTables( $read, $write, $method, $lowPriority = true ) {
3407                 return true;
3408         }
3409
3410         /**
3411          * Unlock specific tables
3412          *
3413          * @param $method String the caller
3414          *
3415          * @return bool
3416          */
3417         public function unlockTables( $method ) {
3418                 return true;
3419         }
3420
3421         /**
3422          * Delete a table
3423          * @param $tableName string
3424          * @param $fName string
3425          * @return bool|ResultWrapper
3426          * @since 1.18
3427          */
3428         public function dropTable( $tableName, $fName = 'DatabaseBase::dropTable' ) {
3429                 if( !$this->tableExists( $tableName, $fName ) ) {
3430                         return false;
3431                 }
3432                 $sql = "DROP TABLE " . $this->tableName( $tableName );
3433                 if( $this->cascadingDeletes() ) {
3434                         $sql .= " CASCADE";
3435                 }
3436                 return $this->query( $sql, $fName );
3437         }
3438
3439         /**
3440          * Get search engine class. All subclasses of this need to implement this
3441          * if they wish to use searching.
3442          *
3443          * @return String
3444          */
3445         public function getSearchEngine() {
3446                 return 'SearchEngineDummy';
3447         }
3448
3449         /**
3450          * Find out when 'infinity' is. Most DBMSes support this. This is a special
3451          * keyword for timestamps in PostgreSQL, and works with CHAR(14) as well
3452          * because "i" sorts after all numbers.
3453          *
3454          * @return String
3455          */
3456         public function getInfinity() {
3457                 return 'infinity';
3458         }
3459
3460         /**
3461          * Encode an expiry time into the DBMS dependent format
3462          *
3463          * @param $expiry String: timestamp for expiry, or the 'infinity' string
3464          * @return String
3465          */
3466         public function encodeExpiry( $expiry ) {
3467                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3468                         ? $this->getInfinity()
3469                         : $this->timestamp( $expiry );
3470         }
3471
3472         /**
3473          * Decode an expiry time into a DBMS independent format
3474          *
3475          * @param $expiry String: DB timestamp field value for expiry
3476          * @param $format integer: TS_* constant, defaults to TS_MW
3477          * @return String
3478          */
3479         public function decodeExpiry( $expiry, $format = TS_MW ) {
3480                 return ( $expiry == '' || $expiry == $this->getInfinity() )
3481                         ? 'infinity'
3482                         : wfTimestamp( $format, $expiry );
3483         }
3484
3485         /**
3486          * Allow or deny "big selects" for this session only. This is done by setting
3487          * the sql_big_selects session variable.
3488          *
3489          * This is a MySQL-specific feature.
3490          *
3491          * @param $value Mixed: true for allow, false for deny, or "default" to
3492          *   restore the initial value
3493          */
3494         public function setBigSelects( $value = true ) {
3495                 // no-op
3496         }
3497 }