includes/db/Database.php

   1 <?php
   2 /**
   3  * @defgroup Database Database
   4  *
   5  * This file deals with database interface functions
   6  * and query specifics/optimisations.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along
  19  * with this program; if not, write to the Free Software Foundation, Inc.,
  20  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  21  * http://www.gnu.org/copyleft/gpl.html
  22  *
  23  * @file
  24  * @ingroup Database
  25  */
  26
  27 /**
  28  * Base interface for all DBMS-specific code. At a bare minimum, all of the
  29  * following must be implemented to support MediaWiki
  30  *
  31  * @file
  32  * @ingroup Database
  33  */
  34 interface DatabaseType {
  35         /**
  36          * Get the type of the DBMS, as it appears in $wgDBtype.
  37          *
  38          * @return string
  39          */
  40         function getType();
  41
  42         /**
  43          * Open a connection to the database. Usually aborts on failure
  44          *
  45          * @param string $server database server host
  46          * @param string $user database user name
  47          * @param string $password database user password
  48          * @param string $dbName database name
  49          * @return bool
  50          * @throws DBConnectionError
  51          */
  52         function open( $server, $user, $password, $dbName );
  53
  54         /**
  55          * Fetch the next row from the given result object, in object form.
  56          * Fields can be retrieved with $row->fieldname, with fields acting like
  57          * member variables.
  58          * If no more rows are available, false is returned.
  59          *
  60          * @param $res ResultWrapper|object as returned from DatabaseBase::query(), etc.
  61          * @return object|bool
  62          * @throws DBUnexpectedError Thrown if the database returns an error
  63          */
  64         function fetchObject( $res );
  65
  66         /**
  67          * Fetch the next row from the given result object, in associative array
  68          * form.  Fields are retrieved with $row['fieldname'].
  69          * If no more rows are available, false is returned.
  70          *
  71          * @param $res ResultWrapper result object as returned from DatabaseBase::query(), etc.
  72          * @return array|bool
  73          * @throws DBUnexpectedError Thrown if the database returns an error
  74          */
  75         function fetchRow( $res );
  76
  77         /**
  78          * Get the number of rows in a result object
  79          *
  80          * @param $res Mixed: A SQL result
  81          * @return int
  82          */
  83         function numRows( $res );
  84
  85         /**
  86          * Get the number of fields in a result object
  87          * @see http://www.php.net/mysql_num_fields
  88          *
  89          * @param $res Mixed: A SQL result
  90          * @return int
  91          */
  92         function numFields( $res );
  93
  94         /**
  95          * Get a field name in a result object
  96          * @see http://www.php.net/mysql_field_name
  97          *
  98          * @param $res Mixed: A SQL result
  99          * @param $n Integer
 100          * @return string
 101          */
 102         function fieldName( $res, $n );
 103
 104         /**
 105          * Get the inserted value of an auto-increment row
 106          *
 107          * The value inserted should be fetched from nextSequenceValue()
 108          *
 109          * Example:
 110          * $id = $dbw->nextSequenceValue( 'page_page_id_seq' );
 111          * $dbw->insert( 'page', array( 'page_id' => $id ) );
 112          * $id = $dbw->insertId();
 113          *
 114          * @return int
 115          */
 116         function insertId();
 117
 118         /**
 119          * Change the position of the cursor in a result object
 120          * @see http://www.php.net/mysql_data_seek
 121          *
 122          * @param $res Mixed: A SQL result
 123          * @param $row Mixed: Either MySQL row or ResultWrapper
 124          */
 125         function dataSeek( $res, $row );
 126
 127         /**
 128          * Get the last error number
 129          * @see http://www.php.net/mysql_errno
 130          *
 131          * @return int
 132          */
 133         function lastErrno();
 134
 135         /**
 136          * Get a description of the last error
 137          * @see http://www.php.net/mysql_error
 138          *
 139          * @return string
 140          */
 141         function lastError();
 142
 143         /**
 144          * mysql_fetch_field() wrapper
 145          * Returns false if the field doesn't exist
 146          *
 147          * @param string $table table name
 148          * @param string $field field name
 149          *
 150          * @return Field
 151          */
 152         function fieldInfo( $table, $field );
 153
 154         /**
 155          * Get information about an index into an object
 156          * @param string $table Table name
 157          * @param string $index Index name
 158          * @param string $fname Calling function name
 159          * @return Mixed: Database-specific index description class or false if the index does not exist
 160          */
 161         function indexInfo( $table, $index, $fname = __METHOD__ );
 162
 163         /**
 164          * Get the number of rows affected by the last write query
 165          * @see http://www.php.net/mysql_affected_rows
 166          *
 167          * @return int
 168          */
 169         function affectedRows();
 170
 171         /**
 172          * Wrapper for addslashes()
 173          *
 174          * @param string $s to be slashed.
 175          * @return string: slashed string.
 176          */
 177         function strencode( $s );
 178
 179         /**
 180          * Returns a wikitext link to the DB's website, e.g.,
 181          *     return "[http://www.mysql.com/ MySQL]";
 182          * Should at least contain plain text, if for some reason
 183          * your database has no website.
 184          *
 185          * @return string: wikitext of a link to the server software's web site
 186          */
 187         function getSoftwareLink();
 188
 189         /**
 190          * A string describing the current software version, like from
 191          * mysql_get_server_info().
 192          *
 193          * @return string: Version information from the database server.
 194          */
 195         function getServerVersion();
 196
 197         /**
 198          * A string describing the current software version, and possibly
 199          * other details in a user-friendly way.  Will be listed on Special:Version, etc.
 200          * Use getServerVersion() to get machine-friendly information.
 201          *
 202          * @return string: Version information from the database server
 203          */
 204         function getServerInfo();
 205 }
 206
 207 /**
 208  * Interface for classes that implement or wrap DatabaseBase
 209  * @ingroup Database
 210  */
 211 interface IDatabase {}
 212
 213 /**
 214  * Database abstraction object
 215  * @ingroup Database
 216  */
 217 abstract class DatabaseBase implements IDatabase, DatabaseType {
 218         /** Number of times to re-try an operation in case of deadlock */
 219         const DEADLOCK_TRIES = 4;
 220         /** Minimum time to wait before retry, in microseconds */
 221         const DEADLOCK_DELAY_MIN = 500000;
 222         /** Maximum time to wait before retry */
 223         const DEADLOCK_DELAY_MAX = 1500000;
 224
 225 # ------------------------------------------------------------------------------
 226 # Variables
 227 # ------------------------------------------------------------------------------
 228
 229         protected $mLastQuery = '';
 230         protected $mDoneWrites = false;
 231         protected $mPHPError = false;
 232
 233         protected $mServer, $mUser, $mPassword, $mDBname;
 234
 235         protected $mConn = null;
 236         protected $mOpened = false;
 237
 238         /** @var callable[] */
 239         protected $mTrxIdleCallbacks = array();
 240         /** @var callable[] */
 241         protected $mTrxPreCommitCallbacks = array();
 242
 243         protected $mTablePrefix;
 244         protected $mFlags;
 245         protected $mForeign;
 246         protected $mTrxLevel = 0;
 247         protected $mErrorCount = 0;
 248         protected $mLBInfo = array();
 249         protected $mFakeSlaveLag = null, $mFakeMaster = false;
 250         protected $mDefaultBigSelects = null;
 251         protected $mSchemaVars = false;
 252
 253         protected $preparedArgs;
 254
 255         protected $htmlErrors;
 256
 257         protected $delimiter = ';';
 258
 259         /**
 260          * Remembers the function name given for starting the most recent transaction via begin().
 261          * Used to provide additional context for error reporting.
 262          *
 263          * @var String
 264          * @see DatabaseBase::mTrxLevel
 265          */
 266         private $mTrxFname = null;
 267
 268         /**
 269          * Record if possible write queries were done in the last transaction started
 270          *
 271          * @var Bool
 272          * @see DatabaseBase::mTrxLevel
 273          */
 274         private $mTrxDoneWrites = false;
 275
 276         /**
 277          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 278          *
 279          * @var Bool
 280          * @see DatabaseBase::mTrxLevel
 281          */
 282         private $mTrxAutomatic = false;
 283
 284         /**
 285          * @since 1.21
 286          * @var file handle for upgrade
 287          */
 288         protected $fileHandle = null;
 289
 290 # ------------------------------------------------------------------------------
 291 # Accessors
 292 # ------------------------------------------------------------------------------
 293         # These optionally set a variable and return the previous state
 294
 295         /**
 296          * A string describing the current software version, and possibly
 297          * other details in a user-friendly way.  Will be listed on Special:Version, etc.
 298          * Use getServerVersion() to get machine-friendly information.
 299          *
 300          * @return string: Version information from the database server
 301          */
 302         public function getServerInfo() {
 303                 return $this->getServerVersion();
 304         }
 305
 306         /**
 307          * @return string: command delimiter used by this database engine
 308          */
 309         public function getDelimiter() {
 310                 return $this->delimiter;
 311         }
 312
 313         /**
 314          * Boolean, controls output of large amounts of debug information.
 315          * @param $debug bool|null
 316          *   - true to enable debugging
 317          *   - false to disable debugging
 318          *   - omitted or null to do nothing
 319          *
 320          * @return bool|null previous value of the flag
 321          */
 322         public function debug( $debug = null ) {
 323                 return wfSetBit( $this->mFlags, DBO_DEBUG, $debug );
 324         }
 325
 326         /**
 327          * Turns buffering of SQL result sets on (true) or off (false). Default is
 328          * "on".
 329          *
 330          * Unbuffered queries are very troublesome in MySQL:
 331          *
 332          *   - If another query is executed while the first query is being read
 333          *     out, the first query is killed. This means you can't call normal
 334          *     MediaWiki functions while you are reading an unbuffered query result
 335          *     from a normal wfGetDB() connection.
 336          *
 337          *   - Unbuffered queries cause the MySQL server to use large amounts of
 338          *     memory and to hold broad locks which block other queries.
 339          *
 340          * If you want to limit client-side memory, it's almost always better to
 341          * split up queries into batches using a LIMIT clause than to switch off
 342          * buffering.
 343          *
 344          * @param $buffer null|bool
 345          *
 346          * @return null|bool The previous value of the flag
 347          */
 348         public function bufferResults( $buffer = null ) {
 349                 if ( is_null( $buffer ) ) {
 350                         return !(bool)( $this->mFlags & DBO_NOBUFFER );
 351                 } else {
 352                         return !wfSetBit( $this->mFlags, DBO_NOBUFFER, !$buffer );
 353                 }
 354         }
 355
 356         /**
 357          * Turns on (false) or off (true) the automatic generation and sending
 358          * of a "we're sorry, but there has been a database error" page on
 359          * database errors. Default is on (false). When turned off, the
 360          * code should use lastErrno() and lastError() to handle the
 361          * situation as appropriate.
 362          *
 363          * Do not use this function outside of the Database classes.
 364          *
 365          * @param $ignoreErrors bool|null
 366          *
 367          * @return bool The previous value of the flag.
 368          */
 369         public function ignoreErrors( $ignoreErrors = null ) {
 370                 return wfSetBit( $this->mFlags, DBO_IGNORE, $ignoreErrors );
 371         }
 372
 373         /**
 374          * Gets or sets the current transaction level.
 375          *
 376          * Historically, transactions were allowed to be "nested". This is no
 377          * longer supported, so this function really only returns a boolean.
 378          *
 379          * @param int $level An integer (0 or 1), or omitted to leave it unchanged.
 380          * @return int The previous value
 381          */
 382         public function trxLevel( $level = null ) {
 383                 return wfSetVar( $this->mTrxLevel, $level );
 384         }
 385
 386         /**
 387          * Get/set the number of errors logged. Only useful when errors are ignored
 388          * @param int $count The count to set, or omitted to leave it unchanged.
 389          * @return int The error count
 390          */
 391         public function errorCount( $count = null ) {
 392                 return wfSetVar( $this->mErrorCount, $count );
 393         }
 394
 395         /**
 396          * Get/set the table prefix.
 397          * @param string $prefix The table prefix to set, or omitted to leave it unchanged.
 398          * @return string The previous table prefix.
 399          */
 400         public function tablePrefix( $prefix = null ) {
 401                 return wfSetVar( $this->mTablePrefix, $prefix );
 402         }
 403
 404         /**
 405          * Set the filehandle to copy write statements to.
 406          *
 407          * @param $fh filehandle
 408          */
 409         public function setFileHandle( $fh ) {
 410                 $this->fileHandle = $fh;
 411         }
 412
 413         /**
 414          * Get properties passed down from the server info array of the load
 415          * balancer.
 416          *
 417          * @param string $name The entry of the info array to get, or null to get the
 418          *   whole array
 419          *
 420          * @return LoadBalancer|null
 421          */
 422         public function getLBInfo( $name = null ) {
 423                 if ( is_null( $name ) ) {
 424                         return $this->mLBInfo;
 425                 } else {
 426                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 427                                 return $this->mLBInfo[$name];
 428                         } else {
 429                                 return null;
 430                         }
 431                 }
 432         }
 433
 434         /**
 435          * Set the LB info array, or a member of it. If called with one parameter,
 436          * the LB info array is set to that parameter. If it is called with two
 437          * parameters, the member with the given name is set to the given value.
 438          *
 439          * @param $name
 440          * @param $value
 441          */
 442         public function setLBInfo( $name, $value = null ) {
 443                 if ( is_null( $value ) ) {
 444                         $this->mLBInfo = $name;
 445                 } else {
 446                         $this->mLBInfo[$name] = $value;
 447                 }
 448         }
 449
 450         /**
 451          * Set lag time in seconds for a fake slave
 452          *
 453          * @param $lag int
 454          */
 455         public function setFakeSlaveLag( $lag ) {
 456                 $this->mFakeSlaveLag = $lag;
 457         }
 458
 459         /**
 460          * Make this connection a fake master
 461          *
 462          * @param $enabled bool
 463          */
 464         public function setFakeMaster( $enabled = true ) {
 465                 $this->mFakeMaster = $enabled;
 466         }
 467
 468         /**
 469          * Returns true if this database supports (and uses) cascading deletes
 470          *
 471          * @return bool
 472          */
 473         public function cascadingDeletes() {
 474                 return false;
 475         }
 476
 477         /**
 478          * Returns true if this database supports (and uses) triggers (e.g. on the page table)
 479          *
 480          * @return bool
 481          */
 482         public function cleanupTriggers() {
 483                 return false;
 484         }
 485
 486         /**
 487          * Returns true if this database is strict about what can be put into an IP field.
 488          * Specifically, it uses a NULL value instead of an empty string.
 489          *
 490          * @return bool
 491          */
 492         public function strictIPs() {
 493                 return false;
 494         }
 495
 496         /**
 497          * Returns true if this database uses timestamps rather than integers
 498          *
 499          * @return bool
 500          */
 501         public function realTimestamps() {
 502                 return false;
 503         }
 504
 505         /**
 506          * Returns true if this database does an implicit sort when doing GROUP BY
 507          *
 508          * @return bool
 509          */
 510         public function implicitGroupby() {
 511                 return true;
 512         }
 513
 514         /**
 515          * Returns true if this database does an implicit order by when the column has an index
 516          * For example: SELECT page_title FROM page LIMIT 1
 517          *
 518          * @return bool
 519          */
 520         public function implicitOrderby() {
 521                 return true;
 522         }
 523
 524         /**
 525          * Returns true if this database can do a native search on IP columns
 526          * e.g. this works as expected: .. WHERE rc_ip = '127.42.12.102/32';
 527          *
 528          * @return bool
 529          */
 530         public function searchableIPs() {
 531                 return false;
 532         }
 533
 534         /**
 535          * Returns true if this database can use functional indexes
 536          *
 537          * @return bool
 538          */
 539         public function functionalIndexes() {
 540                 return false;
 541         }
 542
 543         /**
 544          * Return the last query that went through DatabaseBase::query()
 545          * @return String
 546          */
 547         public function lastQuery() {
 548                 return $this->mLastQuery;
 549         }
 550
 551         /**
 552          * Returns true if the connection may have been used for write queries.
 553          * Should return true if unsure.
 554          *
 555          * @return bool
 556          */
 557         public function doneWrites() {
 558                 return $this->mDoneWrites;
 559         }
 560
 561         /**
 562          * Returns true if there is a transaction open with possible write
 563          * queries or transaction pre-commit/idle callbacks waiting on it to finish.
 564          *
 565          * @return bool
 566          */
 567         public function writesOrCallbacksPending() {
 568                 return $this->mTrxLevel && (
 569                         $this->mTrxDoneWrites || $this->mTrxIdleCallbacks || $this->mTrxPreCommitCallbacks
 570                 );
 571         }
 572
 573         /**
 574          * Is a connection to the database open?
 575          * @return Boolean
 576          */
 577         public function isOpen() {
 578                 return $this->mOpened;
 579         }
 580
 581         /**
 582          * Set a flag for this connection
 583          *
 584          * @param $flag Integer: DBO_* constants from Defines.php:
 585          *   - DBO_DEBUG: output some debug info (same as debug())
 586          *   - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
 587          *   - DBO_TRX: automatically start transactions
 588          *   - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
 589          *       and removes it in command line mode
 590          *   - DBO_PERSISTENT: use persistant database connection
 591          */
 592         public function setFlag( $flag ) {
 593                 global $wgDebugDBTransactions;
 594                 $this->mFlags |= $flag;
 595                 if ( ( $flag & DBO_TRX ) & $wgDebugDBTransactions ) {
 596                         wfDebug( "Implicit transactions are now  disabled.\n" );
 597                 }
 598         }
 599
 600         /**
 601          * Clear a flag for this connection
 602          *
 603          * @param $flag: same as setFlag()'s $flag param
 604          */
 605         public function clearFlag( $flag ) {
 606                 global $wgDebugDBTransactions;
 607                 $this->mFlags &= ~$flag;
 608                 if ( ( $flag & DBO_TRX ) && $wgDebugDBTransactions ) {
 609                         wfDebug( "Implicit transactions are now disabled.\n" );
 610                 }
 611         }
 612
 613         /**
 614          * Returns a boolean whether the flag $flag is set for this connection
 615          *
 616          * @param $flag: same as setFlag()'s $flag param
 617          * @return Boolean
 618          */
 619         public function getFlag( $flag ) {
 620                 return !!( $this->mFlags & $flag );
 621         }
 622
 623         /**
 624          * General read-only accessor
 625          *
 626          * @param $name string
 627          *
 628          * @return string
 629          */
 630         public function getProperty( $name ) {
 631                 return $this->$name;
 632         }
 633
 634         /**
 635          * @return string
 636          */
 637         public function getWikiID() {
 638                 if ( $this->mTablePrefix ) {
 639                         return "{$this->mDBname}-{$this->mTablePrefix}";
 640                 } else {
 641                         return $this->mDBname;
 642                 }
 643         }
 644
 645         /**
 646          * Return a path to the DBMS-specific schema file, otherwise default to tables.sql
 647          *
 648          * @return string
 649          */
 650         public function getSchemaPath() {
 651                 global $IP;
 652                 if ( file_exists( "$IP/maintenance/" . $this->getType() . "/tables.sql" ) ) {
 653                         return "$IP/maintenance/" . $this->getType() . "/tables.sql";
 654                 } else {
 655                         return "$IP/maintenance/tables.sql";
 656                 }
 657         }
 658
 659 # ------------------------------------------------------------------------------
 660 # Other functions
 661 # ------------------------------------------------------------------------------
 662
 663         /**
 664          * Constructor.
 665          * @param string $server database server host
 666          * @param string $user database user name
 667          * @param string $password database user password
 668          * @param string $dbName database name
 669          * @param $flags
 670          * @param string $tablePrefix database table prefixes. By default use the prefix gave in LocalSettings.php
 671          * @param bool $foreign disable some operations specific to local databases
 672          */
 673         function __construct( $server = false, $user = false, $password = false, $dbName = false,
 674                 $flags = 0, $tablePrefix = 'get from global', $foreign = false
 675         ) {
 676                 global $wgDBprefix, $wgCommandLineMode, $wgDebugDBTransactions;
 677
 678                 $this->mFlags = $flags;
 679
 680                 if ( $this->mFlags & DBO_DEFAULT ) {
 681                         if ( $wgCommandLineMode ) {
 682                                 $this->mFlags &= ~DBO_TRX;
 683                                 if ( $wgDebugDBTransactions ) {
 684                                         wfDebug( "Implicit transaction open disabled.\n" );
 685                                 }
 686                         } else {
 687                                 $this->mFlags |= DBO_TRX;
 688                                 if ( $wgDebugDBTransactions ) {
 689                                         wfDebug( "Implicit transaction open enabled.\n" );
 690                                 }
 691                         }
 692                 }
 693
 694                 /** Get the default table prefix*/
 695                 if ( $tablePrefix == 'get from global' ) {
 696                         $this->mTablePrefix = $wgDBprefix;
 697                 } else {
 698                         $this->mTablePrefix = $tablePrefix;
 699                 }
 700
 701                 $this->mForeign = $foreign;
 702
 703                 if ( $user ) {
 704                         $this->open( $server, $user, $password, $dbName );
 705                 }
 706         }
 707
 708         /**
 709          * Called by serialize. Throw an exception when DB connection is serialized.
 710          * This causes problems on some database engines because the connection is
 711          * not restored on unserialize.
 712          */
 713         public function __sleep() {
 714                 throw new MWException( 'Database serialization may cause problems, since the connection is not restored on wakeup.' );
 715         }
 716
 717         /**
 718          * Given a DB type, construct the name of the appropriate child class of
 719          * DatabaseBase. This is designed to replace all of the manual stuff like:
 720          *      $class = 'Database' . ucfirst( strtolower( $dbType ) );
 721          * as well as validate against the canonical list of DB types we have
 722          *
 723          * This factory function is mostly useful for when you need to connect to a
 724          * database other than the MediaWiki default (such as for external auth,
 725          * an extension, et cetera). Do not use this to connect to the MediaWiki
 726          * database. Example uses in core:
 727          * @see LoadBalancer::reallyOpenConnection()
 728          * @see ForeignDBRepo::getMasterDB()
 729          * @see WebInstaller_DBConnect::execute()
 730          *
 731          * @since 1.18
 732          *
 733          * @param string $dbType A possible DB type
 734          * @param array $p An array of options to pass to the constructor.
 735          *    Valid options are: host, user, password, dbname, flags, tablePrefix, driver
 736          * @return DatabaseBase subclass or null
 737          */
 738         final public static function factory( $dbType, $p = array() ) {
 739                 $canonicalDBTypes = array(
 740                         'mysql'    => array( 'mysqli', 'mysql' ),
 741                         'postgres' => array(),
 742                         'sqlite'   => array(),
 743                         'oracle'   => array(),
 744                         'mssql'    => array(),
 745                 );
 746
 747                 $driver = false;
 748                 $dbType = strtolower( $dbType );
 749                 if ( isset( $canonicalDBTypes[$dbType] ) && $canonicalDBTypes[$dbType] ) {
 750                         $possibleDrivers = $canonicalDBTypes[$dbType];
 751                         if ( !empty( $p['driver'] ) ) {
 752                                 if ( in_array( $p['driver'], $possibleDrivers ) ) {
 753                                         $driver = $p['driver'];
 754                                 } else {
 755                                         throw new MWException( __METHOD__ .
 756                                                 " cannot construct Database with type '$dbType' and driver '{$p['driver']}'" );
 757                                 }
 758                         } else {
 759                                 foreach ( $possibleDrivers as $posDriver ) {
 760                                         if ( extension_loaded( $posDriver ) ) {
 761                                                 $driver = $posDriver;
 762                                                 break;
 763                                         }
 764                                 }
 765                         }
 766                 } else {
 767                         $driver = $dbType;
 768                 }
 769                 if ( $driver === false ) {
 770                         throw new MWException( __METHOD__ .
 771                                 " no viable database extension found for type '$dbType'" );
 772                 }
 773
 774                 $class = 'Database' . ucfirst( $driver );
 775                 if ( class_exists( $class ) && is_subclass_of( $class, 'DatabaseBase' ) ) {
 776                         return new $class(
 777                                 isset( $p['host'] ) ? $p['host'] : false,
 778                                 isset( $p['user'] ) ? $p['user'] : false,
 779                                 isset( $p['password'] ) ? $p['password'] : false,
 780                                 isset( $p['dbname'] ) ? $p['dbname'] : false,
 781                                 isset( $p['flags'] ) ? $p['flags'] : 0,
 782                                 isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : 'get from global',
 783                                 isset( $p['foreign'] ) ? $p['foreign'] : false
 784                         );
 785                 } else {
 786                         return null;
 787                 }
 788         }
 789
 790         protected function installErrorHandler() {
 791                 $this->mPHPError = false;
 792                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 793                 set_error_handler( array( $this, 'connectionErrorHandler' ) );
 794         }
 795
 796         /**
 797          * @return bool|string
 798          */
 799         protected function restoreErrorHandler() {
 800                 restore_error_handler();
 801                 if ( $this->htmlErrors !== false ) {
 802                         ini_set( 'html_errors', $this->htmlErrors );
 803                 }
 804                 if ( $this->mPHPError ) {
 805                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 806                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 807                         return $error;
 808                 } else {
 809                         return false;
 810                 }
 811         }
 812
 813         /**
 814          * @param $errno
 815          * @param $errstr
 816          * @access private
 817          */
 818         public function connectionErrorHandler( $errno, $errstr ) {
 819                 $this->mPHPError = $errstr;
 820         }
 821
 822         /**
 823          * Closes a database connection.
 824          * if it is open : commits any open transactions
 825          *
 826          * @throws MWException
 827          * @return Bool operation success. true if already closed.
 828          */
 829         public function close() {
 830                 if ( count( $this->mTrxIdleCallbacks ) ) { // sanity
 831                         throw new MWException( "Transaction idle callbacks still pending." );
 832                 }
 833                 $this->mOpened = false;
 834                 if ( $this->mConn ) {
 835                         if ( $this->trxLevel() ) {
 836                                 if ( !$this->mTrxAutomatic ) {
 837                                         wfWarn( "Transaction still in progress (from {$this->mTrxFname}), " .
 838                                                 " performing implicit commit before closing connection!" );
 839                                 }
 840
 841                                 $this->commit( __METHOD__, 'flush' );
 842                         }
 843
 844                         $ret = $this->closeConnection();
 845                         $this->mConn = false;
 846                         return $ret;
 847                 } else {
 848                         return true;
 849                 }
 850         }
 851
 852         /**
 853          * Closes underlying database connection
 854          * @since 1.20
 855          * @return bool: Whether connection was closed successfully
 856          */
 857         abstract protected function closeConnection();
 858
 859         /**
 860          * @param string $error fallback error message, used if none is given by DB
 861          * @throws DBConnectionError
 862          */
 863         function reportConnectionError( $error = 'Unknown error' ) {
 864                 $myError = $this->lastError();
 865                 if ( $myError ) {
 866                         $error = $myError;
 867                 }
 868
 869                 # New method
 870                 throw new DBConnectionError( $this, $error );
 871         }
 872
 873         /**
 874          * The DBMS-dependent part of query()
 875          *
 876          * @param  $sql String: SQL query.
 877          * @return ResultWrapper Result object to feed to fetchObject, fetchRow, ...; or false on failure
 878          */
 879         abstract protected function doQuery( $sql );
 880
 881         /**
 882          * Determine whether a query writes to the DB.
 883          * Should return true if unsure.
 884          *
 885          * @param $sql string
 886          *
 887          * @return bool
 888          */
 889         public function isWriteQuery( $sql ) {
 890                 return !preg_match( '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 891         }
 892
 893         /**
 894          * Run an SQL query and return the result. Normally throws a DBQueryError
 895          * on failure. If errors are ignored, returns false instead.
 896          *
 897          * In new code, the query wrappers select(), insert(), update(), delete(),
 898          * etc. should be used where possible, since they give much better DBMS
 899          * independence and automatically quote or validate user input in a variety
 900          * of contexts. This function is generally only useful for queries which are
 901          * explicitly DBMS-dependent and are unsupported by the query wrappers, such
 902          * as CREATE TABLE.
 903          *
 904          * However, the query wrappers themselves should call this function.
 905          *
 906          * @param  $sql        String: SQL query
 907          * @param  $fname      String: Name of the calling function, for profiling/SHOW PROCESSLIST
 908          *     comment (you can use __METHOD__ or add some extra info)
 909          * @param  $tempIgnore Boolean:   Whether to avoid throwing an exception on errors...
 910          *     maybe best to catch the exception instead?
 911          * @throws MWException
 912          * @return boolean|ResultWrapper. true for a successful write query, ResultWrapper object
 913          *     for a successful read query, or false on failure if $tempIgnore set
 914          */
 915         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 916                 global $wgUser, $wgDebugDBTransactions;
 917
 918                 $this->mLastQuery = $sql;
 919                 if ( !$this->mDoneWrites && $this->isWriteQuery( $sql ) ) {
 920                         # Set a flag indicating that writes have been done
 921                         wfDebug( __METHOD__ . ": Writes done: $sql\n" );
 922                         $this->mDoneWrites = true;
 923                 }
 924
 925                 # Add a comment for easy SHOW PROCESSLIST interpretation
 926                 if ( is_object( $wgUser ) && $wgUser->isItemLoaded( 'name' ) ) {
 927                         $userName = $wgUser->getName();
 928                         if ( mb_strlen( $userName ) > 15 ) {
 929                                 $userName = mb_substr( $userName, 0, 15 ) . '...';
 930                         }
 931                         $userName = str_replace( '/', '', $userName );
 932                 } else {
 933                         $userName = '';
 934                 }
 935
 936                 // Add trace comment to the begin of the sql string, right after the operator.
 937                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (bug 42598)
 938                 $commentedSql = preg_replace( '/\s|$/', " /* $fname $userName */ ", $sql, 1 );
 939
 940                 # If DBO_TRX is set, start a transaction
 941                 if ( ( $this->mFlags & DBO_TRX ) && !$this->mTrxLevel &&
 942                         $sql != 'BEGIN' && $sql != 'COMMIT' && $sql != 'ROLLBACK' )
 943                 {
 944                         # Avoid establishing transactions for SHOW and SET statements too -
 945                         # that would delay transaction initializations to once connection
 946                         # is really used by application
 947                         $sqlstart = substr( $sql, 0, 10 ); // very much worth it, benchmark certified(tm)
 948                         if ( strpos( $sqlstart, "SHOW " ) !== 0 && strpos( $sqlstart, "SET " ) !== 0 ) {
 949                                 if ( $wgDebugDBTransactions ) {
 950                                         wfDebug( "Implicit transaction start.\n" );
 951                                 }
 952                                 $this->begin( __METHOD__ . " ($fname)" );
 953                                 $this->mTrxAutomatic = true;
 954                         }
 955                 }
 956
 957                 # Keep track of whether the transaction has write queries pending
 958                 if ( $this->mTrxLevel && !$this->mTrxDoneWrites && $this->isWriteQuery( $sql ) ) {
 959                         $this->mTrxDoneWrites = true;
 960                         Profiler::instance()->transactionWritingIn( $this->mServer, $this->mDBname );
 961                 }
 962
 963                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 964                 if ( !Profiler::instance()->isStub() ) {
 965                         # generalizeSQL will probably cut down the query to reasonable
 966                         # logging size most of the time. The substr is really just a sanity check.
 967                         if ( $isMaster ) {
 968                                 $queryProf = 'query-m: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
 969                                 $totalProf = 'DatabaseBase::query-master';
 970                         } else {
 971                                 $queryProf = 'query: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
 972                                 $totalProf = 'DatabaseBase::query';
 973                         }
 974                         wfProfileIn( $totalProf );
 975                         wfProfileIn( $queryProf );
 976                 }
 977
 978                 if ( $this->debug() ) {
 979                         static $cnt = 0;
 980
 981                         $cnt++;
 982                         $sqlx = substr( $commentedSql, 0, 500 );
 983                         $sqlx = strtr( $sqlx, "\t\n", '  ' );
 984
 985                         $master = $isMaster ? 'master' : 'slave';
 986                         wfDebug( "Query {$this->mDBname} ($cnt) ($master): $sqlx\n" );
 987                 }
 988
 989                 $queryId = MWDebug::query( $sql, $fname, $isMaster );
 990
 991                 # Do the query and handle errors
 992                 $ret = $this->doQuery( $commentedSql );
 993
 994                 MWDebug::queryTime( $queryId );
 995
 996                 # Try reconnecting if the connection was lost
 997                 if ( false === $ret && $this->wasErrorReissuable() ) {
 998                         # Transaction is gone, like it or not
 999                         $this->mTrxLevel = 0;
1000                         $this->mTrxIdleCallbacks = array(); // cancel
1001                         $this->mTrxPreCommitCallbacks = array(); // cancel
1002                         wfDebug( "Connection lost, reconnecting...\n" );
1003
1004                         if ( $this->ping() ) {
1005                                 wfDebug( "Reconnected\n" );
1006                                 $sqlx = substr( $commentedSql, 0, 500 );
1007                                 $sqlx = strtr( $sqlx, "\t\n", '  ' );
1008                                 global $wgRequestTime;
1009                                 $elapsed = round( microtime( true ) - $wgRequestTime, 3 );
1010                                 if ( $elapsed < 300 ) {
1011                                         # Not a database error to lose a transaction after a minute or two
1012                                         wfLogDBError( "Connection lost and reconnected after {$elapsed}s, query: $sqlx\n" );
1013                                 }
1014                                 $ret = $this->doQuery( $commentedSql );
1015                         } else {
1016                                 wfDebug( "Failed\n" );
1017                         }
1018                 }
1019
1020                 if ( false === $ret ) {
1021                         $this->reportQueryError( $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
1022                 }
1023
1024                 if ( !Profiler::instance()->isStub() ) {
1025                         wfProfileOut( $queryProf );
1026                         wfProfileOut( $totalProf );
1027                 }
1028
1029                 return $this->resultObject( $ret );
1030         }
1031
1032         /**
1033          * Report a query error. Log the error, and if neither the object ignore
1034          * flag nor the $tempIgnore flag is set, throw a DBQueryError.
1035          *
1036          * @param $error String
1037          * @param $errno Integer
1038          * @param $sql String
1039          * @param $fname String
1040          * @param $tempIgnore Boolean
1041          * @throws DBQueryError
1042          */
1043         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1044                 # Ignore errors during error handling to avoid infinite recursion
1045                 $ignore = $this->ignoreErrors( true );
1046                 ++$this->mErrorCount;
1047
1048                 if ( $ignore || $tempIgnore ) {
1049                         wfDebug( "SQL ERROR (ignored): $error\n" );
1050                         $this->ignoreErrors( $ignore );
1051                 } else {
1052                         $sql1line = str_replace( "\n", "\\n", $sql );
1053                         wfLogDBError( "$fname\t{$this->mServer}\t$errno\t$error\t$sql1line\n" );
1054                         wfDebug( "SQL ERROR: " . $error . "\n" );
1055                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1056                 }
1057         }
1058
1059         /**
1060          * Intended to be compatible with the PEAR::DB wrapper functions.
1061          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
1062          *
1063          * ? = scalar value, quoted as necessary
1064          * ! = raw SQL bit (a function for instance)
1065          * & = filename; reads the file and inserts as a blob
1066          *     (we don't use this though...)
1067          *
1068          * @param $sql string
1069          * @param $func string
1070          *
1071          * @return array
1072          */
1073         protected function prepare( $sql, $func = 'DatabaseBase::prepare' ) {
1074                 /* MySQL doesn't support prepared statements (yet), so just
1075                    pack up the query for reference. We'll manually replace
1076                    the bits later. */
1077                 return array( 'query' => $sql, 'func' => $func );
1078         }
1079
1080         /**
1081          * Free a prepared query, generated by prepare().
1082          * @param $prepared
1083          */
1084         protected function freePrepared( $prepared ) {
1085                 /* No-op by default */
1086         }
1087
1088         /**
1089          * Execute a prepared query with the various arguments
1090          * @param string $prepared the prepared sql
1091          * @param $args Mixed: Either an array here, or put scalars as varargs
1092          *
1093          * @return ResultWrapper
1094          */
1095         public function execute( $prepared, $args = null ) {
1096                 if ( !is_array( $args ) ) {
1097                         # Pull the var args
1098                         $args = func_get_args();
1099                         array_shift( $args );
1100                 }
1101
1102                 $sql = $this->fillPrepared( $prepared['query'], $args );
1103
1104                 return $this->query( $sql, $prepared['func'] );
1105         }
1106
1107         /**
1108          * For faking prepared SQL statements on DBs that don't support it directly.
1109          *
1110          * @param string $preparedQuery a 'preparable' SQL statement
1111          * @param array $args of arguments to fill it with
1112          * @return string executable SQL
1113          */
1114         public function fillPrepared( $preparedQuery, $args ) {
1115                 reset( $args );
1116                 $this->preparedArgs =& $args;
1117
1118                 return preg_replace_callback( '/(\\\\[?!&]|[?!&])/',
1119                         array( &$this, 'fillPreparedArg' ), $preparedQuery );
1120         }
1121
1122         /**
1123          * preg_callback func for fillPrepared()
1124          * The arguments should be in $this->preparedArgs and must not be touched
1125          * while we're doing this.
1126          *
1127          * @param $matches Array
1128          * @throws DBUnexpectedError
1129          * @return String
1130          */
1131         protected function fillPreparedArg( $matches ) {
1132                 switch ( $matches[1] ) {
1133                         case '\\?':
1134                                 return '?';
1135                         case '\\!':
1136                                 return '!';
1137                         case '\\&':
1138                                 return '&';
1139                 }
1140
1141                 list( /* $n */, $arg ) = each( $this->preparedArgs );
1142
1143                 switch ( $matches[1] ) {
1144                         case '?':
1145                                 return $this->addQuotes( $arg );
1146                         case '!':
1147                                 return $arg;
1148                         case '&':
1149                                 # return $this->addQuotes( file_get_contents( $arg ) );
1150                                 throw new DBUnexpectedError( $this, '& mode is not implemented. If it\'s really needed, uncomment the line above.' );
1151                         default:
1152                                 throw new DBUnexpectedError( $this, 'Received invalid match. This should never happen!' );
1153                 }
1154         }
1155
1156         /**
1157          * Free a result object returned by query() or select(). It's usually not
1158          * necessary to call this, just use unset() or let the variable holding
1159          * the result object go out of scope.
1160          *
1161          * @param $res Mixed: A SQL result
1162          */
1163         public function freeResult( $res ) {
1164         }
1165
1166         /**
1167          * A SELECT wrapper which returns a single field from a single result row.
1168          *
1169          * Usually throws a DBQueryError on failure. If errors are explicitly
1170          * ignored, returns false on failure.
1171          *
1172          * If no result rows are returned from the query, false is returned.
1173          *
1174          * @param string|array $table Table name. See DatabaseBase::select() for details.
1175          * @param string $var The field name to select. This must be a valid SQL
1176          *   fragment: do not use unvalidated user input.
1177          * @param string|array $cond The condition array. See DatabaseBase::select() for details.
1178          * @param string $fname The function name of the caller.
1179          * @param string|array $options The query options. See DatabaseBase::select() for details.
1180          *
1181          * @return bool|mixed The value from the field, or false on failure.
1182          */
1183         public function selectField( $table, $var, $cond = '', $fname = __METHOD__,
1184                 $options = array()
1185         ) {
1186                 if ( !is_array( $options ) ) {
1187                         $options = array( $options );
1188                 }
1189
1190                 $options['LIMIT'] = 1;
1191
1192                 $res = $this->select( $table, $var, $cond, $fname, $options );
1193
1194                 if ( $res === false || !$this->numRows( $res ) ) {
1195                         return false;
1196                 }
1197
1198                 $row = $this->fetchRow( $res );
1199
1200                 if ( $row !== false ) {
1201                         return reset( $row );
1202                 } else {
1203                         return false;
1204                 }
1205         }
1206
1207         /**
1208          * Returns an optional USE INDEX clause to go after the table, and a
1209          * string to go at the end of the query.
1210          *
1211          * @param array $options associative array of options to be turned into
1212          *              an SQL query, valid keys are listed in the function.
1213          * @return Array
1214          * @see DatabaseBase::select()
1215          */
1216         public function makeSelectOptions( $options ) {
1217                 $preLimitTail = $postLimitTail = '';
1218                 $startOpts = '';
1219
1220                 $noKeyOptions = array();
1221
1222                 foreach ( $options as $key => $option ) {
1223                         if ( is_numeric( $key ) ) {
1224                                 $noKeyOptions[$option] = true;
1225                         }
1226                 }
1227
1228                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1229
1230                 $preLimitTail .= $this->makeOrderBy( $options );
1231
1232                 // if (isset($options['LIMIT'])) {
1233                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
1234                 //              isset($options['OFFSET']) ? $options['OFFSET']
1235                 //              : false);
1236                 // }
1237
1238                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1239                         $postLimitTail .= ' FOR UPDATE';
1240                 }
1241
1242                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1243                         $postLimitTail .= ' LOCK IN SHARE MODE';
1244                 }
1245
1246                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1247                         $startOpts .= 'DISTINCT';
1248                 }
1249
1250                 # Various MySQL extensions
1251                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1252                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1253                 }
1254
1255                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1256                         $startOpts .= ' HIGH_PRIORITY';
1257                 }
1258
1259                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1260                         $startOpts .= ' SQL_BIG_RESULT';
1261                 }
1262
1263                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1264                         $startOpts .= ' SQL_BUFFER_RESULT';
1265                 }
1266
1267                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1268                         $startOpts .= ' SQL_SMALL_RESULT';
1269                 }
1270
1271                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1272                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1273                 }
1274
1275                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1276                         $startOpts .= ' SQL_CACHE';
1277                 }
1278
1279                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1280                         $startOpts .= ' SQL_NO_CACHE';
1281                 }
1282
1283                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1284                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1285                 } else {
1286                         $useIndex = '';
1287                 }
1288
1289                 return array( $startOpts, $useIndex, $preLimitTail, $postLimitTail );
1290         }
1291
1292         /**
1293          * Returns an optional GROUP BY with an optional HAVING
1294          *
1295          * @param array $options associative array of options
1296          * @return string
1297          * @see DatabaseBase::select()
1298          * @since 1.21
1299          */
1300         public function makeGroupByWithHaving( $options ) {
1301                 $sql = '';
1302                 if ( isset( $options['GROUP BY'] ) ) {
1303                         $gb = is_array( $options['GROUP BY'] )
1304                                 ? implode( ',', $options['GROUP BY'] )
1305                                 : $options['GROUP BY'];
1306                         $sql .= ' GROUP BY ' . $gb;
1307                 }
1308                 if ( isset( $options['HAVING'] ) ) {
1309                         $having = is_array( $options['HAVING'] )
1310                                 ? $this->makeList( $options['HAVING'], LIST_AND )
1311                                 : $options['HAVING'];
1312                         $sql .= ' HAVING ' . $having;
1313                 }
1314                 return $sql;
1315         }
1316
1317         /**
1318          * Returns an optional ORDER BY
1319          *
1320          * @param array $options associative array of options
1321          * @return string
1322          * @see DatabaseBase::select()
1323          * @since 1.21
1324          */
1325         public function makeOrderBy( $options ) {
1326                 if ( isset( $options['ORDER BY'] ) ) {
1327                         $ob = is_array( $options['ORDER BY'] )
1328                                 ? implode( ',', $options['ORDER BY'] )
1329                                 : $options['ORDER BY'];
1330                         return ' ORDER BY ' . $ob;
1331                 }
1332                 return '';
1333         }
1334
1335         /**
1336          * Execute a SELECT query constructed using the various parameters provided.
1337          * See below for full details of the parameters.
1338          *
1339          * @param string|array $table Table name
1340          * @param string|array $vars Field names
1341          * @param string|array $conds Conditions
1342          * @param string $fname Caller function name
1343          * @param array $options Query options
1344          * @param $join_conds Array Join conditions
1345          *
1346          * @param $table string|array
1347          *
1348          * May be either an array of table names, or a single string holding a table
1349          * name. If an array is given, table aliases can be specified, for example:
1350          *
1351          *    array( 'a' => 'user' )
1352          *
1353          * This includes the user table in the query, with the alias "a" available
1354          * for use in field names (e.g. a.user_name).
1355          *
1356          * All of the table names given here are automatically run through
1357          * DatabaseBase::tableName(), which causes the table prefix (if any) to be
1358          * added, and various other table name mappings to be performed.
1359          *
1360          *
1361          * @param $vars string|array
1362          *
1363          * May be either a field name or an array of field names. The field names
1364          * can be complete fragments of SQL, for direct inclusion into the SELECT
1365          * query. If an array is given, field aliases can be specified, for example:
1366          *
1367          *   array( 'maxrev' => 'MAX(rev_id)' )
1368          *
1369          * This includes an expression with the alias "maxrev" in the query.
1370          *
1371          * If an expression is given, care must be taken to ensure that it is
1372          * DBMS-independent.
1373          *
1374          *
1375          * @param $conds string|array
1376          *
1377          * May be either a string containing a single condition, or an array of
1378          * conditions. If an array is given, the conditions constructed from each
1379          * element are combined with AND.
1380          *
1381          * Array elements may take one of two forms:
1382          *
1383          *   - Elements with a numeric key are interpreted as raw SQL fragments.
1384          *   - Elements with a string key are interpreted as equality conditions,
1385          *     where the key is the field name.
1386          *     - If the value of such an array element is a scalar (such as a
1387          *       string), it will be treated as data and thus quoted appropriately.
1388          *       If it is null, an IS NULL clause will be added.
1389          *     - If the value is an array, an IN(...) clause will be constructed,
1390          *       such that the field name may match any of the elements in the
1391          *       array. The elements of the array will be quoted.
1392          *
1393          * Note that expressions are often DBMS-dependent in their syntax.
1394          * DBMS-independent wrappers are provided for constructing several types of
1395          * expression commonly used in condition queries. See:
1396          *    - DatabaseBase::buildLike()
1397          *    - DatabaseBase::conditional()
1398          *
1399          *
1400          * @param $options string|array
1401          *
1402          * Optional: Array of query options. Boolean options are specified by
1403          * including them in the array as a string value with a numeric key, for
1404          * example:
1405          *
1406          *    array( 'FOR UPDATE' )
1407          *
1408          * The supported options are:
1409          *
1410          *   - OFFSET: Skip this many rows at the start of the result set. OFFSET
1411          *     with LIMIT can theoretically be used for paging through a result set,
1412          *     but this is discouraged in MediaWiki for performance reasons.
1413          *
1414          *   - LIMIT: Integer: return at most this many rows. The rows are sorted
1415          *     and then the first rows are taken until the limit is reached. LIMIT
1416          *     is applied to a result set after OFFSET.
1417          *
1418          *   - FOR UPDATE: Boolean: lock the returned rows so that they can't be
1419          *     changed until the next COMMIT.
1420          *
1421          *   - DISTINCT: Boolean: return only unique result rows.
1422          *
1423          *   - GROUP BY: May be either an SQL fragment string naming a field or
1424          *     expression to group by, or an array of such SQL fragments.
1425          *
1426          *   - HAVING: May be either an string containing a HAVING clause or an array of
1427          *     conditions building the HAVING clause. If an array is given, the conditions
1428          *     constructed from each element are combined with AND.
1429          *
1430          *   - ORDER BY: May be either an SQL fragment giving a field name or
1431          *     expression to order by, or an array of such SQL fragments.
1432          *
1433          *   - USE INDEX: This may be either a string giving the index name to use
1434          *     for the query, or an array. If it is an associative array, each key
1435          *     gives the table name (or alias), each value gives the index name to
1436          *     use for that table. All strings are SQL fragments and so should be
1437          *     validated by the caller.
1438          *
1439          *   - EXPLAIN: In MySQL, this causes an EXPLAIN SELECT query to be run,
1440          *     instead of SELECT.
1441          *
1442          * And also the following boolean MySQL extensions, see the MySQL manual
1443          * for documentation:
1444          *
1445          *    - LOCK IN SHARE MODE
1446          *    - STRAIGHT_JOIN
1447          *    - HIGH_PRIORITY
1448          *    - SQL_BIG_RESULT
1449          *    - SQL_BUFFER_RESULT
1450          *    - SQL_SMALL_RESULT
1451          *    - SQL_CALC_FOUND_ROWS
1452          *    - SQL_CACHE
1453          *    - SQL_NO_CACHE
1454          *
1455          *
1456          * @param $join_conds string|array
1457          *
1458          * Optional associative array of table-specific join conditions. In the
1459          * most common case, this is unnecessary, since the join condition can be
1460          * in $conds. However, it is useful for doing a LEFT JOIN.
1461          *
1462          * The key of the array contains the table name or alias. The value is an
1463          * array with two elements, numbered 0 and 1. The first gives the type of
1464          * join, the second is an SQL fragment giving the join condition for that
1465          * table. For example:
1466          *
1467          *    array( 'page' => array( 'LEFT JOIN', 'page_latest=rev_id' ) )
1468          *
1469          * @return ResultWrapper. If the query returned no rows, a ResultWrapper
1470          *   with no rows in it will be returned. If there was a query error, a
1471          *   DBQueryError exception will be thrown, except if the "ignore errors"
1472          *   option was set, in which case false will be returned.
1473          */
1474         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1475                 $options = array(), $join_conds = array() ) {
1476                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1477
1478                 return $this->query( $sql, $fname );
1479         }
1480
1481         /**
1482          * The equivalent of DatabaseBase::select() except that the constructed SQL
1483          * is returned, instead of being immediately executed. This can be useful for
1484          * doing UNION queries, where the SQL text of each query is needed. In general,
1485          * however, callers outside of Database classes should just use select().
1486          *
1487          * @param string|array $table Table name
1488          * @param string|array $vars Field names
1489          * @param string|array $conds Conditions
1490          * @param string $fname Caller function name
1491          * @param string|array $options Query options
1492          * @param $join_conds string|array Join conditions
1493          *
1494          * @return string SQL query string.
1495          * @see DatabaseBase::select()
1496          */
1497         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1498                 $options = array(), $join_conds = array() )
1499         {
1500                 if ( is_array( $vars ) ) {
1501                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1502                 }
1503
1504                 $options = (array)$options;
1505                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1506                         ? $options['USE INDEX']
1507                         : array();
1508
1509                 if ( is_array( $table ) ) {
1510                         $from = ' FROM ' .
1511                                 $this->tableNamesWithUseIndexOrJOIN( $table, $useIndexes, $join_conds );
1512                 } elseif ( $table != '' ) {
1513                         if ( $table[0] == ' ' ) {
1514                                 $from = ' FROM ' . $table;
1515                         } else {
1516                                 $from = ' FROM ' .
1517                                         $this->tableNamesWithUseIndexOrJOIN( array( $table ), $useIndexes, array() );
1518                         }
1519                 } else {
1520                         $from = '';
1521                 }
1522
1523                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail ) =
1524                         $this->makeSelectOptions( $options );
1525
1526                 if ( !empty( $conds ) ) {
1527                         if ( is_array( $conds ) ) {
1528                                 $conds = $this->makeList( $conds, LIST_AND );
1529                         }
1530                         $sql = "SELECT $startOpts $vars $from $useIndex WHERE $conds $preLimitTail";
1531                 } else {
1532                         $sql = "SELECT $startOpts $vars $from $useIndex $preLimitTail";
1533                 }
1534
1535                 if ( isset( $options['LIMIT'] ) ) {
1536                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1537                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1538                 }
1539                 $sql = "$sql $postLimitTail";
1540
1541                 if ( isset( $options['EXPLAIN'] ) ) {
1542                         $sql = 'EXPLAIN ' . $sql;
1543                 }
1544
1545                 return $sql;
1546         }
1547
1548         /**
1549          * Single row SELECT wrapper. Equivalent to DatabaseBase::select(), except
1550          * that a single row object is returned. If the query returns no rows,
1551          * false is returned.
1552          *
1553          * @param string|array $table Table name
1554          * @param string|array $vars Field names
1555          * @param array $conds Conditions
1556          * @param string $fname Caller function name
1557          * @param string|array $options Query options
1558          * @param $join_conds array|string Join conditions
1559          *
1560          * @return object|bool
1561          */
1562         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1563                 $options = array(), $join_conds = array() )
1564         {
1565                 $options = (array)$options;
1566                 $options['LIMIT'] = 1;
1567                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1568
1569                 if ( $res === false ) {
1570                         return false;
1571                 }
1572
1573                 if ( !$this->numRows( $res ) ) {
1574                         return false;
1575                 }
1576
1577                 $obj = $this->fetchObject( $res );
1578
1579                 return $obj;
1580         }
1581
1582         /**
1583          * Estimate rows in dataset.
1584          *
1585          * MySQL allows you to estimate the number of rows that would be returned
1586          * by a SELECT query, using EXPLAIN SELECT. The estimate is provided using
1587          * index cardinality statistics, and is notoriously inaccurate, especially
1588          * when large numbers of rows have recently been added or deleted.
1589          *
1590          * For DBMSs that don't support fast result size estimation, this function
1591          * will actually perform the SELECT COUNT(*).
1592          *
1593          * Takes the same arguments as DatabaseBase::select().
1594          *
1595          * @param string $table table name
1596          * @param array|string $vars : unused
1597          * @param array|string $conds : filters on the table
1598          * @param string $fname function name for profiling
1599          * @param array $options options for select
1600          * @return Integer: row count
1601          */
1602         public function estimateRowCount( $table, $vars = '*', $conds = '',
1603                 $fname = __METHOD__, $options = array() )
1604         {
1605                 $rows = 0;
1606                 $res = $this->select( $table, array( 'rowcount' => 'COUNT(*)' ), $conds, $fname, $options );
1607
1608                 if ( $res ) {
1609                         $row = $this->fetchRow( $res );
1610                         $rows = ( isset( $row['rowcount'] ) ) ? $row['rowcount'] : 0;
1611                 }
1612
1613                 return $rows;
1614         }
1615
1616         /**
1617          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1618          * It's only slightly flawed. Don't use for anything important.
1619          *
1620          * @param string $sql A SQL Query
1621          *
1622          * @return string
1623          */
1624         static function generalizeSQL( $sql ) {
1625                 # This does the same as the regexp below would do, but in such a way
1626                 # as to avoid crashing php on some large strings.
1627                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1628
1629                 $sql = str_replace( "\\\\", '', $sql );
1630                 $sql = str_replace( "\\'", '', $sql );
1631                 $sql = str_replace( "\\\"", '', $sql );
1632                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1633                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1634
1635                 # All newlines, tabs, etc replaced by single space
1636                 $sql = preg_replace( '/\s+/', ' ', $sql );
1637
1638                 # All numbers => N
1639                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1640                 $sql = preg_replace( '/-?\d+/s', 'N', $sql );
1641
1642                 return $sql;
1643         }
1644
1645         /**
1646          * Determines whether a field exists in a table
1647          *
1648          * @param string $table table name
1649          * @param string $field filed to check on that table
1650          * @param string $fname calling function name (optional)
1651          * @return Boolean: whether $table has filed $field
1652          */
1653         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1654                 $info = $this->fieldInfo( $table, $field );
1655
1656                 return (bool)$info;
1657         }
1658
1659         /**
1660          * Determines whether an index exists
1661          * Usually throws a DBQueryError on failure
1662          * If errors are explicitly ignored, returns NULL on failure
1663          *
1664          * @param $table
1665          * @param $index
1666          * @param $fname string
1667          *
1668          * @return bool|null
1669          */
1670         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1671                 if ( !$this->tableExists( $table ) ) {
1672                         return null;
1673                 }
1674
1675                 $info = $this->indexInfo( $table, $index, $fname );
1676                 if ( is_null( $info ) ) {
1677                         return null;
1678                 } else {
1679                         return $info !== false;
1680                 }
1681         }
1682
1683         /**
1684          * Query whether a given table exists
1685          *
1686          * @param $table string
1687          * @param $fname string
1688          *
1689          * @return bool
1690          */
1691         public function tableExists( $table, $fname = __METHOD__ ) {
1692                 $table = $this->tableName( $table );
1693                 $old = $this->ignoreErrors( true );
1694                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname );
1695                 $this->ignoreErrors( $old );
1696
1697                 return (bool)$res;
1698         }
1699
1700         /**
1701          * mysql_field_type() wrapper
1702          * @param $res
1703          * @param $index
1704          * @return string
1705          */
1706         public function fieldType( $res, $index ) {
1707                 if ( $res instanceof ResultWrapper ) {
1708                         $res = $res->result;
1709                 }
1710
1711                 return mysql_field_type( $res, $index );
1712         }
1713
1714         /**
1715          * Determines if a given index is unique
1716          *
1717          * @param $table string
1718          * @param $index string
1719          *
1720          * @return bool
1721          */
1722         public function indexUnique( $table, $index ) {
1723                 $indexInfo = $this->indexInfo( $table, $index );
1724
1725                 if ( !$indexInfo ) {
1726                         return null;
1727                 }
1728
1729                 return !$indexInfo[0]->Non_unique;
1730         }
1731
1732         /**
1733          * Helper for DatabaseBase::insert().
1734          *
1735          * @param $options array
1736          * @return string
1737          */
1738         protected function makeInsertOptions( $options ) {
1739                 return implode( ' ', $options );
1740         }
1741
1742         /**
1743          * INSERT wrapper, inserts an array into a table.
1744          *
1745          * $a may be either:
1746          *
1747          *   - A single associative array. The array keys are the field names, and
1748          *     the values are the values to insert. The values are treated as data
1749          *     and will be quoted appropriately. If NULL is inserted, this will be
1750          *     converted to a database NULL.
1751          *   - An array with numeric keys, holding a list of associative arrays.
1752          *     This causes a multi-row INSERT on DBMSs that support it. The keys in
1753          *     each subarray must be identical to each other, and in the same order.
1754          *
1755          * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
1756          * returns success.
1757          *
1758          * $options is an array of options, with boolean options encoded as values
1759          * with numeric keys, in the same style as $options in
1760          * DatabaseBase::select(). Supported options are:
1761          *
1762          *   - IGNORE: Boolean: if present, duplicate key errors are ignored, and
1763          *     any rows which cause duplicate key errors are not inserted. It's
1764          *     possible to determine how many rows were successfully inserted using
1765          *     DatabaseBase::affectedRows().
1766          *
1767          * @param $table   String Table name. This will be passed through
1768          *                 DatabaseBase::tableName().
1769          * @param $a       Array of rows to insert
1770          * @param $fname   String Calling function name (use __METHOD__) for logs/profiling
1771          * @param array $options of options
1772          *
1773          * @return bool
1774          */
1775         public function insert( $table, $a, $fname = __METHOD__, $options = array() ) {
1776                 # No rows to insert, easy just return now
1777                 if ( !count( $a ) ) {
1778                         return true;
1779                 }
1780
1781                 $table = $this->tableName( $table );
1782
1783                 if ( !is_array( $options ) ) {
1784                         $options = array( $options );
1785                 }
1786
1787                 $fh = null;
1788                 if ( isset( $options['fileHandle'] ) ) {
1789                         $fh = $options['fileHandle'];
1790                 }
1791                 $options = $this->makeInsertOptions( $options );
1792
1793                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1794                         $multi = true;
1795                         $keys = array_keys( $a[0] );
1796                 } else {
1797                         $multi = false;
1798                         $keys = array_keys( $a );
1799                 }
1800
1801                 $sql = 'INSERT ' . $options .
1802                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1803
1804                 if ( $multi ) {
1805                         $first = true;
1806                         foreach ( $a as $row ) {
1807                                 if ( $first ) {
1808                                         $first = false;
1809                                 } else {
1810                                         $sql .= ',';
1811                                 }
1812                                 $sql .= '(' . $this->makeList( $row ) . ')';
1813                         }
1814                 } else {
1815                         $sql .= '(' . $this->makeList( $a ) . ')';
1816                 }
1817
1818                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1819                         return false;
1820                 } elseif ( $fh !== null ) {
1821                         return true;
1822                 }
1823
1824                 return (bool)$this->query( $sql, $fname );
1825         }
1826
1827         /**
1828          * Make UPDATE options for the DatabaseBase::update function
1829          *
1830          * @param array $options The options passed to DatabaseBase::update
1831          * @return string
1832          */
1833         protected function makeUpdateOptions( $options ) {
1834                 if ( !is_array( $options ) ) {
1835                         $options = array( $options );
1836                 }
1837
1838                 $opts = array();
1839
1840                 if ( in_array( 'LOW_PRIORITY', $options ) ) {
1841                         $opts[] = $this->lowPriorityOption();
1842                 }
1843
1844                 if ( in_array( 'IGNORE', $options ) ) {
1845                         $opts[] = 'IGNORE';
1846                 }
1847
1848                 return implode( ' ', $opts );
1849         }
1850
1851         /**
1852          * UPDATE wrapper. Takes a condition array and a SET array.
1853          *
1854          * @param $table  String name of the table to UPDATE. This will be passed through
1855          *                DatabaseBase::tableName().
1856          *
1857          * @param array $values  An array of values to SET. For each array element,
1858          *                the key gives the field name, and the value gives the data
1859          *                to set that field to. The data will be quoted by
1860          *                DatabaseBase::addQuotes().
1861          *
1862          * @param $conds  Array:  An array of conditions (WHERE). See
1863          *                DatabaseBase::select() for the details of the format of
1864          *                condition arrays. Use '*' to update all rows.
1865          *
1866          * @param $fname  String: The function name of the caller (from __METHOD__),
1867          *                for logging and profiling.
1868          *
1869          * @param array $options An array of UPDATE options, can be:
1870          *                   - IGNORE: Ignore unique key conflicts
1871          *                   - LOW_PRIORITY: MySQL-specific, see MySQL manual.
1872          * @return Boolean
1873          */
1874         function update( $table, $values, $conds, $fname = __METHOD__, $options = array() ) {
1875                 $table = $this->tableName( $table );
1876                 $opts = $this->makeUpdateOptions( $options );
1877                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET );
1878
1879                 if ( $conds !== array() && $conds !== '*' ) {
1880                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1881                 }
1882
1883                 return $this->query( $sql, $fname );
1884         }
1885
1886         /**
1887          * Makes an encoded list of strings from an array
1888          * @param array $a containing the data
1889          * @param int $mode Constant
1890          *      - LIST_COMMA:          comma separated, no field names
1891          *      - LIST_AND:            ANDed WHERE clause (without the WHERE). See
1892          *        the documentation for $conds in DatabaseBase::select().
1893          *      - LIST_OR:             ORed WHERE clause (without the WHERE)
1894          *      - LIST_SET:            comma separated with field names, like a SET clause
1895          *      - LIST_NAMES:          comma separated field names
1896          *
1897          * @throws MWException|DBUnexpectedError
1898          * @return string
1899          */
1900         public function makeList( $a, $mode = LIST_COMMA ) {
1901                 if ( !is_array( $a ) ) {
1902                         throw new DBUnexpectedError( $this, 'DatabaseBase::makeList called with incorrect parameters' );
1903                 }
1904
1905                 $first = true;
1906                 $list = '';
1907
1908                 foreach ( $a as $field => $value ) {
1909                         if ( !$first ) {
1910                                 if ( $mode == LIST_AND ) {
1911                                         $list .= ' AND ';
1912                                 } elseif ( $mode == LIST_OR ) {
1913                                         $list .= ' OR ';
1914                                 } else {
1915                                         $list .= ',';
1916                                 }
1917                         } else {
1918                                 $first = false;
1919                         }
1920
1921                         if ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_numeric( $field ) ) {
1922                                 $list .= "($value)";
1923                         } elseif ( ( $mode == LIST_SET ) && is_numeric( $field ) ) {
1924                                 $list .= "$value";
1925                         } elseif ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_array( $value ) ) {
1926                                 if ( count( $value ) == 0 ) {
1927                                         throw new MWException( __METHOD__ . ": empty input for field $field" );
1928                                 } elseif ( count( $value ) == 1 ) {
1929                                         // Special-case single values, as IN isn't terribly efficient
1930                                         // Don't necessarily assume the single key is 0; we don't
1931                                         // enforce linear numeric ordering on other arrays here.
1932                                         $value = array_values( $value );
1933                                         $list .= $field . " = " . $this->addQuotes( $value[0] );
1934                                 } else {
1935                                         $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1936                                 }
1937                         } elseif ( $value === null ) {
1938                                 if ( $mode == LIST_AND || $mode == LIST_OR ) {
1939                                         $list .= "$field IS ";
1940                                 } elseif ( $mode == LIST_SET ) {
1941                                         $list .= "$field = ";
1942                                 }
1943                                 $list .= 'NULL';
1944                         } else {
1945                                 if ( $mode == LIST_AND || $mode == LIST_OR || $mode == LIST_SET ) {
1946                                         $list .= "$field = ";
1947                                 }
1948                                 $list .= $mode == LIST_NAMES ? $value : $this->addQuotes( $value );
1949                         }
1950                 }
1951
1952                 return $list;
1953         }
1954
1955         /**
1956          * Build a partial where clause from a 2-d array such as used for LinkBatch.
1957          * The keys on each level may be either integers or strings.
1958          *
1959          * @param array $data organized as 2-d
1960          *              array(baseKeyVal => array(subKeyVal => [ignored], ...), ...)
1961          * @param string $baseKey field name to match the base-level keys to (eg 'pl_namespace')
1962          * @param string $subKey field name to match the sub-level keys to (eg 'pl_title')
1963          * @return Mixed: string SQL fragment, or false if no items in array.
1964          */
1965         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1966                 $conds = array();
1967
1968                 foreach ( $data as $base => $sub ) {
1969                         if ( count( $sub ) ) {
1970                                 $conds[] = $this->makeList(
1971                                         array( $baseKey => $base, $subKey => array_keys( $sub ) ),
1972                                         LIST_AND );
1973                         }
1974                 }
1975
1976                 if ( $conds ) {
1977                         return $this->makeList( $conds, LIST_OR );
1978                 } else {
1979                         // Nothing to search for...
1980                         return false;
1981                 }
1982         }
1983
1984         /**
1985          * Return aggregated value alias
1986          *
1987          * @param $valuedata
1988          * @param $valuename string
1989          *
1990          * @return string
1991          */
1992         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1993                 return $valuename;
1994         }
1995
1996         /**
1997          * @param $field
1998          * @return string
1999          */
2000         public function bitNot( $field ) {
2001                 return "(~$field)";
2002         }
2003
2004         /**
2005          * @param $fieldLeft
2006          * @param $fieldRight
2007          * @return string
2008          */
2009         public function bitAnd( $fieldLeft, $fieldRight ) {
2010                 return "($fieldLeft & $fieldRight)";
2011         }
2012
2013         /**
2014          * @param  $fieldLeft
2015          * @param  $fieldRight
2016          * @return string
2017          */
2018         public function bitOr( $fieldLeft, $fieldRight ) {
2019                 return "($fieldLeft | $fieldRight)";
2020         }
2021
2022         /**
2023          * Build a concatenation list to feed into a SQL query
2024          * @param array $stringList list of raw SQL expressions; caller is responsible for any quoting
2025          * @return String
2026          */
2027         public function buildConcat( $stringList ) {
2028                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
2029         }
2030
2031         /**
2032          * Change the current database
2033          *
2034          * @todo Explain what exactly will fail if this is not overridden.
2035          *
2036          * @param $db
2037          *
2038          * @return bool Success or failure
2039          */
2040         public function selectDB( $db ) {
2041                 # Stub.  Shouldn't cause serious problems if it's not overridden, but
2042                 # if your database engine supports a concept similar to MySQL's
2043                 # databases you may as well.
2044                 $this->mDBname = $db;
2045                 return true;
2046         }
2047
2048         /**
2049          * Get the current DB name
2050          */
2051         public function getDBname() {
2052                 return $this->mDBname;
2053         }
2054
2055         /**
2056          * Get the server hostname or IP address
2057          */
2058         public function getServer() {
2059                 return $this->mServer;
2060         }
2061
2062         /**
2063          * Format a table name ready for use in constructing an SQL query
2064          *
2065          * This does two important things: it quotes the table names to clean them up,
2066          * and it adds a table prefix if only given a table name with no quotes.
2067          *
2068          * All functions of this object which require a table name call this function
2069          * themselves. Pass the canonical name to such functions. This is only needed
2070          * when calling query() directly.
2071          *
2072          * @param string $name database table name
2073          * @param string $format One of:
2074          *   quoted - Automatically pass the table name through addIdentifierQuotes()
2075          *            so that it can be used in a query.
2076          *   raw - Do not add identifier quotes to the table name
2077          * @return String: full database name
2078          */
2079         public function tableName( $name, $format = 'quoted' ) {
2080                 global $wgSharedDB, $wgSharedPrefix, $wgSharedTables;
2081                 # Skip the entire process when we have a string quoted on both ends.
2082                 # Note that we check the end so that we will still quote any use of
2083                 # use of `database`.table. But won't break things if someone wants
2084                 # to query a database table with a dot in the name.
2085                 if ( $this->isQuotedIdentifier( $name ) ) {
2086                         return $name;
2087                 }
2088
2089                 # Lets test for any bits of text that should never show up in a table
2090                 # name. Basically anything like JOIN or ON which are actually part of
2091                 # SQL queries, but may end up inside of the table value to combine
2092                 # sql. Such as how the API is doing.
2093                 # Note that we use a whitespace test rather than a \b test to avoid
2094                 # any remote case where a word like on may be inside of a table name
2095                 # surrounded by symbols which may be considered word breaks.
2096                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
2097                         return $name;
2098                 }
2099
2100                 # Split database and table into proper variables.
2101                 # We reverse the explode so that database.table and table both output
2102                 # the correct table.
2103                 $dbDetails = explode( '.', $name, 2 );
2104                 if ( count( $dbDetails ) == 2 ) {
2105                         list( $database, $table ) = $dbDetails;
2106                         # We don't want any prefix added in this case
2107                         $prefix = '';
2108                 } else {
2109                         list( $table ) = $dbDetails;
2110                         if ( $wgSharedDB !== null # We have a shared database
2111                                 && $this->mForeign == false # We're not working on a foreign database
2112                                 && !$this->isQuotedIdentifier( $table ) # Paranoia check to prevent shared tables listing '`table`'
2113                                 && in_array( $table, $wgSharedTables ) # A shared table is selected
2114                         ) {
2115                                 $database = $wgSharedDB;
2116                                 $prefix = $wgSharedPrefix === null ? $this->mTablePrefix : $wgSharedPrefix;
2117                         } else {
2118                                 $database = null;
2119                                 $prefix = $this->mTablePrefix; # Default prefix
2120                         }
2121                 }
2122
2123                 # Quote $table and apply the prefix if not quoted.
2124                 $tableName = "{$prefix}{$table}";
2125                 if ( $format == 'quoted' && !$this->isQuotedIdentifier( $tableName ) ) {
2126                         $tableName = $this->addIdentifierQuotes( $tableName );
2127                 }
2128
2129                 # Quote $database and merge it with the table name if needed
2130                 if ( $database !== null ) {
2131                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $database ) ) {
2132                                 $database = $this->addIdentifierQuotes( $database );
2133                         }
2134                         $tableName = $database . '.' . $tableName;
2135                 }
2136
2137                 return $tableName;
2138         }
2139
2140         /**
2141          * Fetch a number of table names into an array
2142          * This is handy when you need to construct SQL for joins
2143          *
2144          * Example:
2145          * extract( $dbr->tableNames( 'user', 'watchlist' ) );
2146          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
2147          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
2148          *
2149          * @return array
2150          */
2151         public function tableNames() {
2152                 $inArray = func_get_args();
2153                 $retVal = array();
2154
2155                 foreach ( $inArray as $name ) {
2156                         $retVal[$name] = $this->tableName( $name );
2157                 }
2158
2159                 return $retVal;
2160         }
2161
2162         /**
2163          * Fetch a number of table names into an zero-indexed numerical array
2164          * This is handy when you need to construct SQL for joins
2165          *
2166          * Example:
2167          * list( $user, $watchlist ) = $dbr->tableNamesN( 'user', 'watchlist' );
2168          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
2169          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
2170          *
2171          * @return array
2172          */
2173         public function tableNamesN() {
2174                 $inArray = func_get_args();
2175                 $retVal = array();
2176
2177                 foreach ( $inArray as $name ) {
2178                         $retVal[] = $this->tableName( $name );
2179                 }
2180
2181                 return $retVal;
2182         }
2183
2184         /**
2185          * Get an aliased table name
2186          * e.g. tableName AS newTableName
2187          *
2188          * @param string $name Table name, see tableName()
2189          * @param string|bool $alias Alias (optional)
2190          * @return string SQL name for aliased table. Will not alias a table to its own name
2191          */
2192         public function tableNameWithAlias( $name, $alias = false ) {
2193                 if ( !$alias || $alias == $name ) {
2194                         return $this->tableName( $name );
2195                 } else {
2196                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
2197                 }
2198         }
2199
2200         /**
2201          * Gets an array of aliased table names
2202          *
2203          * @param $tables array( [alias] => table )
2204          * @return array of strings, see tableNameWithAlias()
2205          */
2206         public function tableNamesWithAlias( $tables ) {
2207                 $retval = array();
2208                 foreach ( $tables as $alias => $table ) {
2209                         if ( is_numeric( $alias ) ) {
2210                                 $alias = $table;
2211                         }
2212                         $retval[] = $this->tableNameWithAlias( $table, $alias );
2213                 }
2214                 return $retval;
2215         }
2216
2217         /**
2218          * Get an aliased field name
2219          * e.g. fieldName AS newFieldName
2220          *
2221          * @param string $name Field name
2222          * @param string|bool $alias Alias (optional)
2223          * @return string SQL name for aliased field. Will not alias a field to its own name
2224          */
2225         public function fieldNameWithAlias( $name, $alias = false ) {
2226                 if ( !$alias || (string)$alias === (string)$name ) {
2227                         return $name;
2228                 } else {
2229                         return $name . ' AS ' . $alias; //PostgreSQL needs AS
2230                 }
2231         }
2232
2233         /**
2234          * Gets an array of aliased field names
2235          *
2236          * @param $fields array( [alias] => field )
2237          * @return array of strings, see fieldNameWithAlias()
2238          */
2239         public function fieldNamesWithAlias( $fields ) {
2240                 $retval = array();
2241                 foreach ( $fields as $alias => $field ) {
2242                         if ( is_numeric( $alias ) ) {
2243                                 $alias = $field;
2244                         }
2245                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
2246                 }
2247                 return $retval;
2248         }
2249
2250         /**
2251          * Get the aliased table name clause for a FROM clause
2252          * which might have a JOIN and/or USE INDEX clause
2253          *
2254          * @param array $tables ( [alias] => table )
2255          * @param $use_index array Same as for select()
2256          * @param $join_conds array Same as for select()
2257          * @return string
2258          */
2259         protected function tableNamesWithUseIndexOrJOIN(
2260                 $tables, $use_index = array(), $join_conds = array()
2261         ) {
2262                 $ret = array();
2263                 $retJOIN = array();
2264                 $use_index = (array)$use_index;
2265                 $join_conds = (array)$join_conds;
2266
2267                 foreach ( $tables as $alias => $table ) {
2268                         if ( !is_string( $alias ) ) {
2269                                 // No alias? Set it equal to the table name
2270                                 $alias = $table;
2271                         }
2272                         // Is there a JOIN clause for this table?
2273                         if ( isset( $join_conds[$alias] ) ) {
2274                                 list( $joinType, $conds ) = $join_conds[$alias];
2275                                 $tableClause = $joinType;
2276                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
2277                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2278                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2279                                         if ( $use != '' ) {
2280                                                 $tableClause .= ' ' . $use;
2281                                         }
2282                                 }
2283                                 $on = $this->makeList( (array)$conds, LIST_AND );
2284                                 if ( $on != '' ) {
2285                                         $tableClause .= ' ON (' . $on . ')';
2286                                 }
2287
2288                                 $retJOIN[] = $tableClause;
2289                         // Is there an INDEX clause for this table?
2290                         } elseif ( isset( $use_index[$alias] ) ) {
2291                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2292                                 $tableClause .= ' ' . $this->useIndexClause(
2293                                         implode( ',', (array)$use_index[$alias] ) );
2294
2295                                 $ret[] = $tableClause;
2296                         } else {
2297                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2298
2299                                 $ret[] = $tableClause;
2300                         }
2301                 }
2302
2303                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2304                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
2305                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
2306
2307                 // Compile our final table clause
2308                 return implode( ' ', array( $implicitJoins, $explicitJoins ) );
2309         }
2310
2311         /**
2312          * Get the name of an index in a given table
2313          *
2314          * @param $index
2315          *
2316          * @return string
2317          */
2318         protected function indexName( $index ) {
2319                 // Backwards-compatibility hack
2320                 $renamed = array(
2321                         'ar_usertext_timestamp' => 'usertext_timestamp',
2322                         'un_user_id' => 'user_id',
2323                         'un_user_ip' => 'user_ip',
2324                 );
2325
2326                 if ( isset( $renamed[$index] ) ) {
2327                         return $renamed[$index];
2328                 } else {
2329                         return $index;
2330                 }
2331         }
2332
2333         /**
2334          * Adds quotes and backslashes.
2335          *
2336          * @param $s string
2337          *
2338          * @return string
2339          */
2340         public function addQuotes( $s ) {
2341                 if ( $s === null ) {
2342                         return 'NULL';
2343                 } else {
2344                         # This will also quote numeric values. This should be harmless,
2345                         # and protects against weird problems that occur when they really
2346                         # _are_ strings such as article titles and string->number->string
2347                         # conversion is not 1:1.
2348                         return "'" . $this->strencode( $s ) . "'";
2349                 }
2350         }
2351
2352         /**
2353          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
2354          * MySQL uses `backticks` while basically everything else uses double quotes.
2355          * Since MySQL is the odd one out here the double quotes are our generic
2356          * and we implement backticks in DatabaseMysql.
2357          *
2358          * @param $s string
2359          *
2360          * @return string
2361          */
2362         public function addIdentifierQuotes( $s ) {
2363                 return '"' . str_replace( '"', '""', $s ) . '"';
2364         }
2365
2366         /**
2367          * Returns if the given identifier looks quoted or not according to
2368          * the database convention for quoting identifiers .
2369          *
2370          * @param $name string
2371          *
2372          * @return boolean
2373          */
2374         public function isQuotedIdentifier( $name ) {
2375                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2376         }
2377
2378         /**
2379          * @param $s string
2380          * @return string
2381          */
2382         protected function escapeLikeInternal( $s ) {
2383                 $s = str_replace( '\\', '\\\\', $s );
2384                 $s = $this->strencode( $s );
2385                 $s = str_replace( array( '%', '_' ), array( '\%', '\_' ), $s );
2386
2387                 return $s;
2388         }
2389
2390         /**
2391          * LIKE statement wrapper, receives a variable-length argument list with parts of pattern to match
2392          * containing either string literals that will be escaped or tokens returned by anyChar() or anyString().
2393          * Alternatively, the function could be provided with an array of aforementioned parameters.
2394          *
2395          * Example: $dbr->buildLike( 'My_page_title/', $dbr->anyString() ) returns a LIKE clause that searches
2396          * for subpages of 'My page title'.
2397          * Alternatively: $pattern = array( 'My_page_title/', $dbr->anyString() ); $query .= $dbr->buildLike( $pattern );
2398          *
2399          * @since 1.16
2400          * @return String: fully built LIKE statement
2401          */
2402         public function buildLike() {
2403                 $params = func_get_args();
2404
2405                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2406                         $params = $params[0];
2407                 }
2408
2409                 $s = '';
2410
2411                 foreach ( $params as $value ) {
2412                         if ( $value instanceof LikeMatch ) {
2413                                 $s .= $value->toString();
2414                         } else {
2415                                 $s .= $this->escapeLikeInternal( $value );
2416                         }
2417                 }
2418
2419                 return " LIKE '" . $s . "' ";
2420         }
2421
2422         /**
2423          * Returns a token for buildLike() that denotes a '_' to be used in a LIKE query
2424          *
2425          * @return LikeMatch
2426          */
2427         public function anyChar() {
2428                 return new LikeMatch( '_' );
2429         }
2430
2431         /**
2432          * Returns a token for buildLike() that denotes a '%' to be used in a LIKE query
2433          *
2434          * @return LikeMatch
2435          */
2436         public function anyString() {
2437                 return new LikeMatch( '%' );
2438         }
2439
2440         /**
2441          * Returns an appropriately quoted sequence value for inserting a new row.
2442          * MySQL has autoincrement fields, so this is just NULL. But the PostgreSQL
2443          * subclass will return an integer, and save the value for insertId()
2444          *
2445          * Any implementation of this function should *not* involve reusing
2446          * sequence numbers created for rolled-back transactions.
2447          * See http://bugs.mysql.com/bug.php?id=30767 for details.
2448          * @param $seqName string
2449          * @return null
2450          */
2451         public function nextSequenceValue( $seqName ) {
2452                 return null;
2453         }
2454
2455         /**
2456          * USE INDEX clause.  Unlikely to be useful for anything but MySQL.  This
2457          * is only needed because a) MySQL must be as efficient as possible due to
2458          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2459          * which index to pick.  Anyway, other databases might have different
2460          * indexes on a given table.  So don't bother overriding this unless you're
2461          * MySQL.
2462          * @param $index
2463          * @return string
2464          */
2465         public function useIndexClause( $index ) {
2466                 return '';
2467         }
2468
2469         /**
2470          * REPLACE query wrapper.
2471          *
2472          * REPLACE is a very handy MySQL extension, which functions like an INSERT
2473          * except that when there is a duplicate key error, the old row is deleted
2474          * and the new row is inserted in its place.
2475          *
2476          * We simulate this with standard SQL with a DELETE followed by INSERT. To
2477          * perform the delete, we need to know what the unique indexes are so that
2478          * we know how to find the conflicting rows.
2479          *
2480          * It may be more efficient to leave off unique indexes which are unlikely
2481          * to collide. However if you do this, you run the risk of encountering
2482          * errors which wouldn't have occurred in MySQL.
2483          *
2484          * @param string $table The table to replace the row(s) in.
2485          * @param array $rows Can be either a single row to insert, or multiple rows,
2486          *    in the same format as for DatabaseBase::insert()
2487          * @param array $uniqueIndexes is an array of indexes. Each element may be either
2488          *    a field name or an array of field names
2489          * @param string $fname Calling function name (use __METHOD__) for logs/profiling
2490          */
2491         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2492                 $quotedTable = $this->tableName( $table );
2493
2494                 if ( count( $rows ) == 0 ) {
2495                         return;
2496                 }
2497
2498                 # Single row case
2499                 if ( !is_array( reset( $rows ) ) ) {
2500                         $rows = array( $rows );
2501                 }
2502
2503                 foreach ( $rows as $row ) {
2504                         # Delete rows which collide
2505                         if ( $uniqueIndexes ) {
2506                                 $sql = "DELETE FROM $quotedTable WHERE ";
2507                                 $first = true;
2508                                 foreach ( $uniqueIndexes as $index ) {
2509                                         if ( $first ) {
2510                                                 $first = false;
2511                                                 $sql .= '( ';
2512                                         } else {
2513                                                 $sql .= ' ) OR ( ';
2514                                         }
2515                                         if ( is_array( $index ) ) {
2516                                                 $first2 = true;
2517                                                 foreach ( $index as $col ) {
2518                                                         if ( $first2 ) {
2519                                                                 $first2 = false;
2520                                                         } else {
2521                                                                 $sql .= ' AND ';
2522                                                         }
2523                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2524                                                 }
2525                                         } else {
2526                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2527                                         }
2528                                 }
2529                                 $sql .= ' )';
2530                                 $this->query( $sql, $fname );
2531                         }
2532
2533                         # Now insert the row
2534                         $this->insert( $table, $row, $fname );
2535                 }
2536         }
2537
2538         /**
2539          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2540          * statement.
2541          *
2542          * @param string $table Table name
2543          * @param array $rows Rows to insert
2544          * @param string $fname Caller function name
2545          *
2546          * @return ResultWrapper
2547          */
2548         protected function nativeReplace( $table, $rows, $fname ) {
2549                 $table = $this->tableName( $table );
2550
2551                 # Single row case
2552                 if ( !is_array( reset( $rows ) ) ) {
2553                         $rows = array( $rows );
2554                 }
2555
2556                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2557                 $first = true;
2558
2559                 foreach ( $rows as $row ) {
2560                         if ( $first ) {
2561                                 $first = false;
2562                         } else {
2563                                 $sql .= ',';
2564                         }
2565
2566                         $sql .= '(' . $this->makeList( $row ) . ')';
2567                 }
2568
2569                 return $this->query( $sql, $fname );
2570         }
2571
2572         /**
2573          * INSERT ON DUPLICATE KEY UPDATE wrapper, upserts an array into a table.
2574          *
2575          * This updates any conflicting rows (according to the unique indexes) using
2576          * the provided SET clause and inserts any remaining (non-conflicted) rows.
2577          *
2578          * $rows may be either:
2579          *   - A single associative array. The array keys are the field names, and
2580          *     the values are the values to insert. The values are treated as data
2581          *     and will be quoted appropriately. If NULL is inserted, this will be
2582          *     converted to a database NULL.
2583          *   - An array with numeric keys, holding a list of associative arrays.
2584          *     This causes a multi-row INSERT on DBMSs that support it. The keys in
2585          *     each subarray must be identical to each other, and in the same order.
2586          *
2587          * It may be more efficient to leave off unique indexes which are unlikely
2588          * to collide. However if you do this, you run the risk of encountering
2589          * errors which wouldn't have occurred in MySQL.
2590          *
2591          * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
2592          * returns success.
2593          *
2594          * @param string $table Table name. This will be passed through DatabaseBase::tableName().
2595          * @param array $rows A single row or list of rows to insert
2596          * @param array $uniqueIndexes List of single field names or field name tuples
2597          * @param array $set An array of values to SET. For each array element,
2598          *                the key gives the field name, and the value gives the data
2599          *                to set that field to. The data will be quoted by
2600          *                DatabaseBase::addQuotes().
2601          * @param string $fname Calling function name (use __METHOD__) for logs/profiling
2602          * @param array $options of options
2603          *
2604          * @return bool
2605          * @since 1.22
2606          */
2607         public function upsert(
2608                 $table, array $rows, array $uniqueIndexes, array $set, $fname = __METHOD__
2609         ) {
2610                 if ( !count( $rows ) ) {
2611                         return true; // nothing to do
2612                 }
2613                 $rows = is_array( reset( $rows ) ) ? $rows : array( $rows );
2614
2615                 if ( count( $uniqueIndexes ) ) {
2616                         $clauses = array(); // list WHERE clauses that each identify a single row
2617                         foreach ( $rows as $row ) {
2618                                 foreach ( $uniqueIndexes as $index ) {
2619                                         $index = is_array( $index ) ? $index : array( $index ); // columns
2620                                         $rowKey = array(); // unique key to this row
2621                                         foreach ( $index as $column ) {
2622                                                 $rowKey[$column] = $row[$column];
2623                                         }
2624                                         $clauses[] = $this->makeList( $rowKey, LIST_AND );
2625                                 }
2626                         }
2627                         $where = array( $this->makeList( $clauses, LIST_OR ) );
2628                 } else {
2629                         $where = false;
2630                 }
2631
2632                 $useTrx = !$this->mTrxLevel;
2633                 if ( $useTrx ) {
2634                         $this->begin( $fname );
2635                 }
2636                 try {
2637                         # Update any existing conflicting row(s)
2638                         if ( $where !== false ) {
2639                                 $ok = $this->update( $table, $set, $where, $fname );
2640                         } else {
2641                                 $ok = true;
2642                         }
2643                         # Now insert any non-conflicting row(s)
2644                         $ok = $this->insert( $table, $rows, $fname, array( 'IGNORE' ) ) && $ok;
2645                 } catch ( Exception $e ) {
2646                         if ( $useTrx ) {
2647                                 $this->rollback( $fname );
2648                         }
2649                         throw $e;
2650                 }
2651                 if ( $useTrx ) {
2652                         $this->commit( $fname );
2653                 }
2654
2655                 return $ok;
2656         }
2657
2658         /**
2659          * DELETE where the condition is a join.
2660          *
2661          * MySQL overrides this to use a multi-table DELETE syntax, in other databases
2662          * we use sub-selects
2663          *
2664          * For safety, an empty $conds will not delete everything. If you want to
2665          * delete all rows where the join condition matches, set $conds='*'.
2666          *
2667          * DO NOT put the join condition in $conds.
2668          *
2669          * @param $delTable   String: The table to delete from.
2670          * @param $joinTable  String: The other table.
2671          * @param $delVar     String: The variable to join on, in the first table.
2672          * @param $joinVar    String: The variable to join on, in the second table.
2673          * @param $conds      Array: Condition array of field names mapped to variables,
2674          *                    ANDed together in the WHERE clause
2675          * @param $fname      String: Calling function name (use __METHOD__) for
2676          *                    logs/profiling
2677          * @throws DBUnexpectedError
2678          */
2679         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2680                 $fname = __METHOD__ )
2681         {
2682                 if ( !$conds ) {
2683                         throw new DBUnexpectedError( $this,
2684                                 'DatabaseBase::deleteJoin() called with empty $conds' );
2685                 }
2686
2687                 $delTable = $this->tableName( $delTable );
2688                 $joinTable = $this->tableName( $joinTable );
2689                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2690                 if ( $conds != '*' ) {
2691                         $sql .= 'WHERE ' . $this->makeList( $conds, LIST_AND );
2692                 }
2693                 $sql .= ')';
2694
2695                 $this->query( $sql, $fname );
2696         }
2697
2698         /**
2699          * Returns the size of a text field, or -1 for "unlimited"
2700          *
2701          * @param $table string
2702          * @param $field string
2703          *
2704          * @return int
2705          */
2706         public function textFieldSize( $table, $field ) {
2707                 $table = $this->tableName( $table );
2708                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2709                 $res = $this->query( $sql, 'DatabaseBase::textFieldSize' );
2710                 $row = $this->fetchObject( $res );
2711
2712                 $m = array();
2713
2714                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2715                         $size = $m[1];
2716                 } else {
2717                         $size = -1;
2718                 }
2719
2720                 return $size;
2721         }
2722
2723         /**
2724          * A string to insert into queries to show that they're low-priority, like
2725          * MySQL's LOW_PRIORITY.  If no such feature exists, return an empty
2726          * string and nothing bad should happen.
2727          *
2728          * @return string Returns the text of the low priority option if it is
2729          *   supported, or a blank string otherwise
2730          */
2731         public function lowPriorityOption() {
2732                 return '';
2733         }
2734
2735         /**
2736          * DELETE query wrapper.
2737          *
2738          * @param array $table Table name
2739          * @param string|array $conds of conditions. See $conds in DatabaseBase::select() for
2740          *               the format. Use $conds == "*" to delete all rows
2741          * @param string $fname name of the calling function
2742          *
2743          * @throws DBUnexpectedError
2744          * @return bool|ResultWrapper
2745          */
2746         public function delete( $table, $conds, $fname = __METHOD__ ) {
2747                 if ( !$conds ) {
2748                         throw new DBUnexpectedError( $this, 'DatabaseBase::delete() called with no conditions' );
2749                 }
2750
2751                 $table = $this->tableName( $table );
2752                 $sql = "DELETE FROM $table";
2753
2754                 if ( $conds != '*' ) {
2755                         if ( is_array( $conds ) ) {
2756                                 $conds = $this->makeList( $conds, LIST_AND );
2757                         }
2758                         $sql .= ' WHERE ' . $conds;
2759                 }
2760
2761                 return $this->query( $sql, $fname );
2762         }
2763
2764         /**
2765          * INSERT SELECT wrapper. Takes data from a SELECT query and inserts it
2766          * into another table.
2767          *
2768          * @param string $destTable The table name to insert into
2769          * @param string|array $srcTable May be either a table name, or an array of table names
2770          *    to include in a join.
2771          *
2772          * @param array $varMap must be an associative array of the form
2773          *    array( 'dest1' => 'source1', ...). Source items may be literals
2774          *    rather than field names, but strings should be quoted with
2775          *    DatabaseBase::addQuotes()
2776          *
2777          * @param array $conds Condition array. See $conds in DatabaseBase::select() for
2778          *    the details of the format of condition arrays. May be "*" to copy the
2779          *    whole table.
2780          *
2781          * @param string $fname The function name of the caller, from __METHOD__
2782          *
2783          * @param array $insertOptions Options for the INSERT part of the query, see
2784          *    DatabaseBase::insert() for details.
2785          * @param array $selectOptions Options for the SELECT part of the query, see
2786          *    DatabaseBase::select() for details.
2787          *
2788          * @return ResultWrapper
2789          */
2790         public function insertSelect( $destTable, $srcTable, $varMap, $conds,
2791                 $fname = __METHOD__,
2792                 $insertOptions = array(), $selectOptions = array() )
2793         {
2794                 $destTable = $this->tableName( $destTable );
2795
2796                 if ( is_array( $insertOptions ) ) {
2797                         $insertOptions = implode( ' ', $insertOptions );
2798                 }
2799
2800                 if ( !is_array( $selectOptions ) ) {
2801                         $selectOptions = array( $selectOptions );
2802                 }
2803
2804                 list( $startOpts, $useIndex, $tailOpts ) = $this->makeSelectOptions( $selectOptions );
2805
2806                 if ( is_array( $srcTable ) ) {
2807                         $srcTable = implode( ',', array_map( array( &$this, 'tableName' ), $srcTable ) );
2808                 } else {
2809                         $srcTable = $this->tableName( $srcTable );
2810                 }
2811
2812                 $sql = "INSERT $insertOptions INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2813                         " SELECT $startOpts " . implode( ',', $varMap ) .
2814                         " FROM $srcTable $useIndex ";
2815
2816                 if ( $conds != '*' ) {
2817                         if ( is_array( $conds ) ) {
2818                                 $conds = $this->makeList( $conds, LIST_AND );
2819                         }
2820                         $sql .= " WHERE $conds";
2821                 }
2822
2823                 $sql .= " $tailOpts";
2824
2825                 return $this->query( $sql, $fname );
2826         }
2827
2828         /**
2829          * Construct a LIMIT query with optional offset.  This is used for query
2830          * pages.  The SQL should be adjusted so that only the first $limit rows
2831          * are returned.  If $offset is provided as well, then the first $offset
2832          * rows should be discarded, and the next $limit rows should be returned.
2833          * If the result of the query is not ordered, then the rows to be returned
2834          * are theoretically arbitrary.
2835          *
2836          * $sql is expected to be a SELECT, if that makes a difference.
2837          *
2838          * The version provided by default works in MySQL and SQLite.  It will very
2839          * likely need to be overridden for most other DBMSes.
2840          *
2841          * @param string $sql SQL query we will append the limit too
2842          * @param $limit Integer the SQL limit
2843          * @param $offset Integer|bool the SQL offset (default false)
2844          *
2845          * @throws DBUnexpectedError
2846          * @return string
2847          */
2848         public function limitResult( $sql, $limit, $offset = false ) {
2849                 if ( !is_numeric( $limit ) ) {
2850                         throw new DBUnexpectedError( $this, "Invalid non-numeric limit passed to limitResult()\n" );
2851                 }
2852                 return "$sql LIMIT "
2853                         . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2854                         . "{$limit} ";
2855         }
2856
2857         /**
2858          * Returns true if current database backend supports ORDER BY or LIMIT for separate subqueries
2859          * within the UNION construct.
2860          * @return Boolean
2861          */
2862         public function unionSupportsOrderAndLimit() {
2863                 return true; // True for almost every DB supported
2864         }
2865
2866         /**
2867          * Construct a UNION query
2868          * This is used for providing overload point for other DB abstractions
2869          * not compatible with the MySQL syntax.
2870          * @param array $sqls SQL statements to combine
2871          * @param $all Boolean: use UNION ALL
2872          * @return String: SQL fragment
2873          */
2874         public function unionQueries( $sqls, $all ) {
2875                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2876                 return '(' . implode( $glue, $sqls ) . ')';
2877         }
2878
2879         /**
2880          * Returns an SQL expression for a simple conditional.  This doesn't need
2881          * to be overridden unless CASE isn't supported in your DBMS.
2882          *
2883          * @param string|array $cond SQL expression which will result in a boolean value
2884          * @param string $trueVal SQL expression to return if true
2885          * @param string $falseVal SQL expression to return if false
2886          * @return String: SQL fragment
2887          */
2888         public function conditional( $cond, $trueVal, $falseVal ) {
2889                 if ( is_array( $cond ) ) {
2890                         $cond = $this->makeList( $cond, LIST_AND );
2891                 }
2892                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2893         }
2894
2895         /**
2896          * Returns a comand for str_replace function in SQL query.
2897          * Uses REPLACE() in MySQL
2898          *
2899          * @param string $orig column to modify
2900          * @param string $old column to seek
2901          * @param string $new column to replace with
2902          *
2903          * @return string
2904          */
2905         public function strreplace( $orig, $old, $new ) {
2906                 return "REPLACE({$orig}, {$old}, {$new})";
2907         }
2908
2909         /**
2910          * Determines how long the server has been up
2911          * STUB
2912          *
2913          * @return int
2914          */
2915         public function getServerUptime() {
2916                 return 0;
2917         }
2918
2919         /**
2920          * Determines if the last failure was due to a deadlock
2921          * STUB
2922          *
2923          * @return bool
2924          */
2925         public function wasDeadlock() {
2926                 return false;
2927         }
2928
2929         /**
2930          * Determines if the last failure was due to a lock timeout
2931          * STUB
2932          *
2933          * @return bool
2934          */
2935         public function wasLockTimeout() {
2936                 return false;
2937         }
2938
2939         /**
2940          * Determines if the last query error was something that should be dealt
2941          * with by pinging the connection and reissuing the query.
2942          * STUB
2943          *
2944          * @return bool
2945          */
2946         public function wasErrorReissuable() {
2947                 return false;
2948         }
2949
2950         /**
2951          * Determines if the last failure was due to the database being read-only.
2952          * STUB
2953          *
2954          * @return bool
2955          */
2956         public function wasReadOnlyError() {
2957                 return false;
2958         }
2959
2960         /**
2961          * Perform a deadlock-prone transaction.
2962          *
2963          * This function invokes a callback function to perform a set of write
2964          * queries. If a deadlock occurs during the processing, the transaction
2965          * will be rolled back and the callback function will be called again.
2966          *
2967          * Usage:
2968          *   $dbw->deadlockLoop( callback, ... );
2969          *
2970          * Extra arguments are passed through to the specified callback function.
2971          *
2972          * Returns whatever the callback function returned on its successful,
2973          * iteration, or false on error, for example if the retry limit was
2974          * reached.
2975          *
2976          * @return bool
2977          */
2978         public function deadlockLoop() {
2979                 $this->begin( __METHOD__ );
2980                 $args = func_get_args();
2981                 $function = array_shift( $args );
2982                 $oldIgnore = $this->ignoreErrors( true );
2983                 $tries = self::DEADLOCK_TRIES;
2984
2985                 if ( is_array( $function ) ) {
2986                         $fname = $function[0];
2987                 } else {
2988                         $fname = $function;
2989                 }
2990
2991                 do {
2992                         $retVal = call_user_func_array( $function, $args );
2993                         $error = $this->lastError();
2994                         $errno = $this->lastErrno();
2995                         $sql = $this->lastQuery();
2996
2997                         if ( $errno ) {
2998                                 if ( $this->wasDeadlock() ) {
2999                                         # Retry
3000                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
3001                                 } else {
3002                                         $this->reportQueryError( $error, $errno, $sql, $fname );
3003                                 }
3004                         }
3005                 } while ( $this->wasDeadlock() && --$tries > 0 );
3006
3007                 $this->ignoreErrors( $oldIgnore );
3008
3009                 if ( $tries <= 0 ) {
3010                         $this->rollback( __METHOD__ );
3011                         $this->reportQueryError( $error, $errno, $sql, $fname );
3012                         return false;
3013                 } else {
3014                         $this->commit( __METHOD__ );
3015                         return $retVal;
3016                 }
3017         }
3018
3019         /**
3020          * Wait for the slave to catch up to a given master position.
3021          *
3022          * @param $pos DBMasterPos object
3023          * @param $timeout Integer: the maximum number of seconds to wait for
3024          *   synchronisation
3025          *
3026          * @return integer: zero if the slave was past that position already,
3027          *   greater than zero if we waited for some period of time, less than
3028          *   zero if we timed out.
3029          */
3030         public function masterPosWait( DBMasterPos $pos, $timeout ) {
3031                 wfProfileIn( __METHOD__ );
3032
3033                 if ( !is_null( $this->mFakeSlaveLag ) ) {
3034                         $wait = intval( ( $pos->pos - microtime( true ) + $this->mFakeSlaveLag ) * 1e6 );
3035
3036                         if ( $wait > $timeout * 1e6 ) {
3037                                 wfDebug( "Fake slave timed out waiting for $pos ($wait us)\n" );
3038                                 wfProfileOut( __METHOD__ );
3039                                 return -1;
3040                         } elseif ( $wait > 0 ) {
3041                                 wfDebug( "Fake slave waiting $wait us\n" );
3042                                 usleep( $wait );
3043                                 wfProfileOut( __METHOD__ );
3044                                 return 1;
3045                         } else {
3046                                 wfDebug( "Fake slave up to date ($wait us)\n" );
3047                                 wfProfileOut( __METHOD__ );
3048                                 return 0;
3049                         }
3050                 }
3051
3052                 wfProfileOut( __METHOD__ );
3053
3054                 # Real waits are implemented in the subclass.
3055                 return 0;
3056         }
3057
3058         /**
3059          * Get the replication position of this slave
3060          *
3061          * @return DBMasterPos, or false if this is not a slave.
3062          */
3063         public function getSlavePos() {
3064                 if ( !is_null( $this->mFakeSlaveLag ) ) {
3065                         $pos = new MySQLMasterPos( 'fake', microtime( true ) - $this->mFakeSlaveLag );
3066                         wfDebug( __METHOD__ . ": fake slave pos = $pos\n" );
3067                         return $pos;
3068                 } else {
3069                         # Stub
3070                         return false;
3071                 }
3072         }
3073
3074         /**
3075          * Get the position of this master
3076          *
3077          * @return DBMasterPos, or false if this is not a master
3078          */
3079         public function getMasterPos() {
3080                 if ( $this->mFakeMaster ) {
3081                         return new MySQLMasterPos( 'fake', microtime( true ) );
3082                 } else {
3083                         return false;
3084                 }
3085         }
3086
3087         /**
3088          * Run an anonymous function as soon as there is no transaction pending.
3089          * If there is a transaction and it is rolled back, then the callback is cancelled.
3090          * Queries in the function will run in AUTO-COMMIT mode unless there are begin() calls.
3091          * Callbacks must commit any transactions that they begin.
3092          *
3093          * This is useful for updates to different systems or when separate transactions are needed.
3094          * For example, one might want to enqueue jobs into a system outside the database, but only
3095          * after the database is updated so that the jobs will see the data when they actually run.
3096          * It can also be used for updates that easily cause deadlocks if locks are held too long.
3097          *
3098          * @param callable $callback
3099          * @since 1.20
3100          */
3101         final public function onTransactionIdle( $callback ) {
3102                 $this->mTrxIdleCallbacks[] = $callback;
3103                 if ( !$this->mTrxLevel ) {
3104                         $this->runOnTransactionIdleCallbacks();
3105                 }
3106         }
3107
3108         /**
3109          * Run an anonymous function before the current transaction commits or now if there is none.
3110          * If there is a transaction and it is rolled back, then the callback is cancelled.
3111          * Callbacks must not start nor commit any transactions.
3112          *
3113          * This is useful for updates that easily cause deadlocks if locks are held too long
3114          * but where atomicity is strongly desired for these updates and some related updates.
3115          *
3116          * @param callable $callback
3117          * @since 1.22
3118          */
3119         final public function onTransactionPreCommitOrIdle( $callback ) {
3120                 if ( $this->mTrxLevel ) {
3121                         $this->mTrxPreCommitCallbacks[] = $callback;
3122                 } else {
3123                         $this->onTransactionIdle( $callback ); // this will trigger immediately
3124                 }
3125         }
3126
3127         /**
3128          * Actually any "on transaction idle" callbacks.
3129          *
3130          * @since 1.20
3131          */
3132         protected function runOnTransactionIdleCallbacks() {
3133                 $autoTrx = $this->getFlag( DBO_TRX ); // automatic begin() enabled?
3134
3135                 $e = null; // last exception
3136                 do { // callbacks may add callbacks :)
3137                         $callbacks = $this->mTrxIdleCallbacks;
3138                         $this->mTrxIdleCallbacks = array(); // recursion guard
3139                         foreach ( $callbacks as $callback ) {
3140                                 try {
3141                                         $this->clearFlag( DBO_TRX ); // make each query its own transaction
3142                                         call_user_func( $callback );
3143                                         $this->setFlag( $autoTrx ? DBO_TRX : 0 ); // restore automatic begin()
3144                                 } catch ( Exception $e ) {}
3145                         }
3146                 } while ( count( $this->mTrxIdleCallbacks ) );
3147
3148                 if ( $e instanceof Exception ) {
3149                         throw $e; // re-throw any last exception
3150                 }
3151         }
3152
3153         /**
3154          * Actually any "on transaction pre-commit" callbacks.
3155          *
3156          * @since 1.22
3157          */
3158         protected function runOnTransactionPreCommitCallbacks() {
3159                 $e = null; // last exception
3160                 do { // callbacks may add callbacks :)
3161                         $callbacks = $this->mTrxPreCommitCallbacks;
3162                         $this->mTrxPreCommitCallbacks = array(); // recursion guard
3163                         foreach ( $callbacks as $callback ) {
3164                                 try {
3165                                         call_user_func( $callback );
3166                                 } catch ( Exception $e ) {}
3167                         }
3168                 } while ( count( $this->mTrxPreCommitCallbacks ) );
3169
3170                 if ( $e instanceof Exception ) {
3171                         throw $e; // re-throw any last exception
3172                 }
3173         }
3174
3175         /**
3176          * Begin a transaction. If a transaction is already in progress, that transaction will be committed before the
3177          * new transaction is started.
3178          *
3179          * Note that when the DBO_TRX flag is set (which is usually the case for web requests, but not for maintenance scripts),
3180          * any previous database query will have started a transaction automatically.
3181          *
3182          * Nesting of transactions is not supported. Attempts to nest transactions will cause a warning, unless the current
3183          * transaction was started automatically because of the DBO_TRX flag.
3184          *
3185          * @param $fname string
3186          */
3187         final public function begin( $fname = __METHOD__ ) {
3188                 global $wgDebugDBTransactions;
3189
3190                 if ( $this->mTrxLevel ) { // implicit commit
3191                         if ( !$this->mTrxAutomatic ) {
3192                                 // We want to warn about inadvertently nested begin/commit pairs, but not about
3193                                 // auto-committing implicit transactions that were started by query() via DBO_TRX
3194                                 $msg = "$fname: Transaction already in progress (from {$this->mTrxFname}), " .
3195                                         " performing implicit commit!";
3196                                 wfWarn( $msg );
3197                                 wfLogDBError( $msg );
3198                         } else {
3199                                 // if the transaction was automatic and has done write operations,
3200                                 // log it if $wgDebugDBTransactions is enabled.
3201                                 if ( $this->mTrxDoneWrites && $wgDebugDBTransactions ) {
3202                                         wfDebug( "$fname: Automatic transaction with writes in progress" .
3203                                                 " (from {$this->mTrxFname}), performing implicit commit!\n"
3204                                         );
3205                                 }
3206                         }
3207
3208                         $this->runOnTransactionPreCommitCallbacks();
3209                         $this->doCommit( $fname );
3210                         if ( $this->mTrxDoneWrites ) {
3211                                 Profiler::instance()->transactionWritingOut( $this->mServer, $this->mDBname );
3212                         }
3213                         $this->runOnTransactionIdleCallbacks();
3214                 }
3215
3216                 $this->doBegin( $fname );
3217                 $this->mTrxFname = $fname;
3218                 $this->mTrxDoneWrites = false;
3219                 $this->mTrxAutomatic = false;
3220         }
3221
3222         /**
3223          * Issues the BEGIN command to the database server.
3224          *
3225          * @see DatabaseBase::begin()
3226          * @param type $fname
3227          */
3228         protected function doBegin( $fname ) {
3229                 $this->query( 'BEGIN', $fname );
3230                 $this->mTrxLevel = 1;
3231         }
3232
3233         /**
3234          * Commits a transaction previously started using begin().
3235          * If no transaction is in progress, a warning is issued.
3236          *
3237          * Nesting of transactions is not supported.
3238          *
3239          * @param $fname string
3240          * @param string $flush Flush flag, set to 'flush' to disable warnings about explicitly committing implicit
3241          *        transactions, or calling commit when no transaction is in progress.
3242          *        This will silently break any ongoing explicit transaction. Only set the flush flag if you are sure
3243          *        that it is safe to ignore these warnings in your context.
3244          */
3245         final public function commit( $fname = __METHOD__, $flush = '' ) {
3246                 if ( $flush != 'flush' ) {
3247                         if ( !$this->mTrxLevel ) {
3248                                 wfWarn( "$fname: No transaction to commit, something got out of sync!" );
3249                         } elseif ( $this->mTrxAutomatic ) {
3250                                 wfWarn( "$fname: Explicit commit of implicit transaction. Something may be out of sync!" );
3251                         }
3252                 } else {
3253                         if ( !$this->mTrxLevel ) {
3254                                 return; // nothing to do
3255                         } elseif ( !$this->mTrxAutomatic ) {
3256                                 wfWarn( "$fname: Flushing an explicit transaction, getting out of sync!" );
3257                         }
3258                 }
3259
3260                 $this->runOnTransactionPreCommitCallbacks();
3261                 $this->doCommit( $fname );
3262                 if ( $this->mTrxDoneWrites ) {
3263                         Profiler::instance()->transactionWritingOut( $this->mServer, $this->mDBname );
3264                 }
3265                 $this->runOnTransactionIdleCallbacks();
3266         }
3267
3268         /**
3269          * Issues the COMMIT command to the database server.
3270          *
3271          * @see DatabaseBase::commit()
3272          * @param type $fname
3273          */
3274         protected function doCommit( $fname ) {
3275                 if ( $this->mTrxLevel ) {
3276                         $this->query( 'COMMIT', $fname );
3277                         $this->mTrxLevel = 0;
3278                 }
3279         }
3280
3281         /**
3282          * Rollback a transaction previously started using begin().
3283          * If no transaction is in progress, a warning is issued.
3284          *
3285          * No-op on non-transactional databases.
3286          *
3287          * @param $fname string
3288          */
3289         final public function rollback( $fname = __METHOD__ ) {
3290                 if ( !$this->mTrxLevel ) {
3291                         wfWarn( "$fname: No transaction to rollback, something got out of sync!" );
3292                 }
3293                 $this->doRollback( $fname );
3294                 $this->mTrxIdleCallbacks = array(); // cancel
3295                 $this->mTrxPreCommitCallbacks = array(); // cancel
3296                 if ( $this->mTrxDoneWrites ) {
3297                         Profiler::instance()->transactionWritingOut( $this->mServer, $this->mDBname );
3298                 }
3299         }
3300
3301         /**
3302          * Issues the ROLLBACK command to the database server.
3303          *
3304          * @see DatabaseBase::rollback()
3305          * @param type $fname
3306          */
3307         protected function doRollback( $fname ) {
3308                 if ( $this->mTrxLevel ) {
3309                         $this->query( 'ROLLBACK', $fname, true );
3310                         $this->mTrxLevel = 0;
3311                 }
3312         }
3313
3314         /**
3315          * Creates a new table with structure copied from existing table
3316          * Note that unlike most database abstraction functions, this function does not
3317          * automatically append database prefix, because it works at a lower
3318          * abstraction level.
3319          * The table names passed to this function shall not be quoted (this
3320          * function calls addIdentifierQuotes when needed).
3321          *
3322          * @param string $oldName name of table whose structure should be copied
3323          * @param string $newName name of table to be created
3324          * @param $temporary Boolean: whether the new table should be temporary
3325          * @param string $fname calling function name
3326          * @throws MWException
3327          * @return Boolean: true if operation was successful
3328          */
3329         public function duplicateTableStructure( $oldName, $newName, $temporary = false,
3330                 $fname = __METHOD__
3331         ) {
3332                 throw new MWException(
3333                         'DatabaseBase::duplicateTableStructure is not implemented in descendant class' );
3334         }
3335
3336         /**
3337          * List all tables on the database
3338          *
3339          * @param string $prefix Only show tables with this prefix, e.g. mw_
3340          * @param string $fname calling function name
3341          * @throws MWException
3342          */
3343         function listTables( $prefix = null, $fname = __METHOD__ ) {
3344                 throw new MWException( 'DatabaseBase::listTables is not implemented in descendant class' );
3345         }
3346
3347         /**
3348          * Convert a timestamp in one of the formats accepted by wfTimestamp()
3349          * to the format used for inserting into timestamp fields in this DBMS.
3350          *
3351          * The result is unquoted, and needs to be passed through addQuotes()
3352          * before it can be included in raw SQL.
3353          *
3354          * @param $ts string|int
3355          *
3356          * @return string
3357          */
3358         public function timestamp( $ts = 0 ) {
3359                 return wfTimestamp( TS_MW, $ts );
3360         }
3361
3362         /**
3363          * Convert a timestamp in one of the formats accepted by wfTimestamp()
3364          * to the format used for inserting into timestamp fields in this DBMS. If
3365          * NULL is input, it is passed through, allowing NULL values to be inserted
3366          * into timestamp fields.
3367          *
3368          * The result is unquoted, and needs to be passed through addQuotes()
3369          * before it can be included in raw SQL.
3370          *
3371          * @param $ts string|int
3372          *
3373          * @return string
3374          */
3375         public function timestampOrNull( $ts = null ) {
3376                 if ( is_null( $ts ) ) {
3377                         return null;
3378                 } else {
3379                         return $this->timestamp( $ts );
3380                 }
3381         }
3382
3383         /**
3384          * Take the result from a query, and wrap it in a ResultWrapper if
3385          * necessary. Boolean values are passed through as is, to indicate success
3386          * of write queries or failure.
3387          *
3388          * Once upon a time, DatabaseBase::query() returned a bare MySQL result
3389          * resource, and it was necessary to call this function to convert it to
3390          * a wrapper. Nowadays, raw database objects are never exposed to external
3391          * callers, so this is unnecessary in external code. For compatibility with
3392          * old code, ResultWrapper objects are passed through unaltered.
3393          *
3394          * @param $result bool|ResultWrapper
3395          *
3396          * @return bool|ResultWrapper
3397          */
3398         public function resultObject( $result ) {
3399                 if ( empty( $result ) ) {
3400                         return false;
3401                 } elseif ( $result instanceof ResultWrapper ) {
3402                         return $result;
3403                 } elseif ( $result === true ) {
3404                         // Successful write query
3405                         return $result;
3406                 } else {
3407                         return new ResultWrapper( $this, $result );
3408                 }
3409         }
3410
3411         /**
3412          * Ping the server and try to reconnect if it there is no connection
3413          *
3414          * @return bool Success or failure
3415          */
3416         public function ping() {
3417                 # Stub.  Not essential to override.
3418                 return true;
3419         }
3420
3421         /**
3422          * Get slave lag. Currently supported only by MySQL.
3423          *
3424          * Note that this function will generate a fatal error on many
3425          * installations. Most callers should use LoadBalancer::safeGetLag()
3426          * instead.
3427          *
3428          * @return int Database replication lag in seconds
3429          */
3430         public function getLag() {
3431                 return intval( $this->mFakeSlaveLag );
3432         }
3433
3434         /**
3435          * Return the maximum number of items allowed in a list, or 0 for unlimited.
3436          *
3437          * @return int
3438          */
3439         function maxListLen() {
3440                 return 0;
3441         }
3442
3443         /**
3444          * Some DBMSs have a special format for inserting into blob fields, they
3445          * don't allow simple quoted strings to be inserted. To insert into such
3446          * a field, pass the data through this function before passing it to
3447          * DatabaseBase::insert().
3448          * @param $b string
3449          * @return string
3450          */
3451         public function encodeBlob( $b ) {
3452                 return $b;
3453         }
3454
3455         /**
3456          * Some DBMSs return a special placeholder object representing blob fields
3457          * in result objects. Pass the object through this function to return the
3458          * original string.
3459          * @param $b string
3460          * @return string
3461          */
3462         public function decodeBlob( $b ) {
3463                 return $b;
3464         }
3465
3466         /**
3467          * Override database's default behavior. $options include:
3468          *     'connTimeout' : Set the connection timeout value in seconds.
3469          *                     May be useful for very long batch queries such as
3470          *                     full-wiki dumps, where a single query reads out over
3471          *                     hours or days.
3472          *
3473          * @param $options Array
3474          * @return void
3475          */
3476         public function setSessionOptions( array $options ) {
3477         }
3478
3479         /**
3480          * Read and execute SQL commands from a file.
3481          *
3482          * Returns true on success, error string or exception on failure (depending
3483          * on object's error ignore settings).
3484          *
3485          * @param string $filename File name to open
3486          * @param bool|callable $lineCallback Optional function called before reading each line
3487          * @param bool|callable $resultCallback Optional function called for each MySQL result
3488          * @param bool|string $fname Calling function name or false if name should be
3489          *      generated dynamically using $filename
3490          * @param bool|callable $inputCallback Callback: Optional function called for each complete line sent
3491          * @throws MWException
3492          * @throws Exception|MWException
3493          * @return bool|string
3494          */
3495         public function sourceFile(
3496                 $filename, $lineCallback = false, $resultCallback = false, $fname = false, $inputCallback = false
3497         ) {
3498                 wfSuppressWarnings();
3499                 $fp = fopen( $filename, 'r' );
3500                 wfRestoreWarnings();
3501
3502                 if ( false === $fp ) {
3503                         throw new MWException( "Could not open \"{$filename}\".\n" );
3504                 }
3505
3506                 if ( !$fname ) {
3507                         $fname = __METHOD__ . "( $filename )";
3508                 }
3509
3510                 try {
3511                         $error = $this->sourceStream( $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3512                 }
3513                 catch ( MWException $e ) {
3514                         fclose( $fp );
3515                         throw $e;
3516                 }
3517
3518                 fclose( $fp );
3519
3520                 return $error;
3521         }
3522
3523         /**
3524          * Get the full path of a patch file. Originally based on archive()
3525          * from updaters.inc. Keep in mind this always returns a patch, as
3526          * it fails back to MySQL if no DB-specific patch can be found
3527          *
3528          * @param string $patch The name of the patch, like patch-something.sql
3529          * @return String Full path to patch file
3530          */
3531         public function patchPath( $patch ) {
3532                 global $IP;
3533
3534                 $dbType = $this->getType();
3535                 if ( file_exists( "$IP/maintenance/$dbType/archives/$patch" ) ) {
3536                         return "$IP/maintenance/$dbType/archives/$patch";
3537                 } else {
3538                         return "$IP/maintenance/archives/$patch";
3539                 }
3540         }
3541
3542         /**
3543          * Set variables to be used in sourceFile/sourceStream, in preference to the
3544          * ones in $GLOBALS. If an array is set here, $GLOBALS will not be used at
3545          * all. If it's set to false, $GLOBALS will be used.
3546          *
3547          * @param bool|array $vars mapping variable name to value.
3548          */
3549         public function setSchemaVars( $vars ) {
3550                 $this->mSchemaVars = $vars;
3551         }
3552
3553         /**
3554          * Read and execute commands from an open file handle.
3555          *
3556          * Returns true on success, error string or exception on failure (depending
3557          * on object's error ignore settings).
3558          *
3559          * @param $fp Resource: File handle
3560          * @param $lineCallback Callback: Optional function called before reading each query
3561          * @param $resultCallback Callback: Optional function called for each MySQL result
3562          * @param string $fname Calling function name
3563          * @param $inputCallback Callback: Optional function called for each complete query sent
3564          * @return bool|string
3565          */
3566         public function sourceStream( $fp, $lineCallback = false, $resultCallback = false,
3567                 $fname = __METHOD__, $inputCallback = false )
3568         {
3569                 $cmd = '';
3570
3571                 while ( !feof( $fp ) ) {
3572                         if ( $lineCallback ) {
3573                                 call_user_func( $lineCallback );
3574                         }
3575
3576                         $line = trim( fgets( $fp ) );
3577
3578                         if ( $line == '' ) {
3579                                 continue;
3580                         }
3581
3582                         if ( '-' == $line[0] && '-' == $line[1] ) {
3583                                 continue;
3584                         }
3585
3586                         if ( $cmd != '' ) {
3587                                 $cmd .= ' ';
3588                         }
3589
3590                         $done = $this->streamStatementEnd( $cmd, $line );
3591
3592                         $cmd .= "$line\n";
3593
3594                         if ( $done || feof( $fp ) ) {
3595                                 $cmd = $this->replaceVars( $cmd );
3596
3597                                 if ( ( $inputCallback && call_user_func( $inputCallback, $cmd ) ) || !$inputCallback ) {
3598                                         $res = $this->query( $cmd, $fname );
3599
3600                                         if ( $resultCallback ) {
3601                                                 call_user_func( $resultCallback, $res, $this );
3602                                         }
3603
3604                                         if ( false === $res ) {
3605                                                 $err = $this->lastError();
3606                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3607                                         }
3608                                 }
3609                                 $cmd = '';
3610                         }
3611                 }
3612
3613                 return true;
3614         }
3615
3616         /**
3617          * Called by sourceStream() to check if we've reached a statement end
3618          *
3619          * @param string $sql SQL assembled so far
3620          * @param string $newLine New line about to be added to $sql
3621          * @return Bool Whether $newLine contains end of the statement
3622          */
3623         public function streamStatementEnd( &$sql, &$newLine ) {
3624                 if ( $this->delimiter ) {
3625                         $prev = $newLine;
3626                         $newLine = preg_replace( '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3627                         if ( $newLine != $prev ) {
3628                                 return true;
3629                         }
3630                 }
3631                 return false;
3632         }
3633
3634         /**
3635          * Database independent variable replacement. Replaces a set of variables
3636          * in an SQL statement with their contents as given by $this->getSchemaVars().
3637          *
3638          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3639          *
3640          * - '{$var}' should be used for text and is passed through the database's
3641          *   addQuotes method.
3642          * - `{$var}` should be used for identifiers (eg: table and database names),
3643          *   it is passed through the database's addIdentifierQuotes method which
3644          *   can be overridden if the database uses something other than backticks.
3645          * - / *$var* / is just encoded, besides traditional table prefix and
3646          *   table options its use should be avoided.
3647          *
3648          * @param string $ins SQL statement to replace variables in
3649          * @return String The new SQL statement with variables replaced
3650          */
3651         protected function replaceSchemaVars( $ins ) {
3652                 $vars = $this->getSchemaVars();
3653                 foreach ( $vars as $var => $value ) {
3654                         // replace '{$var}'
3655                         $ins = str_replace( '\'{$' . $var . '}\'', $this->addQuotes( $value ), $ins );
3656                         // replace `{$var}`
3657                         $ins = str_replace( '`{$' . $var . '}`', $this->addIdentifierQuotes( $value ), $ins );
3658                         // replace /*$var*/
3659                         $ins = str_replace( '/*$' . $var . '*/', $this->strencode( $value ), $ins );
3660                 }
3661                 return $ins;
3662         }
3663
3664         /**
3665          * Replace variables in sourced SQL
3666          *
3667          * @param $ins string
3668          *
3669          * @return string
3670          */
3671         protected function replaceVars( $ins ) {
3672                 $ins = $this->replaceSchemaVars( $ins );
3673
3674                 // Table prefixes
3675                 $ins = preg_replace_callback( '!/\*(?:\$wgDBprefix|_)\*/([a-zA-Z_0-9]*)!',
3676                         array( $this, 'tableNameCallback' ), $ins );
3677
3678                 // Index names
3679                 $ins = preg_replace_callback( '!/\*i\*/([a-zA-Z_0-9]*)!',
3680                         array( $this, 'indexNameCallback' ), $ins );
3681
3682                 return $ins;
3683         }
3684
3685         /**
3686          * Get schema variables. If none have been set via setSchemaVars(), then
3687          * use some defaults from the current object.
3688          *
3689          * @return array
3690          */
3691         protected function getSchemaVars() {
3692                 if ( $this->mSchemaVars ) {
3693                         return $this->mSchemaVars;
3694                 } else {
3695                         return $this->getDefaultSchemaVars();
3696                 }
3697         }
3698
3699         /**
3700          * Get schema variables to use if none have been set via setSchemaVars().
3701          *
3702          * Override this in derived classes to provide variables for tables.sql
3703          * and SQL patch files.
3704          *
3705          * @return array
3706          */
3707         protected function getDefaultSchemaVars() {
3708                 return array();
3709         }
3710
3711         /**
3712          * Table name callback
3713          *
3714          * @param $matches array
3715          *
3716          * @return string
3717          */
3718         protected function tableNameCallback( $matches ) {
3719                 return $this->tableName( $matches[1] );
3720         }
3721
3722         /**
3723          * Index name callback
3724          *
3725          * @param $matches array
3726          *
3727          * @return string
3728          */
3729         protected function indexNameCallback( $matches ) {
3730                 return $this->indexName( $matches[1] );
3731         }
3732
3733         /**
3734          * Check to see if a named lock is available. This is non-blocking.
3735          *
3736          * @param string $lockName name of lock to poll
3737          * @param string $method name of method calling us
3738          * @return Boolean
3739          * @since 1.20
3740          */
3741         public function lockIsFree( $lockName, $method ) {
3742                 return true;
3743         }
3744
3745         /**
3746          * Acquire a named lock
3747          *
3748          * Abstracted from Filestore::lock() so child classes can implement for
3749          * their own needs.
3750          *
3751          * @param string $lockName name of lock to aquire
3752          * @param string $method name of method calling us
3753          * @param $timeout Integer: timeout
3754          * @return Boolean
3755          */
3756         public function lock( $lockName, $method, $timeout = 5 ) {
3757                 return true;
3758         }
3759
3760         /**
3761          * Release a lock.
3762          *
3763          * @param string $lockName Name of lock to release
3764          * @param string $method Name of method calling us
3765          *
3766          * @return int Returns 1 if the lock was released, 0 if the lock was not established
3767          * by this thread (in which case the lock is not released), and NULL if the named
3768          * lock did not exist
3769          */
3770         public function unlock( $lockName, $method ) {
3771                 return true;
3772         }
3773
3774         /**
3775          * Lock specific tables
3776          *
3777          * @param array $read of tables to lock for read access
3778          * @param array $write of tables to lock for write access
3779          * @param string $method name of caller
3780          * @param bool $lowPriority Whether to indicate writes to be LOW PRIORITY
3781          *
3782          * @return bool
3783          */
3784         public function lockTables( $read, $write, $method, $lowPriority = true ) {
3785                 return true;
3786         }
3787
3788         /**
3789          * Unlock specific tables
3790          *
3791          * @param string $method the caller
3792          *
3793          * @return bool
3794          */
3795         public function unlockTables( $method ) {
3796                 return true;
3797         }
3798
3799         /**
3800          * Delete a table
3801          * @param $tableName string
3802          * @param $fName string
3803          * @return bool|ResultWrapper
3804          * @since 1.18
3805          */
3806         public function dropTable( $tableName, $fName = __METHOD__ ) {
3807                 if ( !$this->tableExists( $tableName, $fName ) ) {
3808                         return false;
3809                 }
3810                 $sql = "DROP TABLE " . $this->tableName( $tableName );
3811                 if ( $this->cascadingDeletes() ) {
3812                         $sql .= " CASCADE";
3813                 }
3814                 return $this->query( $sql, $fName );
3815         }
3816
3817         /**
3818          * Get search engine class. All subclasses of this need to implement this
3819          * if they wish to use searching.
3820          *
3821          * @return String
3822          */
3823         public function getSearchEngine() {
3824                 return 'SearchEngineDummy';
3825         }
3826
3827         /**
3828          * Find out when 'infinity' is. Most DBMSes support this. This is a special
3829          * keyword for timestamps in PostgreSQL, and works with CHAR(14) as well
3830          * because "i" sorts after all numbers.
3831          *
3832          * @return String
3833          */
3834         public function getInfinity() {
3835                 return 'infinity';
3836         }
3837
3838         /**
3839          * Encode an expiry time into the DBMS dependent format
3840          *
3841          * @param string $expiry timestamp for expiry, or the 'infinity' string
3842          * @return String
3843          */
3844         public function encodeExpiry( $expiry ) {
3845                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3846                         ? $this->getInfinity()
3847                         : $this->timestamp( $expiry );
3848         }
3849
3850         /**
3851          * Decode an expiry time into a DBMS independent format
3852          *
3853          * @param string $expiry DB timestamp field value for expiry
3854          * @param $format integer: TS_* constant, defaults to TS_MW
3855          * @return String
3856          */
3857         public function decodeExpiry( $expiry, $format = TS_MW ) {
3858                 return ( $expiry == '' || $expiry == $this->getInfinity() )
3859                         ? 'infinity'
3860                         : wfTimestamp( $format, $expiry );
3861         }
3862
3863         /**
3864          * Allow or deny "big selects" for this session only. This is done by setting
3865          * the sql_big_selects session variable.
3866          *
3867          * This is a MySQL-specific feature.
3868          *
3869          * @param $value Mixed: true for allow, false for deny, or "default" to
3870          *   restore the initial value
3871          */
3872         public function setBigSelects( $value = true ) {
3873                 // no-op
3874         }
3875
3876         /**
3877          * @since 1.19
3878          */
3879         public function __toString() {
3880                 return (string)$this->mConn;
3881         }
3882
3883         public function __destruct() {
3884                 if ( count( $this->mTrxIdleCallbacks ) || count( $this->mTrxPreCommitCallbacks ) ) {
3885                         trigger_error( "Transaction idle or pre-commit callbacks still pending." ); // sanity
3886                 }
3887         }
3888 }