includes/db/Database.php

   1 <?php
   2 /**
   3  * @defgroup Database Database
   4  *
   5  * @file
   6  * @ingroup Database
   7  * This file deals with database interface functions
   8  * and query specifics/optimisations
   9  */
  10
  11 /** Number of times to re-try an operation in case of deadlock */
  12 define( 'DEADLOCK_TRIES', 4 );
  13 /** Minimum time to wait before retry, in microseconds */
  14 define( 'DEADLOCK_DELAY_MIN', 500000 );
  15 /** Maximum time to wait before retry */
  16 define( 'DEADLOCK_DELAY_MAX', 1500000 );
  17
  18 /**
  19  * Base interface for all DBMS-specific code. At a bare minimum, all of the
  20  * following must be implemented to support MediaWiki
  21  *
  22  * @file
  23  * @ingroup Database
  24  */
  25 interface DatabaseType {
  26         /**
  27          * Get the type of the DBMS, as it appears in $wgDBtype.
  28          *
  29          * @return string
  30          */
  31         function getType();
  32
  33         /**
  34          * Open a connection to the database. Usually aborts on failure
  35          *
  36          * @param $server String: database server host
  37          * @param $user String: database user name
  38          * @param $password String: database user password
  39          * @param $dbName String: database name
  40          * @return bool
  41          * @throws DBConnectionError
  42          */
  43         function open( $server, $user, $password, $dbName );
  44
  45         /**
  46          * Fetch the next row from the given result object, in object form.
  47          * Fields can be retrieved with $row->fieldname, with fields acting like
  48          * member variables.
  49          *
  50          * @param $res ResultWrapper|object as returned from DatabaseBase::query(), etc.
  51          * @return Row object
  52          * @throws DBUnexpectedError Thrown if the database returns an error
  53          */
  54         function fetchObject( $res );
  55
  56         /**
  57          * Fetch the next row from the given result object, in associative array
  58          * form.  Fields are retrieved with $row['fieldname'].
  59          *
  60          * @param $res ResultWrapper result object as returned from DatabaseBase::query(), etc.
  61          * @return Row object
  62          * @throws DBUnexpectedError Thrown if the database returns an error
  63          */
  64         function fetchRow( $res );
  65
  66         /**
  67          * Get the number of rows in a result object
  68          *
  69          * @param $res Mixed: A SQL result
  70          * @return int
  71          */
  72         function numRows( $res );
  73
  74         /**
  75          * Get the number of fields in a result object
  76          * @see http://www.php.net/mysql_num_fields
  77          *
  78          * @param $res Mixed: A SQL result
  79          * @return int
  80          */
  81         function numFields( $res );
  82
  83         /**
  84          * Get a field name in a result object
  85          * @see http://www.php.net/mysql_field_name
  86          *
  87          * @param $res Mixed: A SQL result
  88          * @param $n Integer
  89          * @return string
  90          */
  91         function fieldName( $res, $n );
  92
  93         /**
  94          * Get the inserted value of an auto-increment row
  95          *
  96          * The value inserted should be fetched from nextSequenceValue()
  97          *
  98          * Example:
  99          * $id = $dbw->nextSequenceValue('page_page_id_seq');
 100          * $dbw->insert('page',array('page_id' => $id));
 101          * $id = $dbw->insertId();
 102          *
 103          * @return int
 104          */
 105         function insertId();
 106
 107         /**
 108          * Change the position of the cursor in a result object
 109          * @see http://www.php.net/mysql_data_seek
 110          *
 111          * @param $res Mixed: A SQL result
 112          * @param $row Mixed: Either MySQL row or ResultWrapper
 113          */
 114         function dataSeek( $res, $row );
 115
 116         /**
 117          * Get the last error number
 118          * @see http://www.php.net/mysql_errno
 119          *
 120          * @return int
 121          */
 122         function lastErrno();
 123
 124         /**
 125          * Get a description of the last error
 126          * @see http://www.php.net/mysql_error
 127          *
 128          * @return string
 129          */
 130         function lastError();
 131
 132         /**
 133          * mysql_fetch_field() wrapper
 134          * Returns false if the field doesn't exist
 135          *
 136          * @param $table string: table name
 137          * @param $field string: field name
 138          *
 139          * @return Field
 140          */
 141         function fieldInfo( $table, $field );
 142
 143         /**
 144          * Get information about an index into an object
 145          * @param $table string: Table name
 146          * @param $index string: Index name
 147          * @param $fname string: Calling function name
 148          * @return Mixed: Database-specific index description class or false if the index does not exist
 149          */
 150         function indexInfo( $table, $index, $fname = 'Database::indexInfo' );
 151
 152         /**
 153          * Get the number of rows affected by the last write query
 154          * @see http://www.php.net/mysql_affected_rows
 155          *
 156          * @return int
 157          */
 158         function affectedRows();
 159
 160         /**
 161          * Wrapper for addslashes()
 162          *
 163          * @param $s string: to be slashed.
 164          * @return string: slashed string.
 165          */
 166         function strencode( $s );
 167
 168         /**
 169          * Returns a wikitext link to the DB's website, e.g.,
 170          *     return "[http://www.mysql.com/ MySQL]";
 171          * Should at least contain plain text, if for some reason
 172          * your database has no website.
 173          *
 174          * @return string: wikitext of a link to the server software's web site
 175          */
 176         static function getSoftwareLink();
 177
 178         /**
 179          * A string describing the current software version, like from
 180          * mysql_get_server_info().
 181          *
 182          * @return string: Version information from the database server.
 183          */
 184         function getServerVersion();
 185
 186         /**
 187          * A string describing the current software version, and possibly
 188          * other details in a user-friendly way.  Will be listed on Special:Version, etc.
 189          * Use getServerVersion() to get machine-friendly information.
 190          *
 191          * @return string: Version information from the database server
 192          */
 193         function getServerInfo();
 194 }
 195
 196 /**
 197  * Database abstraction object
 198  * @ingroup Database
 199  */
 200 abstract class DatabaseBase implements DatabaseType {
 201
 202 # ------------------------------------------------------------------------------
 203 # Variables
 204 # ------------------------------------------------------------------------------
 205
 206         protected $mLastQuery = '';
 207         protected $mDoneWrites = false;
 208         protected $mPHPError = false;
 209
 210         protected $mServer, $mUser, $mPassword, $mDBname;
 211
 212         /**
 213          * @var DatabaseBase
 214          */
 215         protected $mConn = null;
 216         protected $mOpened = false;
 217
 218         protected $mTablePrefix;
 219         protected $mFlags;
 220         protected $mTrxLevel = 0;
 221         protected $mErrorCount = 0;
 222         protected $mLBInfo = array();
 223         protected $mFakeSlaveLag = null, $mFakeMaster = false;
 224         protected $mDefaultBigSelects = null;
 225         protected $mSchemaVars = false;
 226
 227         protected $preparedArgs;
 228
 229         protected $htmlErrors;
 230
 231         protected $delimiter = ';';
 232
 233 # ------------------------------------------------------------------------------
 234 # Accessors
 235 # ------------------------------------------------------------------------------
 236         # These optionally set a variable and return the previous state
 237
 238         /**
 239          * A string describing the current software version, and possibly
 240          * other details in a user-friendly way.  Will be listed on Special:Version, etc.
 241          * Use getServerVersion() to get machine-friendly information.
 242          *
 243          * @return string: Version information from the database server
 244          */
 245         public function getServerInfo() {
 246                 return $this->getServerVersion();
 247         }
 248
 249         /**
 250          * Boolean, controls output of large amounts of debug information.
 251          * @param $debug bool|null
 252          *   - true to enable debugging
 253          *   - false to disable debugging
 254          *   - omitted or null to do nothing
 255          *
 256          * @return bool|null previous value of the flag
 257          */
 258         function debug( $debug = null ) {
 259                 return wfSetBit( $this->mFlags, DBO_DEBUG, $debug );
 260         }
 261
 262         /**
 263          * Turns buffering of SQL result sets on (true) or off (false). Default is
 264          * "on".
 265          *
 266          * Unbuffered queries are very troublesome in MySQL:
 267          *
 268          *   - If another query is executed while the first query is being read
 269          *     out, the first query is killed. This means you can't call normal
 270          *     MediaWiki functions while you are reading an unbuffered query result
 271          *     from a normal wfGetDB() connection.
 272          *
 273          *   - Unbuffered queries cause the MySQL server to use large amounts of
 274          *     memory and to hold broad locks which block other queries.
 275          *
 276          * If you want to limit client-side memory, it's almost always better to
 277          * split up queries into batches using a LIMIT clause than to switch off
 278          * buffering.
 279          *
 280          * @param $buffer null|bool
 281          *
 282          * @return null|bool The previous value of the flag
 283          */
 284         function bufferResults( $buffer = null ) {
 285                 if ( is_null( $buffer ) ) {
 286                         return !(bool)( $this->mFlags & DBO_NOBUFFER );
 287                 } else {
 288                         return !wfSetBit( $this->mFlags, DBO_NOBUFFER, !$buffer );
 289                 }
 290         }
 291
 292         /**
 293          * Turns on (false) or off (true) the automatic generation and sending
 294          * of a "we're sorry, but there has been a database error" page on
 295          * database errors. Default is on (false). When turned off, the
 296          * code should use lastErrno() and lastError() to handle the
 297          * situation as appropriate.
 298          *
 299          * @param $ignoreErrors bool|null
 300          *
 301          * @return bool The previous value of the flag.
 302          */
 303         function ignoreErrors( $ignoreErrors = null ) {
 304                 return wfSetBit( $this->mFlags, DBO_IGNORE, $ignoreErrors );
 305         }
 306
 307         /**
 308          * Gets or sets the current transaction level.
 309          *
 310          * Historically, transactions were allowed to be "nested". This is no
 311          * longer supported, so this function really only returns a boolean.
 312          *
 313          * @param $level int An integer (0 or 1), or omitted to leave it unchanged.
 314          * @return int The previous value
 315          */
 316         function trxLevel( $level = null ) {
 317                 return wfSetVar( $this->mTrxLevel, $level );
 318         }
 319
 320         /**
 321          * Get/set the number of errors logged. Only useful when errors are ignored
 322          * @param $count int The count to set, or omitted to leave it unchanged.
 323          * @return int The error count
 324          */
 325         function errorCount( $count = null ) {
 326                 return wfSetVar( $this->mErrorCount, $count );
 327         }
 328
 329         /**
 330          * Get/set the table prefix.
 331          * @param $prefix string The table prefix to set, or omitted to leave it unchanged.
 332          * @return string The previous table prefix.
 333          */
 334         function tablePrefix( $prefix = null ) {
 335                 return wfSetVar( $this->mTablePrefix, $prefix );
 336         }
 337
 338         /**
 339          * Get properties passed down from the server info array of the load
 340          * balancer.
 341          *
 342          * @param $name string The entry of the info array to get, or null to get the
 343          *   whole array
 344          *
 345          * @return LoadBalancer|null
 346          */
 347         function getLBInfo( $name = null ) {
 348                 if ( is_null( $name ) ) {
 349                         return $this->mLBInfo;
 350                 } else {
 351                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 352                                 return $this->mLBInfo[$name];
 353                         } else {
 354                                 return null;
 355                         }
 356                 }
 357         }
 358
 359         /**
 360          * Set the LB info array, or a member of it. If called with one parameter,
 361          * the LB info array is set to that parameter. If it is called with two
 362          * parameters, the member with the given name is set to the given value.
 363          *
 364          * @param $name
 365          * @param $value
 366          */
 367         function setLBInfo( $name, $value = null ) {
 368                 if ( is_null( $value ) ) {
 369                         $this->mLBInfo = $name;
 370                 } else {
 371                         $this->mLBInfo[$name] = $value;
 372                 }
 373         }
 374
 375         /**
 376          * Set lag time in seconds for a fake slave
 377          *
 378          * @param $lag int
 379          */
 380         function setFakeSlaveLag( $lag ) {
 381                 $this->mFakeSlaveLag = $lag;
 382         }
 383
 384         /**
 385          * Make this connection a fake master
 386          *
 387          * @param $enabled bool
 388          */
 389         function setFakeMaster( $enabled = true ) {
 390                 $this->mFakeMaster = $enabled;
 391         }
 392
 393         /**
 394          * Returns true if this database supports (and uses) cascading deletes
 395          *
 396          * @return bool
 397          */
 398         function cascadingDeletes() {
 399                 return false;
 400         }
 401
 402         /**
 403          * Returns true if this database supports (and uses) triggers (e.g. on the page table)
 404          *
 405          * @return bool
 406          */
 407         function cleanupTriggers() {
 408                 return false;
 409         }
 410
 411         /**
 412          * Returns true if this database is strict about what can be put into an IP field.
 413          * Specifically, it uses a NULL value instead of an empty string.
 414          *
 415          * @return bool
 416          */
 417         function strictIPs() {
 418                 return false;
 419         }
 420
 421         /**
 422          * Returns true if this database uses timestamps rather than integers
 423          *
 424          * @return bool
 425         */
 426         function realTimestamps() {
 427                 return false;
 428         }
 429
 430         /**
 431          * Returns true if this database does an implicit sort when doing GROUP BY
 432          *
 433          * @return bool
 434          */
 435         function implicitGroupby() {
 436                 return true;
 437         }
 438
 439         /**
 440          * Returns true if this database does an implicit order by when the column has an index
 441          * For example: SELECT page_title FROM page LIMIT 1
 442          *
 443          * @return bool
 444          */
 445         function implicitOrderby() {
 446                 return true;
 447         }
 448
 449         /**
 450          * Returns true if this database requires that SELECT DISTINCT queries require that all
 451            ORDER BY expressions occur in the SELECT list per the SQL92 standard
 452          *
 453          * @return bool
 454          */
 455         function standardSelectDistinct() {
 456                 return true;
 457         }
 458
 459         /**
 460          * Returns true if this database can do a native search on IP columns
 461          * e.g. this works as expected: .. WHERE rc_ip = '127.42.12.102/32';
 462          *
 463          * @return bool
 464          */
 465         function searchableIPs() {
 466                 return false;
 467         }
 468
 469         /**
 470          * Returns true if this database can use functional indexes
 471          *
 472          * @return bool
 473          */
 474         function functionalIndexes() {
 475                 return false;
 476         }
 477
 478         /**
 479          * Return the last query that went through DatabaseBase::query()
 480          * @return String
 481          */
 482         function lastQuery() {
 483                 return $this->mLastQuery;
 484         }
 485
 486         /**
 487          * Returns true if the connection may have been used for write queries.
 488          * Should return true if unsure.
 489          *
 490          * @return bool
 491          */
 492         function doneWrites() {
 493                 return $this->mDoneWrites;
 494         }
 495
 496         /**
 497          * Is a connection to the database open?
 498          * @return Boolean
 499          */
 500         function isOpen() {
 501                 return $this->mOpened;
 502         }
 503
 504         /**
 505          * Set a flag for this connection
 506          *
 507          * @param $flag Integer: DBO_* constants from Defines.php:
 508          *   - DBO_DEBUG: output some debug info (same as debug())
 509          *   - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
 510          *   - DBO_IGNORE: ignore errors (same as ignoreErrors())
 511          *   - DBO_TRX: automatically start transactions
 512          *   - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
 513          *       and removes it in command line mode
 514          *   - DBO_PERSISTENT: use persistant database connection
 515          */
 516         function setFlag( $flag ) {
 517                 $this->mFlags |= $flag;
 518         }
 519
 520         /**
 521          * Clear a flag for this connection
 522          *
 523          * @param $flag: same as setFlag()'s $flag param
 524          */
 525         function clearFlag( $flag ) {
 526                 $this->mFlags &= ~$flag;
 527         }
 528
 529         /**
 530          * Returns a boolean whether the flag $flag is set for this connection
 531          *
 532          * @param $flag: same as setFlag()'s $flag param
 533          * @return Boolean
 534          */
 535         function getFlag( $flag ) {
 536                 return !!( $this->mFlags & $flag );
 537         }
 538
 539         /**
 540          * General read-only accessor
 541          *
 542          * @param $name string
 543          *
 544          * @return string
 545          */
 546         function getProperty( $name ) {
 547                 return $this->$name;
 548         }
 549
 550         /**
 551          * @return string
 552          */
 553         function getWikiID() {
 554                 if ( $this->mTablePrefix ) {
 555                         return "{$this->mDBname}-{$this->mTablePrefix}";
 556                 } else {
 557                         return $this->mDBname;
 558                 }
 559         }
 560
 561         /**
 562          * Return a path to the DBMS-specific schema file, otherwise default to tables.sql
 563          *
 564          * @return string
 565          */
 566         public function getSchemaPath() {
 567                 global $IP;
 568                 if ( file_exists( "$IP/maintenance/" . $this->getType() . "/tables.sql" ) ) {
 569                         return "$IP/maintenance/" . $this->getType() . "/tables.sql";
 570                 } else {
 571                         return "$IP/maintenance/tables.sql";
 572                 }
 573         }
 574
 575 # ------------------------------------------------------------------------------
 576 # Other functions
 577 # ------------------------------------------------------------------------------
 578
 579         /**
 580          * Constructor.
 581          * @param $server String: database server host
 582          * @param $user String: database user name
 583          * @param $password String: database user password
 584          * @param $dbName String: database name
 585          * @param $flags
 586          * @param $tablePrefix String: database table prefixes. By default use the prefix gave in LocalSettings.php
 587          */
 588         function __construct( $server = false, $user = false, $password = false, $dbName = false,
 589                 $flags = 0, $tablePrefix = 'get from global'
 590         ) {
 591                 global $wgDBprefix, $wgCommandLineMode;
 592
 593                 $this->mFlags = $flags;
 594
 595                 if ( $this->mFlags & DBO_DEFAULT ) {
 596                         if ( $wgCommandLineMode ) {
 597                                 $this->mFlags &= ~DBO_TRX;
 598                         } else {
 599                                 $this->mFlags |= DBO_TRX;
 600                         }
 601                 }
 602
 603                 /** Get the default table prefix*/
 604                 if ( $tablePrefix == 'get from global' ) {
 605                         $this->mTablePrefix = $wgDBprefix;
 606                 } else {
 607                         $this->mTablePrefix = $tablePrefix;
 608                 }
 609
 610                 if ( $user ) {
 611                         $this->open( $server, $user, $password, $dbName );
 612                 }
 613         }
 614
 615         /**
 616          * Called by serialize. Throw an exception when DB connection is serialized.
 617          * This causes problems on some database engines because the connection is
 618          * not restored on unserialize.
 619          */
 620         public function __sleep() {
 621                 throw new MWException( 'Database serialization may cause problems, since the connection is not restored on wakeup.' );
 622         }
 623
 624         /**
 625          * Same as new DatabaseMysql( ... ), kept for backward compatibility
 626          * @deprecated since 1.17
 627          *
 628          * @param $server
 629          * @param $user
 630          * @param $password
 631          * @param $dbName
 632          * @param $flags int
 633          * @return DatabaseMysql
 634          */
 635         static function newFromParams( $server, $user, $password, $dbName, $flags = 0 ) {
 636                 wfDeprecated( __METHOD__, '1.17' );
 637                 return new DatabaseMysql( $server, $user, $password, $dbName, $flags );
 638         }
 639
 640         /**
 641          * Same as new factory( ... ), kept for backward compatibility
 642          * @deprecated since 1.18
 643          * @see Database::factory()
 644          * @return DatabaseBase
 645          */
 646         public final static function newFromType( $dbType, $p = array() ) {
 647                 wfDeprecated( __METHOD__, '1.18' );
 648                 if ( isset( $p['tableprefix'] ) ) {
 649                         $p['tablePrefix'] = $p['tableprefix'];
 650                 }
 651                 return self::factory( $dbType, $p );
 652         }
 653
 654         /**
 655          * Given a DB type, construct the name of the appropriate child class of
 656          * DatabaseBase. This is designed to replace all of the manual stuff like:
 657          *      $class = 'Database' . ucfirst( strtolower( $type ) );
 658          * as well as validate against the canonical list of DB types we have
 659          *
 660          * This factory function is mostly useful for when you need to connect to a
 661          * database other than the MediaWiki default (such as for external auth,
 662          * an extension, et cetera). Do not use this to connect to the MediaWiki
 663          * database. Example uses in core:
 664          * @see LoadBalancer::reallyOpenConnection()
 665          * @see ExternalUser_MediaWiki::initFromCond()
 666          * @see ForeignDBRepo::getMasterDB()
 667          * @see WebInstaller_DBConnect::execute()
 668          *
 669          * @since 1.18
 670          *
 671          * @param $dbType String A possible DB type
 672          * @param $p Array An array of options to pass to the constructor.
 673          *    Valid options are: host, user, password, dbname, flags, tablePrefix
 674          * @return DatabaseBase subclass or null
 675          */
 676         public final static function factory( $dbType, $p = array() ) {
 677                 $canonicalDBTypes = array(
 678                         'mysql', 'postgres', 'sqlite', 'oracle', 'mssql', 'ibm_db2'
 679                 );
 680                 $dbType = strtolower( $dbType );
 681                 $class = 'Database' . ucfirst( $dbType );
 682
 683                 if( in_array( $dbType, $canonicalDBTypes ) || ( class_exists( $class ) && is_subclass_of( $class, 'DatabaseBase' ) ) ) {
 684                         return new $class(
 685                                 isset( $p['host'] ) ? $p['host'] : false,
 686                                 isset( $p['user'] ) ? $p['user'] : false,
 687                                 isset( $p['password'] ) ? $p['password'] : false,
 688                                 isset( $p['dbname'] ) ? $p['dbname'] : false,
 689                                 isset( $p['flags'] ) ? $p['flags'] : 0,
 690                                 isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : 'get from global'
 691                         );
 692                 } else {
 693                         return null;
 694                 }
 695         }
 696
 697         protected function installErrorHandler() {
 698                 $this->mPHPError = false;
 699                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 700                 set_error_handler( array( $this, 'connectionErrorHandler' ) );
 701         }
 702
 703         /**
 704          * @return bool|string
 705          */
 706         protected function restoreErrorHandler() {
 707                 restore_error_handler();
 708                 if ( $this->htmlErrors !== false ) {
 709                         ini_set( 'html_errors', $this->htmlErrors );
 710                 }
 711                 if ( $this->mPHPError ) {
 712                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 713                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 714                         return $error;
 715                 } else {
 716                         return false;
 717                 }
 718         }
 719
 720         /**
 721          * @param $errno
 722          * @param $errstr
 723          */
 724         protected function connectionErrorHandler( $errno,  $errstr ) {
 725                 $this->mPHPError = $errstr;
 726         }
 727
 728         /**
 729          * Closes a database connection.
 730          * if it is open : commits any open transactions
 731          *
 732          * @return Bool operation success. true if already closed.
 733          */
 734         public function close() {
 735                 $this->mOpened = false;
 736                 if ( $this->mConn ) {
 737                         if ( $this->trxLevel() ) {
 738                                 $this->commit( __METHOD__ );
 739                         }
 740                         $ret = $this->closeConnection();
 741                         $this->mConn = false;
 742                         return $ret;
 743                 } else {
 744                         return true;
 745                 }
 746         }
 747
 748         /**
 749          * Closes underlying database connection
 750          * @since 1.20
 751          * @return bool: Whether connection was closed successfully
 752          */
 753         protected abstract function closeConnection();
 754
 755         /**
 756          * @param $error String: fallback error message, used if none is given by DB
 757          */
 758         function reportConnectionError( $error = 'Unknown error' ) {
 759                 $myError = $this->lastError();
 760                 if ( $myError ) {
 761                         $error = $myError;
 762                 }
 763
 764                 # New method
 765                 throw new DBConnectionError( $this, $error );
 766         }
 767
 768         /**
 769          * The DBMS-dependent part of query()
 770          *
 771          * @param  $sql String: SQL query.
 772          * @return ResultWrapper Result object to feed to fetchObject, fetchRow, ...; or false on failure
 773          */
 774         protected abstract function doQuery( $sql );
 775
 776         /**
 777          * Determine whether a query writes to the DB.
 778          * Should return true if unsure.
 779          *
 780          * @param $sql string
 781          *
 782          * @return bool
 783          */
 784         function isWriteQuery( $sql ) {
 785                 return !preg_match( '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|\(SELECT)\b/i', $sql );
 786         }
 787
 788         /**
 789          * Run an SQL query and return the result. Normally throws a DBQueryError
 790          * on failure. If errors are ignored, returns false instead.
 791          *
 792          * In new code, the query wrappers select(), insert(), update(), delete(),
 793          * etc. should be used where possible, since they give much better DBMS
 794          * independence and automatically quote or validate user input in a variety
 795          * of contexts. This function is generally only useful for queries which are
 796          * explicitly DBMS-dependent and are unsupported by the query wrappers, such
 797          * as CREATE TABLE.
 798          *
 799          * However, the query wrappers themselves should call this function.
 800          *
 801          * @param  $sql        String: SQL query
 802          * @param  $fname      String: Name of the calling function, for profiling/SHOW PROCESSLIST
 803          *     comment (you can use __METHOD__ or add some extra info)
 804          * @param  $tempIgnore Boolean:   Whether to avoid throwing an exception on errors...
 805          *     maybe best to catch the exception instead?
 806          * @return boolean|ResultWrapper. true for a successful write query, ResultWrapper object
 807          *     for a successful read query, or false on failure if $tempIgnore set
 808          * @throws DBQueryError Thrown when the database returns an error of any kind
 809          */
 810         public function query( $sql, $fname = '', $tempIgnore = false ) {
 811                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 812                 if ( !Profiler::instance()->isStub() ) {
 813                         # generalizeSQL will probably cut down the query to reasonable
 814                         # logging size most of the time. The substr is really just a sanity check.
 815
 816                         if ( $isMaster ) {
 817                                 $queryProf = 'query-m: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
 818                                 $totalProf = 'DatabaseBase::query-master';
 819                         } else {
 820                                 $queryProf = 'query: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
 821                                 $totalProf = 'DatabaseBase::query';
 822                         }
 823
 824                         wfProfileIn( $totalProf );
 825                         wfProfileIn( $queryProf );
 826                 }
 827
 828                 $this->mLastQuery = $sql;
 829                 if ( !$this->mDoneWrites && $this->isWriteQuery( $sql ) ) {
 830                         # Set a flag indicating that writes have been done
 831                         wfDebug( __METHOD__ . ": Writes done: $sql\n" );
 832                         $this->mDoneWrites = true;
 833                 }
 834
 835                 # Add a comment for easy SHOW PROCESSLIST interpretation
 836                 global $wgUser;
 837                 if ( is_object( $wgUser ) && $wgUser->isItemLoaded( 'name' ) ) {
 838                         $userName = $wgUser->getName();
 839                         if ( mb_strlen( $userName ) > 15 ) {
 840                                 $userName = mb_substr( $userName, 0, 15 ) . '...';
 841                         }
 842                         $userName = str_replace( '/', '', $userName );
 843                 } else {
 844                         $userName = '';
 845                 }
 846                 $commentedSql = preg_replace( '/\s/', " /* $fname $userName */ ", $sql, 1 );
 847
 848                 # If DBO_TRX is set, start a transaction
 849                 if ( ( $this->mFlags & DBO_TRX ) && !$this->trxLevel() &&
 850                         $sql != 'BEGIN' && $sql != 'COMMIT' && $sql != 'ROLLBACK' ) {
 851                         # avoid establishing transactions for SHOW and SET statements too -
 852                         # that would delay transaction initializations to once connection
 853                         # is really used by application
 854                         $sqlstart = substr( $sql, 0, 10 ); // very much worth it, benchmark certified(tm)
 855                         if ( strpos( $sqlstart, "SHOW " ) !== 0 && strpos( $sqlstart, "SET " ) !== 0 )
 856                                 $this->begin( __METHOD__ . " ($fname)" );
 857                 }
 858
 859                 if ( $this->debug() ) {
 860                         static $cnt = 0;
 861
 862                         $cnt++;
 863                         $sqlx = substr( $commentedSql, 0, 500 );
 864                         $sqlx = strtr( $sqlx, "\t\n", '  ' );
 865
 866                         $master = $isMaster ? 'master' : 'slave';
 867                         wfDebug( "Query {$this->mDBname} ($cnt) ($master): $sqlx\n" );
 868                 }
 869
 870                 if ( istainted( $sql ) & TC_MYSQL ) {
 871                         throw new MWException( 'Tainted query found' );
 872                 }
 873
 874                 $queryId = MWDebug::query( $sql, $fname, $isMaster );
 875
 876                 # Do the query and handle errors
 877                 $ret = $this->doQuery( $commentedSql );
 878
 879                 MWDebug::queryTime( $queryId );
 880
 881                 # Try reconnecting if the connection was lost
 882                 if ( false === $ret && $this->wasErrorReissuable() ) {
 883                         # Transaction is gone, like it or not
 884                         $this->mTrxLevel = 0;
 885                         wfDebug( "Connection lost, reconnecting...\n" );
 886
 887                         if ( $this->ping() ) {
 888                                 wfDebug( "Reconnected\n" );
 889                                 $sqlx = substr( $commentedSql, 0, 500 );
 890                                 $sqlx = strtr( $sqlx, "\t\n", '  ' );
 891                                 global $wgRequestTime;
 892                                 $elapsed = round( microtime( true ) - $wgRequestTime, 3 );
 893                                 if ( $elapsed < 300 ) {
 894                                         # Not a database error to lose a transaction after a minute or two
 895                                         wfLogDBError( "Connection lost and reconnected after {$elapsed}s, query: $sqlx\n" );
 896                                 }
 897                                 $ret = $this->doQuery( $commentedSql );
 898                         } else {
 899                                 wfDebug( "Failed\n" );
 900                         }
 901                 }
 902
 903                 if ( false === $ret ) {
 904                         $this->reportQueryError( $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 905                 }
 906
 907                 if ( !Profiler::instance()->isStub() ) {
 908                         wfProfileOut( $queryProf );
 909                         wfProfileOut( $totalProf );
 910                 }
 911
 912                 return $this->resultObject( $ret );
 913         }
 914
 915         /**
 916          * Report a query error. Log the error, and if neither the object ignore
 917          * flag nor the $tempIgnore flag is set, throw a DBQueryError.
 918          *
 919          * @param $error String
 920          * @param $errno Integer
 921          * @param $sql String
 922          * @param $fname String
 923          * @param $tempIgnore Boolean
 924          */
 925         function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
 926                 # Ignore errors during error handling to avoid infinite recursion
 927                 $ignore = $this->ignoreErrors( true );
 928                 ++$this->mErrorCount;
 929
 930                 if ( $ignore || $tempIgnore ) {
 931                         wfDebug( "SQL ERROR (ignored): $error\n" );
 932                         $this->ignoreErrors( $ignore );
 933                 } else {
 934                         $sql1line = str_replace( "\n", "\\n", $sql );
 935                         wfLogDBError( "$fname\t{$this->mServer}\t$errno\t$error\t$sql1line\n" );
 936                         wfDebug( "SQL ERROR: " . $error . "\n" );
 937                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
 938                 }
 939         }
 940
 941         /**
 942          * Intended to be compatible with the PEAR::DB wrapper functions.
 943          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
 944          *
 945          * ? = scalar value, quoted as necessary
 946          * ! = raw SQL bit (a function for instance)
 947          * & = filename; reads the file and inserts as a blob
 948          *     (we don't use this though...)
 949          *
 950          * This function should not be used directly by new code outside of the
 951          * database classes. The query wrapper functions (select() etc.) should be
 952          * used instead.
 953          *
 954          * @param $sql string
 955          * @param $func string
 956          *
 957          * @return array
 958          */
 959         function prepare( $sql, $func = 'DatabaseBase::prepare' ) {
 960                 /* MySQL doesn't support prepared statements (yet), so just
 961                    pack up the query for reference. We'll manually replace
 962                    the bits later. */
 963                 return array( 'query' => $sql, 'func' => $func );
 964         }
 965
 966         /**
 967          * Free a prepared query, generated by prepare().
 968          * @param $prepared
 969          */
 970         function freePrepared( $prepared ) {
 971                 /* No-op by default */
 972         }
 973
 974         /**
 975          * Execute a prepared query with the various arguments
 976          * @param $prepared String: the prepared sql
 977          * @param $args Mixed: Either an array here, or put scalars as varargs
 978          *
 979          * @return ResultWrapper
 980          */
 981         function execute( $prepared, $args = null ) {
 982                 if ( !is_array( $args ) ) {
 983                         # Pull the var args
 984                         $args = func_get_args();
 985                         array_shift( $args );
 986                 }
 987
 988                 $sql = $this->fillPrepared( $prepared['query'], $args );
 989
 990                 return $this->query( $sql, $prepared['func'] );
 991         }
 992
 993         /**
 994          * Prepare & execute an SQL statement, quoting and inserting arguments
 995          * in the appropriate places.
 996          *
 997          * This function should not be used directly by new code outside of the
 998          * database classes. The query wrapper functions (select() etc.) should be
 999          * used instead.
1000          *
1001          * @param $query String
1002          * @param $args ...
1003          *
1004          * @return ResultWrapper
1005          */
1006         function safeQuery( $query, $args = null ) {
1007                 $prepared = $this->prepare( $query, 'DatabaseBase::safeQuery' );
1008
1009                 if ( !is_array( $args ) ) {
1010                         # Pull the var args
1011                         $args = func_get_args();
1012                         array_shift( $args );
1013                 }
1014
1015                 $retval = $this->execute( $prepared, $args );
1016                 $this->freePrepared( $prepared );
1017
1018                 return $retval;
1019         }
1020
1021         /**
1022          * For faking prepared SQL statements on DBs that don't support
1023          * it directly.
1024          * @param $preparedQuery String: a 'preparable' SQL statement
1025          * @param $args Array of arguments to fill it with
1026          * @return string executable SQL
1027          */
1028         function fillPrepared( $preparedQuery, $args ) {
1029                 reset( $args );
1030                 $this->preparedArgs =& $args;
1031
1032                 return preg_replace_callback( '/(\\\\[?!&]|[?!&])/',
1033                         array( &$this, 'fillPreparedArg' ), $preparedQuery );
1034         }
1035
1036         /**
1037          * preg_callback func for fillPrepared()
1038          * The arguments should be in $this->preparedArgs and must not be touched
1039          * while we're doing this.
1040          *
1041          * @param $matches Array
1042          * @return String
1043          */
1044         function fillPreparedArg( $matches ) {
1045                 switch( $matches[1] ) {
1046                         case '\\?': return '?';
1047                         case '\\!': return '!';
1048                         case '\\&': return '&';
1049                 }
1050
1051                 list( /* $n */ , $arg ) = each( $this->preparedArgs );
1052
1053                 switch( $matches[1] ) {
1054                         case '?': return $this->addQuotes( $arg );
1055                         case '!': return $arg;
1056                         case '&':
1057                                 # return $this->addQuotes( file_get_contents( $arg ) );
1058                                 throw new DBUnexpectedError( $this, '& mode is not implemented. If it\'s really needed, uncomment the line above.' );
1059                         default:
1060                                 throw new DBUnexpectedError( $this, 'Received invalid match. This should never happen!' );
1061                 }
1062         }
1063
1064         /**
1065          * Free a result object returned by query() or select(). It's usually not
1066          * necessary to call this, just use unset() or let the variable holding
1067          * the result object go out of scope.
1068          *
1069          * @param $res Mixed: A SQL result
1070          */
1071         function freeResult( $res ) {
1072         }
1073
1074         /**
1075          * Simple UPDATE wrapper.
1076          * Usually throws a DBQueryError on failure.
1077          * If errors are explicitly ignored, returns success
1078          *
1079          * This function exists for historical reasons, DatabaseBase::update() has a more standard
1080          * calling convention and feature set
1081          *
1082          * @param $table string
1083          * @param $var
1084          * @param $value
1085          * @param $cond
1086          * @param $fname string
1087          *
1088          * @return bool
1089          */
1090         function set( $table, $var, $value, $cond, $fname = 'DatabaseBase::set' ) {
1091                 $table = $this->tableName( $table );
1092                 $sql = "UPDATE $table SET $var = '" .
1093                   $this->strencode( $value ) . "' WHERE ($cond)";
1094
1095                 return (bool)$this->query( $sql, $fname );
1096         }
1097
1098         /**
1099          * A SELECT wrapper which returns a single field from a single result row.
1100          *
1101          * Usually throws a DBQueryError on failure. If errors are explicitly
1102          * ignored, returns false on failure.
1103          *
1104          * If no result rows are returned from the query, false is returned.
1105          *
1106          * @param $table string|array Table name. See DatabaseBase::select() for details.
1107          * @param $var string The field name to select. This must be a valid SQL
1108          *   fragment: do not use unvalidated user input.
1109          * @param $cond string|array The condition array. See DatabaseBase::select() for details.
1110          * @param $fname string The function name of the caller.
1111          * @param $options string|array The query options. See DatabaseBase::select() for details.
1112          *
1113          * @return bool|mixed The value from the field, or false on failure.
1114          */
1115         function selectField( $table, $var, $cond = '', $fname = 'DatabaseBase::selectField',
1116                 $options = array() )
1117         {
1118                 if ( !is_array( $options ) ) {
1119                         $options = array( $options );
1120                 }
1121
1122                 $options['LIMIT'] = 1;
1123
1124                 $res = $this->select( $table, $var, $cond, $fname, $options );
1125
1126                 if ( $res === false || !$this->numRows( $res ) ) {
1127                         return false;
1128                 }
1129
1130                 $row = $this->fetchRow( $res );
1131
1132                 if ( $row !== false ) {
1133                         return reset( $row );
1134                 } else {
1135                         return false;
1136                 }
1137         }
1138
1139         /**
1140          * Returns an optional USE INDEX clause to go after the table, and a
1141          * string to go at the end of the query.
1142          *
1143          * @param $options Array: associative array of options to be turned into
1144          *              an SQL query, valid keys are listed in the function.
1145          * @return Array
1146          * @see DatabaseBase::select()
1147          */
1148         function makeSelectOptions( $options ) {
1149                 $preLimitTail = $postLimitTail = '';
1150                 $startOpts = '';
1151
1152                 $noKeyOptions = array();
1153
1154                 foreach ( $options as $key => $option ) {
1155                         if ( is_numeric( $key ) ) {
1156                                 $noKeyOptions[$option] = true;
1157                         }
1158                 }
1159
1160                 if ( isset( $options['GROUP BY'] ) ) {
1161                         $gb = is_array( $options['GROUP BY'] )
1162                                 ? implode( ',', $options['GROUP BY'] )
1163                                 : $options['GROUP BY'];
1164                         $preLimitTail .= " GROUP BY {$gb}";
1165                 }
1166
1167                 if ( isset( $options['HAVING'] ) ) {
1168                         $preLimitTail .= " HAVING {$options['HAVING']}";
1169                 }
1170
1171                 if ( isset( $options['ORDER BY'] ) ) {
1172                         $ob = is_array( $options['ORDER BY'] )
1173                                 ? implode( ',', $options['ORDER BY'] )
1174                                 : $options['ORDER BY'];
1175                         $preLimitTail .= " ORDER BY {$ob}";
1176                 }
1177
1178                 // if (isset($options['LIMIT'])) {
1179                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
1180                 //              isset($options['OFFSET']) ? $options['OFFSET']
1181                 //              : false);
1182                 // }
1183
1184                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1185                         $postLimitTail .= ' FOR UPDATE';
1186                 }
1187
1188                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1189                         $postLimitTail .= ' LOCK IN SHARE MODE';
1190                 }
1191
1192                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1193                         $startOpts .= 'DISTINCT';
1194                 }
1195
1196                 # Various MySQL extensions
1197                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1198                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1199                 }
1200
1201                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1202                         $startOpts .= ' HIGH_PRIORITY';
1203                 }
1204
1205                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1206                         $startOpts .= ' SQL_BIG_RESULT';
1207                 }
1208
1209                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1210                         $startOpts .= ' SQL_BUFFER_RESULT';
1211                 }
1212
1213                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1214                         $startOpts .= ' SQL_SMALL_RESULT';
1215                 }
1216
1217                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1218                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1219                 }
1220
1221                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1222                         $startOpts .= ' SQL_CACHE';
1223                 }
1224
1225                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1226                         $startOpts .= ' SQL_NO_CACHE';
1227                 }
1228
1229                 if ( isset( $options['USE INDEX'] ) && ! is_array( $options['USE INDEX'] ) ) {
1230                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1231                 } else {
1232                         $useIndex = '';
1233                 }
1234
1235                 return array( $startOpts, $useIndex, $preLimitTail, $postLimitTail );
1236         }
1237
1238         /**
1239          * Execute a SELECT query constructed using the various parameters provided.
1240          * See below for full details of the parameters.
1241          *
1242          * @param $table String|Array Table name
1243          * @param $vars String|Array Field names
1244          * @param $conds String|Array Conditions
1245          * @param $fname String Caller function name
1246          * @param $options Array Query options
1247          * @param $join_conds Array Join conditions
1248          *
1249          * @param $table string|array
1250          *
1251          * May be either an array of table names, or a single string holding a table
1252          * name. If an array is given, table aliases can be specified, for example:
1253          *
1254          *    array( 'a' => 'user' )
1255          *
1256          * This includes the user table in the query, with the alias "a" available
1257          * for use in field names (e.g. a.user_name).
1258          *
1259          * All of the table names given here are automatically run through
1260          * DatabaseBase::tableName(), which causes the table prefix (if any) to be
1261          * added, and various other table name mappings to be performed.
1262          *
1263          *
1264          * @param $vars string|array
1265          *
1266          * May be either a field name or an array of field names. The field names
1267          * here are complete fragments of SQL, for direct inclusion into the SELECT
1268          * query. Expressions and aliases may be specified as in SQL, for example:
1269          *
1270          *   array( 'MAX(rev_id) AS maxrev' )
1271          *
1272          * If an expression is given, care must be taken to ensure that it is
1273          * DBMS-independent.
1274          *
1275          *
1276          * @param $conds string|array
1277          *
1278          * May be either a string containing a single condition, or an array of
1279          * conditions. If an array is given, the conditions constructed from each
1280          * element are combined with AND.
1281          *
1282          * Array elements may take one of two forms:
1283          *
1284          *   - Elements with a numeric key are interpreted as raw SQL fragments.
1285          *   - Elements with a string key are interpreted as equality conditions,
1286          *     where the key is the field name.
1287          *     - If the value of such an array element is a scalar (such as a
1288          *       string), it will be treated as data and thus quoted appropriately.
1289          *       If it is null, an IS NULL clause will be added.
1290          *     - If the value is an array, an IN(...) clause will be constructed,
1291          *       such that the field name may match any of the elements in the
1292          *       array. The elements of the array will be quoted.
1293          *
1294          * Note that expressions are often DBMS-dependent in their syntax.
1295          * DBMS-independent wrappers are provided for constructing several types of
1296          * expression commonly used in condition queries. See:
1297          *    - DatabaseBase::buildLike()
1298          *    - DatabaseBase::conditional()
1299          *
1300          *
1301          * @param $options string|array
1302          *
1303          * Optional: Array of query options. Boolean options are specified by
1304          * including them in the array as a string value with a numeric key, for
1305          * example:
1306          *
1307          *    array( 'FOR UPDATE' )
1308          *
1309          * The supported options are:
1310          *
1311          *   - OFFSET: Skip this many rows at the start of the result set. OFFSET
1312          *     with LIMIT can theoretically be used for paging through a result set,
1313          *     but this is discouraged in MediaWiki for performance reasons.
1314          *
1315          *   - LIMIT: Integer: return at most this many rows. The rows are sorted
1316          *     and then the first rows are taken until the limit is reached. LIMIT
1317          *     is applied to a result set after OFFSET.
1318          *
1319          *   - FOR UPDATE: Boolean: lock the returned rows so that they can't be
1320          *     changed until the next COMMIT.
1321          *
1322          *   - DISTINCT: Boolean: return only unique result rows.
1323          *
1324          *   - GROUP BY: May be either an SQL fragment string naming a field or
1325          *     expression to group by, or an array of such SQL fragments.
1326          *
1327          *   - HAVING: A string containing a HAVING clause.
1328          *
1329          *   - ORDER BY: May be either an SQL fragment giving a field name or
1330          *     expression to order by, or an array of such SQL fragments.
1331          *
1332          *   - USE INDEX: This may be either a string giving the index name to use
1333          *     for the query, or an array. If it is an associative array, each key
1334          *     gives the table name (or alias), each value gives the index name to
1335          *     use for that table. All strings are SQL fragments and so should be
1336          *     validated by the caller.
1337          *
1338          *   - EXPLAIN: In MySQL, this causes an EXPLAIN SELECT query to be run,
1339          *     instead of SELECT.
1340          *
1341          * And also the following boolean MySQL extensions, see the MySQL manual
1342          * for documentation:
1343          *
1344          *    - LOCK IN SHARE MODE
1345          *    - STRAIGHT_JOIN
1346          *    - HIGH_PRIORITY
1347          *    - SQL_BIG_RESULT
1348          *    - SQL_BUFFER_RESULT
1349          *    - SQL_SMALL_RESULT
1350          *    - SQL_CALC_FOUND_ROWS
1351          *    - SQL_CACHE
1352          *    - SQL_NO_CACHE
1353          *
1354          *
1355          * @param $join_conds string|array
1356          *
1357          * Optional associative array of table-specific join conditions. In the
1358          * most common case, this is unnecessary, since the join condition can be
1359          * in $conds. However, it is useful for doing a LEFT JOIN.
1360          *
1361          * The key of the array contains the table name or alias. The value is an
1362          * array with two elements, numbered 0 and 1. The first gives the type of
1363          * join, the second is an SQL fragment giving the join condition for that
1364          * table. For example:
1365          *
1366          *    array( 'page' => array('LEFT JOIN','page_latest=rev_id') )
1367          *
1368          * @return ResultWrapper. If the query returned no rows, a ResultWrapper
1369          *   with no rows in it will be returned. If there was a query error, a
1370          *   DBQueryError exception will be thrown, except if the "ignore errors"
1371          *   option was set, in which case false will be returned.
1372          */
1373         function select( $table, $vars, $conds = '', $fname = 'DatabaseBase::select',
1374                 $options = array(), $join_conds = array() ) {
1375                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1376
1377                 return $this->query( $sql, $fname );
1378         }
1379
1380         /**
1381          * The equivalent of DatabaseBase::select() except that the constructed SQL
1382          * is returned, instead of being immediately executed.
1383          *
1384          * @param $table string|array Table name
1385          * @param $vars string|array Field names
1386          * @param $conds string|array Conditions
1387          * @param $fname string Caller function name
1388          * @param $options string|array Query options
1389          * @param $join_conds string|array Join conditions
1390          *
1391          * @return string SQL query string.
1392          * @see DatabaseBase::select()
1393          */
1394         function selectSQLText( $table, $vars, $conds = '', $fname = 'DatabaseBase::select', $options = array(), $join_conds = array() ) {
1395                 if ( is_array( $vars ) ) {
1396                         $vars = implode( ',', $vars );
1397                 }
1398
1399                 $options = (array)$options;
1400
1401                 if ( is_array( $table ) ) {
1402                         $useIndex = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1403                                 ? $options['USE INDEX']
1404                                 : array();
1405                         if ( count( $join_conds ) || count( $useIndex ) ) {
1406                                 $from = ' FROM ' .
1407                                         $this->tableNamesWithUseIndexOrJOIN( $table, $useIndex, $join_conds );
1408                         } else {
1409                                 $from = ' FROM ' . implode( ',', $this->tableNamesWithAlias( $table ) );
1410                         }
1411                 } elseif ( $table != '' ) {
1412                         if ( $table[0] == ' ' ) {
1413                                 $from = ' FROM ' . $table;
1414                         } else {
1415                                 $from = ' FROM ' . $this->tableName( $table );
1416                         }
1417                 } else {
1418                         $from = '';
1419                 }
1420
1421                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail ) = $this->makeSelectOptions( $options );
1422
1423                 if ( !empty( $conds ) ) {
1424                         if ( is_array( $conds ) ) {
1425                                 $conds = $this->makeList( $conds, LIST_AND );
1426                         }
1427                         $sql = "SELECT $startOpts $vars $from $useIndex WHERE $conds $preLimitTail";
1428                 } else {
1429                         $sql = "SELECT $startOpts $vars $from $useIndex $preLimitTail";
1430                 }
1431
1432                 if ( isset( $options['LIMIT'] ) ) {
1433                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1434                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1435                 }
1436                 $sql = "$sql $postLimitTail";
1437
1438                 if ( isset( $options['EXPLAIN'] ) ) {
1439                         $sql = 'EXPLAIN ' . $sql;
1440                 }
1441
1442                 return $sql;
1443         }
1444
1445         /**
1446          * Single row SELECT wrapper. Equivalent to DatabaseBase::select(), except
1447          * that a single row object is returned. If the query returns no rows,
1448          * false is returned.
1449          *
1450          * @param $table string|array Table name
1451          * @param $vars string|array Field names
1452          * @param $conds array Conditions
1453          * @param $fname string Caller function name
1454          * @param $options string|array Query options
1455          * @param $join_conds array|string Join conditions
1456          *
1457          * @return object|bool
1458          */
1459         function selectRow( $table, $vars, $conds, $fname = 'DatabaseBase::selectRow',
1460                 $options = array(), $join_conds = array() )
1461         {
1462                 $options['LIMIT'] = 1;
1463                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1464
1465                 if ( $res === false ) {
1466                         return false;
1467                 }
1468
1469                 if ( !$this->numRows( $res ) ) {
1470                         return false;
1471                 }
1472
1473                 $obj = $this->fetchObject( $res );
1474
1475                 return $obj;
1476         }
1477
1478         /**
1479          * Estimate rows in dataset.
1480          *
1481          * MySQL allows you to estimate the number of rows that would be returned
1482          * by a SELECT query, using EXPLAIN SELECT. The estimate is provided using
1483          * index cardinality statistics, and is notoriously inaccurate, especially
1484          * when large numbers of rows have recently been added or deleted.
1485          *
1486          * For DBMSs that don't support fast result size estimation, this function
1487          * will actually perform the SELECT COUNT(*).
1488          *
1489          * Takes the same arguments as DatabaseBase::select().
1490          *
1491          * @param $table String: table name
1492          * @param Array|string $vars : unused
1493          * @param Array|string $conds : filters on the table
1494          * @param $fname String: function name for profiling
1495          * @param $options Array: options for select
1496          * @return Integer: row count
1497          */
1498         public function estimateRowCount( $table, $vars = '*', $conds = '',
1499                 $fname = 'DatabaseBase::estimateRowCount', $options = array() )
1500         {
1501                 $rows = 0;
1502                 $res = $this->select ( $table, 'COUNT(*) AS rowcount', $conds, $fname, $options );
1503
1504                 if ( $res ) {
1505                         $row = $this->fetchRow( $res );
1506                         $rows = ( isset( $row['rowcount'] ) ) ? $row['rowcount'] : 0;
1507                 }
1508
1509                 return $rows;
1510         }
1511
1512         /**
1513          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1514          * It's only slightly flawed. Don't use for anything important.
1515          *
1516          * @param $sql String A SQL Query
1517          *
1518          * @return string
1519          */
1520         static function generalizeSQL( $sql ) {
1521                 # This does the same as the regexp below would do, but in such a way
1522                 # as to avoid crashing php on some large strings.
1523                 # $sql = preg_replace ( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql);
1524
1525                 $sql = str_replace ( "\\\\", '', $sql );
1526                 $sql = str_replace ( "\\'", '', $sql );
1527                 $sql = str_replace ( "\\\"", '', $sql );
1528                 $sql = preg_replace ( "/'.*'/s", "'X'", $sql );
1529                 $sql = preg_replace ( '/".*"/s', "'X'", $sql );
1530
1531                 # All newlines, tabs, etc replaced by single space
1532                 $sql = preg_replace ( '/\s+/', ' ', $sql );
1533
1534                 # All numbers => N
1535                 $sql = preg_replace ( '/-?[0-9]+/s', 'N', $sql );
1536
1537                 return $sql;
1538         }
1539
1540         /**
1541          * Determines whether a field exists in a table
1542          *
1543          * @param $table String: table name
1544          * @param $field String: filed to check on that table
1545          * @param $fname String: calling function name (optional)
1546          * @return Boolean: whether $table has filed $field
1547          */
1548         function fieldExists( $table, $field, $fname = 'DatabaseBase::fieldExists' ) {
1549                 $info = $this->fieldInfo( $table, $field );
1550
1551                 return (bool)$info;
1552         }
1553
1554         /**
1555          * Determines whether an index exists
1556          * Usually throws a DBQueryError on failure
1557          * If errors are explicitly ignored, returns NULL on failure
1558          *
1559          * @param $table
1560          * @param $index
1561          * @param $fname string
1562          *
1563          * @return bool|null
1564          */
1565         function indexExists( $table, $index, $fname = 'DatabaseBase::indexExists' ) {
1566                 $info = $this->indexInfo( $table, $index, $fname );
1567                 if ( is_null( $info ) ) {
1568                         return null;
1569                 } else {
1570                         return $info !== false;
1571                 }
1572         }
1573
1574         /**
1575          * Query whether a given table exists
1576          *
1577          * @param $table string
1578          * @param $fname string
1579          *
1580          * @return bool
1581          */
1582         function tableExists( $table, $fname = __METHOD__ ) {
1583                 $table = $this->tableName( $table );
1584                 $old = $this->ignoreErrors( true );
1585                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname );
1586                 $this->ignoreErrors( $old );
1587
1588                 return (bool)$res;
1589         }
1590
1591         /**
1592          * mysql_field_type() wrapper
1593          * @param $res
1594          * @param $index
1595          * @return string
1596          */
1597         function fieldType( $res, $index ) {
1598                 if ( $res instanceof ResultWrapper ) {
1599                         $res = $res->result;
1600                 }
1601
1602                 return mysql_field_type( $res, $index );
1603         }
1604
1605         /**
1606          * Determines if a given index is unique
1607          *
1608          * @param $table string
1609          * @param $index string
1610          *
1611          * @return bool
1612          */
1613         function indexUnique( $table, $index ) {
1614                 $indexInfo = $this->indexInfo( $table, $index );
1615
1616                 if ( !$indexInfo ) {
1617                         return null;
1618                 }
1619
1620                 return !$indexInfo[0]->Non_unique;
1621         }
1622
1623         /**
1624          * Helper for DatabaseBase::insert().
1625          *
1626          * @param $options array
1627          * @return string
1628          */
1629         function makeInsertOptions( $options ) {
1630                 return implode( ' ', $options );
1631         }
1632
1633         /**
1634          * INSERT wrapper, inserts an array into a table.
1635          *
1636          * $a may be either:
1637          *
1638          *   - A single associative array. The array keys are the field names, and
1639          *     the values are the values to insert. The values are treated as data
1640          *     and will be quoted appropriately. If NULL is inserted, this will be
1641          *     converted to a database NULL.
1642          *   - An array with numeric keys, holding a list of associative arrays.
1643          *     This causes a multi-row INSERT on DBMSs that support it. The keys in
1644          *     each subarray must be identical to each other, and in the same order.
1645          *
1646          * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
1647          * returns success.
1648          *
1649          * $options is an array of options, with boolean options encoded as values
1650          * with numeric keys, in the same style as $options in
1651          * DatabaseBase::select(). Supported options are:
1652          *
1653          *   - IGNORE: Boolean: if present, duplicate key errors are ignored, and
1654          *     any rows which cause duplicate key errors are not inserted. It's
1655          *     possible to determine how many rows were successfully inserted using
1656          *     DatabaseBase::affectedRows().
1657          *
1658          * @param $table   String Table name. This will be passed through
1659          *                 DatabaseBase::tableName().
1660          * @param $a       Array of rows to insert
1661          * @param $fname   String Calling function name (use __METHOD__) for logs/profiling
1662          * @param $options Array of options
1663          *
1664          * @return bool
1665          */
1666         function insert( $table, $a, $fname = 'DatabaseBase::insert', $options = array() ) {
1667                 # No rows to insert, easy just return now
1668                 if ( !count( $a ) ) {
1669                         return true;
1670                 }
1671
1672                 $table = $this->tableName( $table );
1673
1674                 if ( !is_array( $options ) ) {
1675                         $options = array( $options );
1676                 }
1677
1678                 $options = $this->makeInsertOptions( $options );
1679
1680                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1681                         $multi = true;
1682                         $keys = array_keys( $a[0] );
1683                 } else {
1684                         $multi = false;
1685                         $keys = array_keys( $a );
1686                 }
1687
1688                 $sql = 'INSERT ' . $options .
1689                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1690
1691                 if ( $multi ) {
1692                         $first = true;
1693                         foreach ( $a as $row ) {
1694                                 if ( $first ) {
1695                                         $first = false;
1696                                 } else {
1697                                         $sql .= ',';
1698                                 }
1699                                 $sql .= '(' . $this->makeList( $row ) . ')';
1700                         }
1701                 } else {
1702                         $sql .= '(' . $this->makeList( $a ) . ')';
1703                 }
1704
1705                 return (bool)$this->query( $sql, $fname );
1706         }
1707
1708         /**
1709          * Make UPDATE options for the DatabaseBase::update function
1710          *
1711          * @param $options Array: The options passed to DatabaseBase::update
1712          * @return string
1713          */
1714         function makeUpdateOptions( $options ) {
1715                 if ( !is_array( $options ) ) {
1716                         $options = array( $options );
1717                 }
1718
1719                 $opts = array();
1720
1721                 if ( in_array( 'LOW_PRIORITY', $options ) ) {
1722                         $opts[] = $this->lowPriorityOption();
1723                 }
1724
1725                 if ( in_array( 'IGNORE', $options ) ) {
1726                         $opts[] = 'IGNORE';
1727                 }
1728
1729                 return implode( ' ', $opts );
1730         }
1731
1732         /**
1733          * UPDATE wrapper. Takes a condition array and a SET array.
1734          *
1735          * @param $table  String name of the table to UPDATE. This will be passed through
1736          *                DatabaseBase::tableName().
1737          *
1738          * @param $values Array:  An array of values to SET. For each array element,
1739          *                the key gives the field name, and the value gives the data
1740          *                to set that field to. The data will be quoted by
1741          *                DatabaseBase::addQuotes().
1742          *
1743          * @param $conds  Array:  An array of conditions (WHERE). See
1744          *                DatabaseBase::select() for the details of the format of
1745          *                condition arrays. Use '*' to update all rows.
1746          *
1747          * @param $fname  String: The function name of the caller (from __METHOD__),
1748          *                for logging and profiling.
1749          *
1750          * @param $options Array: An array of UPDATE options, can be:
1751          *                   - IGNORE: Ignore unique key conflicts
1752          *                   - LOW_PRIORITY: MySQL-specific, see MySQL manual.
1753          * @return Boolean
1754          */
1755         function update( $table, $values, $conds, $fname = 'DatabaseBase::update', $options = array() ) {
1756                 $table = $this->tableName( $table );
1757                 $opts = $this->makeUpdateOptions( $options );
1758                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET );
1759
1760                 if ( $conds !== array() && $conds !== '*' ) {
1761                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1762                 }
1763
1764                 return $this->query( $sql, $fname );
1765         }
1766
1767         /**
1768          * Makes an encoded list of strings from an array
1769          * @param $a Array containing the data
1770          * @param $mode int Constant
1771          *      - LIST_COMMA:          comma separated, no field names
1772          *      - LIST_AND:            ANDed WHERE clause (without the WHERE). See
1773          *        the documentation for $conds in DatabaseBase::select().
1774          *      - LIST_OR:             ORed WHERE clause (without the WHERE)
1775          *      - LIST_SET:            comma separated with field names, like a SET clause
1776          *      - LIST_NAMES:          comma separated field names
1777          *
1778          * @return string
1779          */
1780         function makeList( $a, $mode = LIST_COMMA ) {
1781                 if ( !is_array( $a ) ) {
1782                         throw new DBUnexpectedError( $this, 'DatabaseBase::makeList called with incorrect parameters' );
1783                 }
1784
1785                 $first = true;
1786                 $list = '';
1787
1788                 foreach ( $a as $field => $value ) {
1789                         if ( !$first ) {
1790                                 if ( $mode == LIST_AND ) {
1791                                         $list .= ' AND ';
1792                                 } elseif ( $mode == LIST_OR ) {
1793                                         $list .= ' OR ';
1794                                 } else {
1795                                         $list .= ',';
1796                                 }
1797                         } else {
1798                                 $first = false;
1799                         }
1800
1801                         if ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_numeric( $field ) ) {
1802                                 $list .= "($value)";
1803                         } elseif ( ( $mode == LIST_SET ) && is_numeric( $field ) ) {
1804                                 $list .= "$value";
1805                         } elseif ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_array( $value ) ) {
1806                                 if ( count( $value ) == 0 ) {
1807                                         throw new MWException( __METHOD__ . ': empty input' );
1808                                 } elseif ( count( $value ) == 1 ) {
1809                                         // Special-case single values, as IN isn't terribly efficient
1810                                         // Don't necessarily assume the single key is 0; we don't
1811                                         // enforce linear numeric ordering on other arrays here.
1812                                         $value = array_values( $value );
1813                                         $list .= $field . " = " . $this->addQuotes( $value[0] );
1814                                 } else {
1815                                         $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1816                                 }
1817                         } elseif ( $value === null ) {
1818                                 if ( $mode == LIST_AND || $mode == LIST_OR ) {
1819                                         $list .= "$field IS ";
1820                                 } elseif ( $mode == LIST_SET ) {
1821                                         $list .= "$field = ";
1822                                 }
1823                                 $list .= 'NULL';
1824                         } else {
1825                                 if ( $mode == LIST_AND || $mode == LIST_OR || $mode == LIST_SET ) {
1826                                         $list .= "$field = ";
1827                                 }
1828                                 $list .= $mode == LIST_NAMES ? $value : $this->addQuotes( $value );
1829                         }
1830                 }
1831
1832                 return $list;
1833         }
1834
1835         /**
1836          * Build a partial where clause from a 2-d array such as used for LinkBatch.
1837          * The keys on each level may be either integers or strings.
1838          *
1839          * @param $data Array: organized as 2-d
1840          *              array(baseKeyVal => array(subKeyVal => <ignored>, ...), ...)
1841          * @param $baseKey String: field name to match the base-level keys to (eg 'pl_namespace')
1842          * @param $subKey String: field name to match the sub-level keys to (eg 'pl_title')
1843          * @return Mixed: string SQL fragment, or false if no items in array.
1844          */
1845         function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1846                 $conds = array();
1847
1848                 foreach ( $data as $base => $sub ) {
1849                         if ( count( $sub ) ) {
1850                                 $conds[] = $this->makeList(
1851                                         array( $baseKey => $base, $subKey => array_keys( $sub ) ),
1852                                         LIST_AND );
1853                         }
1854                 }
1855
1856                 if ( $conds ) {
1857                         return $this->makeList( $conds, LIST_OR );
1858                 } else {
1859                         // Nothing to search for...
1860                         return false;
1861                 }
1862         }
1863
1864         /**
1865          * Bitwise operations
1866          */
1867
1868         /**
1869          * @param $field
1870          * @return string
1871          */
1872         function bitNot( $field ) {
1873                 return "(~$field)";
1874         }
1875
1876         /**
1877          * @param $fieldLeft
1878          * @param $fieldRight
1879          * @return string
1880          */
1881         function bitAnd( $fieldLeft, $fieldRight ) {
1882                 return "($fieldLeft & $fieldRight)";
1883         }
1884
1885         /**
1886          * @param  $fieldLeft
1887          * @param  $fieldRight
1888          * @return string
1889          */
1890         function bitOr( $fieldLeft, $fieldRight ) {
1891                 return "($fieldLeft | $fieldRight)";
1892         }
1893
1894         /**
1895          * Change the current database
1896          *
1897          * @todo Explain what exactly will fail if this is not overridden.
1898          *
1899          * @param $db
1900          *
1901          * @return bool Success or failure
1902          */
1903         function selectDB( $db ) {
1904                 # Stub.  Shouldn't cause serious problems if it's not overridden, but
1905                 # if your database engine supports a concept similar to MySQL's
1906                 # databases you may as well.
1907                 $this->mDBname = $db;
1908                 return true;
1909         }
1910
1911         /**
1912          * Get the current DB name
1913          */
1914         function getDBname() {
1915                 return $this->mDBname;
1916         }
1917
1918         /**
1919          * Get the server hostname or IP address
1920          */
1921         function getServer() {
1922                 return $this->mServer;
1923         }
1924
1925         /**
1926          * Format a table name ready for use in constructing an SQL query
1927          *
1928          * This does two important things: it quotes the table names to clean them up,
1929          * and it adds a table prefix if only given a table name with no quotes.
1930          *
1931          * All functions of this object which require a table name call this function
1932          * themselves. Pass the canonical name to such functions. This is only needed
1933          * when calling query() directly.
1934          *
1935          * @param $name String: database table name
1936          * @param $format String One of:
1937          *   quoted - Automatically pass the table name through addIdentifierQuotes()
1938          *            so that it can be used in a query.
1939          *   raw - Do not add identifier quotes to the table name
1940          * @return String: full database name
1941          */
1942         function tableName( $name, $format = 'quoted' ) {
1943                 global $wgSharedDB, $wgSharedPrefix, $wgSharedTables;
1944                 # Skip the entire process when we have a string quoted on both ends.
1945                 # Note that we check the end so that we will still quote any use of
1946                 # use of `database`.table. But won't break things if someone wants
1947                 # to query a database table with a dot in the name.
1948                 if ( $this->isQuotedIdentifier( $name ) ) {
1949                         return $name;
1950                 }
1951
1952                 # Lets test for any bits of text that should never show up in a table
1953                 # name. Basically anything like JOIN or ON which are actually part of
1954                 # SQL queries, but may end up inside of the table value to combine
1955                 # sql. Such as how the API is doing.
1956                 # Note that we use a whitespace test rather than a \b test to avoid
1957                 # any remote case where a word like on may be inside of a table name
1958                 # surrounded by symbols which may be considered word breaks.
1959                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1960                         return $name;
1961                 }
1962
1963                 # Split database and table into proper variables.
1964                 # We reverse the explode so that database.table and table both output
1965                 # the correct table.
1966                 $dbDetails = array_reverse( explode( '.', $name, 2 ) );
1967                 if ( isset( $dbDetails[1] ) ) {
1968                         list( $table, $database ) = $dbDetails;
1969                 } else {
1970                         list( $table ) = $dbDetails;
1971                 }
1972                 $prefix = $this->mTablePrefix; # Default prefix
1973
1974                 # A database name has been specified in input. We don't want any
1975                 # prefixes added.
1976                 if ( isset( $database ) ) {
1977                         $prefix = '';
1978                 }
1979
1980                 # Note that we use the long format because php will complain in in_array if
1981                 # the input is not an array, and will complain in is_array if it is not set.
1982                 if ( !isset( $database ) # Don't use shared database if pre selected.
1983                  && isset( $wgSharedDB ) # We have a shared database
1984                  && !$this->isQuotedIdentifier( $table ) # Paranoia check to prevent shared tables listing '`table`'
1985                  && isset( $wgSharedTables )
1986                  && is_array( $wgSharedTables )
1987                  && in_array( $table, $wgSharedTables ) ) { # A shared table is selected
1988                         $database = $wgSharedDB;
1989                         $prefix   = isset( $wgSharedPrefix ) ? $wgSharedPrefix : $prefix;
1990                 }
1991
1992                 # Quote the $database and $table and apply the prefix if not quoted.
1993                 if ( isset( $database ) ) {
1994                         $database = ( $format == 'quoted' || $this->isQuotedIdentifier( $database ) ? $database : $this->addIdentifierQuotes( $database ) );
1995                 }
1996
1997                 $table = "{$prefix}{$table}";
1998                 if ( $format == 'quoted' && !$this->isQuotedIdentifier( $table ) ) {
1999                         $table = $this->addIdentifierQuotes( "{$table}" );
2000                 }
2001
2002                 # Merge our database and table into our final table name.
2003                 $tableName = ( isset( $database ) ? "{$database}.{$table}" : "{$table}" );
2004
2005                 return $tableName;
2006         }
2007
2008         /**
2009          * Fetch a number of table names into an array
2010          * This is handy when you need to construct SQL for joins
2011          *
2012          * Example:
2013          * extract($dbr->tableNames('user','watchlist'));
2014          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
2015          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
2016          *
2017          * @return array
2018          */
2019         public function tableNames() {
2020                 $inArray = func_get_args();
2021                 $retVal = array();
2022
2023                 foreach ( $inArray as $name ) {
2024                         $retVal[$name] = $this->tableName( $name );
2025                 }
2026
2027                 return $retVal;
2028         }
2029
2030         /**
2031          * Fetch a number of table names into an zero-indexed numerical array
2032          * This is handy when you need to construct SQL for joins
2033          *
2034          * Example:
2035          * list( $user, $watchlist ) = $dbr->tableNamesN('user','watchlist');
2036          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
2037          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
2038          *
2039          * @return array
2040          */
2041         public function tableNamesN() {
2042                 $inArray = func_get_args();
2043                 $retVal = array();
2044
2045                 foreach ( $inArray as $name ) {
2046                         $retVal[] = $this->tableName( $name );
2047                 }
2048
2049                 return $retVal;
2050         }
2051
2052         /**
2053          * Get an aliased table name
2054          * e.g. tableName AS newTableName
2055          *
2056          * @param $name string Table name, see tableName()
2057          * @param $alias string|bool Alias (optional)
2058          * @return string SQL name for aliased table. Will not alias a table to its own name
2059          */
2060         public function tableNameWithAlias( $name, $alias = false ) {
2061                 if ( !$alias || $alias == $name ) {
2062                         return $this->tableName( $name );
2063                 } else {
2064                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
2065                 }
2066         }
2067
2068         /**
2069          * Gets an array of aliased table names
2070          *
2071          * @param $tables array( [alias] => table )
2072          * @return array of strings, see tableNameWithAlias()
2073          */
2074         public function tableNamesWithAlias( $tables ) {
2075                 $retval = array();
2076                 foreach ( $tables as $alias => $table ) {
2077                         if ( is_numeric( $alias ) ) {
2078                                 $alias = $table;
2079                         }
2080                         $retval[] = $this->tableNameWithAlias( $table, $alias );
2081                 }
2082                 return $retval;
2083         }
2084
2085         /**
2086          * Get the aliased table name clause for a FROM clause
2087          * which might have a JOIN and/or USE INDEX clause
2088          *
2089          * @param $tables array ( [alias] => table )
2090          * @param $use_index array Same as for select()
2091          * @param $join_conds array Same as for select()
2092          * @return string
2093          */
2094         protected function tableNamesWithUseIndexOrJOIN(
2095                 $tables, $use_index = array(), $join_conds = array()
2096         ) {
2097                 $ret = array();
2098                 $retJOIN = array();
2099                 $use_index = (array)$use_index;
2100                 $join_conds = (array)$join_conds;
2101
2102                 foreach ( $tables as $alias => $table ) {
2103                         if ( !is_string( $alias ) ) {
2104                                 // No alias? Set it equal to the table name
2105                                 $alias = $table;
2106                         }
2107                         // Is there a JOIN clause for this table?
2108                         if ( isset( $join_conds[$alias] ) ) {
2109                                 list( $joinType, $conds ) = $join_conds[$alias];
2110                                 $tableClause = $joinType;
2111                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
2112                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2113                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2114                                         if ( $use != '' ) {
2115                                                 $tableClause .= ' ' . $use;
2116                                         }
2117                                 }
2118                                 $on = $this->makeList( (array)$conds, LIST_AND );
2119                                 if ( $on != '' ) {
2120                                         $tableClause .= ' ON (' . $on . ')';
2121                                 }
2122
2123                                 $retJOIN[] = $tableClause;
2124                         // Is there an INDEX clause for this table?
2125                         } elseif ( isset( $use_index[$alias] ) ) {
2126                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2127                                 $tableClause .= ' ' . $this->useIndexClause(
2128                                         implode( ',', (array)$use_index[$alias] ) );
2129
2130                                 $ret[] = $tableClause;
2131                         } else {
2132                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2133
2134                                 $ret[] = $tableClause;
2135                         }
2136                 }
2137
2138                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2139                 $straightJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
2140                 $otherJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
2141
2142                 // Compile our final table clause
2143                 return implode( ' ', array( $straightJoins, $otherJoins ) );
2144         }
2145
2146         /**
2147          * Get the name of an index in a given table
2148          *
2149          * @param $index
2150          *
2151          * @return string
2152          */
2153         function indexName( $index ) {
2154                 // Backwards-compatibility hack
2155                 $renamed = array(
2156                         'ar_usertext_timestamp' => 'usertext_timestamp',
2157                         'un_user_id'            => 'user_id',
2158                         'un_user_ip'            => 'user_ip',
2159                 );
2160
2161                 if ( isset( $renamed[$index] ) ) {
2162                         return $renamed[$index];
2163                 } else {
2164                         return $index;
2165                 }
2166         }
2167
2168         /**
2169          * If it's a string, adds quotes and backslashes
2170          * Otherwise returns as-is
2171          *
2172          * @param $s string
2173          *
2174          * @return string
2175          */
2176         function addQuotes( $s ) {
2177                 if ( $s === null ) {
2178                         return 'NULL';
2179                 } else {
2180                         # This will also quote numeric values. This should be harmless,
2181                         # and protects against weird problems that occur when they really
2182                         # _are_ strings such as article titles and string->number->string
2183                         # conversion is not 1:1.
2184                         return "'" . $this->strencode( $s ) . "'";
2185                 }
2186         }
2187
2188         /**
2189          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
2190          * MySQL uses `backticks` while basically everything else uses double quotes.
2191          * Since MySQL is the odd one out here the double quotes are our generic
2192          * and we implement backticks in DatabaseMysql.
2193          *
2194          * @param $s string
2195          *
2196          * @return string
2197          */
2198         public function addIdentifierQuotes( $s ) {
2199                 return '"' . str_replace( '"', '""', $s ) . '"';
2200         }
2201
2202         /**
2203          * Returns if the given identifier looks quoted or not according to
2204          * the database convention for quoting identifiers .
2205          *
2206          * @param $name string
2207          *
2208          * @return boolean
2209          */
2210         public function isQuotedIdentifier( $name ) {
2211                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2212         }
2213
2214         /**
2215          * Backwards compatibility, identifier quoting originated in DatabasePostgres
2216          * which used quote_ident which does not follow our naming conventions
2217          * was renamed to addIdentifierQuotes.
2218          * @deprecated since 1.18 use addIdentifierQuotes
2219          *
2220          * @param $s string
2221          *
2222          * @return string
2223          */
2224         function quote_ident( $s ) {
2225                 wfDeprecated( __METHOD__, '1.18' );
2226                 return $this->addIdentifierQuotes( $s );
2227         }
2228
2229         /**
2230          * Escape string for safe LIKE usage.
2231          * WARNING: you should almost never use this function directly,
2232          * instead use buildLike() that escapes everything automatically
2233          * @deprecated since 1.17, warnings in 1.17, removed in ???
2234          *
2235          * @param $s string
2236          *
2237          * @return string
2238          */
2239         public function escapeLike( $s ) {
2240                 wfDeprecated( __METHOD__, '1.17' );
2241                 return $this->escapeLikeInternal( $s );
2242         }
2243
2244         /**
2245          * @param $s string
2246          * @return string
2247          */
2248         protected function escapeLikeInternal( $s ) {
2249                 $s = str_replace( '\\', '\\\\', $s );
2250                 $s = $this->strencode( $s );
2251                 $s = str_replace( array( '%', '_' ), array( '\%', '\_' ), $s );
2252
2253                 return $s;
2254         }
2255
2256         /**
2257          * LIKE statement wrapper, receives a variable-length argument list with parts of pattern to match
2258          * containing either string literals that will be escaped or tokens returned by anyChar() or anyString().
2259          * Alternatively, the function could be provided with an array of aforementioned parameters.
2260          *
2261          * Example: $dbr->buildLike( 'My_page_title/', $dbr->anyString() ) returns a LIKE clause that searches
2262          * for subpages of 'My page title'.
2263          * Alternatively: $pattern = array( 'My_page_title/', $dbr->anyString() ); $query .= $dbr->buildLike( $pattern );
2264          *
2265          * @since 1.16
2266          * @return String: fully built LIKE statement
2267          */
2268         function buildLike() {
2269                 $params = func_get_args();
2270
2271                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2272                         $params = $params[0];
2273                 }
2274
2275                 $s = '';
2276
2277                 foreach ( $params as $value ) {
2278                         if ( $value instanceof LikeMatch ) {
2279                                 $s .= $value->toString();
2280                         } else {
2281                                 $s .= $this->escapeLikeInternal( $value );
2282                         }
2283                 }
2284
2285                 return " LIKE '" . $s . "' ";
2286         }
2287
2288         /**
2289          * Returns a token for buildLike() that denotes a '_' to be used in a LIKE query
2290          *
2291          * @return LikeMatch
2292          */
2293         function anyChar() {
2294                 return new LikeMatch( '_' );
2295         }
2296
2297         /**
2298          * Returns a token for buildLike() that denotes a '%' to be used in a LIKE query
2299          *
2300          * @return LikeMatch
2301          */
2302         function anyString() {
2303                 return new LikeMatch( '%' );
2304         }
2305
2306         /**
2307          * Returns an appropriately quoted sequence value for inserting a new row.
2308          * MySQL has autoincrement fields, so this is just NULL. But the PostgreSQL
2309          * subclass will return an integer, and save the value for insertId()
2310          *
2311          * Any implementation of this function should *not* involve reusing
2312          * sequence numbers created for rolled-back transactions.
2313          * See http://bugs.mysql.com/bug.php?id=30767 for details.
2314          * @param $seqName string
2315          * @return null
2316          */
2317         function nextSequenceValue( $seqName ) {
2318                 return null;
2319         }
2320
2321         /**
2322          * USE INDEX clause.  Unlikely to be useful for anything but MySQL.  This
2323          * is only needed because a) MySQL must be as efficient as possible due to
2324          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2325          * which index to pick.  Anyway, other databases might have different
2326          * indexes on a given table.  So don't bother overriding this unless you're
2327          * MySQL.
2328          * @param $index
2329          * @return string
2330          */
2331         function useIndexClause( $index ) {
2332                 return '';
2333         }
2334
2335         /**
2336          * REPLACE query wrapper.
2337          *
2338          * REPLACE is a very handy MySQL extension, which functions like an INSERT
2339          * except that when there is a duplicate key error, the old row is deleted
2340          * and the new row is inserted in its place.
2341          *
2342          * We simulate this with standard SQL with a DELETE followed by INSERT. To
2343          * perform the delete, we need to know what the unique indexes are so that
2344          * we know how to find the conflicting rows.
2345          *
2346          * It may be more efficient to leave off unique indexes which are unlikely
2347          * to collide. However if you do this, you run the risk of encountering
2348          * errors which wouldn't have occurred in MySQL.
2349          *
2350          * @param $table String: The table to replace the row(s) in.
2351          * @param $rows array Can be either a single row to insert, or multiple rows,
2352          *    in the same format as for DatabaseBase::insert()
2353          * @param $uniqueIndexes array is an array of indexes. Each element may be either
2354          *    a field name or an array of field names
2355          * @param $fname String: Calling function name (use __METHOD__) for logs/profiling
2356          */
2357         function replace( $table, $uniqueIndexes, $rows, $fname = 'DatabaseBase::replace' ) {
2358                 $quotedTable = $this->tableName( $table );
2359
2360                 if ( count( $rows ) == 0 ) {
2361                         return;
2362                 }
2363
2364                 # Single row case
2365                 if ( !is_array( reset( $rows ) ) ) {
2366                         $rows = array( $rows );
2367                 }
2368
2369                 foreach( $rows as $row ) {
2370                         # Delete rows which collide
2371                         if ( $uniqueIndexes ) {
2372                                 $sql = "DELETE FROM $quotedTable WHERE ";
2373                                 $first = true;
2374                                 foreach ( $uniqueIndexes as $index ) {
2375                                         if ( $first ) {
2376                                                 $first = false;
2377                                                 $sql .= '( ';
2378                                         } else {
2379                                                 $sql .= ' ) OR ( ';
2380                                         }
2381                                         if ( is_array( $index ) ) {
2382                                                 $first2 = true;
2383                                                 foreach ( $index as $col ) {
2384                                                         if ( $first2 ) {
2385                                                                 $first2 = false;
2386                                                         } else {
2387                                                                 $sql .= ' AND ';
2388                                                         }
2389                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2390                                                 }
2391                                         } else {
2392                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2393                                         }
2394                                 }
2395                                 $sql .= ' )';
2396                                 $this->query( $sql, $fname );
2397                         }
2398
2399                         # Now insert the row
2400                         $this->insert( $table, $row );
2401                 }
2402         }
2403
2404         /**
2405          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2406          * statement.
2407          *
2408          * @param $table string Table name
2409          * @param $rows array Rows to insert
2410          * @param $fname string Caller function name
2411          *
2412          * @return ResultWrapper
2413          */
2414         protected function nativeReplace( $table, $rows, $fname ) {
2415                 $table = $this->tableName( $table );
2416
2417                 # Single row case
2418                 if ( !is_array( reset( $rows ) ) ) {
2419                         $rows = array( $rows );
2420                 }
2421
2422                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2423                 $first = true;
2424
2425                 foreach ( $rows as $row ) {
2426                         if ( $first ) {
2427                                 $first = false;
2428                         } else {
2429                                 $sql .= ',';
2430                         }
2431
2432                         $sql .= '(' . $this->makeList( $row ) . ')';
2433                 }
2434
2435                 return $this->query( $sql, $fname );
2436         }
2437
2438         /**
2439          * DELETE where the condition is a join.
2440          *
2441          * MySQL overrides this to use a multi-table DELETE syntax, in other databases
2442          * we use sub-selects
2443          *
2444          * For safety, an empty $conds will not delete everything. If you want to
2445          * delete all rows where the join condition matches, set $conds='*'.
2446          *
2447          * DO NOT put the join condition in $conds.
2448          *
2449          * @param $delTable   String: The table to delete from.
2450          * @param $joinTable  String: The other table.
2451          * @param $delVar     String: The variable to join on, in the first table.
2452          * @param $joinVar    String: The variable to join on, in the second table.
2453          * @param $conds      Array: Condition array of field names mapped to variables,
2454          *                    ANDed together in the WHERE clause
2455          * @param $fname      String: Calling function name (use __METHOD__) for
2456          *                    logs/profiling
2457          */
2458         function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2459                 $fname = 'DatabaseBase::deleteJoin' )
2460         {
2461                 if ( !$conds ) {
2462                         throw new DBUnexpectedError( $this,
2463                                 'DatabaseBase::deleteJoin() called with empty $conds' );
2464                 }
2465
2466                 $delTable = $this->tableName( $delTable );
2467                 $joinTable = $this->tableName( $joinTable );
2468                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2469                 if ( $conds != '*' ) {
2470                         $sql .= 'WHERE ' . $this->makeList( $conds, LIST_AND );
2471                 }
2472                 $sql .= ')';
2473
2474                 $this->query( $sql, $fname );
2475         }
2476
2477         /**
2478          * Returns the size of a text field, or -1 for "unlimited"
2479          *
2480          * @param $table string
2481          * @param $field string
2482          *
2483          * @return int
2484          */
2485         function textFieldSize( $table, $field ) {
2486                 $table = $this->tableName( $table );
2487                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2488                 $res = $this->query( $sql, 'DatabaseBase::textFieldSize' );
2489                 $row = $this->fetchObject( $res );
2490
2491                 $m = array();
2492
2493                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2494                         $size = $m[1];
2495                 } else {
2496                         $size = -1;
2497                 }
2498
2499                 return $size;
2500         }
2501
2502         /**
2503          * A string to insert into queries to show that they're low-priority, like
2504          * MySQL's LOW_PRIORITY.  If no such feature exists, return an empty
2505          * string and nothing bad should happen.
2506          *
2507          * @return string Returns the text of the low priority option if it is
2508          *   supported, or a blank string otherwise
2509          */
2510         function lowPriorityOption() {
2511                 return '';
2512         }
2513
2514         /**
2515          * DELETE query wrapper.
2516          *
2517          * @param $table Array Table name
2518          * @param $conds String|Array of conditions. See $conds in DatabaseBase::select() for
2519          *               the format. Use $conds == "*" to delete all rows
2520          * @param $fname String name of the calling function
2521          *
2522          * @return bool
2523          */
2524         function delete( $table, $conds, $fname = 'DatabaseBase::delete' ) {
2525                 if ( !$conds ) {
2526                         throw new DBUnexpectedError( $this, 'DatabaseBase::delete() called with no conditions' );
2527                 }
2528
2529                 $table = $this->tableName( $table );
2530                 $sql = "DELETE FROM $table";
2531
2532                 if ( $conds != '*' ) {
2533                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
2534                 }
2535
2536                 return $this->query( $sql, $fname );
2537         }
2538
2539         /**
2540          * INSERT SELECT wrapper. Takes data from a SELECT query and inserts it
2541          * into another table.
2542          *
2543          * @param $destTable string The table name to insert into
2544          * @param $srcTable string|array May be either a table name, or an array of table names
2545          *    to include in a join.
2546          *
2547          * @param $varMap array must be an associative array of the form
2548          *    array( 'dest1' => 'source1', ...). Source items may be literals
2549          *    rather than field names, but strings should be quoted with
2550          *    DatabaseBase::addQuotes()
2551          *
2552          * @param $conds array Condition array. See $conds in DatabaseBase::select() for
2553          *    the details of the format of condition arrays. May be "*" to copy the
2554          *    whole table.
2555          *
2556          * @param $fname string The function name of the caller, from __METHOD__
2557          *
2558          * @param $insertOptions array Options for the INSERT part of the query, see
2559          *    DatabaseBase::insert() for details.
2560          * @param $selectOptions array Options for the SELECT part of the query, see
2561          *    DatabaseBase::select() for details.
2562          *
2563          * @return ResultWrapper
2564          */
2565         function insertSelect( $destTable, $srcTable, $varMap, $conds,
2566                 $fname = 'DatabaseBase::insertSelect',
2567                 $insertOptions = array(), $selectOptions = array() )
2568         {
2569                 $destTable = $this->tableName( $destTable );
2570
2571                 if ( is_array( $insertOptions ) ) {
2572                         $insertOptions = implode( ' ', $insertOptions );
2573                 }
2574
2575                 if ( !is_array( $selectOptions ) ) {
2576                         $selectOptions = array( $selectOptions );
2577                 }
2578
2579                 list( $startOpts, $useIndex, $tailOpts ) = $this->makeSelectOptions( $selectOptions );
2580
2581                 if ( is_array( $srcTable ) ) {
2582                         $srcTable =  implode( ',', array_map( array( &$this, 'tableName' ), $srcTable ) );
2583                 } else {
2584                         $srcTable = $this->tableName( $srcTable );
2585                 }
2586
2587                 $sql = "INSERT $insertOptions INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2588                         " SELECT $startOpts " . implode( ',', $varMap ) .
2589                         " FROM $srcTable $useIndex ";
2590
2591                 if ( $conds != '*' ) {
2592                         if ( is_array( $conds ) ) {
2593                                 $conds = $this->makeList( $conds, LIST_AND );
2594                         }
2595                         $sql .= " WHERE $conds";
2596                 }
2597
2598                 $sql .= " $tailOpts";
2599
2600                 return $this->query( $sql, $fname );
2601         }
2602
2603         /**
2604          * Construct a LIMIT query with optional offset.  This is used for query
2605          * pages.  The SQL should be adjusted so that only the first $limit rows
2606          * are returned.  If $offset is provided as well, then the first $offset
2607          * rows should be discarded, and the next $limit rows should be returned.
2608          * If the result of the query is not ordered, then the rows to be returned
2609          * are theoretically arbitrary.
2610          *
2611          * $sql is expected to be a SELECT, if that makes a difference.  For
2612          * UPDATE, limitResultForUpdate should be used.
2613          *
2614          * The version provided by default works in MySQL and SQLite.  It will very
2615          * likely need to be overridden for most other DBMSes.
2616          *
2617          * @param $sql String SQL query we will append the limit too
2618          * @param $limit Integer the SQL limit
2619          * @param $offset Integer|bool the SQL offset (default false)
2620          *
2621          * @return string
2622          */
2623         function limitResult( $sql, $limit, $offset = false ) {
2624                 if ( !is_numeric( $limit ) ) {
2625                         throw new DBUnexpectedError( $this, "Invalid non-numeric limit passed to limitResult()\n" );
2626                 }
2627
2628                 return "$sql LIMIT "
2629                                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2630                                 . "{$limit} ";
2631         }
2632
2633         /**
2634          * @param $sql
2635          * @param $num
2636          * @return string
2637          */
2638         function limitResultForUpdate( $sql, $num ) {
2639                 return $this->limitResult( $sql, $num, 0 );
2640         }
2641
2642         /**
2643          * Returns true if current database backend supports ORDER BY or LIMIT for separate subqueries
2644          * within the UNION construct.
2645          * @return Boolean
2646          */
2647         function unionSupportsOrderAndLimit() {
2648                 return true; // True for almost every DB supported
2649         }
2650
2651         /**
2652          * Construct a UNION query
2653          * This is used for providing overload point for other DB abstractions
2654          * not compatible with the MySQL syntax.
2655          * @param $sqls Array: SQL statements to combine
2656          * @param $all Boolean: use UNION ALL
2657          * @return String: SQL fragment
2658          */
2659         function unionQueries( $sqls, $all ) {
2660                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2661                 return '(' . implode( $glue, $sqls ) . ')';
2662         }
2663
2664         /**
2665          * Returns an SQL expression for a simple conditional.  This doesn't need
2666          * to be overridden unless CASE isn't supported in your DBMS.
2667          *
2668          * @param $cond String: SQL expression which will result in a boolean value
2669          * @param $trueVal String: SQL expression to return if true
2670          * @param $falseVal String: SQL expression to return if false
2671          * @return String: SQL fragment
2672          */
2673         function conditional( $cond, $trueVal, $falseVal ) {
2674                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2675         }
2676
2677         /**
2678          * Returns a comand for str_replace function in SQL query.
2679          * Uses REPLACE() in MySQL
2680          *
2681          * @param $orig String: column to modify
2682          * @param $old String: column to seek
2683          * @param $new String: column to replace with
2684          *
2685          * @return string
2686          */
2687         function strreplace( $orig, $old, $new ) {
2688                 return "REPLACE({$orig}, {$old}, {$new})";
2689         }
2690
2691         /**
2692          * Determines how long the server has been up
2693          * STUB
2694          *
2695          * @return int
2696          */
2697         function getServerUptime() {
2698                 return 0;
2699         }
2700
2701         /**
2702          * Determines if the last failure was due to a deadlock
2703          * STUB
2704          *
2705          * @return bool
2706          */
2707         function wasDeadlock() {
2708                 return false;
2709         }
2710
2711         /**
2712          * Determines if the last failure was due to a lock timeout
2713          * STUB
2714          *
2715          * @return bool
2716          */
2717         function wasLockTimeout() {
2718                 return false;
2719         }
2720
2721         /**
2722          * Determines if the last query error was something that should be dealt
2723          * with by pinging the connection and reissuing the query.
2724          * STUB
2725          *
2726          * @return bool
2727          */
2728         function wasErrorReissuable() {
2729                 return false;
2730         }
2731
2732         /**
2733          * Determines if the last failure was due to the database being read-only.
2734          * STUB
2735          *
2736          * @return bool
2737          */
2738         function wasReadOnlyError() {
2739                 return false;
2740         }
2741
2742         /**
2743          * Perform a deadlock-prone transaction.
2744          *
2745          * This function invokes a callback function to perform a set of write
2746          * queries. If a deadlock occurs during the processing, the transaction
2747          * will be rolled back and the callback function will be called again.
2748          *
2749          * Usage:
2750          *   $dbw->deadlockLoop( callback, ... );
2751          *
2752          * Extra arguments are passed through to the specified callback function.
2753          *
2754          * Returns whatever the callback function returned on its successful,
2755          * iteration, or false on error, for example if the retry limit was
2756          * reached.
2757          *
2758          * @return bool
2759          */
2760         function deadlockLoop() {
2761
2762                 $this->begin( __METHOD__ );
2763                 $args = func_get_args();
2764                 $function = array_shift( $args );
2765                 $oldIgnore = $this->ignoreErrors( true );
2766                 $tries = DEADLOCK_TRIES;
2767
2768                 if ( is_array( $function ) ) {
2769                         $fname = $function[0];
2770                 } else {
2771                         $fname = $function;
2772                 }
2773
2774                 do {
2775                         $retVal = call_user_func_array( $function, $args );
2776                         $error = $this->lastError();
2777                         $errno = $this->lastErrno();
2778                         $sql = $this->lastQuery();
2779
2780                         if ( $errno ) {
2781                                 if ( $this->wasDeadlock() ) {
2782                                         # Retry
2783                                         usleep( mt_rand( DEADLOCK_DELAY_MIN, DEADLOCK_DELAY_MAX ) );
2784                                 } else {
2785                                         $this->reportQueryError( $error, $errno, $sql, $fname );
2786                                 }
2787                         }
2788                 } while ( $this->wasDeadlock() && --$tries > 0 );
2789
2790                 $this->ignoreErrors( $oldIgnore );
2791
2792                 if ( $tries <= 0 ) {
2793                         $this->rollback( __METHOD__ );
2794                         $this->reportQueryError( $error, $errno, $sql, $fname );
2795                         return false;
2796                 } else {
2797                         $this->commit( __METHOD__ );
2798                         return $retVal;
2799                 }
2800         }
2801
2802         /**
2803          * Wait for the slave to catch up to a given master position.
2804          *
2805          * @param $pos DBMasterPos object
2806          * @param $timeout Integer: the maximum number of seconds to wait for
2807          *   synchronisation
2808          *
2809          * @return integer: zero if the slave was past that position already,
2810          *   greater than zero if we waited for some period of time, less than
2811          *   zero if we timed out.
2812          */
2813         function masterPosWait( DBMasterPos $pos, $timeout ) {
2814                 wfProfileIn( __METHOD__ );
2815
2816                 if ( !is_null( $this->mFakeSlaveLag ) ) {
2817                         $wait = intval( ( $pos->pos - microtime( true ) + $this->mFakeSlaveLag ) * 1e6 );
2818
2819                         if ( $wait > $timeout * 1e6 ) {
2820                                 wfDebug( "Fake slave timed out waiting for $pos ($wait us)\n" );
2821                                 wfProfileOut( __METHOD__ );
2822                                 return -1;
2823                         } elseif ( $wait > 0 ) {
2824                                 wfDebug( "Fake slave waiting $wait us\n" );
2825                                 usleep( $wait );
2826                                 wfProfileOut( __METHOD__ );
2827                                 return 1;
2828                         } else {
2829                                 wfDebug( "Fake slave up to date ($wait us)\n" );
2830                                 wfProfileOut( __METHOD__ );
2831                                 return 0;
2832                         }
2833                 }
2834
2835                 wfProfileOut( __METHOD__ );
2836
2837                 # Real waits are implemented in the subclass.
2838                 return 0;
2839         }
2840
2841         /**
2842          * Get the replication position of this slave
2843          *
2844          * @return DBMasterPos, or false if this is not a slave.
2845          */
2846         function getSlavePos() {
2847                 if ( !is_null( $this->mFakeSlaveLag ) ) {
2848                         $pos = new MySQLMasterPos( 'fake', microtime( true ) - $this->mFakeSlaveLag );
2849                         wfDebug( __METHOD__ . ": fake slave pos = $pos\n" );
2850                         return $pos;
2851                 } else {
2852                         # Stub
2853                         return false;
2854                 }
2855         }
2856
2857         /**
2858          * Get the position of this master
2859          *
2860          * @return DBMasterPos, or false if this is not a master
2861          */
2862         function getMasterPos() {
2863                 if ( $this->mFakeMaster ) {
2864                         return new MySQLMasterPos( 'fake', microtime( true ) );
2865                 } else {
2866                         return false;
2867                 }
2868         }
2869
2870         /**
2871          * Begin a transaction, committing any previously open transaction
2872          *
2873          * @param $fname string
2874          */
2875         function begin( $fname = 'DatabaseBase::begin' ) {
2876                 $this->query( 'BEGIN', $fname );
2877                 $this->mTrxLevel = 1;
2878         }
2879
2880         /**
2881          * End a transaction
2882          *
2883          * @param $fname string
2884          */
2885         function commit( $fname = 'DatabaseBase::commit' ) {
2886                 if ( $this->mTrxLevel ) {
2887                         $this->query( 'COMMIT', $fname );
2888                         $this->mTrxLevel = 0;
2889                 }
2890         }
2891
2892         /**
2893          * Rollback a transaction.
2894          * No-op on non-transactional databases.
2895          *
2896          * @param $fname string
2897          */
2898         function rollback( $fname = 'DatabaseBase::rollback' ) {
2899                 if ( $this->mTrxLevel ) {
2900                         $this->query( 'ROLLBACK', $fname, true );
2901                         $this->mTrxLevel = 0;
2902                 }
2903         }
2904
2905         /**
2906          * Creates a new table with structure copied from existing table
2907          * Note that unlike most database abstraction functions, this function does not
2908          * automatically append database prefix, because it works at a lower
2909          * abstraction level.
2910          * The table names passed to this function shall not be quoted (this
2911          * function calls addIdentifierQuotes when needed).
2912          *
2913          * @param $oldName String: name of table whose structure should be copied
2914          * @param $newName String: name of table to be created
2915          * @param $temporary Boolean: whether the new table should be temporary
2916          * @param $fname String: calling function name
2917          * @return Boolean: true if operation was successful
2918          */
2919         function duplicateTableStructure( $oldName, $newName, $temporary = false,
2920                 $fname = 'DatabaseBase::duplicateTableStructure' )
2921         {
2922                 throw new MWException(
2923                         'DatabaseBase::duplicateTableStructure is not implemented in descendant class' );
2924         }
2925
2926         /**
2927          * List all tables on the database
2928          *
2929          * @param $prefix string Only show tables with this prefix, e.g. mw_
2930          * @param $fname String: calling function name
2931          */
2932         function listTables( $prefix = null, $fname = 'DatabaseBase::listTables' ) {
2933                 throw new MWException( 'DatabaseBase::listTables is not implemented in descendant class' );
2934         }
2935
2936         /**
2937          * Convert a timestamp in one of the formats accepted by wfTimestamp()
2938          * to the format used for inserting into timestamp fields in this DBMS.
2939          *
2940          * The result is unquoted, and needs to be passed through addQuotes()
2941          * before it can be included in raw SQL.
2942          *
2943          * @param $ts string|int
2944          *
2945          * @return string
2946          */
2947         function timestamp( $ts = 0 ) {
2948                 return wfTimestamp( TS_MW, $ts );
2949         }
2950
2951         /**
2952          * Convert a timestamp in one of the formats accepted by wfTimestamp()
2953          * to the format used for inserting into timestamp fields in this DBMS. If
2954          * NULL is input, it is passed through, allowing NULL values to be inserted
2955          * into timestamp fields.
2956          *
2957          * The result is unquoted, and needs to be passed through addQuotes()
2958          * before it can be included in raw SQL.
2959          *
2960          * @param $ts string|int
2961          *
2962          * @return string
2963          */
2964         function timestampOrNull( $ts = null ) {
2965                 if ( is_null( $ts ) ) {
2966                         return null;
2967                 } else {
2968                         return $this->timestamp( $ts );
2969                 }
2970         }
2971
2972         /**
2973          * Take the result from a query, and wrap it in a ResultWrapper if
2974          * necessary. Boolean values are passed through as is, to indicate success
2975          * of write queries or failure.
2976          *
2977          * Once upon a time, DatabaseBase::query() returned a bare MySQL result
2978          * resource, and it was necessary to call this function to convert it to
2979          * a wrapper. Nowadays, raw database objects are never exposed to external
2980          * callers, so this is unnecessary in external code. For compatibility with
2981          * old code, ResultWrapper objects are passed through unaltered.
2982          *
2983          * @param $result bool|ResultWrapper
2984          *
2985          * @return bool|ResultWrapper
2986          */
2987         function resultObject( $result ) {
2988                 if ( empty( $result ) ) {
2989                         return false;
2990                 } elseif ( $result instanceof ResultWrapper ) {
2991                         return $result;
2992                 } elseif ( $result === true ) {
2993                         // Successful write query
2994                         return $result;
2995                 } else {
2996                         return new ResultWrapper( $this, $result );
2997                 }
2998         }
2999
3000         /**
3001          * Return aggregated value alias
3002          *
3003          * @param $valuedata
3004          * @param $valuename string
3005          *
3006          * @return string
3007          */
3008         function aggregateValue ( $valuedata, $valuename = 'value' ) {
3009                 return $valuename;
3010         }
3011
3012         /**
3013          * Ping the server and try to reconnect if it there is no connection
3014          *
3015          * @return bool Success or failure
3016          */
3017         function ping() {
3018                 # Stub.  Not essential to override.
3019                 return true;
3020         }
3021
3022         /**
3023          * Get slave lag. Currently supported only by MySQL.
3024          *
3025          * Note that this function will generate a fatal error on many
3026          * installations. Most callers should use LoadBalancer::safeGetLag()
3027          * instead.
3028          *
3029          * @return int Database replication lag in seconds
3030          */
3031         function getLag() {
3032                 return intval( $this->mFakeSlaveLag );
3033         }
3034
3035         /**
3036          * Return the maximum number of items allowed in a list, or 0 for unlimited.
3037          *
3038          * @return int
3039          */
3040         function maxListLen() {
3041                 return 0;
3042         }
3043
3044         /**
3045          * Some DBMSs have a special format for inserting into blob fields, they
3046          * don't allow simple quoted strings to be inserted. To insert into such
3047          * a field, pass the data through this function before passing it to
3048          * DatabaseBase::insert().
3049          * @param $b string
3050          * @return string
3051          */
3052         function encodeBlob( $b ) {
3053                 return $b;
3054         }
3055
3056         /**
3057          * Some DBMSs return a special placeholder object representing blob fields
3058          * in result objects. Pass the object through this function to return the
3059          * original string.
3060          * @param $b string
3061          * @return string
3062          */
3063         function decodeBlob( $b ) {
3064                 return $b;
3065         }
3066
3067         /**
3068          * Override database's default connection timeout
3069          *
3070          * @param $timeout Integer in seconds
3071          * @return void
3072          * @deprecated since 1.19; use setSessionOptions()
3073          */
3074         public function setTimeout( $timeout ) {
3075                 wfDeprecated( __METHOD__, '1.19' );
3076                 $this->setSessionOptions( array( 'connTimeout' => $timeout ) );
3077         }
3078
3079         /**
3080          * Override database's default behavior. $options include:
3081          *     'connTimeout' : Set the connection timeout value in seconds.
3082          *                     May be useful for very long batch queries such as
3083          *                     full-wiki dumps, where a single query reads out over
3084          *                     hours or days.
3085          *
3086          * @param $options Array
3087          * @return void
3088          */
3089         public function setSessionOptions( array $options ) {}
3090
3091         /**
3092          * Read and execute SQL commands from a file.
3093          *
3094          * Returns true on success, error string or exception on failure (depending
3095          * on object's error ignore settings).
3096          *
3097          * @param $filename String: File name to open
3098          * @param $lineCallback Callback: Optional function called before reading each line
3099          * @param $resultCallback Callback: Optional function called for each MySQL result
3100          * @param $fname String: Calling function name or false if name should be
3101          *      generated dynamically using $filename
3102          * @return bool|string
3103          */
3104         function sourceFile( $filename, $lineCallback = false, $resultCallback = false, $fname = false ) {
3105                 wfSuppressWarnings();
3106                 $fp = fopen( $filename, 'r' );
3107                 wfRestoreWarnings();
3108
3109                 if ( false === $fp ) {
3110                         throw new MWException( "Could not open \"{$filename}\".\n" );
3111                 }
3112
3113                 if ( !$fname ) {
3114                         $fname = __METHOD__ . "( $filename )";
3115                 }
3116
3117                 try {
3118                         $error = $this->sourceStream( $fp, $lineCallback, $resultCallback, $fname );
3119                 }
3120                 catch ( MWException $e ) {
3121                         fclose( $fp );
3122                         throw $e;
3123                 }
3124
3125                 fclose( $fp );
3126
3127                 return $error;
3128         }
3129
3130         /**
3131          * Get the full path of a patch file. Originally based on archive()
3132          * from updaters.inc. Keep in mind this always returns a patch, as
3133          * it fails back to MySQL if no DB-specific patch can be found
3134          *
3135          * @param $patch String The name of the patch, like patch-something.sql
3136          * @return String Full path to patch file
3137          */
3138         public function patchPath( $patch ) {
3139                 global $IP;
3140
3141                 $dbType = $this->getType();
3142                 if ( file_exists( "$IP/maintenance/$dbType/archives/$patch" ) ) {
3143                         return "$IP/maintenance/$dbType/archives/$patch";
3144                 } else {
3145                         return "$IP/maintenance/archives/$patch";
3146                 }
3147         }
3148
3149         /**
3150          * Set variables to be used in sourceFile/sourceStream, in preference to the
3151          * ones in $GLOBALS. If an array is set here, $GLOBALS will not be used at
3152          * all. If it's set to false, $GLOBALS will be used.
3153          *
3154          * @param $vars bool|array mapping variable name to value.
3155          */
3156         function setSchemaVars( $vars ) {
3157                 $this->mSchemaVars = $vars;
3158         }
3159
3160         /**
3161          * Read and execute commands from an open file handle.
3162          *
3163          * Returns true on success, error string or exception on failure (depending
3164          * on object's error ignore settings).
3165          *
3166          * @param $fp Resource: File handle
3167          * @param $lineCallback Callback: Optional function called before reading each line
3168          * @param $resultCallback Callback: Optional function called for each MySQL result
3169          * @param $fname String: Calling function name
3170          * @param $inputCallback Callback: Optional function called for each complete line (ended with ;) sent
3171          * @return bool|string
3172          */
3173         public function sourceStream( $fp, $lineCallback = false, $resultCallback = false,
3174                 $fname = 'DatabaseBase::sourceStream', $inputCallback = false )
3175         {
3176                 $cmd = '';
3177
3178                 while ( !feof( $fp ) ) {
3179                         if ( $lineCallback ) {
3180                                 call_user_func( $lineCallback );
3181                         }
3182
3183                         $line = trim( fgets( $fp ) );
3184
3185                         if ( $line == '' ) {
3186                                 continue;
3187                         }
3188
3189                         if ( '-' == $line[0] && '-' == $line[1] ) {
3190                                 continue;
3191                         }
3192
3193                         if ( $cmd != '' ) {
3194                                 $cmd .= ' ';
3195                         }
3196
3197                         $done = $this->streamStatementEnd( $cmd, $line );
3198
3199                         $cmd .= "$line\n";
3200
3201                         if ( $done || feof( $fp ) ) {
3202                                 $cmd = $this->replaceVars( $cmd );
3203                                 if ( $inputCallback ) {
3204                                         call_user_func( $inputCallback, $cmd );
3205                                 }
3206                                 $res = $this->query( $cmd, $fname );
3207
3208                                 if ( $resultCallback ) {
3209                                         call_user_func( $resultCallback, $res, $this );
3210                                 }
3211
3212                                 if ( false === $res ) {
3213                                         $err = $this->lastError();
3214                                         return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3215                                 }
3216
3217                                 $cmd = '';
3218                         }
3219                 }
3220
3221                 return true;
3222         }
3223
3224         /**
3225          * Called by sourceStream() to check if we've reached a statement end
3226          *
3227          * @param $sql String SQL assembled so far
3228          * @param $newLine String New line about to be added to $sql
3229          * @return Bool Whether $newLine contains end of the statement
3230          */
3231         public function streamStatementEnd( &$sql, &$newLine ) {
3232                 if ( $this->delimiter ) {
3233                         $prev = $newLine;
3234                         $newLine = preg_replace( '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3235                         if ( $newLine != $prev ) {
3236                                 return true;
3237                         }
3238                 }
3239                 return false;
3240         }
3241
3242         /**
3243          * Database independent variable replacement. Replaces a set of variables
3244          * in an SQL statement with their contents as given by $this->getSchemaVars().
3245          *
3246          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3247          *
3248          * - '{$var}' should be used for text and is passed through the database's
3249          *   addQuotes method.
3250          * - `{$var}` should be used for identifiers (eg: table and database names),
3251          *   it is passed through the database's addIdentifierQuotes method which
3252          *   can be overridden if the database uses something other than backticks.
3253          * - / *$var* / is just encoded, besides traditional table prefix and
3254          *   table options its use should be avoided.
3255          *
3256          * @param $ins String: SQL statement to replace variables in
3257          * @return String The new SQL statement with variables replaced
3258          */
3259         protected function replaceSchemaVars( $ins ) {
3260                 $vars = $this->getSchemaVars();
3261                 foreach ( $vars as $var => $value ) {
3262                         // replace '{$var}'
3263                         $ins = str_replace( '\'{$' . $var . '}\'', $this->addQuotes( $value ), $ins );
3264                         // replace `{$var}`
3265                         $ins = str_replace( '`{$' . $var . '}`', $this->addIdentifierQuotes( $value ), $ins );
3266                         // replace /*$var*/
3267                         $ins = str_replace( '/*$' . $var . '*/', $this->strencode( $value ) , $ins );
3268                 }
3269                 return $ins;
3270         }
3271
3272         /**
3273          * Replace variables in sourced SQL
3274          *
3275          * @param $ins string
3276          *
3277          * @return string
3278          */
3279         protected function replaceVars( $ins ) {
3280                 $ins = $this->replaceSchemaVars( $ins );
3281
3282                 // Table prefixes
3283                 $ins = preg_replace_callback( '!/\*(?:\$wgDBprefix|_)\*/([a-zA-Z_0-9]*)!',
3284                         array( $this, 'tableNameCallback' ), $ins );
3285
3286                 // Index names
3287                 $ins = preg_replace_callback( '!/\*i\*/([a-zA-Z_0-9]*)!',
3288                         array( $this, 'indexNameCallback' ), $ins );
3289
3290                 return $ins;
3291         }
3292
3293         /**
3294          * Get schema variables. If none have been set via setSchemaVars(), then
3295          * use some defaults from the current object.
3296          *
3297          * @return array
3298          */
3299         protected function getSchemaVars() {
3300                 if ( $this->mSchemaVars ) {
3301                         return $this->mSchemaVars;
3302                 } else {
3303                         return $this->getDefaultSchemaVars();
3304                 }
3305         }
3306
3307         /**
3308          * Get schema variables to use if none have been set via setSchemaVars().
3309          *
3310          * Override this in derived classes to provide variables for tables.sql
3311          * and SQL patch files.
3312          *
3313          * @return array
3314          */
3315         protected function getDefaultSchemaVars() {
3316                 return array();
3317         }
3318
3319         /**
3320          * Table name callback
3321          *
3322          * @param $matches array
3323          *
3324          * @return string
3325          */
3326         protected function tableNameCallback( $matches ) {
3327                 return $this->tableName( $matches[1] );
3328         }
3329
3330         /**
3331          * Index name callback
3332          *
3333          * @param $matches array
3334          *
3335          * @return string
3336          */
3337         protected function indexNameCallback( $matches ) {
3338                 return $this->indexName( $matches[1] );
3339         }
3340
3341         /**
3342          * Build a concatenation list to feed into a SQL query
3343          * @param $stringList Array: list of raw SQL expressions; caller is responsible for any quoting
3344          * @return String
3345          */
3346         function buildConcat( $stringList ) {
3347                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
3348         }
3349
3350         /**
3351          * Acquire a named lock
3352          *
3353          * Abstracted from Filestore::lock() so child classes can implement for
3354          * their own needs.
3355          *
3356          * @param $lockName String: name of lock to aquire
3357          * @param $method String: name of method calling us
3358          * @param $timeout Integer: timeout
3359          * @return Boolean
3360          */
3361         public function lock( $lockName, $method, $timeout = 5 ) {
3362                 return true;
3363         }
3364
3365         /**
3366          * Release a lock.
3367          *
3368          * @param $lockName String: Name of lock to release
3369          * @param $method String: Name of method calling us
3370          *
3371          * @return int Returns 1 if the lock was released, 0 if the lock was not established
3372          * by this thread (in which case the lock is not released), and NULL if the named
3373          * lock did not exist
3374          */
3375         public function unlock( $lockName, $method ) {
3376                 return true;
3377         }
3378
3379         /**
3380          * Lock specific tables
3381          *
3382          * @param $read Array of tables to lock for read access
3383          * @param $write Array of tables to lock for write access
3384          * @param $method String name of caller
3385          * @param $lowPriority bool Whether to indicate writes to be LOW PRIORITY
3386          *
3387          * @return bool
3388          */
3389         public function lockTables( $read, $write, $method, $lowPriority = true ) {
3390                 return true;
3391         }
3392
3393         /**
3394          * Unlock specific tables
3395          *
3396          * @param $method String the caller
3397          *
3398          * @return bool
3399          */
3400         public function unlockTables( $method ) {
3401                 return true;
3402         }
3403
3404         /**
3405          * Delete a table
3406          * @param $tableName string
3407          * @param $fName string
3408          * @return bool|ResultWrapper
3409          * @since 1.18
3410          */
3411         public function dropTable( $tableName, $fName = 'DatabaseBase::dropTable' ) {
3412                 if( !$this->tableExists( $tableName, $fName ) ) {
3413                         return false;
3414                 }
3415                 $sql = "DROP TABLE " . $this->tableName( $tableName );
3416                 if( $this->cascadingDeletes() ) {
3417                         $sql .= " CASCADE";
3418                 }
3419                 return $this->query( $sql, $fName );
3420         }
3421
3422         /**
3423          * Get search engine class. All subclasses of this need to implement this
3424          * if they wish to use searching.
3425          *
3426          * @return String
3427          */
3428         public function getSearchEngine() {
3429                 return 'SearchEngineDummy';
3430         }
3431
3432         /**
3433          * Find out when 'infinity' is. Most DBMSes support this. This is a special
3434          * keyword for timestamps in PostgreSQL, and works with CHAR(14) as well
3435          * because "i" sorts after all numbers.
3436          *
3437          * @return String
3438          */
3439         public function getInfinity() {
3440                 return 'infinity';
3441         }
3442
3443         /**
3444          * Encode an expiry time into the DBMS dependent format
3445          *
3446          * @param $expiry String: timestamp for expiry, or the 'infinity' string
3447          * @return String
3448          */
3449         public function encodeExpiry( $expiry ) {
3450                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
3451                         ? $this->getInfinity()
3452                         : $this->timestamp( $expiry );
3453         }
3454
3455         /**
3456          * Decode an expiry time into a DBMS independent format
3457          *
3458          * @param $expiry String: DB timestamp field value for expiry
3459          * @param $format integer: TS_* constant, defaults to TS_MW
3460          * @return String
3461          */
3462         public function decodeExpiry( $expiry, $format = TS_MW ) {
3463                 return ( $expiry == '' || $expiry == $this->getInfinity() )
3464                         ? 'infinity'
3465                         : wfTimestamp( $format, $expiry );
3466         }
3467
3468         /**
3469          * Allow or deny "big selects" for this session only. This is done by setting
3470          * the sql_big_selects session variable.
3471          *
3472          * This is a MySQL-specific feature.
3473          *
3474          * @param $value Mixed: true for allow, false for deny, or "default" to
3475          *   restore the initial value
3476          */
3477         public function setBigSelects( $value = true ) {
3478                 // no-op
3479         }
3480 }