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 SQL result 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 # ------------------------------------------------------------------------------
 228 # Accessors
 229 # ------------------------------------------------------------------------------
 230         # These optionally set a variable and return the previous state
 231
 232         /**
 233          * A string describing the current software version, and possibly
 234          * other details in a user-friendly way.  Will be listed on Special:Version, etc.
 235          * Use getServerVersion() to get machine-friendly information.
 236          *
 237          * @return string: Version information from the database server
 238          */
 239         public function getServerInfo() {
 240                 return $this->getServerVersion();
 241         }
 242
 243         /**
 244          * Boolean, controls output of large amounts of debug information.
 245          * @param $debug bool|null
 246          *   - true to enable debugging
 247          *   - false to disable debugging
 248          *   - omitted or null to do nothing
 249          *
 250          * @return The previous value of the flag
 251          */
 252         function debug( $debug = null ) {
 253                 return wfSetBit( $this->mFlags, DBO_DEBUG, $debug );
 254         }
 255
 256         /**
 257          * Turns buffering of SQL result sets on (true) or off (false). Default is
 258          * "on".
 259          *
 260          * Unbuffered queries are very troublesome in MySQL:
 261          *
 262          *   - If another query is executed while the first query is being read
 263          *     out, the first query is killed. This means you can't call normal
 264          *     MediaWiki functions while you are reading an unbuffered query result
 265          *     from a normal wfGetDB() connection.
 266          *
 267          *   - Unbuffered queries cause the MySQL server to use large amounts of
 268          *     memory and to hold broad locks which block other queries.
 269          *
 270          * If you want to limit client-side memory, it's almost always better to
 271          * split up queries into batches using a LIMIT clause than to switch off
 272          * buffering.
 273          *
 274          * @param $buffer null|bool
 275          *
 276          * @return The previous value of the flag
 277          */
 278         function bufferResults( $buffer = null ) {
 279                 if ( is_null( $buffer ) ) {
 280                         return !(bool)( $this->mFlags & DBO_NOBUFFER );
 281                 } else {
 282                         return !wfSetBit( $this->mFlags, DBO_NOBUFFER, !$buffer );
 283                 }
 284         }
 285
 286         /**
 287          * Turns on (false) or off (true) the automatic generation and sending
 288          * of a "we're sorry, but there has been a database error" page on
 289          * database errors. Default is on (false). When turned off, the
 290          * code should use lastErrno() and lastError() to handle the
 291          * situation as appropriate.
 292          *
 293          * @param $ignoreErrors
 294          *
 295          * @return The previous value of the flag.
 296          */
 297         function ignoreErrors( $ignoreErrors = null ) {
 298                 return wfSetBit( $this->mFlags, DBO_IGNORE, $ignoreErrors );
 299         }
 300
 301         /**
 302          * Gets or sets the current transaction level.
 303          *
 304          * Historically, transactions were allowed to be "nested". This is no
 305          * longer supported, so this function really only returns a boolean.
 306          *
 307          * @param $level An integer (0 or 1), or omitted to leave it unchanged.
 308          * @return The previous value
 309          */
 310         function trxLevel( $level = null ) {
 311                 return wfSetVar( $this->mTrxLevel, $level );
 312         }
 313
 314         /**
 315          * Get/set the number of errors logged. Only useful when errors are ignored
 316          * @param $count The count to set, or omitted to leave it unchanged.
 317          * @return The error count
 318          */
 319         function errorCount( $count = null ) {
 320                 return wfSetVar( $this->mErrorCount, $count );
 321         }
 322
 323         /**
 324          * Get/set the table prefix.
 325          * @param $prefix The table prefix to set, or omitted to leave it unchanged.
 326          * @return The previous table prefix.
 327          */
 328         function tablePrefix( $prefix = null ) {
 329                 return wfSetVar( $this->mTablePrefix, $prefix );
 330         }
 331
 332         /**
 333          * Get properties passed down from the server info array of the load
 334          * balancer.
 335          *
 336          * @param $name string The entry of the info array to get, or null to get the
 337          *   whole array
 338          *
 339          * @return LoadBalancer|null
 340          */
 341         function getLBInfo( $name = null ) {
 342                 if ( is_null( $name ) ) {
 343                         return $this->mLBInfo;
 344                 } else {
 345                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 346                                 return $this->mLBInfo[$name];
 347                         } else {
 348                                 return null;
 349                         }
 350                 }
 351         }
 352
 353         /**
 354          * Set the LB info array, or a member of it. If called with one parameter,
 355          * the LB info array is set to that parameter. If it is called with two
 356          * parameters, the member with the given name is set to the given value.
 357          *
 358          * @param $name
 359          * @param $value
 360          */
 361         function setLBInfo( $name, $value = null ) {
 362                 if ( is_null( $value ) ) {
 363                         $this->mLBInfo = $name;
 364                 } else {
 365                         $this->mLBInfo[$name] = $value;
 366                 }
 367         }
 368
 369         /**
 370          * Set lag time in seconds for a fake slave
 371          *
 372          * @param $lag int
 373          */
 374         function setFakeSlaveLag( $lag ) {
 375                 $this->mFakeSlaveLag = $lag;
 376         }
 377
 378         /**
 379          * Make this connection a fake master
 380          *
 381          * @param $enabled bool
 382          */
 383         function setFakeMaster( $enabled = true ) {
 384                 $this->mFakeMaster = $enabled;
 385         }
 386
 387         /**
 388          * Returns true if this database supports (and uses) cascading deletes
 389          *
 390          * @return bool
 391          */
 392         function cascadingDeletes() {
 393                 return false;
 394         }
 395
 396         /**
 397          * Returns true if this database supports (and uses) triggers (e.g. on the page table)
 398          *
 399          * @return bool
 400          */
 401         function cleanupTriggers() {
 402                 return false;
 403         }
 404
 405         /**
 406          * Returns true if this database is strict about what can be put into an IP field.
 407          * Specifically, it uses a NULL value instead of an empty string.
 408          *
 409          * @return bool
 410          */
 411         function strictIPs() {
 412                 return false;
 413         }
 414
 415         /**
 416          * Returns true if this database uses timestamps rather than integers
 417          *
 418          * @return bool
 419         */
 420         function realTimestamps() {
 421                 return false;
 422         }
 423
 424         /**
 425          * Returns true if this database does an implicit sort when doing GROUP BY
 426          *
 427          * @return bool
 428          */
 429         function implicitGroupby() {
 430                 return true;
 431         }
 432
 433         /**
 434          * Returns true if this database does an implicit order by when the column has an index
 435          * For example: SELECT page_title FROM page LIMIT 1
 436          */
 437         function implicitOrderby() {
 438                 return true;
 439         }
 440
 441         /**
 442          * Returns true if this database requires that SELECT DISTINCT queries require that all
 443            ORDER BY expressions occur in the SELECT list per the SQL92 standard
 444          *
 445          * @return bool
 446          */
 447         function standardSelectDistinct() {
 448                 return true;
 449         }
 450
 451         /**
 452          * Returns true if this database can do a native search on IP columns
 453          * e.g. this works as expected: .. WHERE rc_ip = '127.42.12.102/32';
 454          *
 455          * @return bool
 456          */
 457         function searchableIPs() {
 458                 return false;
 459         }
 460
 461         /**
 462          * Returns true if this database can use functional indexes
 463          *
 464          * @return bool
 465          */
 466         function functionalIndexes() {
 467                 return false;
 468         }
 469
 470         /**
 471          * Return the last query that went through DatabaseBase::query()
 472          * @return String
 473          */
 474         function lastQuery() {
 475                 return $this->mLastQuery;
 476         }
 477
 478         /**
 479          * Returns true if the connection may have been used for write queries.
 480          * Should return true if unsure.
 481          *
 482          * @return bool
 483          */
 484         function doneWrites() {
 485                 return $this->mDoneWrites;
 486         }
 487
 488         /**
 489          * Is a connection to the database open?
 490          * @return Boolean
 491          */
 492         function isOpen() {
 493                 return $this->mOpened;
 494         }
 495
 496         /**
 497          * Set a flag for this connection
 498          *
 499          * @param $flag Integer: DBO_* constants from Defines.php:
 500          *   - DBO_DEBUG: output some debug info (same as debug())
 501          *   - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
 502          *   - DBO_IGNORE: ignore errors (same as ignoreErrors())
 503          *   - DBO_TRX: automatically start transactions
 504          *   - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
 505          *       and removes it in command line mode
 506          *   - DBO_PERSISTENT: use persistant database connection
 507          */
 508         function setFlag( $flag ) {
 509                 $this->mFlags |= $flag;
 510         }
 511
 512         /**
 513          * Clear a flag for this connection
 514          *
 515          * @param $flag: same as setFlag()'s $flag param
 516          */
 517         function clearFlag( $flag ) {
 518                 $this->mFlags &= ~$flag;
 519         }
 520
 521         /**
 522          * Returns a boolean whether the flag $flag is set for this connection
 523          *
 524          * @param $flag: same as setFlag()'s $flag param
 525          * @return Boolean
 526          */
 527         function getFlag( $flag ) {
 528                 return !!( $this->mFlags & $flag );
 529         }
 530
 531         /**
 532          * General read-only accessor
 533          */
 534         function getProperty( $name ) {
 535                 return $this->$name;
 536         }
 537
 538         /**
 539          * @return string
 540          */
 541         function getWikiID() {
 542                 if ( $this->mTablePrefix ) {
 543                         return "{$this->mDBname}-{$this->mTablePrefix}";
 544                 } else {
 545                         return $this->mDBname;
 546                 }
 547         }
 548
 549         /**
 550          * Return a path to the DBMS-specific schema file, otherwise default to tables.sql
 551          *
 552          * @return string
 553          */
 554         public function getSchemaPath() {
 555                 global $IP;
 556                 if ( file_exists( "$IP/maintenance/" . $this->getType() . "/tables.sql" ) ) {
 557                         return "$IP/maintenance/" . $this->getType() . "/tables.sql";
 558                 } else {
 559                         return "$IP/maintenance/tables.sql";
 560                 }
 561         }
 562
 563 # ------------------------------------------------------------------------------
 564 # Other functions
 565 # ------------------------------------------------------------------------------
 566
 567         /**
 568          * Constructor.
 569          * @param $server String: database server host
 570          * @param $user String: database user name
 571          * @param $password String: database user password
 572          * @param $dbName String: database name
 573          * @param $flags
 574          * @param $tablePrefix String: database table prefixes. By default use the prefix gave in LocalSettings.php
 575          */
 576         function __construct( $server = false, $user = false, $password = false, $dbName = false,
 577                 $flags = 0, $tablePrefix = 'get from global'
 578         ) {
 579                 global $wgDBprefix, $wgCommandLineMode;
 580
 581                 $this->mFlags = $flags;
 582
 583                 if ( $this->mFlags & DBO_DEFAULT ) {
 584                         if ( $wgCommandLineMode ) {
 585                                 $this->mFlags &= ~DBO_TRX;
 586                         } else {
 587                                 $this->mFlags |= DBO_TRX;
 588                         }
 589                 }
 590
 591                 /** Get the default table prefix*/
 592                 if ( $tablePrefix == 'get from global' ) {
 593                         $this->mTablePrefix = $wgDBprefix;
 594                 } else {
 595                         $this->mTablePrefix = $tablePrefix;
 596                 }
 597
 598                 if ( $user ) {
 599                         $this->open( $server, $user, $password, $dbName );
 600                 }
 601         }
 602
 603         /**
 604          * Same as new DatabaseMysql( ... ), kept for backward compatibility
 605          * @deprecated since 1.17
 606          *
 607          * @return DatabaseMysql
 608          */
 609         static function newFromParams( $server, $user, $password, $dbName, $flags = 0 ) {
 610                 wfDeprecated( __METHOD__ );
 611                 return new DatabaseMysql( $server, $user, $password, $dbName, $flags );
 612         }
 613
 614         /**
 615          * Given a DB type, construct the name of the appropriate child class of
 616          * DatabaseBase. This is designed to replace all of the manual stuff like:
 617          *      $class = 'Database' . ucfirst( strtolower( $type ) );
 618          * as well as validate against the canonical list of DB types we have
 619          *
 620          * This factory function is mostly useful for when you need to connect to a
 621          * database other than the MediaWiki default (such as for external auth,
 622          * an extension, et cetera). Do not use this to connect to the MediaWiki
 623          * database. Example uses in core:
 624          * @see LoadBalancer::reallyOpenConnection()
 625          * @see ExternalUser_MediaWiki::initFromCond()
 626          * @see ForeignDBRepo::getMasterDB()
 627          * @see WebInstaller_DBConnect::execute()
 628          *
 629          * @param $dbType String A possible DB type
 630          * @param $p Array An array of options to pass to the constructor.
 631          *    Valid options are: host, user, password, dbname, flags, tablePrefix
 632          * @return DatabaseBase subclass or null
 633          */
 634         public final static function factory( $dbType, $p = array() ) {
 635                 $canonicalDBTypes = array(
 636                         'mysql', 'postgres', 'sqlite', 'oracle', 'mssql', 'ibm_db2'
 637                 );
 638                 $dbType = strtolower( $dbType );
 639
 640                 if( in_array( $dbType, $canonicalDBTypes ) ) {
 641                         $class = 'Database' . ucfirst( $dbType );
 642                         return new $class(
 643                                 isset( $p['host'] ) ? $p['host'] : false,
 644                                 isset( $p['user'] ) ? $p['user'] : false,
 645                                 isset( $p['password'] ) ? $p['password'] : false,
 646                                 isset( $p['dbname'] ) ? $p['dbname'] : false,
 647                                 isset( $p['flags'] ) ? $p['flags'] : 0,
 648                                 isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : 'get from global'
 649                         );
 650                 } else {
 651                         return null;
 652                 }
 653         }
 654
 655         protected function installErrorHandler() {
 656                 $this->mPHPError = false;
 657                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 658                 set_error_handler( array( $this, 'connectionErrorHandler' ) );
 659         }
 660
 661         /**
 662          * @return bool|string
 663          */
 664         protected function restoreErrorHandler() {
 665                 restore_error_handler();
 666                 if ( $this->htmlErrors !== false ) {
 667                         ini_set( 'html_errors', $this->htmlErrors );
 668                 }
 669                 if ( $this->mPHPError ) {
 670                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 671                         $error = preg_replace( '!^.*?:(.*)$!', '$1', $error );
 672                         return $error;
 673                 } else {
 674                         return false;
 675                 }
 676         }
 677
 678         protected function connectionErrorHandler( $errno,  $errstr ) {
 679                 $this->mPHPError = $errstr;
 680         }
 681
 682         /**
 683          * Closes a database connection.
 684          * if it is open : commits any open transactions
 685          *
 686          * @return Bool operation success. true if already closed.
 687          */
 688         function close() {
 689                 # Stub, should probably be overridden
 690                 return true;
 691         }
 692
 693         /**
 694          * @param $error String: fallback error message, used if none is given by DB
 695          */
 696         function reportConnectionError( $error = 'Unknown error' ) {
 697                 $myError = $this->lastError();
 698                 if ( $myError ) {
 699                         $error = $myError;
 700                 }
 701
 702                 # New method
 703                 throw new DBConnectionError( $this, $error );
 704         }
 705
 706         /**
 707          * The DBMS-dependent part of query()
 708          *
 709          * @param  $sql String: SQL query.
 710          * @return Result object to feed to fetchObject, fetchRow, ...; or false on failure
 711          */
 712         protected abstract function doQuery( $sql );
 713
 714         /**
 715          * Determine whether a query writes to the DB.
 716          * Should return true if unsure.
 717          *
 718          * @param $sql string
 719          *
 720          * @return bool
 721          */
 722         function isWriteQuery( $sql ) {
 723                 return !preg_match( '/^(?:SELECT|BEGIN|COMMIT|SET|SHOW|\(SELECT)\b/i', $sql );
 724         }
 725
 726         /**
 727          * Run an SQL query and return the result. Normally throws a DBQueryError
 728          * on failure. If errors are ignored, returns false instead.
 729          *
 730          * In new code, the query wrappers select(), insert(), update(), delete(),
 731          * etc. should be used where possible, since they give much better DBMS
 732          * independence and automatically quote or validate user input in a variety
 733          * of contexts. This function is generally only useful for queries which are
 734          * explicitly DBMS-dependent and are unsupported by the query wrappers, such
 735          * as CREATE TABLE.
 736          *
 737          * However, the query wrappers themselves should call this function.
 738          *
 739          * @param  $sql        String: SQL query
 740          * @param  $fname      String: Name of the calling function, for profiling/SHOW PROCESSLIST
 741          *     comment (you can use __METHOD__ or add some extra info)
 742          * @param  $tempIgnore Boolean:   Whether to avoid throwing an exception on errors...
 743          *     maybe best to catch the exception instead?
 744          * @return boolean|ResultWrapper. true for a successful write query, ResultWrapper object
 745          *     for a successful read query, or false on failure if $tempIgnore set
 746          * @throws DBQueryError Thrown when the database returns an error of any kind
 747          */
 748         public function query( $sql, $fname = '', $tempIgnore = false ) {
 749                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 750                 if ( !Profiler::instance()->isStub() ) {
 751                         # generalizeSQL will probably cut down the query to reasonable
 752                         # logging size most of the time. The substr is really just a sanity check.
 753
 754                         if ( $isMaster ) {
 755                                 $queryProf = 'query-m: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
 756                                 $totalProf = 'DatabaseBase::query-master';
 757                         } else {
 758                                 $queryProf = 'query: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
 759                                 $totalProf = 'DatabaseBase::query';
 760                         }
 761
 762                         wfProfileIn( $totalProf );
 763                         wfProfileIn( $queryProf );
 764                 }
 765
 766                 $this->mLastQuery = $sql;
 767                 if ( !$this->mDoneWrites && $this->isWriteQuery( $sql ) ) {
 768                         # Set a flag indicating that writes have been done
 769                         wfDebug( __METHOD__ . ": Writes done: $sql\n" );
 770                         $this->mDoneWrites = true;
 771                 }
 772
 773                 # Add a comment for easy SHOW PROCESSLIST interpretation
 774                 global $wgUser;
 775                 if ( is_object( $wgUser ) && $wgUser->isItemLoaded( 'name' ) ) {
 776                         $userName = $wgUser->getName();
 777                         if ( mb_strlen( $userName ) > 15 ) {
 778                                 $userName = mb_substr( $userName, 0, 15 ) . '...';
 779                         }
 780                         $userName = str_replace( '/', '', $userName );
 781                 } else {
 782                         $userName = '';
 783                 }
 784                 $commentedSql = preg_replace( '/\s/', " /* $fname $userName */ ", $sql, 1 );
 785
 786                 # If DBO_TRX is set, start a transaction
 787                 if ( ( $this->mFlags & DBO_TRX ) && !$this->trxLevel() &&
 788                         $sql != 'BEGIN' && $sql != 'COMMIT' && $sql != 'ROLLBACK' ) {
 789                         # avoid establishing transactions for SHOW and SET statements too -
 790                         # that would delay transaction initializations to once connection
 791                         # is really used by application
 792                         $sqlstart = substr( $sql, 0, 10 ); // very much worth it, benchmark certified(tm)
 793                         if ( strpos( $sqlstart, "SHOW " ) !== 0 and strpos( $sqlstart, "SET " ) !== 0 )
 794                                 $this->begin();
 795                 }
 796
 797                 if ( $this->debug() ) {
 798                         static $cnt = 0;
 799
 800                         $cnt++;
 801                         $sqlx = substr( $commentedSql, 0, 500 );
 802                         $sqlx = strtr( $sqlx, "\t\n", '  ' );
 803
 804                         if ( $isMaster ) {
 805                                 wfDebug( "Query $cnt (master): $sqlx\n" );
 806                         } else {
 807                                 wfDebug( "Query $cnt (slave): $sqlx\n" );
 808                         }
 809                 }
 810
 811                 if ( istainted( $sql ) & TC_MYSQL ) {
 812                         throw new MWException( 'Tainted query found' );
 813                 }
 814
 815                 # Do the query and handle errors
 816                 $ret = $this->doQuery( $commentedSql );
 817
 818                 # Try reconnecting if the connection was lost
 819                 if ( false === $ret && $this->wasErrorReissuable() ) {
 820                         # Transaction is gone, like it or not
 821                         $this->mTrxLevel = 0;
 822                         wfDebug( "Connection lost, reconnecting...\n" );
 823
 824                         if ( $this->ping() ) {
 825                                 wfDebug( "Reconnected\n" );
 826                                 $sqlx = substr( $commentedSql, 0, 500 );
 827                                 $sqlx = strtr( $sqlx, "\t\n", '  ' );
 828                                 global $wgRequestTime;
 829                                 $elapsed = round( microtime( true ) - $wgRequestTime, 3 );
 830                                 if ( $elapsed < 300 ) {
 831                                         # Not a database error to lose a transaction after a minute or two
 832                                         wfLogDBError( "Connection lost and reconnected after {$elapsed}s, query: $sqlx\n" );
 833                                 }
 834                                 $ret = $this->doQuery( $commentedSql );
 835                         } else {
 836                                 wfDebug( "Failed\n" );
 837                         }
 838                 }
 839
 840                 if ( false === $ret ) {
 841                         $this->reportQueryError( $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 842                 }
 843
 844                 if ( !Profiler::instance()->isStub() ) {
 845                         wfProfileOut( $queryProf );
 846                         wfProfileOut( $totalProf );
 847                 }
 848
 849                 return $this->resultObject( $ret );
 850         }
 851
 852         /**
 853          * Report a query error. Log the error, and if neither the object ignore
 854          * flag nor the $tempIgnore flag is set, throw a DBQueryError.
 855          *
 856          * @param $error String
 857          * @param $errno Integer
 858          * @param $sql String
 859          * @param $fname String
 860          * @param $tempIgnore Boolean
 861          */
 862         function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
 863                 # Ignore errors during error handling to avoid infinite recursion
 864                 $ignore = $this->ignoreErrors( true );
 865                 ++$this->mErrorCount;
 866
 867                 if ( $ignore || $tempIgnore ) {
 868                         wfDebug( "SQL ERROR (ignored): $error\n" );
 869                         $this->ignoreErrors( $ignore );
 870                 } else {
 871                         $sql1line = str_replace( "\n", "\\n", $sql );
 872                         wfLogDBError( "$fname\t{$this->mServer}\t$errno\t$error\t$sql1line\n" );
 873                         wfDebug( "SQL ERROR: " . $error . "\n" );
 874                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
 875                 }
 876         }
 877
 878         /**
 879          * Intended to be compatible with the PEAR::DB wrapper functions.
 880          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
 881          *
 882          * ? = scalar value, quoted as necessary
 883          * ! = raw SQL bit (a function for instance)
 884          * & = filename; reads the file and inserts as a blob
 885          *     (we don't use this though...)
 886          *
 887          * This function should not be used directly by new code outside of the
 888          * database classes. The query wrapper functions (select() etc.) should be
 889          * used instead.
 890          *
 891          * @param $sql string
 892          * @param $func string
 893          *
 894          * @return array
 895          */
 896         function prepare( $sql, $func = 'DatabaseBase::prepare' ) {
 897                 /* MySQL doesn't support prepared statements (yet), so just
 898                    pack up the query for reference. We'll manually replace
 899                    the bits later. */
 900                 return array( 'query' => $sql, 'func' => $func );
 901         }
 902
 903         /**
 904          * Free a prepared query, generated by prepare().
 905          */
 906         function freePrepared( $prepared ) {
 907                 /* No-op by default */
 908         }
 909
 910         /**
 911          * Execute a prepared query with the various arguments
 912          * @param $prepared String: the prepared sql
 913          * @param $args Mixed: Either an array here, or put scalars as varargs
 914          *
 915          * @return ResultWrapper
 916          */
 917         function execute( $prepared, $args = null ) {
 918                 if ( !is_array( $args ) ) {
 919                         # Pull the var args
 920                         $args = func_get_args();
 921                         array_shift( $args );
 922                 }
 923
 924                 $sql = $this->fillPrepared( $prepared['query'], $args );
 925
 926                 return $this->query( $sql, $prepared['func'] );
 927         }
 928
 929         /**
 930          * Prepare & execute an SQL statement, quoting and inserting arguments
 931          * in the appropriate places.
 932          *
 933          * This function should not be used directly by new code outside of the
 934          * database classes. The query wrapper functions (select() etc.) should be
 935          * used instead.
 936          *
 937          * @param $query String
 938          * @param $args ...
 939          *
 940          * @return ResultWrapper
 941          */
 942         function safeQuery( $query, $args = null ) {
 943                 $prepared = $this->prepare( $query, 'DatabaseBase::safeQuery' );
 944
 945                 if ( !is_array( $args ) ) {
 946                         # Pull the var args
 947                         $args = func_get_args();
 948                         array_shift( $args );
 949                 }
 950
 951                 $retval = $this->execute( $prepared, $args );
 952                 $this->freePrepared( $prepared );
 953
 954                 return $retval;
 955         }
 956
 957         /**
 958          * For faking prepared SQL statements on DBs that don't support
 959          * it directly.
 960          * @param $preparedQuery String: a 'preparable' SQL statement
 961          * @param $args Array of arguments to fill it with
 962          * @return string executable SQL
 963          */
 964         function fillPrepared( $preparedQuery, $args ) {
 965                 reset( $args );
 966                 $this->preparedArgs =& $args;
 967
 968                 return preg_replace_callback( '/(\\\\[?!&]|[?!&])/',
 969                         array( &$this, 'fillPreparedArg' ), $preparedQuery );
 970         }
 971
 972         /**
 973          * preg_callback func for fillPrepared()
 974          * The arguments should be in $this->preparedArgs and must not be touched
 975          * while we're doing this.
 976          *
 977          * @param $matches Array
 978          * @return String
 979          */
 980         function fillPreparedArg( $matches ) {
 981                 switch( $matches[1] ) {
 982                         case '\\?': return '?';
 983                         case '\\!': return '!';
 984                         case '\\&': return '&';
 985                 }
 986
 987                 list( /* $n */ , $arg ) = each( $this->preparedArgs );
 988
 989                 switch( $matches[1] ) {
 990                         case '?': return $this->addQuotes( $arg );
 991                         case '!': return $arg;
 992                         case '&':
 993                                 # return $this->addQuotes( file_get_contents( $arg ) );
 994                                 throw new DBUnexpectedError( $this, '& mode is not implemented. If it\'s really needed, uncomment the line above.' );
 995                         default:
 996                                 throw new DBUnexpectedError( $this, 'Received invalid match. This should never happen!' );
 997                 }
 998         }
 999
1000         /**
1001          * Free a result object returned by query() or select(). It's usually not
1002          * necessary to call this, just use unset() or let the variable holding
1003          * the result object go out of scope.
1004          *
1005          * @param $res Mixed: A SQL result
1006          */
1007         function freeResult( $res ) {
1008         }
1009
1010         /**
1011          * Simple UPDATE wrapper.
1012          * Usually throws a DBQueryError on failure.
1013          * If errors are explicitly ignored, returns success
1014          *
1015          * This function exists for historical reasons, DatabaseBase::update() has a more standard
1016          * calling convention and feature set
1017          *
1018          * @param $table string
1019          * @param $var
1020          * @param $value
1021          * @param $cond
1022          * @param $fname string
1023          *
1024          * @return bool
1025          */
1026         function set( $table, $var, $value, $cond, $fname = 'DatabaseBase::set' ) {
1027                 $table = $this->tableName( $table );
1028                 $sql = "UPDATE $table SET $var = '" .
1029                   $this->strencode( $value ) . "' WHERE ($cond)";
1030
1031                 return (bool)$this->query( $sql, $fname );
1032         }
1033
1034         /**
1035          * A SELECT wrapper which returns a single field from a single result row.
1036          *
1037          * Usually throws a DBQueryError on failure. If errors are explicitly
1038          * ignored, returns false on failure.
1039          *
1040          * If no result rows are returned from the query, false is returned.
1041          *
1042          * @param $table string|array Table name. See DatabaseBase::select() for details.
1043          * @param $var string The field name to select. This must be a valid SQL
1044          *   fragment: do not use unvalidated user input.
1045          * @param $cond string|array The condition array. See DatabaseBase::select() for details.
1046          * @param $fname string The function name of the caller.
1047          * @param $options string|array The query options. See DatabaseBase::select() for details.
1048          *
1049          * @return false|mixed The value from the field, or false on failure.
1050          */
1051         function selectField( $table, $var, $cond = '', $fname = 'DatabaseBase::selectField',
1052                 $options = array() )
1053         {
1054                 if ( !is_array( $options ) ) {
1055                         $options = array( $options );
1056                 }
1057
1058                 $options['LIMIT'] = 1;
1059
1060                 $res = $this->select( $table, $var, $cond, $fname, $options );
1061
1062                 if ( $res === false || !$this->numRows( $res ) ) {
1063                         return false;
1064                 }
1065
1066                 $row = $this->fetchRow( $res );
1067
1068                 if ( $row !== false ) {
1069                         return reset( $row );
1070                 } else {
1071                         return false;
1072                 }
1073         }
1074
1075         /**
1076          * Returns an optional USE INDEX clause to go after the table, and a
1077          * string to go at the end of the query.
1078          *
1079          * @param $options Array: associative array of options to be turned into
1080          *              an SQL query, valid keys are listed in the function.
1081          * @return Array
1082          * @see DatabaseBase::select()
1083          */
1084         function makeSelectOptions( $options ) {
1085                 $preLimitTail = $postLimitTail = '';
1086                 $startOpts = '';
1087
1088                 $noKeyOptions = array();
1089
1090                 foreach ( $options as $key => $option ) {
1091                         if ( is_numeric( $key ) ) {
1092                                 $noKeyOptions[$option] = true;
1093                         }
1094                 }
1095
1096                 if ( isset( $options['GROUP BY'] ) ) {
1097                         $gb = is_array( $options['GROUP BY'] )
1098                                 ? implode( ',', $options['GROUP BY'] )
1099                                 : $options['GROUP BY'];
1100                         $preLimitTail .= " GROUP BY {$gb}";
1101                 }
1102
1103                 if ( isset( $options['HAVING'] ) ) {
1104                         $preLimitTail .= " HAVING {$options['HAVING']}";
1105                 }
1106
1107                 if ( isset( $options['ORDER BY'] ) ) {
1108                         $ob = is_array( $options['ORDER BY'] )
1109                                 ? implode( ',', $options['ORDER BY'] )
1110                                 : $options['ORDER BY'];
1111                         $preLimitTail .= " ORDER BY {$ob}";
1112                 }
1113
1114                 // if (isset($options['LIMIT'])) {
1115                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
1116                 //              isset($options['OFFSET']) ? $options['OFFSET']
1117                 //              : false);
1118                 // }
1119
1120                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1121                         $postLimitTail .= ' FOR UPDATE';
1122                 }
1123
1124                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1125                         $postLimitTail .= ' LOCK IN SHARE MODE';
1126                 }
1127
1128                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1129                         $startOpts .= 'DISTINCT';
1130                 }
1131
1132                 # Various MySQL extensions
1133                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1134                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1135                 }
1136
1137                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1138                         $startOpts .= ' HIGH_PRIORITY';
1139                 }
1140
1141                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1142                         $startOpts .= ' SQL_BIG_RESULT';
1143                 }
1144
1145                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1146                         $startOpts .= ' SQL_BUFFER_RESULT';
1147                 }
1148
1149                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1150                         $startOpts .= ' SQL_SMALL_RESULT';
1151                 }
1152
1153                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1154                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1155                 }
1156
1157                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1158                         $startOpts .= ' SQL_CACHE';
1159                 }
1160
1161                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1162                         $startOpts .= ' SQL_NO_CACHE';
1163                 }
1164
1165                 if ( isset( $options['USE INDEX'] ) && ! is_array( $options['USE INDEX'] ) ) {
1166                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1167                 } else {
1168                         $useIndex = '';
1169                 }
1170
1171                 return array( $startOpts, $useIndex, $preLimitTail, $postLimitTail );
1172         }
1173
1174         /**
1175          * Execute a SELECT query constructed using the various parameters provided.
1176          * See below for full details of the parameters.
1177          *
1178          * @param $table String|Array Table name
1179          * @param $vars String|Array Field names
1180          * @param $conds String|Array Conditions
1181          * @param $fname String Caller function name
1182          * @param $options Array Query options
1183          * @param $join_conds Array Join conditions
1184          *
1185          *
1186          * @param $table string|array
1187          *
1188          * May be either an array of table names, or a single string holding a table
1189          * name. If an array is given, table aliases can be specified, for example:
1190          *
1191          *    array( 'a' => 'user' )
1192          *
1193          * This includes the user table in the query, with the alias "a" available
1194          * for use in field names (e.g. a.user_name).
1195          *
1196          * All of the table names given here are automatically run through
1197          * DatabaseBase::tableName(), which causes the table prefix (if any) to be
1198          * added, and various other table name mappings to be performed.
1199          *
1200          *
1201          * @param $vars string|array
1202          *
1203          * May be either a field name or an array of field names. The field names
1204          * here are complete fragments of SQL, for direct inclusion into the SELECT
1205          * query. Expressions and aliases may be specified as in SQL, for example:
1206          *
1207          *   array( 'MAX(rev_id) AS maxrev' )
1208          *
1209          * If an expression is given, care must be taken to ensure that it is
1210          * DBMS-independent.
1211          *
1212          *
1213          * @param $conds string|array
1214          *
1215          * May be either a string containing a single condition, or an array of
1216          * conditions. If an array is given, the conditions constructed from each
1217          * element are combined with AND.
1218          *
1219          * Array elements may take one of two forms:
1220          *
1221          *   - Elements with a numeric key are interpreted as raw SQL fragments.
1222          *   - Elements with a string key are interpreted as equality conditions,
1223          *     where the key is the field name.
1224          *     - If the value of such an array element is a scalar (such as a
1225          *       string), it will be treated as data and thus quoted appropriately.
1226          *       If it is null, an IS NULL clause will be added.
1227          *     - If the value is an array, an IN(...) clause will be constructed,
1228          *       such that the field name may match any of the elements in the
1229          *       array. The elements of the array will be quoted.
1230          *     - If the field name ends with "!", this is taken as a flag which
1231          *       inverts the comparison, allowing NOT IN clauses to be constructed,
1232          *       for example: array( 'user_id!' => array( 1, 2, 3 ) )
1233          *
1234          * Note that expressions are often DBMS-dependent in their syntax.
1235          * DBMS-independent wrappers are provided for constructing several types of
1236          * expression commonly used in condition queries. See:
1237          *    - DatabaseBase::buildLike()
1238          *    - DatabaseBase::conditional()
1239          *
1240          *
1241          * @param $options string|array
1242          *
1243          * Optional: Array of query options. Boolean options are specified by
1244          * including them in the array as a string value with a numeric key, for
1245          * example:
1246          *
1247          *    array( 'FOR UPDATE' )
1248          *
1249          * The supported options are:
1250          *
1251          *   - OFFSET: Skip this many rows at the start of the result set. OFFSET
1252          *     with LIMIT can theoretically be used for paging through a result set,
1253          *     but this is discouraged in MediaWiki for performance reasons.
1254          *
1255          *   - LIMIT: Integer: return at most this many rows. The rows are sorted
1256          *     and then the first rows are taken until the limit is reached. LIMIT
1257          *     is applied to a result set after OFFSET.
1258          *
1259          *   - FOR UPDATE: Boolean: lock the returned rows so that they can't be
1260          *     changed until the next COMMIT.
1261          *
1262          *   - DISTINCT: Boolean: return only unique result rows.
1263          *
1264          *   - GROUP BY: May be either an SQL fragment string naming a field or
1265          *     expression to group by, or an array of such SQL fragments.
1266          *
1267          *   - HAVING: A string containing a HAVING clause.
1268          *
1269          *   - ORDER BY: May be either an SQL fragment giving a field name or
1270          *     expression to order by, or an array of such SQL fragments.
1271          *
1272          *   - USE INDEX: This may be either a string giving the index name to use
1273          *     for the query, or an array. If it is an associative array, each key
1274          *     gives the table name (or alias), each value gives the index name to
1275          *     use for that table. All strings are SQL fragments and so should be
1276          *     validated by the caller.
1277          *
1278          *   - EXPLAIN: In MySQL, this causes an EXPLAIN SELECT query to be run,
1279          *     instead of SELECT.
1280          *
1281          * And also the following boolean MySQL extensions, see the MySQL manual
1282          * for documentation:
1283          *
1284          *    - LOCK IN SHARE MODE
1285          *    - STRAIGHT_JOIN
1286          *    - HIGH_PRIORITY
1287          *    - SQL_BIG_RESULT
1288          *    - SQL_BUFFER_RESULT
1289          *    - SQL_SMALL_RESULT
1290          *    - SQL_CALC_FOUND_ROWS
1291          *    - SQL_CACHE
1292          *    - SQL_NO_CACHE
1293          *
1294          *
1295          * @param $join_conds string|array
1296          *
1297          * Optional associative array of table-specific join conditions. In the
1298          * most common case, this is unnecessary, since the join condition can be
1299          * in $conds. However, it is useful for doing a LEFT JOIN.
1300          *
1301          * The key of the array contains the table name or alias. The value is an
1302          * array with two elements, numbered 0 and 1. The first gives the type of
1303          * join, the second is an SQL fragment giving the join condition for that
1304          * table. For example:
1305          *
1306          *    array( 'page' => array('LEFT JOIN','page_latest=rev_id') )
1307          *
1308          * @return ResultWrapper. If the query returned no rows, a ResultWrapper
1309          *   with no rows in it will be returned. If there was a query error, a
1310          *   DBQueryError exception will be thrown, except if the "ignore errors"
1311          *   option was set, in which case false will be returned.
1312          */
1313         function select( $table, $vars, $conds = '', $fname = 'DatabaseBase::select',
1314                 $options = array(), $join_conds = array() ) {
1315                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1316
1317                 return $this->query( $sql, $fname );
1318         }
1319
1320         /**
1321          * The equivalent of DatabaseBase::select() except that the constructed SQL
1322          * is returned, instead of being immediately executed.
1323          *
1324          * @param $table string|array Table name
1325          * @param $vars string|array Field names
1326          * @param $conds string|array Conditions
1327          * @param $fname string Caller function name
1328          * @param $options string|array Query options
1329          * @param $join_conds string|array Join conditions
1330          *
1331          * @return SQL query string.
1332          * @see DatabaseBase::select()
1333          */
1334         function selectSQLText( $table, $vars, $conds = '', $fname = 'DatabaseBase::select', $options = array(), $join_conds = array() ) {
1335                 if ( is_array( $vars ) ) {
1336                         $vars = implode( ',', $vars );
1337                 }
1338
1339                 $options = (array)$options;
1340
1341                 if ( is_array( $table ) ) {
1342                         $useIndex = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1343                                 ? $options['USE INDEX']
1344                                 : array();
1345                         if ( count( $join_conds ) || count( $useIndex ) ) {
1346                                 $from = ' FROM ' .
1347                                         $this->tableNamesWithUseIndexOrJOIN( $table, $useIndex, $join_conds );
1348                         } else {
1349                                 $from = ' FROM ' . implode( ',', $this->tableNamesWithAlias( $table ) );
1350                         }
1351                 } elseif ( $table != '' ) {
1352                         if ( $table { 0 } == ' ' ) {
1353                                 $from = ' FROM ' . $table;
1354                         } else {
1355                                 $from = ' FROM ' . $this->tableName( $table );
1356                         }
1357                 } else {
1358                         $from = '';
1359                 }
1360
1361                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail ) = $this->makeSelectOptions( $options );
1362
1363                 if ( !empty( $conds ) ) {
1364                         if ( is_array( $conds ) ) {
1365                                 $conds = $this->makeList( $conds, LIST_AND );
1366                         }
1367                         $sql = "SELECT $startOpts $vars $from $useIndex WHERE $conds $preLimitTail";
1368                 } else {
1369                         $sql = "SELECT $startOpts $vars $from $useIndex $preLimitTail";
1370                 }
1371
1372                 if ( isset( $options['LIMIT'] ) ) {
1373                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1374                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1375                 }
1376                 $sql = "$sql $postLimitTail";
1377
1378                 if ( isset( $options['EXPLAIN'] ) ) {
1379                         $sql = 'EXPLAIN ' . $sql;
1380                 }
1381
1382                 return $sql;
1383         }
1384
1385         /**
1386          * Single row SELECT wrapper. Equivalent to DatabaseBase::select(), except
1387          * that a single row object is returned. If the query returns no rows,
1388          * false is returned.
1389          *
1390          * @param $table string|array Table name
1391          * @param $vars string|array Field names
1392          * @param $conds|array Conditions
1393          * @param $fname string Caller function name
1394          * @param $options string|array Query options
1395          * @param $join_conds array|string Join conditions
1396          *
1397          * @return ResultWrapper|bool
1398          */
1399         function selectRow( $table, $vars, $conds, $fname = 'DatabaseBase::selectRow',
1400                 $options = array(), $join_conds = array() )
1401         {
1402                 $options['LIMIT'] = 1;
1403                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1404
1405                 if ( $res === false ) {
1406                         return false;
1407                 }
1408
1409                 if ( !$this->numRows( $res ) ) {
1410                         return false;
1411                 }
1412
1413                 $obj = $this->fetchObject( $res );
1414
1415                 return $obj;
1416         }
1417
1418         /**
1419          * Estimate rows in dataset.
1420          *
1421          * MySQL allows you to estimate the number of rows that would be returned
1422          * by a SELECT query, using EXPLAIN SELECT. The estimate is provided using
1423          * index cardinality statistics, and is notoriously inaccurate, especially
1424          * when large numbers of rows have recently been added or deleted.
1425          *
1426          * For DBMSs that don't support fast result size estimation, this function
1427          * will actually perform the SELECT COUNT(*).
1428          *
1429          * Takes the same arguments as DatabaseBase::select().
1430          *
1431          * @param $table String: table name
1432          * @param $vars Array: unused
1433          * @param $conds Array: filters on the table
1434          * @param $fname String: function name for profiling
1435          * @param $options Array: options for select
1436          * @return Integer: row count
1437          */
1438         public function estimateRowCount( $table, $vars = '*', $conds = '',
1439                 $fname = 'DatabaseBase::estimateRowCount', $options = array() )
1440         {
1441                 $rows = 0;
1442                 $res = $this->select ( $table, 'COUNT(*) AS rowcount', $conds, $fname, $options );
1443
1444                 if ( $res ) {
1445                         $row = $this->fetchRow( $res );
1446                         $rows = ( isset( $row['rowcount'] ) ) ? $row['rowcount'] : 0;
1447                 }
1448
1449                 return $rows;
1450         }
1451
1452         /**
1453          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1454          * It's only slightly flawed. Don't use for anything important.
1455          *
1456          * @param $sql String A SQL Query
1457          *
1458          * @return string
1459          */
1460         static function generalizeSQL( $sql ) {
1461                 # This does the same as the regexp below would do, but in such a way
1462                 # as to avoid crashing php on some large strings.
1463                 # $sql = preg_replace ( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql);
1464
1465                 $sql = str_replace ( "\\\\", '', $sql );
1466                 $sql = str_replace ( "\\'", '', $sql );
1467                 $sql = str_replace ( "\\\"", '', $sql );
1468                 $sql = preg_replace ( "/'.*'/s", "'X'", $sql );
1469                 $sql = preg_replace ( '/".*"/s', "'X'", $sql );
1470
1471                 # All newlines, tabs, etc replaced by single space
1472                 $sql = preg_replace ( '/\s+/', ' ', $sql );
1473
1474                 # All numbers => N
1475                 $sql = preg_replace ( '/-?[0-9]+/s', 'N', $sql );
1476
1477                 return $sql;
1478         }
1479
1480         /**
1481          * Determines whether a field exists in a table
1482          *
1483          * @param $table String: table name
1484          * @param $field String: filed to check on that table
1485          * @param $fname String: calling function name (optional)
1486          * @return Boolean: whether $table has filed $field
1487          */
1488         function fieldExists( $table, $field, $fname = 'DatabaseBase::fieldExists' ) {
1489                 $info = $this->fieldInfo( $table, $field );
1490
1491                 return (bool)$info;
1492         }
1493
1494         /**
1495          * Determines whether an index exists
1496          * Usually throws a DBQueryError on failure
1497          * If errors are explicitly ignored, returns NULL on failure
1498          *
1499          * @param $table
1500          * @param $index
1501          * @param $fname string
1502          *
1503          * @return bool|null
1504          */
1505         function indexExists( $table, $index, $fname = 'DatabaseBase::indexExists' ) {
1506                 $info = $this->indexInfo( $table, $index, $fname );
1507                 if ( is_null( $info ) ) {
1508                         return null;
1509                 } else {
1510                         return $info !== false;
1511                 }
1512         }
1513
1514         /**
1515          * Query whether a given table exists
1516          *
1517          * @param $table string
1518          *
1519          * @return bool
1520          */
1521         function tableExists( $table ) {
1522                 $table = $this->tableName( $table );
1523                 $old = $this->ignoreErrors( true );
1524                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", __METHOD__ );
1525                 $this->ignoreErrors( $old );
1526
1527                 return (bool)$res;
1528         }
1529
1530         /**
1531          * @todo document
1532          * mysql_field_type() wrapper
1533          */
1534         function fieldType( $res, $index ) {
1535                 if ( $res instanceof ResultWrapper ) {
1536                         $res = $res->result;
1537                 }
1538
1539                 return mysql_field_type( $res, $index );
1540         }
1541
1542         /**
1543          * Determines if a given index is unique
1544          *
1545          * @param $table string
1546          * @param $index string
1547          *
1548          * @return bool
1549          */
1550         function indexUnique( $table, $index ) {
1551                 $indexInfo = $this->indexInfo( $table, $index );
1552
1553                 if ( !$indexInfo ) {
1554                         return null;
1555                 }
1556
1557                 return !$indexInfo[0]->Non_unique;
1558         }
1559
1560         /**
1561          * Helper for DatabaseBase::insert().
1562          *
1563          * @param $options array
1564          * @return string
1565          */
1566         function makeInsertOptions( $options ) {
1567                 return implode( ' ', $options );
1568         }
1569
1570         /**
1571          * INSERT wrapper, inserts an array into a table.
1572          *
1573          * $a may be either:
1574          *
1575          *   - A single associative array. The array keys are the field names, and
1576          *     the values are the values to insert. The values are treated as data
1577          *     and will be quoted appropriately. If NULL is inserted, this will be
1578          *     converted to a database NULL.
1579          *   - An array with numeric keys, holding a list of associative arrays.
1580          *     This causes a multi-row INSERT on DBMSs that support it. The keys in
1581          *     each subarray must be identical to each other, and in the same order.
1582          *
1583          * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
1584          * returns success.
1585          *
1586          * $options is an array of options, with boolean options encoded as values
1587          * with numeric keys, in the same style as $options in
1588          * DatabaseBase::select(). Supported options are:
1589          *
1590          *   - IGNORE: Boolean: if present, duplicate key errors are ignored, and
1591          *     any rows which cause duplicate key errors are not inserted. It's
1592          *     possible to determine how many rows were successfully inserted using
1593          *     DatabaseBase::affectedRows().
1594          *
1595          * @param $table   String Table name. This will be passed through
1596          *                 DatabaseBase::tableName().
1597          * @param $a       Array of rows to insert
1598          * @param $fname   String Calling function name (use __METHOD__) for logs/profiling
1599          * @param $options Array of options
1600          *
1601          * @return bool
1602          */
1603         function insert( $table, $a, $fname = 'DatabaseBase::insert', $options = array() ) {
1604                 # No rows to insert, easy just return now
1605                 if ( !count( $a ) ) {
1606                         return true;
1607                 }
1608
1609                 $table = $this->tableName( $table );
1610
1611                 if ( !is_array( $options ) ) {
1612                         $options = array( $options );
1613                 }
1614
1615                 $options = $this->makeInsertOptions( $options );
1616
1617                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1618                         $multi = true;
1619                         $keys = array_keys( $a[0] );
1620                 } else {
1621                         $multi = false;
1622                         $keys = array_keys( $a );
1623                 }
1624
1625                 $sql = 'INSERT ' . $options .
1626                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1627
1628                 if ( $multi ) {
1629                         $first = true;
1630                         foreach ( $a as $row ) {
1631                                 if ( $first ) {
1632                                         $first = false;
1633                                 } else {
1634                                         $sql .= ',';
1635                                 }
1636                                 $sql .= '(' . $this->makeList( $row ) . ')';
1637                         }
1638                 } else {
1639                         $sql .= '(' . $this->makeList( $a ) . ')';
1640                 }
1641
1642                 return (bool)$this->query( $sql, $fname );
1643         }
1644
1645         /**
1646          * Make UPDATE options for the DatabaseBase::update function
1647          *
1648          * @param $options Array: The options passed to DatabaseBase::update
1649          * @return string
1650          */
1651         function makeUpdateOptions( $options ) {
1652                 if ( !is_array( $options ) ) {
1653                         $options = array( $options );
1654                 }
1655
1656                 $opts = array();
1657
1658                 if ( in_array( 'LOW_PRIORITY', $options ) ) {
1659                         $opts[] = $this->lowPriorityOption();
1660                 }
1661
1662                 if ( in_array( 'IGNORE', $options ) ) {
1663                         $opts[] = 'IGNORE';
1664                 }
1665
1666                 return implode( ' ', $opts );
1667         }
1668
1669         /**
1670          * UPDATE wrapper. Takes a condition array and a SET array.
1671          *
1672          * @param $table  String name of the table to UPDATE. This will be passed through
1673          *                DatabaseBase::tableName().
1674          *
1675          * @param $values Array:  An array of values to SET. For each array element,
1676          *                the key gives the field name, and the value gives the data
1677          *                to set that field to. The data will be quoted by
1678          *                DatabaseBase::addQuotes().
1679          *
1680          * @param $conds  Array:  An array of conditions (WHERE). See
1681          *                DatabaseBase::select() for the details of the format of
1682          *                condition arrays. Use '*' to update all rows.
1683          *
1684          * @param $fname  String: The function name of the caller (from __METHOD__),
1685          *                for logging and profiling.
1686          *
1687          * @param $options Array: An array of UPDATE options, can be:
1688          *                   - IGNORE: Ignore unique key conflicts
1689          *                   - LOW_PRIORITY: MySQL-specific, see MySQL manual.
1690          * @return Boolean
1691          */
1692         function update( $table, $values, $conds, $fname = 'DatabaseBase::update', $options = array() ) {
1693                 $table = $this->tableName( $table );
1694                 $opts = $this->makeUpdateOptions( $options );
1695                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET );
1696
1697                 if ( $conds !== array() && $conds !== '*' ) {
1698                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1699                 }
1700
1701                 return $this->query( $sql, $fname );
1702         }
1703
1704         /**
1705          * Makes an encoded list of strings from an array
1706          * @param $a Array containing the data
1707          * @param $mode int Constant
1708          *      - LIST_COMMA:          comma separated, no field names
1709          *      - LIST_AND:            ANDed WHERE clause (without the WHERE). See
1710          *        the documentation for $conds in DatabaseBase::select().
1711          *      - LIST_OR:             ORed WHERE clause (without the WHERE)
1712          *      - LIST_SET:            comma separated with field names, like a SET clause
1713          *      - LIST_NAMES:          comma separated field names
1714          *
1715          * @return string
1716          */
1717         function makeList( $a, $mode = LIST_COMMA ) {
1718                 if ( !is_array( $a ) ) {
1719                         throw new DBUnexpectedError( $this, 'DatabaseBase::makeList called with incorrect parameters' );
1720                 }
1721
1722                 $first = true;
1723                 $list = '';
1724
1725                 foreach ( $a as $field => $value ) {
1726                         if ( !$first ) {
1727                                 if ( $mode == LIST_AND ) {
1728                                         $list .= ' AND ';
1729                                 } elseif ( $mode == LIST_OR ) {
1730                                         $list .= ' OR ';
1731                                 } else {
1732                                         $list .= ',';
1733                                 }
1734                         } else {
1735                                 $first = false;
1736                         }
1737
1738                         if ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_numeric( $field ) ) {
1739                                 $list .= "($value)";
1740                         } elseif ( ( $mode == LIST_SET ) && is_numeric( $field ) ) {
1741                                 $list .= "$value";
1742                         } elseif ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_array( $value ) ) {
1743                                 if ( count( $value ) == 0 ) {
1744                                         throw new MWException( __METHOD__ . ': empty input' );
1745                                 } elseif ( count( $value ) == 1 ) {
1746                                         // Special-case single values, as IN isn't terribly efficient
1747                                         // Don't necessarily assume the single key is 0; we don't
1748                                         // enforce linear numeric ordering on other arrays here.
1749                                         $value = array_values( $value );
1750                                         $list .= $field . " = " . $this->addQuotes( $value[0] );
1751                                 } else {
1752                                         $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1753                                 }
1754                         } elseif ( $value === null ) {
1755                                 if ( $mode == LIST_AND || $mode == LIST_OR ) {
1756                                         $list .= "$field IS ";
1757                                         if ( $not ) {
1758                                                 $list .= "NOT ";
1759                                         }
1760                                 } elseif ( $mode == LIST_SET ) {
1761                                         $list .= "$field = ";
1762                                 }
1763                                 $list .= 'NULL';
1764                         } else {
1765                                 if ( $mode == LIST_AND || $mode == LIST_OR || $mode == LIST_SET ) {
1766                                         $list .= "$field = ";
1767                                 }
1768                                 $list .= $mode == LIST_NAMES ? $value : $this->addQuotes( $value );
1769                         }
1770                 }
1771
1772                 return $list;
1773         }
1774
1775         /**
1776          * Build a partial where clause from a 2-d array such as used for LinkBatch.
1777          * The keys on each level may be either integers or strings.
1778          *
1779          * @param $data Array: organized as 2-d
1780          *              array(baseKeyVal => array(subKeyVal => <ignored>, ...), ...)
1781          * @param $baseKey String: field name to match the base-level keys to (eg 'pl_namespace')
1782          * @param $subKey String: field name to match the sub-level keys to (eg 'pl_title')
1783          * @return Mixed: string SQL fragment, or false if no items in array.
1784          */
1785         function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1786                 $conds = array();
1787
1788                 foreach ( $data as $base => $sub ) {
1789                         if ( count( $sub ) ) {
1790                                 $conds[] = $this->makeList(
1791                                         array( $baseKey => $base, $subKey => array_keys( $sub ) ),
1792                                         LIST_AND );
1793                         }
1794                 }
1795
1796                 if ( $conds ) {
1797                         return $this->makeList( $conds, LIST_OR );
1798                 } else {
1799                         // Nothing to search for...
1800                         return false;
1801                 }
1802         }
1803
1804         /**
1805          * Build a partial where clause from a 3-d array
1806          * The keys on each level may be either integers or strings.
1807          *
1808          * @param $data Array: organized as 3-d array(baseKeyVal => array(middleKeyVal => array(subKeyVal => <ignored>, ...), ...), ...)
1809          * @param $baseKey String: field name to match the base-level keys to (eg 'gtl_to_prefix')
1810          * @param $middleKey String: field name to match the middle-level keys to (eg 'gtl_to_namespace')
1811          * @param $subKey String: field name to match the sub-level keys to (eg 'gtl_to_title')
1812          * @return Mixed: string SQL fragment, or false if no items in array.
1813          */
1814         function makeWhereFrom3d( $data, $baseKey, $middleKey, $subKey ) {
1815                 $conds = array();
1816                 foreach ( $data as $base => $subdata ) {
1817                         foreach ( $subdata as $middle => $sub ) {
1818                                 if ( count( $sub ) ) {
1819                                         $conds[] = $this->makeList(
1820                                                 array( $baseKey => $base,
1821                                                         $middleKey => $middle,
1822                                                         $subKey => array_keys( $sub ) ),
1823                                                 LIST_AND
1824                                         );
1825                                 }
1826                         }
1827                 }
1828
1829                 if ( $conds ) {
1830                         return $this->makeList( $conds, LIST_OR );
1831                 } else {
1832                         // Nothing to search for...
1833                         return false;
1834                 }
1835         }
1836
1837         /**
1838          * Bitwise operations
1839          */
1840
1841         /**
1842          * @param $field
1843          * @return string
1844          */
1845         function bitNot( $field ) {
1846                 return "(~$field)";
1847         }
1848
1849         /**
1850          * @param $fieldLeft
1851          * @param $fieldRight
1852          * @return string
1853          */
1854         function bitAnd( $fieldLeft, $fieldRight ) {
1855                 return "($fieldLeft & $fieldRight)";
1856         }
1857
1858         /**
1859          * @param  $fieldLeft
1860          * @param  $fieldRight
1861          * @return string
1862          */
1863         function bitOr( $fieldLeft, $fieldRight ) {
1864                 return "($fieldLeft | $fieldRight)";
1865         }
1866
1867         /**
1868          * Change the current database
1869          *
1870          * @todo Explain what exactly will fail if this is not overridden.
1871          *
1872          * @param $db
1873          *
1874          * @return bool Success or failure
1875          */
1876         function selectDB( $db ) {
1877                 # Stub.  Shouldn't cause serious problems if it's not overridden, but
1878                 # if your database engine supports a concept similar to MySQL's
1879                 # databases you may as well.
1880                 $this->mDBname = $db;
1881                 return true;
1882         }
1883
1884         /**
1885          * Get the current DB name
1886          */
1887         function getDBname() {
1888                 return $this->mDBname;
1889         }
1890
1891         /**
1892          * Get the server hostname or IP address
1893          */
1894         function getServer() {
1895                 return $this->mServer;
1896         }
1897
1898         /**
1899          * Format a table name ready for use in constructing an SQL query
1900          *
1901          * This does two important things: it quotes the table names to clean them up,
1902          * and it adds a table prefix if only given a table name with no quotes.
1903          *
1904          * All functions of this object which require a table name call this function
1905          * themselves. Pass the canonical name to such functions. This is only needed
1906          * when calling query() directly.
1907          *
1908          * @param $name String: database table name
1909          * @param $format String One of:
1910          *   quoted - Automatically pass the table name through addIdentifierQuotes()
1911          *            so that it can be used in a query.
1912          *   raw - Do not add identifier quotes to the table name
1913          * @return String: full database name
1914          */
1915         function tableName( $name, $format = 'quoted' ) {
1916                 global $wgSharedDB, $wgSharedPrefix, $wgSharedTables;
1917                 # Skip the entire process when we have a string quoted on both ends.
1918                 # Note that we check the end so that we will still quote any use of
1919                 # use of `database`.table. But won't break things if someone wants
1920                 # to query a database table with a dot in the name.
1921                 if ( $this->isQuotedIdentifier( $name ) ) {
1922                         return $name;
1923                 }
1924
1925                 # Lets test for any bits of text that should never show up in a table
1926                 # name. Basically anything like JOIN or ON which are actually part of
1927                 # SQL queries, but may end up inside of the table value to combine
1928                 # sql. Such as how the API is doing.
1929                 # Note that we use a whitespace test rather than a \b test to avoid
1930                 # any remote case where a word like on may be inside of a table name
1931                 # surrounded by symbols which may be considered word breaks.
1932                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1933                         return $name;
1934                 }
1935
1936                 # Split database and table into proper variables.
1937                 # We reverse the explode so that database.table and table both output
1938                 # the correct table.
1939                 $dbDetails = array_reverse( explode( '.', $name, 2 ) );
1940                 if ( isset( $dbDetails[1] ) ) {
1941                         list( $table, $database ) = $dbDetails;
1942                 } else {
1943                         list( $table ) = $dbDetails;
1944                 }
1945                 $prefix = $this->mTablePrefix; # Default prefix
1946
1947                 # A database name has been specified in input. We don't want any
1948                 # prefixes added.
1949                 if ( isset( $database ) ) {
1950                         $prefix = '';
1951                 }
1952
1953                 # Note that we use the long format because php will complain in in_array if
1954                 # the input is not an array, and will complain in is_array if it is not set.
1955                 if ( !isset( $database ) # Don't use shared database if pre selected.
1956                  && isset( $wgSharedDB ) # We have a shared database
1957                  && !$this->isQuotedIdentifier( $table ) # Paranoia check to prevent shared tables listing '`table`'
1958                  && isset( $wgSharedTables )
1959                  && is_array( $wgSharedTables )
1960                  && in_array( $table, $wgSharedTables ) ) { # A shared table is selected
1961                         $database = $wgSharedDB;
1962                         $prefix   = isset( $wgSharedPrefix ) ? $wgSharedPrefix : $prefix;
1963                 }
1964
1965                 # Quote the $database and $table and apply the prefix if not quoted.
1966                 if ( isset( $database ) ) {
1967                         $database = ( $format == 'quoted' || $this->isQuotedIdentifier( $database ) ? $database : $this->addIdentifierQuotes( $database ) );
1968                 }
1969
1970                 $table = "{$prefix}{$table}";
1971                 if ( $format == 'quoted' && !$this->isQuotedIdentifier( $table ) ) {
1972                         $table = $this->addIdentifierQuotes( "{$table}" );
1973                 }
1974
1975                 # Merge our database and table into our final table name.
1976                 $tableName = ( isset( $database ) ? "{$database}.{$table}" : "{$table}" );
1977
1978                 return $tableName;
1979         }
1980
1981         /**
1982          * Fetch a number of table names into an array
1983          * This is handy when you need to construct SQL for joins
1984          *
1985          * Example:
1986          * extract($dbr->tableNames('user','watchlist'));
1987          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1988          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
1989          *
1990          * @return array
1991          */
1992         public function tableNames() {
1993                 $inArray = func_get_args();
1994                 $retVal = array();
1995
1996                 foreach ( $inArray as $name ) {
1997                         $retVal[$name] = $this->tableName( $name );
1998                 }
1999
2000                 return $retVal;
2001         }
2002
2003         /**
2004          * Fetch a number of table names into an zero-indexed numerical array
2005          * This is handy when you need to construct SQL for joins
2006          *
2007          * Example:
2008          * list( $user, $watchlist ) = $dbr->tableNamesN('user','watchlist');
2009          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
2010          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
2011          *
2012          * @return array
2013          */
2014         public function tableNamesN() {
2015                 $inArray = func_get_args();
2016                 $retVal = array();
2017
2018                 foreach ( $inArray as $name ) {
2019                         $retVal[] = $this->tableName( $name );
2020                 }
2021
2022                 return $retVal;
2023         }
2024
2025         /**
2026          * Get an aliased table name
2027          * e.g. tableName AS newTableName
2028          *
2029          * @param $name string Table name, see tableName()
2030          * @param $alias string|bool Alias (optional)
2031          * @return string SQL name for aliased table. Will not alias a table to its own name
2032          */
2033         public function tableNameWithAlias( $name, $alias = false ) {
2034                 if ( !$alias || $alias == $name ) {
2035                         return $this->tableName( $name );
2036                 } else {
2037                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
2038                 }
2039         }
2040
2041         /**
2042          * Gets an array of aliased table names
2043          *
2044          * @param $tables array( [alias] => table )
2045          * @return array of strings, see tableNameWithAlias()
2046          */
2047         public function tableNamesWithAlias( $tables ) {
2048                 $retval = array();
2049                 foreach ( $tables as $alias => $table ) {
2050                         if ( is_numeric( $alias ) ) {
2051                                 $alias = $table;
2052                         }
2053                         $retval[] = $this->tableNameWithAlias( $table, $alias );
2054                 }
2055                 return $retval;
2056         }
2057
2058         /**
2059          * Get the aliased table name clause for a FROM clause
2060          * which might have a JOIN and/or USE INDEX clause
2061          *
2062          * @param $tables array ( [alias] => table )
2063          * @param $use_index array Same as for select()
2064          * @param $join_conds array Same as for select()
2065          * @return string
2066          */
2067         protected function tableNamesWithUseIndexOrJOIN(
2068                 $tables, $use_index = array(), $join_conds = array()
2069         ) {
2070                 $ret = array();
2071                 $retJOIN = array();
2072                 $use_index = (array)$use_index;
2073                 $join_conds = (array)$join_conds;
2074
2075                 foreach ( $tables as $alias => $table ) {
2076                         if ( !is_string( $alias ) ) {
2077                                 // No alias? Set it equal to the table name
2078                                 $alias = $table;
2079                         }
2080                         // Is there a JOIN clause for this table?
2081                         if ( isset( $join_conds[$alias] ) ) {
2082                                 list( $joinType, $conds ) = $join_conds[$alias];
2083                                 $tableClause = $joinType;
2084                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
2085                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2086                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2087                                         if ( $use != '' ) {
2088                                                 $tableClause .= ' ' . $use;
2089                                         }
2090                                 }
2091                                 $on = $this->makeList( (array)$conds, LIST_AND );
2092                                 if ( $on != '' ) {
2093                                         $tableClause .= ' ON (' . $on . ')';
2094                                 }
2095
2096                                 $retJOIN[] = $tableClause;
2097                         // Is there an INDEX clause for this table?
2098                         } elseif ( isset( $use_index[$alias] ) ) {
2099                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2100                                 $tableClause .= ' ' . $this->useIndexClause(
2101                                         implode( ',', (array)$use_index[$alias] ) );
2102
2103                                 $ret[] = $tableClause;
2104                         } else {
2105                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2106
2107                                 $ret[] = $tableClause;
2108                         }
2109                 }
2110
2111                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2112                 $straightJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
2113                 $otherJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
2114
2115                 // Compile our final table clause
2116                 return implode( ' ', array( $straightJoins, $otherJoins ) );
2117         }
2118
2119         /**
2120          * Get the name of an index in a given table
2121          *
2122          * @param $index
2123          *
2124          * @return string
2125          */
2126         function indexName( $index ) {
2127                 // Backwards-compatibility hack
2128                 $renamed = array(
2129                         'ar_usertext_timestamp' => 'usertext_timestamp',
2130                         'un_user_id'            => 'user_id',
2131                         'un_user_ip'            => 'user_ip',
2132                 );
2133
2134                 if ( isset( $renamed[$index] ) ) {
2135                         return $renamed[$index];
2136                 } else {
2137                         return $index;
2138                 }
2139         }
2140
2141         /**
2142          * If it's a string, adds quotes and backslashes
2143          * Otherwise returns as-is
2144          *
2145          * @param $s string
2146          *
2147          * @return string
2148          */
2149         function addQuotes( $s ) {
2150                 if ( $s === null ) {
2151                         return 'NULL';
2152                 } else {
2153                         # This will also quote numeric values. This should be harmless,
2154                         # and protects against weird problems that occur when they really
2155                         # _are_ strings such as article titles and string->number->string
2156                         # conversion is not 1:1.
2157                         return "'" . $this->strencode( $s ) . "'";
2158                 }
2159         }
2160
2161         /**
2162          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
2163          * MySQL uses `backticks` while basically everything else uses double quotes.
2164          * Since MySQL is the odd one out here the double quotes are our generic
2165          * and we implement backticks in DatabaseMysql.
2166          *
2167          * @param $s string
2168          *
2169          * @return string
2170          */
2171         public function addIdentifierQuotes( $s ) {
2172                 return '"' . str_replace( '"', '""', $s ) . '"';
2173         }
2174
2175         /**
2176          * Returns if the given identifier looks quoted or not according to
2177          * the database convention for quoting identifiers .
2178          *
2179          * @param $name string
2180          *
2181          * @return boolean
2182          */
2183         public function isQuotedIdentifier( $name ) {
2184                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2185         }
2186
2187         /**
2188          * Backwards compatibility, identifier quoting originated in DatabasePostgres
2189          * which used quote_ident which does not follow our naming conventions
2190          * was renamed to addIdentifierQuotes.
2191          * @deprecated since 1.18 use addIdentifierQuotes
2192          *
2193          * @param $s string
2194          *
2195          * @return string
2196          */
2197         function quote_ident( $s ) {
2198                 wfDeprecated( __METHOD__ );
2199                 return $this->addIdentifierQuotes( $s );
2200         }
2201
2202         /**
2203          * Escape string for safe LIKE usage.
2204          * WARNING: you should almost never use this function directly,
2205          * instead use buildLike() that escapes everything automatically
2206          * @deprecated since 1.17, warnings in 1.17, removed in ???
2207          *
2208          * @param $s string
2209          *
2210          * @return string
2211          */
2212         public function escapeLike( $s ) {
2213                 wfDeprecated( __METHOD__ );
2214                 return $this->escapeLikeInternal( $s );
2215         }
2216
2217         /**
2218          * @param $s string
2219          * @return string
2220          */
2221         protected function escapeLikeInternal( $s ) {
2222                 $s = str_replace( '\\', '\\\\', $s );
2223                 $s = $this->strencode( $s );
2224                 $s = str_replace( array( '%', '_' ), array( '\%', '\_' ), $s );
2225
2226                 return $s;
2227         }
2228
2229         /**
2230          * LIKE statement wrapper, receives a variable-length argument list with parts of pattern to match
2231          * containing either string literals that will be escaped or tokens returned by anyChar() or anyString().
2232          * Alternatively, the function could be provided with an array of aforementioned parameters.
2233          *
2234          * Example: $dbr->buildLike( 'My_page_title/', $dbr->anyString() ) returns a LIKE clause that searches
2235          * for subpages of 'My page title'.
2236          * Alternatively: $pattern = array( 'My_page_title/', $dbr->anyString() ); $query .= $dbr->buildLike( $pattern );
2237          *
2238          * @since 1.16
2239          * @return String: fully built LIKE statement
2240          */
2241         function buildLike() {
2242                 $params = func_get_args();
2243
2244                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2245                         $params = $params[0];
2246                 }
2247
2248                 $s = '';
2249
2250                 foreach ( $params as $value ) {
2251                         if ( $value instanceof LikeMatch ) {
2252                                 $s .= $value->toString();
2253                         } else {
2254                                 $s .= $this->escapeLikeInternal( $value );
2255                         }
2256                 }
2257
2258                 return " LIKE '" . $s . "' ";
2259         }
2260
2261         /**
2262          * Returns a token for buildLike() that denotes a '_' to be used in a LIKE query
2263          *
2264          * @return LikeMatch
2265          */
2266         function anyChar() {
2267                 return new LikeMatch( '_' );
2268         }
2269
2270         /**
2271          * Returns a token for buildLike() that denotes a '%' to be used in a LIKE query
2272          *
2273          * @return LikeMatch
2274          */
2275         function anyString() {
2276                 return new LikeMatch( '%' );
2277         }
2278
2279         /**
2280          * Returns an appropriately quoted sequence value for inserting a new row.
2281          * MySQL has autoincrement fields, so this is just NULL. But the PostgreSQL
2282          * subclass will return an integer, and save the value for insertId()
2283          */
2284         function nextSequenceValue( $seqName ) {
2285                 return null;
2286         }
2287
2288         /**
2289          * USE INDEX clause.  Unlikely to be useful for anything but MySQL.  This
2290          * is only needed because a) MySQL must be as efficient as possible due to
2291          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2292          * which index to pick.  Anyway, other databases might have different
2293          * indexes on a given table.  So don't bother overriding this unless you're
2294          * MySQL.
2295          */
2296         function useIndexClause( $index ) {
2297                 return '';
2298         }
2299
2300         /**
2301          * REPLACE query wrapper.
2302          *
2303          * REPLACE is a very handy MySQL extension, which functions like an INSERT
2304          * except that when there is a duplicate key error, the old row is deleted
2305          * and the new row is inserted in its place.
2306          *
2307          * We simulate this with standard SQL with a DELETE followed by INSERT. To
2308          * perform the delete, we need to know what the unique indexes are so that
2309          * we know how to find the conflicting rows.
2310          *
2311          * It may be more efficient to leave off unique indexes which are unlikely
2312          * to collide. However if you do this, you run the risk of encountering
2313          * errors which wouldn't have occurred in MySQL.
2314          *
2315          * @param $table String: The table to replace the row(s) in.
2316          * @param $rows array Can be either a single row to insert, or multiple rows,
2317          *    in the same format as for DatabaseBase::insert()
2318          * @param $uniqueIndexes array is an array of indexes. Each element may be either
2319          *    a field name or an array of field names
2320          * @param $fname String: Calling function name (use __METHOD__) for logs/profiling
2321          */
2322         function replace( $table, $uniqueIndexes, $rows, $fname = 'DatabaseBase::replace' ) {
2323                 $quotedTable = $this->tableName( $table );
2324
2325                 if ( count( $rows ) == 0 ) {
2326                         return;
2327                 }
2328
2329                 # Single row case
2330                 if ( !is_array( reset( $rows ) ) ) {
2331                         $rows = array( $rows );
2332                 }
2333
2334                 foreach( $rows as $row ) {
2335                         # Delete rows which collide
2336                         if ( $uniqueIndexes ) {
2337                                 $sql = "DELETE FROM $quotedTable WHERE ";
2338                                 $first = true;
2339                                 foreach ( $uniqueIndexes as $index ) {
2340                                         if ( $first ) {
2341                                                 $first = false;
2342                                                 $sql .= '( ';
2343                                         } else {
2344                                                 $sql .= ' ) OR ( ';
2345                                         }
2346                                         if ( is_array( $index ) ) {
2347                                                 $first2 = true;
2348                                                 foreach ( $index as $col ) {
2349                                                         if ( $first2 ) {
2350                                                                 $first2 = false;
2351                                                         } else {
2352                                                                 $sql .= ' AND ';
2353                                                         }
2354                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2355                                                 }
2356                                         } else {
2357                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2358                                         }
2359                                 }
2360                                 $sql .= ' )';
2361                                 $this->query( $sql, $fname );
2362                         }
2363
2364                         # Now insert the row
2365                         $this->insert( $table, $row );
2366                 }
2367         }
2368
2369         /**
2370          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2371          * statement.
2372          *
2373          * @param $table Table name
2374          * @param $rows Rows to insert
2375          * @param $fname Caller function name
2376          *
2377          * @return ResultWrapper
2378          */
2379         protected function nativeReplace( $table, $rows, $fname ) {
2380                 $table = $this->tableName( $table );
2381
2382                 # Single row case
2383                 if ( !is_array( reset( $rows ) ) ) {
2384                         $rows = array( $rows );
2385                 }
2386
2387                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2388                 $first = true;
2389
2390                 foreach ( $rows as $row ) {
2391                         if ( $first ) {
2392                                 $first = false;
2393                         } else {
2394                                 $sql .= ',';
2395                         }
2396
2397                         $sql .= '(' . $this->makeList( $row ) . ')';
2398                 }
2399
2400                 return $this->query( $sql, $fname );
2401         }
2402
2403         /**
2404          * DELETE where the condition is a join.
2405          *
2406          * MySQL overrides this to use a multi-table DELETE syntax, in other databases
2407          * we use sub-selects
2408          *
2409          * For safety, an empty $conds will not delete everything. If you want to
2410          * delete all rows where the join condition matches, set $conds='*'.
2411          *
2412          * DO NOT put the join condition in $conds.
2413          *
2414          * @param $delTable   String: The table to delete from.
2415          * @param $joinTable  String: The other table.
2416          * @param $delVar     String: The variable to join on, in the first table.
2417          * @param $joinVar    String: The variable to join on, in the second table.
2418          * @param $conds      Array: Condition array of field names mapped to variables,
2419          *                    ANDed together in the WHERE clause
2420          * @param $fname      String: Calling function name (use __METHOD__) for
2421          *                    logs/profiling
2422          */
2423         function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2424                 $fname = 'DatabaseBase::deleteJoin' )
2425         {
2426                 if ( !$conds ) {
2427                         throw new DBUnexpectedError( $this,
2428                                 'DatabaseBase::deleteJoin() called with empty $conds' );
2429                 }
2430
2431                 $delTable = $this->tableName( $delTable );
2432                 $joinTable = $this->tableName( $joinTable );
2433                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2434                 if ( $conds != '*' ) {
2435                         $sql .= 'WHERE ' . $this->makeList( $conds, LIST_AND );
2436                 }
2437                 $sql .= ')';
2438
2439                 $this->query( $sql, $fname );
2440         }
2441
2442         /**
2443          * Returns the size of a text field, or -1 for "unlimited"
2444          *
2445          * @param $table string
2446          * @param $field string
2447          *
2448          * @return int
2449          */
2450         function textFieldSize( $table, $field ) {
2451                 $table = $this->tableName( $table );
2452                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2453                 $res = $this->query( $sql, 'DatabaseBase::textFieldSize' );
2454                 $row = $this->fetchObject( $res );
2455
2456                 $m = array();
2457
2458                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2459                         $size = $m[1];
2460                 } else {
2461                         $size = -1;
2462                 }
2463
2464                 return $size;
2465         }
2466
2467         /**
2468          * A string to insert into queries to show that they're low-priority, like
2469          * MySQL's LOW_PRIORITY.  If no such feature exists, return an empty
2470          * string and nothing bad should happen.
2471          *
2472          * @return string Returns the text of the low priority option if it is
2473          *   supported, or a blank string otherwise
2474          */
2475         function lowPriorityOption() {
2476                 return '';
2477         }
2478
2479         /**
2480          * DELETE query wrapper.
2481          *
2482          * @param $table Array Table name
2483          * @param $conds String|Array of conditions. See $conds in DatabaseBase::select() for
2484          *               the format. Use $conds == "*" to delete all rows
2485          * @param $fname String name of the calling function
2486          *
2487          * @return bool
2488          */
2489         function delete( $table, $conds, $fname = 'DatabaseBase::delete' ) {
2490                 if ( !$conds ) {
2491                         throw new DBUnexpectedError( $this, 'DatabaseBase::delete() called with no conditions' );
2492                 }
2493
2494                 $table = $this->tableName( $table );
2495                 $sql = "DELETE FROM $table";
2496
2497                 if ( $conds != '*' ) {
2498                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
2499                 }
2500
2501                 return $this->query( $sql, $fname );
2502         }
2503
2504         /**
2505          * INSERT SELECT wrapper. Takes data from a SELECT query and inserts it
2506          * into another table.
2507          *
2508          * @param $destTable string The table name to insert into
2509          * @param $srcTable string|array May be either a table name, or an array of table names
2510          *    to include in a join.
2511          *
2512          * @param $varMap array must be an associative array of the form
2513          *    array( 'dest1' => 'source1', ...). Source items may be literals
2514          *    rather than field names, but strings should be quoted with
2515          *    DatabaseBase::addQuotes()
2516          *
2517          * @param $conds array Condition array. See $conds in DatabaseBase::select() for
2518          *    the details of the format of condition arrays. May be "*" to copy the
2519          *    whole table.
2520          *
2521          * @param $fname string The function name of the caller, from __METHOD__
2522          *
2523          * @param $insertOptions array Options for the INSERT part of the query, see
2524          *    DatabaseBase::insert() for details.
2525          * @param $selectOptions array Options for the SELECT part of the query, see
2526          *    DatabaseBase::select() for details.
2527          *
2528          * @return ResultWrapper
2529          */
2530         function insertSelect( $destTable, $srcTable, $varMap, $conds,
2531                 $fname = 'DatabaseBase::insertSelect',
2532                 $insertOptions = array(), $selectOptions = array() )
2533         {
2534                 $destTable = $this->tableName( $destTable );
2535
2536                 if ( is_array( $insertOptions ) ) {
2537                         $insertOptions = implode( ' ', $insertOptions );
2538                 }
2539
2540                 if ( !is_array( $selectOptions ) ) {
2541                         $selectOptions = array( $selectOptions );
2542                 }
2543
2544                 list( $startOpts, $useIndex, $tailOpts ) = $this->makeSelectOptions( $selectOptions );
2545
2546                 if ( is_array( $srcTable ) ) {
2547                         $srcTable =  implode( ',', array_map( array( &$this, 'tableName' ), $srcTable ) );
2548                 } else {
2549                         $srcTable = $this->tableName( $srcTable );
2550                 }
2551
2552                 $sql = "INSERT $insertOptions INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2553                         " SELECT $startOpts " . implode( ',', $varMap ) .
2554                         " FROM $srcTable $useIndex ";
2555
2556                 if ( $conds != '*' ) {
2557                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
2558                 }
2559
2560                 $sql .= " $tailOpts";
2561
2562                 return $this->query( $sql, $fname );
2563         }
2564
2565         /**
2566          * Construct a LIMIT query with optional offset.  This is used for query
2567          * pages.  The SQL should be adjusted so that only the first $limit rows
2568          * are returned.  If $offset is provided as well, then the first $offset
2569          * rows should be discarded, and the next $limit rows should be returned.
2570          * If the result of the query is not ordered, then the rows to be returned
2571          * are theoretically arbitrary.
2572          *
2573          * $sql is expected to be a SELECT, if that makes a difference.  For
2574          * UPDATE, limitResultForUpdate should be used.
2575          *
2576          * The version provided by default works in MySQL and SQLite.  It will very
2577          * likely need to be overridden for most other DBMSes.
2578          *
2579          * @param $sql String SQL query we will append the limit too
2580          * @param $limit Integer the SQL limit
2581          * @param $offset Integer|false the SQL offset (default false)
2582          *
2583          * @return string
2584          */
2585         function limitResult( $sql, $limit, $offset = false ) {
2586                 if ( !is_numeric( $limit ) ) {
2587                         throw new DBUnexpectedError( $this, "Invalid non-numeric limit passed to limitResult()\n" );
2588                 }
2589
2590                 return "$sql LIMIT "
2591                                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2592                                 . "{$limit} ";
2593         }
2594
2595         /**
2596          * @param $sql
2597          * @param $num
2598          * @return string
2599          */
2600         function limitResultForUpdate( $sql, $num ) {
2601                 return $this->limitResult( $sql, $num, 0 );
2602         }
2603
2604         /**
2605          * Returns true if current database backend supports ORDER BY or LIMIT for separate subqueries
2606          * within the UNION construct.
2607          * @return Boolean
2608          */
2609         function unionSupportsOrderAndLimit() {
2610                 return true; // True for almost every DB supported
2611         }
2612
2613         /**
2614          * Construct a UNION query
2615          * This is used for providing overload point for other DB abstractions
2616          * not compatible with the MySQL syntax.
2617          * @param $sqls Array: SQL statements to combine
2618          * @param $all Boolean: use UNION ALL
2619          * @return String: SQL fragment
2620          */
2621         function unionQueries( $sqls, $all ) {
2622                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2623                 return '(' . implode( $glue, $sqls ) . ')';
2624         }
2625
2626         /**
2627          * Returns an SQL expression for a simple conditional.  This doesn't need
2628          * to be overridden unless CASE isn't supported in your DBMS.
2629          *
2630          * @param $cond String: SQL expression which will result in a boolean value
2631          * @param $trueVal String: SQL expression to return if true
2632          * @param $falseVal String: SQL expression to return if false
2633          * @return String: SQL fragment
2634          */
2635         function conditional( $cond, $trueVal, $falseVal ) {
2636                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2637         }
2638
2639         /**
2640          * Returns a comand for str_replace function in SQL query.
2641          * Uses REPLACE() in MySQL
2642          *
2643          * @param $orig String: column to modify
2644          * @param $old String: column to seek
2645          * @param $new String: column to replace with
2646          *
2647          * @return string
2648          */
2649         function strreplace( $orig, $old, $new ) {
2650                 return "REPLACE({$orig}, {$old}, {$new})";
2651         }
2652
2653         /**
2654          * Determines if the last failure was due to a deadlock
2655          * STUB
2656          *
2657          * @return bool
2658          */
2659         function wasDeadlock() {
2660                 return false;
2661         }
2662
2663         /**
2664          * Determines if the last query error was something that should be dealt
2665          * with by pinging the connection and reissuing the query.
2666          * STUB
2667          *
2668          * @return bool
2669          */
2670         function wasErrorReissuable() {
2671                 return false;
2672         }
2673
2674         /**
2675          * Determines if the last failure was due to the database being read-only.
2676          * STUB
2677          *
2678          * @return bool
2679          */
2680         function wasReadOnlyError() {
2681                 return false;
2682         }
2683
2684         /**
2685          * Perform a deadlock-prone transaction.
2686          *
2687          * This function invokes a callback function to perform a set of write
2688          * queries. If a deadlock occurs during the processing, the transaction
2689          * will be rolled back and the callback function will be called again.
2690          *
2691          * Usage:
2692          *   $dbw->deadlockLoop( callback, ... );
2693          *
2694          * Extra arguments are passed through to the specified callback function.
2695          *
2696          * Returns whatever the callback function returned on its successful,
2697          * iteration, or false on error, for example if the retry limit was
2698          * reached.
2699          *
2700          * @return bool
2701          */
2702         function deadlockLoop() {
2703                 $myFname = 'DatabaseBase::deadlockLoop';
2704
2705                 $this->begin();
2706                 $args = func_get_args();
2707                 $function = array_shift( $args );
2708                 $oldIgnore = $this->ignoreErrors( true );
2709                 $tries = DEADLOCK_TRIES;
2710
2711                 if ( is_array( $function ) ) {
2712                         $fname = $function[0];
2713                 } else {
2714                         $fname = $function;
2715                 }
2716
2717                 do {
2718                         $retVal = call_user_func_array( $function, $args );
2719                         $error = $this->lastError();
2720                         $errno = $this->lastErrno();
2721                         $sql = $this->lastQuery();
2722
2723                         if ( $errno ) {
2724                                 if ( $this->wasDeadlock() ) {
2725                                         # Retry
2726                                         usleep( mt_rand( DEADLOCK_DELAY_MIN, DEADLOCK_DELAY_MAX ) );
2727                                 } else {
2728                                         $this->reportQueryError( $error, $errno, $sql, $fname );
2729                                 }
2730                         }
2731                 } while ( $this->wasDeadlock() && --$tries > 0 );
2732
2733                 $this->ignoreErrors( $oldIgnore );
2734
2735                 if ( $tries <= 0 ) {
2736                         $this->rollback( $myFname );
2737                         $this->reportQueryError( $error, $errno, $sql, $fname );
2738                         return false;
2739                 } else {
2740                         $this->commit( $myFname );
2741                         return $retVal;
2742                 }
2743         }
2744
2745         /**
2746          * Wait for the slave to catch up to a given master position.
2747          *
2748          * @param $pos DBMasterPos object
2749          * @param $timeout Integer: the maximum number of seconds to wait for
2750          *   synchronisation
2751          *
2752          * @return An integer: zero if the slave was past that position already,
2753          *   greater than zero if we waited for some period of time, less than
2754          *   zero if we timed out.
2755          */
2756         function masterPosWait( DBMasterPos $pos, $timeout ) {
2757                 $fname = 'DatabaseBase::masterPosWait';
2758                 wfProfileIn( $fname );
2759
2760                 if ( !is_null( $this->mFakeSlaveLag ) ) {
2761                         $wait = intval( ( $pos->pos - microtime( true ) + $this->mFakeSlaveLag ) * 1e6 );
2762
2763                         if ( $wait > $timeout * 1e6 ) {
2764                                 wfDebug( "Fake slave timed out waiting for $pos ($wait us)\n" );
2765                                 wfProfileOut( $fname );
2766                                 return -1;
2767                         } elseif ( $wait > 0 ) {
2768                                 wfDebug( "Fake slave waiting $wait us\n" );
2769                                 usleep( $wait );
2770                                 wfProfileOut( $fname );
2771                                 return 1;
2772                         } else {
2773                                 wfDebug( "Fake slave up to date ($wait us)\n" );
2774                                 wfProfileOut( $fname );
2775                                 return 0;
2776                         }
2777                 }
2778
2779                 wfProfileOut( $fname );
2780
2781                 # Real waits are implemented in the subclass.
2782                 return 0;
2783         }
2784
2785         /**
2786          * Get the replication position of this slave
2787          *
2788          * @return DBMasterPos, or false if this is not a slave.
2789          */
2790         function getSlavePos() {
2791                 if ( !is_null( $this->mFakeSlaveLag ) ) {
2792                         $pos = new MySQLMasterPos( 'fake', microtime( true ) - $this->mFakeSlaveLag );
2793                         wfDebug( __METHOD__ . ": fake slave pos = $pos\n" );
2794                         return $pos;
2795                 } else {
2796                         # Stub
2797                         return false;
2798                 }
2799         }
2800
2801         /**
2802          * Get the position of this master
2803          *
2804          * @return DBMasterPos, or false if this is not a master
2805          */
2806         function getMasterPos() {
2807                 if ( $this->mFakeMaster ) {
2808                         return new MySQLMasterPos( 'fake', microtime( true ) );
2809                 } else {
2810                         return false;
2811                 }
2812         }
2813
2814         /**
2815          * Begin a transaction, committing any previously open transaction
2816          *
2817          * @param $fname string
2818          */
2819         function begin( $fname = 'DatabaseBase::begin' ) {
2820                 $this->query( 'BEGIN', $fname );
2821                 $this->mTrxLevel = 1;
2822         }
2823
2824         /**
2825          * End a transaction
2826          *
2827          * @param $fname string
2828          */
2829         function commit( $fname = 'DatabaseBase::commit' ) {
2830                 if ( $this->mTrxLevel ) {
2831                         $this->query( 'COMMIT', $fname );
2832                         $this->mTrxLevel = 0;
2833                 }
2834         }
2835
2836         /**
2837          * Rollback a transaction.
2838          * No-op on non-transactional databases.
2839          *
2840          * @param $fname string
2841          */
2842         function rollback( $fname = 'DatabaseBase::rollback' ) {
2843                 if ( $this->mTrxLevel ) {
2844                         $this->query( 'ROLLBACK', $fname, true );
2845                         $this->mTrxLevel = 0;
2846                 }
2847         }
2848
2849         /**
2850          * Creates a new table with structure copied from existing table
2851          * Note that unlike most database abstraction functions, this function does not
2852          * automatically append database prefix, because it works at a lower
2853          * abstraction level.
2854          * The table names passed to this function shall not be quoted (this
2855          * function calls addIdentifierQuotes when needed).
2856          *
2857          * @param $oldName String: name of table whose structure should be copied
2858          * @param $newName String: name of table to be created
2859          * @param $temporary Boolean: whether the new table should be temporary
2860          * @param $fname String: calling function name
2861          * @return Boolean: true if operation was successful
2862          */
2863         function duplicateTableStructure( $oldName, $newName, $temporary = false,
2864                 $fname = 'DatabaseBase::duplicateTableStructure' )
2865         {
2866                 throw new MWException(
2867                         'DatabaseBase::duplicateTableStructure is not implemented in descendant class' );
2868         }
2869
2870         /**
2871          * List all tables on the database
2872          *
2873          * @param $prefix Only show tables with this prefix, e.g. mw_
2874          * @param $fname String: calling function name
2875          */
2876         function listTables( $prefix = null, $fname = 'DatabaseBase::listTables' ) {
2877                 throw new MWException( 'DatabaseBase::listTables is not implemented in descendant class' );
2878         }
2879
2880         /**
2881          * Convert a timestamp in one of the formats accepted by wfTimestamp()
2882          * to the format used for inserting into timestamp fields in this DBMS.
2883          *
2884          * The result is unquoted, and needs to be passed through addQuotes()
2885          * before it can be included in raw SQL.
2886          *
2887          * @param $ts string|int
2888          *
2889          * @return string
2890          */
2891         function timestamp( $ts = 0 ) {
2892                 return wfTimestamp( TS_MW, $ts );
2893         }
2894
2895         /**
2896          * Convert a timestamp in one of the formats accepted by wfTimestamp()
2897          * to the format used for inserting into timestamp fields in this DBMS. If
2898          * NULL is input, it is passed through, allowing NULL values to be inserted
2899          * into timestamp fields.
2900          *
2901          * The result is unquoted, and needs to be passed through addQuotes()
2902          * before it can be included in raw SQL.
2903          *
2904          * @param $ts string|int
2905          *
2906          * @return string
2907          */
2908         function timestampOrNull( $ts = null ) {
2909                 if ( is_null( $ts ) ) {
2910                         return null;
2911                 } else {
2912                         return $this->timestamp( $ts );
2913                 }
2914         }
2915
2916         /**
2917          * Take the result from a query, and wrap it in a ResultWrapper if
2918          * necessary. Boolean values are passed through as is, to indicate success
2919          * of write queries or failure.
2920          *
2921          * Once upon a time, DatabaseBase::query() returned a bare MySQL result
2922          * resource, and it was necessary to call this function to convert it to
2923          * a wrapper. Nowadays, raw database objects are never exposed to external
2924          * callers, so this is unnecessary in external code. For compatibility with
2925          * old code, ResultWrapper objects are passed through unaltered.
2926          *
2927          * @param $result bool|ResultWrapper
2928          *
2929          * @param bool|ResultWrapper
2930          */
2931         function resultObject( $result ) {
2932                 if ( empty( $result ) ) {
2933                         return false;
2934                 } elseif ( $result instanceof ResultWrapper ) {
2935                         return $result;
2936                 } elseif ( $result === true ) {
2937                         // Successful write query
2938                         return $result;
2939                 } else {
2940                         return new ResultWrapper( $this, $result );
2941                 }
2942         }
2943
2944         /**
2945          * Return aggregated value alias
2946          *
2947          * @param $valuedata
2948          * @param $valuename string
2949          *
2950          * @return string
2951          */
2952         function aggregateValue ( $valuedata, $valuename = 'value' ) {
2953                 return $valuename;
2954         }
2955
2956         /**
2957          * Ping the server and try to reconnect if it there is no connection
2958          *
2959          * @return bool Success or failure
2960          */
2961         function ping() {
2962                 # Stub.  Not essential to override.
2963                 return true;
2964         }
2965
2966         /**
2967          * Get slave lag. Currently supported only by MySQL.
2968          *
2969          * Note that this function will generate a fatal error on many
2970          * installations. Most callers should use LoadBalancer::safeGetLag()
2971          * instead.
2972          *
2973          * @return Database replication lag in seconds
2974          */
2975         function getLag() {
2976                 return intval( $this->mFakeSlaveLag );
2977         }
2978
2979         /**
2980          * Return the maximum number of items allowed in a list, or 0 for unlimited.
2981          *
2982          * @return int
2983          */
2984         function maxListLen() {
2985                 return 0;
2986         }
2987
2988         /**
2989          * Some DBMSs have a special format for inserting into blob fields, they
2990          * don't allow simple quoted strings to be inserted. To insert into such
2991          * a field, pass the data through this function before passing it to
2992          * DatabaseBase::insert().
2993          */
2994         function encodeBlob( $b ) {
2995                 return $b;
2996         }
2997
2998         /**
2999          * Some DBMSs return a special placeholder object representing blob fields
3000          * in result objects. Pass the object through this function to return the
3001          * original string.
3002          */
3003         function decodeBlob( $b ) {
3004                 return $b;
3005         }
3006
3007         /**
3008          * Override database's default connection timeout.  May be useful for very
3009          * long batch queries such as full-wiki dumps, where a single query reads
3010          * out over hours or days.  May or may not be necessary for non-MySQL
3011          * databases.  For most purposes, leaving it as a no-op should be fine.
3012          *
3013          * @param $timeout Integer in seconds
3014          */
3015         public function setTimeout( $timeout ) {}
3016
3017         /**
3018          * Read and execute SQL commands from a file.
3019          *
3020          * Returns true on success, error string or exception on failure (depending
3021          * on object's error ignore settings).
3022          *
3023          * @param $filename String: File name to open
3024          * @param $lineCallback Callback: Optional function called before reading each line
3025          * @param $resultCallback Callback: Optional function called for each MySQL result
3026          * @param $fname String: Calling function name or false if name should be
3027          *      generated dynamically using $filename
3028          */
3029         function sourceFile( $filename, $lineCallback = false, $resultCallback = false, $fname = false ) {
3030                 wfSuppressWarnings();
3031                 $fp = fopen( $filename, 'r' );
3032                 wfRestoreWarnings();
3033
3034                 if ( false === $fp ) {
3035                         throw new MWException( "Could not open \"{$filename}\".\n" );
3036                 }
3037
3038                 if ( !$fname ) {
3039                         $fname = __METHOD__ . "( $filename )";
3040                 }
3041
3042                 try {
3043                         $error = $this->sourceStream( $fp, $lineCallback, $resultCallback, $fname );
3044                 }
3045                 catch ( MWException $e ) {
3046                         fclose( $fp );
3047                         throw $e;
3048                 }
3049
3050                 fclose( $fp );
3051
3052                 return $error;
3053         }
3054
3055         /**
3056          * Get the full path of a patch file. Originally based on archive()
3057          * from updaters.inc. Keep in mind this always returns a patch, as
3058          * it fails back to MySQL if no DB-specific patch can be found
3059          *
3060          * @param $patch String The name of the patch, like patch-something.sql
3061          * @return String Full path to patch file
3062          */
3063         public function patchPath( $patch ) {
3064                 global $IP;
3065
3066                 $dbType = $this->getType();
3067                 if ( file_exists( "$IP/maintenance/$dbType/archives/$patch" ) ) {
3068                         return "$IP/maintenance/$dbType/archives/$patch";
3069                 } else {
3070                         return "$IP/maintenance/archives/$patch";
3071                 }
3072         }
3073
3074         /**
3075          * Set variables to be used in sourceFile/sourceStream, in preference to the
3076          * ones in $GLOBALS. If an array is set here, $GLOBALS will not be used at
3077          * all. If it's set to false, $GLOBALS will be used.
3078          *
3079          * @param $vars False, or array mapping variable name to value.
3080          */
3081         function setSchemaVars( $vars ) {
3082                 $this->mSchemaVars = $vars;
3083         }
3084
3085         /**
3086          * Read and execute commands from an open file handle.
3087          *
3088          * Returns true on success, error string or exception on failure (depending
3089          * on object's error ignore settings).
3090          *
3091          * @param $fp Resource: File handle
3092          * @param $lineCallback Callback: Optional function called before reading each line
3093          * @param $resultCallback Callback: Optional function called for each MySQL result
3094          * @param $fname String: Calling function name
3095          */
3096         function sourceStream( $fp, $lineCallback = false, $resultCallback = false,
3097                 $fname = 'DatabaseBase::sourceStream' )
3098         {
3099                 $cmd = "";
3100                 $done = false;
3101                 $dollarquote = false;
3102
3103                 while ( ! feof( $fp ) ) {
3104                         if ( $lineCallback ) {
3105                                 call_user_func( $lineCallback );
3106                         }
3107
3108                         $line = trim( fgets( $fp ) );
3109                         $sl = strlen( $line ) - 1;
3110
3111                         if ( $sl < 0 ) {
3112                                 continue;
3113                         }
3114
3115                         if ( '-' == $line { 0 } && '-' == $line { 1 } ) {
3116                                 continue;
3117                         }
3118
3119                         # # Allow dollar quoting for function declarations
3120                         if ( substr( $line, 0, 4 ) == '$mw$' ) {
3121                                 if ( $dollarquote ) {
3122                                         $dollarquote = false;
3123                                         $done = true;
3124                                 }
3125                                 else {
3126                                         $dollarquote = true;
3127                                 }
3128                         }
3129                         elseif ( !$dollarquote ) {
3130                                 if ( ';' == $line { $sl } && ( $sl < 2 || ';' != $line { $sl - 1 } ) ) {
3131                                         $done = true;
3132                                         $line = substr( $line, 0, $sl );
3133                                 }
3134                         }
3135
3136                         if ( $cmd != '' ) {
3137                                 $cmd .= ' ';
3138                         }
3139
3140                         $cmd .= "$line\n";
3141
3142                         if ( $done ) {
3143                                 $cmd = str_replace( ';;', ";", $cmd );
3144                                 $cmd = $this->replaceVars( $cmd );
3145                                 $res = $this->query( $cmd, $fname );
3146
3147                                 if ( $resultCallback ) {
3148                                         call_user_func( $resultCallback, $res, $this );
3149                                 }
3150
3151                                 if ( false === $res ) {
3152                                         $err = $this->lastError();
3153                                         return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3154                                 }
3155
3156                                 $cmd = '';
3157                                 $done = false;
3158                         }
3159                 }
3160
3161                 return true;
3162         }
3163
3164         /**
3165          * Database independent variable replacement. Replaces a set of variables
3166          * in an SQL statement with their contents as given by $this->getSchemaVars().
3167          *
3168          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3169          *
3170          * - '{$var}' should be used for text and is passed through the database's
3171          *   addQuotes method.
3172          * - `{$var}` should be used for identifiers (eg: table and database names),
3173          *   it is passed through the database's addIdentifierQuotes method which
3174          *   can be overridden if the database uses something other than backticks.
3175          * - / *$var* / is just encoded, besides traditional table prefix and
3176          *   table options its use should be avoided.
3177          *
3178          * @param $ins String: SQL statement to replace variables in
3179          * @return String The new SQL statement with variables replaced
3180          */
3181         protected function replaceSchemaVars( $ins ) {
3182                 $vars = $this->getSchemaVars();
3183                 foreach ( $vars as $var => $value ) {
3184                         // replace '{$var}'
3185                         $ins = str_replace( '\'{$' . $var . '}\'', $this->addQuotes( $value ), $ins );
3186                         // replace `{$var}`
3187                         $ins = str_replace( '`{$' . $var . '}`', $this->addIdentifierQuotes( $value ), $ins );
3188                         // replace /*$var*/
3189                         $ins = str_replace( '/*$' . $var . '*/', $this->strencode( $value ) , $ins );
3190                 }
3191                 return $ins;
3192         }
3193
3194         /**
3195          * Replace variables in sourced SQL
3196          *
3197          * @param $ins string
3198          *
3199          * @return string
3200          */
3201         protected function replaceVars( $ins ) {
3202                 $ins = $this->replaceSchemaVars( $ins );
3203
3204                 // Table prefixes
3205                 $ins = preg_replace_callback( '!/\*(?:\$wgDBprefix|_)\*/([a-zA-Z_0-9]*)!',
3206                         array( $this, 'tableNameCallback' ), $ins );
3207
3208                 // Index names
3209                 $ins = preg_replace_callback( '!/\*i\*/([a-zA-Z_0-9]*)!',
3210                         array( $this, 'indexNameCallback' ), $ins );
3211
3212                 return $ins;
3213         }
3214
3215         /**
3216          * Get schema variables. If none have been set via setSchemaVars(), then
3217          * use some defaults from the current object.
3218          */
3219         protected function getSchemaVars() {
3220                 if ( $this->mSchemaVars ) {
3221                         return $this->mSchemaVars;
3222                 } else {
3223                         return $this->getDefaultSchemaVars();
3224                 }
3225         }
3226
3227         /**
3228          * Get schema variables to use if none have been set via setSchemaVars().
3229          *
3230          * Override this in derived classes to provide variables for tables.sql
3231          * and SQL patch files.
3232          *
3233          * @return array
3234          */
3235         protected function getDefaultSchemaVars() {
3236                 return array();
3237         }
3238
3239         /**
3240          * Table name callback
3241          *
3242          * @param $matches array
3243          *
3244          * @return string
3245          */
3246         protected function tableNameCallback( $matches ) {
3247                 return $this->tableName( $matches[1] );
3248         }
3249
3250         /**
3251          * Index name callback
3252          *
3253          * @param $matches array
3254          *
3255          * @return string
3256          */
3257         protected function indexNameCallback( $matches ) {
3258                 return $this->indexName( $matches[1] );
3259         }
3260
3261         /**
3262          * Build a concatenation list to feed into a SQL query
3263          * @param $stringList Array: list of raw SQL expressions; caller is responsible for any quoting
3264          * @return String
3265          */
3266         function buildConcat( $stringList ) {
3267                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
3268         }
3269
3270         /**
3271          * Acquire a named lock
3272          *
3273          * Abstracted from Filestore::lock() so child classes can implement for
3274          * their own needs.
3275          *
3276          * @param $lockName String: name of lock to aquire
3277          * @param $method String: name of method calling us
3278          * @param $timeout Integer: timeout
3279          * @return Boolean
3280          */
3281         public function lock( $lockName, $method, $timeout = 5 ) {
3282                 return true;
3283         }
3284
3285         /**
3286          * Release a lock.
3287          *
3288          * @param $lockName String: Name of lock to release
3289          * @param $method String: Name of method calling us
3290          *
3291          * @return Returns 1 if the lock was released, 0 if the lock was not established
3292          * by this thread (in which case the lock is not released), and NULL if the named
3293          * lock did not exist
3294          */
3295         public function unlock( $lockName, $method ) {
3296                 return true;
3297         }
3298
3299         /**
3300          * Lock specific tables
3301          *
3302          * @param $read Array of tables to lock for read access
3303          * @param $write Array of tables to lock for write access
3304          * @param $method String name of caller
3305          * @param $lowPriority bool Whether to indicate writes to be LOW PRIORITY
3306          *
3307          * @return bool
3308          */
3309         public function lockTables( $read, $write, $method, $lowPriority = true ) {
3310                 return true;
3311         }
3312
3313         /**
3314          * Unlock specific tables
3315          *
3316          * @param $method String the caller
3317          *
3318          * @return bool
3319          */
3320         public function unlockTables( $method ) {
3321                 return true;
3322         }
3323
3324         /**
3325          * Delete a table
3326          * @param $tableName string
3327          * @param $fName string
3328          * @return bool|ResultWrapper
3329          */
3330         public function dropTable( $tableName, $fName = 'DatabaseBase::dropTable' ) {
3331                 if( !$this->tableExists( $tableName ) ) {
3332                         return false;
3333                 }
3334                 $sql = "DROP TABLE " . $this->tableName( $tableName );
3335                 if( $this->cascadingDeletes() ) {
3336                         $sql .= " CASCADE";
3337                 }
3338                 return $this->query( $sql, $fName );
3339         }
3340
3341         /**
3342          * Get search engine class. All subclasses of this need to implement this
3343          * if they wish to use searching.
3344          *
3345          * @return String
3346          */
3347         public function getSearchEngine() {
3348                 return 'SearchEngineDummy';
3349         }
3350
3351         /**
3352          * Find out when 'infinity' is. Most DBMSes support this. This is a special
3353          * keyword for timestamps in PostgreSQL, and works with CHAR(14) as well
3354          * because "i" sorts after all numbers.
3355          *
3356          * @return String
3357          */
3358         public function getInfinity() {
3359                 return 'infinity';
3360         }
3361
3362         /**
3363          * Encode an expiry time
3364          *
3365          * @param $expiry String: timestamp for expiry, or the 'infinity' string
3366          * @return String
3367          */
3368         public function encodeExpiry( $expiry ) {
3369                 if ( $expiry == '' || $expiry == $this->getInfinity() ) {
3370                         return $this->getInfinity();
3371                 } else {
3372                         return $this->timestamp( $expiry );
3373                 }
3374         }
3375
3376         /**
3377          * Allow or deny "big selects" for this session only. This is done by setting
3378          * the sql_big_selects session variable.
3379          *
3380          * This is a MySQL-specific feature.
3381          *
3382          * @param $value Mixed: true for allow, false for deny, or "default" to
3383          *   restore the initial value
3384          */
3385         public function setBigSelects( $value = true ) {
3386                 // no-op
3387         }
3388 }