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