includes/libs/rdbms/database/DatabaseMysqlBase.php

   1 <?php
   2 /**
   3  * This is the MySQL database abstraction layer.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @ingroup Database
  22  */
  23 namespace Wikimedia\Rdbms;
  24
  25 use DateTime;
  26 use DateTimeZone;
  27 use MediaWiki;
  28 use InvalidArgumentException;
  29 use Exception;
  30 use stdClass;
  31
  32 /**
  33  * Database abstraction object for MySQL.
  34  * Defines methods independent on used MySQL extension.
  35  *
  36  * @ingroup Database
  37  * @since 1.22
  38  * @see Database
  39  */
  40 abstract class DatabaseMysqlBase extends Database {
  41         /** @var MysqlMasterPos */
  42         protected $lastKnownReplicaPos;
  43         /** @var string Method to detect replica DB lag */
  44         protected $lagDetectionMethod;
  45         /** @var array Method to detect replica DB lag */
  46         protected $lagDetectionOptions = [];
  47         /** @var bool bool Whether to use GTID methods */
  48         protected $useGTIDs = false;
  49         /** @var string|null */
  50         protected $sslKeyPath;
  51         /** @var string|null */
  52         protected $sslCertPath;
  53         /** @var string|null */
  54         protected $sslCAFile;
  55         /** @var string|null */
  56         protected $sslCAPath;
  57         /** @var string[]|null */
  58         protected $sslCiphers;
  59         /** @var string sql_mode value to send on connection */
  60         protected $sqlMode;
  61         /** @var bool Use experimental UTF-8 transmission encoding */
  62         protected $utf8Mode;
  63
  64         /** @var string|null */
  65         private $serverVersion = null;
  66         /** @var bool|null */
  67         private $insertSelectIsSafe = null;
  68
  69         /**
  70          * Additional $params include:
  71          *   - lagDetectionMethod : set to one of (Seconds_Behind_Master,pt-heartbeat).
  72          *       pt-heartbeat assumes the table is at heartbeat.heartbeat
  73          *       and uses UTC timestamps in the heartbeat.ts column.
  74          *       (https://www.percona.com/doc/percona-toolkit/2.2/pt-heartbeat.html)
  75          *   - lagDetectionOptions : if using pt-heartbeat, this can be set to an array map to change
  76          *       the default behavior. Normally, the heartbeat row with the server
  77          *       ID of this server's master will be used. Set the "conds" field to
  78          *       override the query conditions, e.g. ['shard' => 's1'].
  79          *   - useGTIDs : use GTID methods like MASTER_GTID_WAIT() when possible.
  80          *   - insertSelectIsSafe : force that native INSERT SELECT is or is not safe [default: null]
  81          *   - sslKeyPath : path to key file [default: null]
  82          *   - sslCertPath : path to certificate file [default: null]
  83          *   - sslCAFile: path to a single certificate authority PEM file [default: null]
  84          *   - sslCAPath : parth to certificate authority PEM directory [default: null]
  85          *   - sslCiphers : array list of allowable ciphers [default: null]
  86          * @param array $params
  87          */
  88         function __construct( array $params ) {
  89                 $this->lagDetectionMethod = isset( $params['lagDetectionMethod'] )
  90                         ? $params['lagDetectionMethod']
  91                         : 'Seconds_Behind_Master';
  92                 $this->lagDetectionOptions = isset( $params['lagDetectionOptions'] )
  93                         ? $params['lagDetectionOptions']
  94                         : [];
  95                 $this->useGTIDs = !empty( $params['useGTIDs' ] );
  96                 foreach ( [ 'KeyPath', 'CertPath', 'CAFile', 'CAPath', 'Ciphers' ] as $name ) {
  97                         $var = "ssl{$name}";
  98                         if ( isset( $params[$var] ) ) {
  99                                 $this->$var = $params[$var];
 100                         }
 101                 }
 102                 $this->sqlMode = isset( $params['sqlMode'] ) ? $params['sqlMode'] : '';
 103                 $this->utf8Mode = !empty( $params['utf8Mode'] );
 104                 $this->insertSelectIsSafe = isset( $params['insertSelectIsSafe'] )
 105                         ? (bool)$params['insertSelectIsSafe'] : null;
 106
 107                 parent::__construct( $params );
 108         }
 109
 110         /**
 111          * @return string
 112          */
 113         public function getType() {
 114                 return 'mysql';
 115         }
 116
 117         /**
 118          * @param string $server
 119          * @param string $user
 120          * @param string $password
 121          * @param string $dbName
 122          * @throws Exception|DBConnectionError
 123          * @return bool
 124          */
 125         public function open( $server, $user, $password, $dbName ) {
 126                 # Close/unset connection handle
 127                 $this->close();
 128
 129                 $this->mServer = $server;
 130                 $this->mUser = $user;
 131                 $this->mPassword = $password;
 132                 $this->mDBname = $dbName;
 133
 134                 $this->installErrorHandler();
 135                 try {
 136                         $this->mConn = $this->mysqlConnect( $this->mServer );
 137                 } catch ( Exception $ex ) {
 138                         $this->restoreErrorHandler();
 139                         throw $ex;
 140                 }
 141                 $error = $this->restoreErrorHandler();
 142
 143                 # Always log connection errors
 144                 if ( !$this->mConn ) {
 145                         if ( !$error ) {
 146                                 $error = $this->lastError();
 147                         }
 148                         $this->connLogger->error(
 149                                 "Error connecting to {db_server}: {error}",
 150                                 $this->getLogContext( [
 151                                         'method' => __METHOD__,
 152                                         'error' => $error,
 153                                 ] )
 154                         );
 155                         $this->connLogger->debug( "DB connection error\n" .
 156                                 "Server: $server, User: $user, Password: " .
 157                                 substr( $password, 0, 3 ) . "..., error: " . $error . "\n" );
 158
 159                         $this->reportConnectionError( $error );
 160                 }
 161
 162                 if ( $dbName != '' ) {
 163                         MediaWiki\suppressWarnings();
 164                         $success = $this->selectDB( $dbName );
 165                         MediaWiki\restoreWarnings();
 166                         if ( !$success ) {
 167                                 $this->queryLogger->error(
 168                                         "Error selecting database {db_name} on server {db_server}",
 169                                         $this->getLogContext( [
 170                                                 'method' => __METHOD__,
 171                                         ] )
 172                                 );
 173                                 $this->queryLogger->debug(
 174                                         "Error selecting database $dbName on server {$this->mServer}" );
 175
 176                                 $this->reportConnectionError( "Error selecting database $dbName" );
 177                         }
 178                 }
 179
 180                 // Tell the server what we're communicating with
 181                 if ( !$this->connectInitCharset() ) {
 182                         $this->reportConnectionError( "Error setting character set" );
 183                 }
 184
 185                 // Abstract over any insane MySQL defaults
 186                 $set = [ 'group_concat_max_len = 262144' ];
 187                 // Set SQL mode, default is turning them all off, can be overridden or skipped with null
 188                 if ( is_string( $this->sqlMode ) ) {
 189                         $set[] = 'sql_mode = ' . $this->addQuotes( $this->sqlMode );
 190                 }
 191                 // Set any custom settings defined by site config
 192                 // (e.g. https://dev.mysql.com/doc/refman/4.1/en/innodb-parameters.html)
 193                 foreach ( $this->mSessionVars as $var => $val ) {
 194                         // Escape strings but not numbers to avoid MySQL complaining
 195                         if ( !is_int( $val ) && !is_float( $val ) ) {
 196                                 $val = $this->addQuotes( $val );
 197                         }
 198                         $set[] = $this->addIdentifierQuotes( $var ) . ' = ' . $val;
 199                 }
 200
 201                 if ( $set ) {
 202                         // Use doQuery() to avoid opening implicit transactions (DBO_TRX)
 203                         $success = $this->doQuery( 'SET ' . implode( ', ', $set ) );
 204                         if ( !$success ) {
 205                                 $this->queryLogger->error(
 206                                         'Error setting MySQL variables on server {db_server} (check $wgSQLMode)',
 207                                         $this->getLogContext( [
 208                                                 'method' => __METHOD__,
 209                                         ] )
 210                                 );
 211                                 $this->reportConnectionError(
 212                                         'Error setting MySQL variables on server {db_server} (check $wgSQLMode)' );
 213                         }
 214                 }
 215
 216                 $this->mOpened = true;
 217
 218                 return true;
 219         }
 220
 221         /**
 222          * Set the character set information right after connection
 223          * @return bool
 224          */
 225         protected function connectInitCharset() {
 226                 if ( $this->utf8Mode ) {
 227                         // Tell the server we're communicating with it in UTF-8.
 228                         // This may engage various charset conversions.
 229                         return $this->mysqlSetCharset( 'utf8' );
 230                 } else {
 231                         return $this->mysqlSetCharset( 'binary' );
 232                 }
 233         }
 234
 235         /**
 236          * Open a connection to a MySQL server
 237          *
 238          * @param string $realServer
 239          * @return mixed Raw connection
 240          * @throws DBConnectionError
 241          */
 242         abstract protected function mysqlConnect( $realServer );
 243
 244         /**
 245          * Set the character set of the MySQL link
 246          *
 247          * @param string $charset
 248          * @return bool
 249          */
 250         abstract protected function mysqlSetCharset( $charset );
 251
 252         /**
 253          * @param ResultWrapper|resource $res
 254          * @throws DBUnexpectedError
 255          */
 256         public function freeResult( $res ) {
 257                 if ( $res instanceof ResultWrapper ) {
 258                         $res = $res->result;
 259                 }
 260                 MediaWiki\suppressWarnings();
 261                 $ok = $this->mysqlFreeResult( $res );
 262                 MediaWiki\restoreWarnings();
 263                 if ( !$ok ) {
 264                         throw new DBUnexpectedError( $this, "Unable to free MySQL result" );
 265                 }
 266         }
 267
 268         /**
 269          * Free result memory
 270          *
 271          * @param resource $res Raw result
 272          * @return bool
 273          */
 274         abstract protected function mysqlFreeResult( $res );
 275
 276         /**
 277          * @param ResultWrapper|resource $res
 278          * @return stdClass|bool
 279          * @throws DBUnexpectedError
 280          */
 281         public function fetchObject( $res ) {
 282                 if ( $res instanceof ResultWrapper ) {
 283                         $res = $res->result;
 284                 }
 285                 MediaWiki\suppressWarnings();
 286                 $row = $this->mysqlFetchObject( $res );
 287                 MediaWiki\restoreWarnings();
 288
 289                 $errno = $this->lastErrno();
 290                 // Unfortunately, mysql_fetch_object does not reset the last errno.
 291                 // Only check for CR_SERVER_LOST and CR_UNKNOWN_ERROR, as
 292                 // these are the only errors mysql_fetch_object can cause.
 293                 // See https://dev.mysql.com/doc/refman/5.0/en/mysql-fetch-row.html.
 294                 if ( $errno == 2000 || $errno == 2013 ) {
 295                         throw new DBUnexpectedError(
 296                                 $this,
 297                                 'Error in fetchObject(): ' . htmlspecialchars( $this->lastError() )
 298                         );
 299                 }
 300
 301                 return $row;
 302         }
 303
 304         /**
 305          * Fetch a result row as an object
 306          *
 307          * @param resource $res Raw result
 308          * @return stdClass
 309          */
 310         abstract protected function mysqlFetchObject( $res );
 311
 312         /**
 313          * @param ResultWrapper|resource $res
 314          * @return array|bool
 315          * @throws DBUnexpectedError
 316          */
 317         public function fetchRow( $res ) {
 318                 if ( $res instanceof ResultWrapper ) {
 319                         $res = $res->result;
 320                 }
 321                 MediaWiki\suppressWarnings();
 322                 $row = $this->mysqlFetchArray( $res );
 323                 MediaWiki\restoreWarnings();
 324
 325                 $errno = $this->lastErrno();
 326                 // Unfortunately, mysql_fetch_array does not reset the last errno.
 327                 // Only check for CR_SERVER_LOST and CR_UNKNOWN_ERROR, as
 328                 // these are the only errors mysql_fetch_array can cause.
 329                 // See https://dev.mysql.com/doc/refman/5.0/en/mysql-fetch-row.html.
 330                 if ( $errno == 2000 || $errno == 2013 ) {
 331                         throw new DBUnexpectedError(
 332                                 $this,
 333                                 'Error in fetchRow(): ' . htmlspecialchars( $this->lastError() )
 334                         );
 335                 }
 336
 337                 return $row;
 338         }
 339
 340         /**
 341          * Fetch a result row as an associative and numeric array
 342          *
 343          * @param resource $res Raw result
 344          * @return array
 345          */
 346         abstract protected function mysqlFetchArray( $res );
 347
 348         /**
 349          * @throws DBUnexpectedError
 350          * @param ResultWrapper|resource $res
 351          * @return int
 352          */
 353         function numRows( $res ) {
 354                 if ( $res instanceof ResultWrapper ) {
 355                         $res = $res->result;
 356                 }
 357                 MediaWiki\suppressWarnings();
 358                 $n = $this->mysqlNumRows( $res );
 359                 MediaWiki\restoreWarnings();
 360
 361                 // Unfortunately, mysql_num_rows does not reset the last errno.
 362                 // We are not checking for any errors here, since
 363                 // these are no errors mysql_num_rows can cause.
 364                 // See https://dev.mysql.com/doc/refman/5.0/en/mysql-fetch-row.html.
 365                 // See https://phabricator.wikimedia.org/T44430
 366                 return $n;
 367         }
 368
 369         /**
 370          * Get number of rows in result
 371          *
 372          * @param resource $res Raw result
 373          * @return int
 374          */
 375         abstract protected function mysqlNumRows( $res );
 376
 377         /**
 378          * @param ResultWrapper|resource $res
 379          * @return int
 380          */
 381         public function numFields( $res ) {
 382                 if ( $res instanceof ResultWrapper ) {
 383                         $res = $res->result;
 384                 }
 385
 386                 return $this->mysqlNumFields( $res );
 387         }
 388
 389         /**
 390          * Get number of fields in result
 391          *
 392          * @param resource $res Raw result
 393          * @return int
 394          */
 395         abstract protected function mysqlNumFields( $res );
 396
 397         /**
 398          * @param ResultWrapper|resource $res
 399          * @param int $n
 400          * @return string
 401          */
 402         public function fieldName( $res, $n ) {
 403                 if ( $res instanceof ResultWrapper ) {
 404                         $res = $res->result;
 405                 }
 406
 407                 return $this->mysqlFieldName( $res, $n );
 408         }
 409
 410         /**
 411          * Get the name of the specified field in a result
 412          *
 413          * @param ResultWrapper|resource $res
 414          * @param int $n
 415          * @return string
 416          */
 417         abstract protected function mysqlFieldName( $res, $n );
 418
 419         /**
 420          * mysql_field_type() wrapper
 421          * @param ResultWrapper|resource $res
 422          * @param int $n
 423          * @return string
 424          */
 425         public function fieldType( $res, $n ) {
 426                 if ( $res instanceof ResultWrapper ) {
 427                         $res = $res->result;
 428                 }
 429
 430                 return $this->mysqlFieldType( $res, $n );
 431         }
 432
 433         /**
 434          * Get the type of the specified field in a result
 435          *
 436          * @param ResultWrapper|resource $res
 437          * @param int $n
 438          * @return string
 439          */
 440         abstract protected function mysqlFieldType( $res, $n );
 441
 442         /**
 443          * @param ResultWrapper|resource $res
 444          * @param int $row
 445          * @return bool
 446          */
 447         public function dataSeek( $res, $row ) {
 448                 if ( $res instanceof ResultWrapper ) {
 449                         $res = $res->result;
 450                 }
 451
 452                 return $this->mysqlDataSeek( $res, $row );
 453         }
 454
 455         /**
 456          * Move internal result pointer
 457          *
 458          * @param ResultWrapper|resource $res
 459          * @param int $row
 460          * @return bool
 461          */
 462         abstract protected function mysqlDataSeek( $res, $row );
 463
 464         /**
 465          * @return string
 466          */
 467         public function lastError() {
 468                 if ( $this->mConn ) {
 469                         # Even if it's non-zero, it can still be invalid
 470                         MediaWiki\suppressWarnings();
 471                         $error = $this->mysqlError( $this->mConn );
 472                         if ( !$error ) {
 473                                 $error = $this->mysqlError();
 474                         }
 475                         MediaWiki\restoreWarnings();
 476                 } else {
 477                         $error = $this->mysqlError();
 478                 }
 479                 if ( $error ) {
 480                         $error .= ' (' . $this->mServer . ')';
 481                 }
 482
 483                 return $error;
 484         }
 485
 486         /**
 487          * Returns the text of the error message from previous MySQL operation
 488          *
 489          * @param resource $conn Raw connection
 490          * @return string
 491          */
 492         abstract protected function mysqlError( $conn = null );
 493
 494         protected function wasQueryTimeout( $error, $errno ) {
 495                 return $errno == 2062;
 496         }
 497
 498         /**
 499          * @param string $table
 500          * @param array $uniqueIndexes
 501          * @param array $rows
 502          * @param string $fname
 503          * @return ResultWrapper
 504          */
 505         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
 506                 return $this->nativeReplace( $table, $rows, $fname );
 507         }
 508
 509         protected function nativeInsertSelect(
 510                 $destTable, $srcTable, $varMap, $conds,
 511                 $fname = __METHOD__, $insertOptions = [], $selectOptions = [], $selectJoinConds = []
 512         ) {
 513                 if ( $this->insertSelectIsSafe === null ) {
 514                         // In MySQL, an INSERT SELECT is only replication safe with row-based
 515                         // replication or if innodb_autoinc_lock_mode is 0. When those
 516                         // conditions aren't met, use non-native mode.
 517                         // While we could try to determine if the insert is safe anyway by
 518                         // checking if the target table has an auto-increment column that
 519                         // isn't set in $varMap, that seems unlikely to be worth the extra
 520                         // complexity.
 521                         $row = $this->selectRow(
 522                                 false,
 523                                 [
 524                                         'innodb_autoinc_lock_mode' => '@@innodb_autoinc_lock_mode',
 525                                         'binlog_format' => '@@binlog_format',
 526                                 ],
 527                                 [],
 528                                 __METHOD__
 529                         );
 530                         $this->insertSelectIsSafe = $row->binlog_format === 'ROW' ||
 531                                 (int)$row->innodb_autoinc_lock_mode === 0;
 532                 }
 533
 534                 if ( !$this->insertSelectIsSafe ) {
 535                         return $this->nonNativeInsertSelect(
 536                                 $destTable,
 537                                 $srcTable,
 538                                 $varMap,
 539                                 $conds,
 540                                 $fname,
 541                                 $insertOptions,
 542                                 $selectOptions,
 543                                 $selectJoinConds
 544                         );
 545                 } else {
 546                         return parent::nativeInsertSelect(
 547                                 $destTable,
 548                                 $srcTable,
 549                                 $varMap,
 550                                 $conds,
 551                                 $fname,
 552                                 $insertOptions,
 553                                 $selectOptions,
 554                                 $selectJoinConds
 555                         );
 556                 }
 557         }
 558
 559         /**
 560          * Estimate rows in dataset
 561          * Returns estimated count, based on EXPLAIN output
 562          * Takes same arguments as Database::select()
 563          *
 564          * @param string|array $table
 565          * @param string|array $vars
 566          * @param string|array $conds
 567          * @param string $fname
 568          * @param string|array $options
 569          * @return bool|int
 570          */
 571         public function estimateRowCount( $table, $vars = '*', $conds = '',
 572                 $fname = __METHOD__, $options = []
 573         ) {
 574                 $options['EXPLAIN'] = true;
 575                 $res = $this->select( $table, $vars, $conds, $fname, $options );
 576                 if ( $res === false ) {
 577                         return false;
 578                 }
 579                 if ( !$this->numRows( $res ) ) {
 580                         return 0;
 581                 }
 582
 583                 $rows = 1;
 584                 foreach ( $res as $plan ) {
 585                         $rows *= $plan->rows > 0 ? $plan->rows : 1; // avoid resetting to zero
 586                 }
 587
 588                 return (int)$rows;
 589         }
 590
 591         public function tableExists( $table, $fname = __METHOD__ ) {
 592                 // Split database and table into proper variables as Database::tableName() returns
 593                 // shared tables prefixed with their database, which do not work in SHOW TABLES statements
 594                 list( $database, , $prefix, $table ) = $this->qualifiedTableComponents( $table );
 595                 $tableName = "{$prefix}{$table}";
 596
 597                 if ( isset( $this->mSessionTempTables[$tableName] ) ) {
 598                         return true; // already known to exist and won't show in SHOW TABLES anyway
 599                 }
 600
 601                 // We can't use buildLike() here, because it specifies an escape character
 602                 // other than the backslash, which is the only one supported by SHOW TABLES
 603                 $encLike = $this->escapeLikeInternal( $tableName, '\\' );
 604
 605                 // If the database has been specified (such as for shared tables), use "FROM"
 606                 if ( $database !== '' ) {
 607                         $encDatabase = $this->addIdentifierQuotes( $database );
 608                         $query = "SHOW TABLES FROM $encDatabase LIKE '$encLike'";
 609                 } else {
 610                         $query = "SHOW TABLES LIKE '$encLike'";
 611                 }
 612
 613                 return $this->query( $query, $fname )->numRows() > 0;
 614         }
 615
 616         /**
 617          * @param string $table
 618          * @param string $field
 619          * @return bool|MySQLField
 620          */
 621         public function fieldInfo( $table, $field ) {
 622                 $table = $this->tableName( $table );
 623                 $res = $this->query( "SELECT * FROM $table LIMIT 1", __METHOD__, true );
 624                 if ( !$res ) {
 625                         return false;
 626                 }
 627                 $n = $this->mysqlNumFields( $res->result );
 628                 for ( $i = 0; $i < $n; $i++ ) {
 629                         $meta = $this->mysqlFetchField( $res->result, $i );
 630                         if ( $field == $meta->name ) {
 631                                 return new MySQLField( $meta );
 632                         }
 633                 }
 634
 635                 return false;
 636         }
 637
 638         /**
 639          * Get column information from a result
 640          *
 641          * @param resource $res Raw result
 642          * @param int $n
 643          * @return stdClass
 644          */
 645         abstract protected function mysqlFetchField( $res, $n );
 646
 647         /**
 648          * Get information about an index into an object
 649          * Returns false if the index does not exist
 650          *
 651          * @param string $table
 652          * @param string $index
 653          * @param string $fname
 654          * @return bool|array|null False or null on failure
 655          */
 656         public function indexInfo( $table, $index, $fname = __METHOD__ ) {
 657                 # SHOW INDEX works in MySQL 3.23.58, but SHOW INDEXES does not.
 658                 # SHOW INDEX should work for 3.x and up:
 659                 # https://dev.mysql.com/doc/mysql/en/SHOW_INDEX.html
 660                 $table = $this->tableName( $table );
 661                 $index = $this->indexName( $index );
 662
 663                 $sql = 'SHOW INDEX FROM ' . $table;
 664                 $res = $this->query( $sql, $fname );
 665
 666                 if ( !$res ) {
 667                         return null;
 668                 }
 669
 670                 $result = [];
 671
 672                 foreach ( $res as $row ) {
 673                         if ( $row->Key_name == $index ) {
 674                                 $result[] = $row;
 675                         }
 676                 }
 677
 678                 return empty( $result ) ? false : $result;
 679         }
 680
 681         /**
 682          * @param string $s
 683          * @return string
 684          */
 685         public function strencode( $s ) {
 686                 return $this->mysqlRealEscapeString( $s );
 687         }
 688
 689         /**
 690          * @param string $s
 691          * @return mixed
 692          */
 693         abstract protected function mysqlRealEscapeString( $s );
 694
 695         public function addQuotes( $s ) {
 696                 if ( is_bool( $s ) ) {
 697                         // Parent would transform to int, which does not play nice with MySQL type juggling.
 698                         // When searching for an int in a string column, the strings are cast to int, which
 699                         // means false would match any string not starting with a number.
 700                         $s = (string)(int)$s;
 701                 }
 702                 return parent::addQuotes( $s );
 703         }
 704
 705         /**
 706          * MySQL uses `backticks` for identifier quoting instead of the sql standard "double quotes".
 707          *
 708          * @param string $s
 709          * @return string
 710          */
 711         public function addIdentifierQuotes( $s ) {
 712                 // Characters in the range \u0001-\uFFFF are valid in a quoted identifier
 713                 // Remove NUL bytes and escape backticks by doubling
 714                 return '`' . str_replace( [ "\0", '`' ], [ '', '``' ], $s ) . '`';
 715         }
 716
 717         /**
 718          * @param string $name
 719          * @return bool
 720          */
 721         public function isQuotedIdentifier( $name ) {
 722                 return strlen( $name ) && $name[0] == '`' && substr( $name, -1, 1 ) == '`';
 723         }
 724
 725         public function getLag() {
 726                 if ( $this->getLagDetectionMethod() === 'pt-heartbeat' ) {
 727                         return $this->getLagFromPtHeartbeat();
 728                 } else {
 729                         return $this->getLagFromSlaveStatus();
 730                 }
 731         }
 732
 733         /**
 734          * @return string
 735          */
 736         protected function getLagDetectionMethod() {
 737                 return $this->lagDetectionMethod;
 738         }
 739
 740         /**
 741          * @return bool|int
 742          */
 743         protected function getLagFromSlaveStatus() {
 744                 $res = $this->query( 'SHOW SLAVE STATUS', __METHOD__ );
 745                 $row = $res ? $res->fetchObject() : false;
 746                 if ( $row && strval( $row->Seconds_Behind_Master ) !== '' ) {
 747                         return intval( $row->Seconds_Behind_Master );
 748                 }
 749
 750                 return false;
 751         }
 752
 753         /**
 754          * @return bool|float
 755          */
 756         protected function getLagFromPtHeartbeat() {
 757                 $options = $this->lagDetectionOptions;
 758
 759                 if ( isset( $options['conds'] ) ) {
 760                         // Best method for multi-DC setups: use logical channel names
 761                         $data = $this->getHeartbeatData( $options['conds'] );
 762                 } else {
 763                         // Standard method: use master server ID (works with stock pt-heartbeat)
 764                         $masterInfo = $this->getMasterServerInfo();
 765                         if ( !$masterInfo ) {
 766                                 $this->queryLogger->error(
 767                                         "Unable to query master of {db_server} for server ID",
 768                                         $this->getLogContext( [
 769                                                 'method' => __METHOD__
 770                                         ] )
 771                                 );
 772
 773                                 return false; // could not get master server ID
 774                         }
 775
 776                         $conds = [ 'server_id' => intval( $masterInfo['serverId'] ) ];
 777                         $data = $this->getHeartbeatData( $conds );
 778                 }
 779
 780                 list( $time, $nowUnix ) = $data;
 781                 if ( $time !== null ) {
 782                         // @time is in ISO format like "2015-09-25T16:48:10.000510"
 783                         $dateTime = new DateTime( $time, new DateTimeZone( 'UTC' ) );
 784                         $timeUnix = (int)$dateTime->format( 'U' ) + $dateTime->format( 'u' ) / 1e6;
 785
 786                         return max( $nowUnix - $timeUnix, 0.0 );
 787                 }
 788
 789                 $this->queryLogger->error(
 790                         "Unable to find pt-heartbeat row for {db_server}",
 791                         $this->getLogContext( [
 792                                 'method' => __METHOD__
 793                         ] )
 794                 );
 795
 796                 return false;
 797         }
 798
 799         protected function getMasterServerInfo() {
 800                 $cache = $this->srvCache;
 801                 $key = $cache->makeGlobalKey(
 802                         'mysql',
 803                         'master-info',
 804                         // Using one key for all cluster replica DBs is preferable
 805                         $this->getLBInfo( 'clusterMasterHost' ) ?: $this->getServer()
 806                 );
 807
 808                 return $cache->getWithSetCallback(
 809                         $key,
 810                         $cache::TTL_INDEFINITE,
 811                         function () use ( $cache, $key ) {
 812                                 // Get and leave a lock key in place for a short period
 813                                 if ( !$cache->lock( $key, 0, 10 ) ) {
 814                                         return false; // avoid master connection spike slams
 815                                 }
 816
 817                                 $conn = $this->getLazyMasterHandle();
 818                                 if ( !$conn ) {
 819                                         return false; // something is misconfigured
 820                                 }
 821
 822                                 // Connect to and query the master; catch errors to avoid outages
 823                                 try {
 824                                         $res = $conn->query( 'SELECT @@server_id AS id', __METHOD__ );
 825                                         $row = $res ? $res->fetchObject() : false;
 826                                         $id = $row ? (int)$row->id : 0;
 827                                 } catch ( DBError $e ) {
 828                                         $id = 0;
 829                                 }
 830
 831                                 // Cache the ID if it was retrieved
 832                                 return $id ? [ 'serverId' => $id, 'asOf' => time() ] : false;
 833                         }
 834                 );
 835         }
 836
 837         /**
 838          * @param array $conds WHERE clause conditions to find a row
 839          * @return array (heartbeat `ts` column value or null, UNIX timestamp) for the newest beat
 840          * @see https://www.percona.com/doc/percona-toolkit/2.1/pt-heartbeat.html
 841          */
 842         protected function getHeartbeatData( array $conds ) {
 843                 // Query time and trip time are not counted
 844                 $nowUnix = microtime( true );
 845                 // Do not bother starting implicit transactions here
 846                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
 847                 try {
 848                         $whereSQL = $this->makeList( $conds, self::LIST_AND );
 849                         // Use ORDER BY for channel based queries since that field might not be UNIQUE.
 850                         // Note: this would use "TIMESTAMPDIFF(MICROSECOND,ts,UTC_TIMESTAMP(6))" but the
 851                         // percision field is not supported in MySQL <= 5.5.
 852                         $res = $this->query(
 853                                 "SELECT ts FROM heartbeat.heartbeat WHERE $whereSQL ORDER BY ts DESC LIMIT 1"
 854                         );
 855                         $row = $res ? $res->fetchObject() : false;
 856                 } finally {
 857                         $this->restoreFlags();
 858                 }
 859
 860                 return [ $row ? $row->ts : null, $nowUnix ];
 861         }
 862
 863         protected function getApproximateLagStatus() {
 864                 if ( $this->getLagDetectionMethod() === 'pt-heartbeat' ) {
 865                         // Disable caching since this is fast enough and we don't wan't
 866                         // to be *too* pessimistic by having both the cache TTL and the
 867                         // pt-heartbeat interval count as lag in getSessionLagStatus()
 868                         return parent::getApproximateLagStatus();
 869                 }
 870
 871                 $key = $this->srvCache->makeGlobalKey( 'mysql-lag', $this->getServer() );
 872                 $approxLag = $this->srvCache->get( $key );
 873                 if ( !$approxLag ) {
 874                         $approxLag = parent::getApproximateLagStatus();
 875                         $this->srvCache->set( $key, $approxLag, 1 );
 876                 }
 877
 878                 return $approxLag;
 879         }
 880
 881         public function masterPosWait( DBMasterPos $pos, $timeout ) {
 882                 if ( !( $pos instanceof MySQLMasterPos ) ) {
 883                         throw new InvalidArgumentException( "Position not an instance of MySQLMasterPos" );
 884                 }
 885
 886                 if ( $this->getLBInfo( 'is static' ) === true ) {
 887                         return 0; // this is a copy of a read-only dataset with no master DB
 888                 } elseif ( $this->lastKnownReplicaPos && $this->lastKnownReplicaPos->hasReached( $pos ) ) {
 889                         return 0; // already reached this point for sure
 890                 }
 891
 892                 $useGTID = ( $this->useGTIDs && $pos->gtids );
 893
 894                 // Call doQuery() directly, to avoid opening a transaction if DBO_TRX is set
 895                 if ( $useGTID ) {
 896                         // Wait on the GTID set (MariaDB only)
 897                         $gtidArg = $this->addQuotes( implode( ',', $pos->gtids ) );
 898                         $res = $this->doQuery( "SELECT MASTER_GTID_WAIT($gtidArg, $timeout)" );
 899                 } else {
 900                         // Wait on the binlog coordinates
 901                         $encFile = $this->addQuotes( $pos->file );
 902                         $encPos = intval( $pos->pos );
 903                         $res = $this->doQuery( "SELECT MASTER_POS_WAIT($encFile, $encPos, $timeout)" );
 904                 }
 905
 906                 $row = $res ? $this->fetchRow( $res ) : false;
 907                 if ( !$row ) {
 908                         throw new DBExpectedError( $this,
 909                                 "MASTER_POS_WAIT() or MASTER_GTID_WAIT() failed: {$this->lastError()}" );
 910                 }
 911
 912                 // Result can be NULL (error), -1 (timeout), or 0+ per the MySQL manual
 913                 $status = ( $row[0] !== null ) ? intval( $row[0] ) : null;
 914                 if ( $status === null ) {
 915                         if ( !$useGTID ) {
 916                                 // T126436: jobs programmed to wait on master positions might be referencing
 917                                 // binlogs with an old master hostname; this makes MASTER_POS_WAIT() return null.
 918                                 // Try to detect this case and treat the replica DB as having reached the given
 919                                 // position (any master switchover already requires that the new master be caught
 920                                 // up before the switch).
 921                                 $replicationPos = $this->getReplicaPos();
 922                                 if ( $replicationPos && !$replicationPos->channelsMatch( $pos ) ) {
 923                                         $this->lastKnownReplicaPos = $replicationPos;
 924                                         $status = 0;
 925                                 }
 926                         }
 927                 } elseif ( $status >= 0 ) {
 928                         // Remember that this position was reached to save queries next time
 929                         $this->lastKnownReplicaPos = $pos;
 930                 }
 931
 932                 return $status;
 933         }
 934
 935         /**
 936          * Get the position of the master from SHOW SLAVE STATUS
 937          *
 938          * @return MySQLMasterPos|bool
 939          */
 940         public function getReplicaPos() {
 941                 $res = $this->query( 'SHOW SLAVE STATUS', __METHOD__ );
 942                 $row = $this->fetchObject( $res );
 943
 944                 if ( $row ) {
 945                         $pos = isset( $row->Exec_master_log_pos )
 946                                 ? $row->Exec_master_log_pos
 947                                 : $row->Exec_Master_Log_Pos;
 948                         // Also fetch the last-applied GTID set (MariaDB)
 949                         if ( $this->useGTIDs ) {
 950                                 $res = $this->query( "SHOW GLOBAL VARIABLES LIKE 'gtid_slave_pos'", __METHOD__ );
 951                                 $gtidRow = $this->fetchObject( $res );
 952                                 $gtidSet = $gtidRow ? $gtidRow->Value : '';
 953                         } else {
 954                                 $gtidSet = '';
 955                         }
 956
 957                         return new MySQLMasterPos( $row->Relay_Master_Log_File, $pos, $gtidSet );
 958                 } else {
 959                         return false;
 960                 }
 961         }
 962
 963         /**
 964          * Get the position of the master from SHOW MASTER STATUS
 965          *
 966          * @return MySQLMasterPos|bool
 967          */
 968         public function getMasterPos() {
 969                 $res = $this->query( 'SHOW MASTER STATUS', __METHOD__ );
 970                 $row = $this->fetchObject( $res );
 971
 972                 if ( $row ) {
 973                         // Also fetch the last-written GTID set (MariaDB)
 974                         if ( $this->useGTIDs ) {
 975                                 $res = $this->query( "SHOW GLOBAL VARIABLES LIKE 'gtid_binlog_pos'", __METHOD__ );
 976                                 $gtidRow = $this->fetchObject( $res );
 977                                 $gtidSet = $gtidRow ? $gtidRow->Value : '';
 978                         } else {
 979                                 $gtidSet = '';
 980                         }
 981
 982                         return new MySQLMasterPos( $row->File, $row->Position, $gtidSet );
 983                 } else {
 984                         return false;
 985                 }
 986         }
 987
 988         public function serverIsReadOnly() {
 989                 $res = $this->query( "SHOW GLOBAL VARIABLES LIKE 'read_only'", __METHOD__ );
 990                 $row = $this->fetchObject( $res );
 991
 992                 return $row ? ( strtolower( $row->Value ) === 'on' ) : false;
 993         }
 994
 995         /**
 996          * @param string $index
 997          * @return string
 998          */
 999         function useIndexClause( $index ) {
1000                 return "FORCE INDEX (" . $this->indexName( $index ) . ")";
1001         }
1002
1003         /**
1004          * @param string $index
1005          * @return string
1006          */
1007         function ignoreIndexClause( $index ) {
1008                 return "IGNORE INDEX (" . $this->indexName( $index ) . ")";
1009         }
1010
1011         /**
1012          * @return string
1013          */
1014         function lowPriorityOption() {
1015                 return 'LOW_PRIORITY';
1016         }
1017
1018         /**
1019          * @return string
1020          */
1021         public function getSoftwareLink() {
1022                 // MariaDB includes its name in its version string; this is how MariaDB's version of
1023                 // the mysql command-line client identifies MariaDB servers (see mariadb_connection()
1024                 // in libmysql/libmysql.c).
1025                 $version = $this->getServerVersion();
1026                 if ( strpos( $version, 'MariaDB' ) !== false || strpos( $version, '-maria-' ) !== false ) {
1027                         return '[{{int:version-db-mariadb-url}} MariaDB]';
1028                 }
1029
1030                 // Percona Server's version suffix is not very distinctive, and @@version_comment
1031                 // doesn't give the necessary info for source builds, so assume the server is MySQL.
1032                 // (Even Percona's version of mysql doesn't try to make the distinction.)
1033                 return '[{{int:version-db-mysql-url}} MySQL]';
1034         }
1035
1036         /**
1037          * @return string
1038          */
1039         public function getServerVersion() {
1040                 // Not using mysql_get_server_info() or similar for consistency: in the handshake,
1041                 // MariaDB 10 adds the prefix "5.5.5-", and only some newer client libraries strip
1042                 // it off (see RPL_VERSION_HACK in include/mysql_com.h).
1043                 if ( $this->serverVersion === null ) {
1044                         $this->serverVersion = $this->selectField( '', 'VERSION()', '', __METHOD__ );
1045                 }
1046                 return $this->serverVersion;
1047         }
1048
1049         /**
1050          * @param array $options
1051          */
1052         public function setSessionOptions( array $options ) {
1053                 if ( isset( $options['connTimeout'] ) ) {
1054                         $timeout = (int)$options['connTimeout'];
1055                         $this->query( "SET net_read_timeout=$timeout" );
1056                         $this->query( "SET net_write_timeout=$timeout" );
1057                 }
1058         }
1059
1060         /**
1061          * @param string &$sql
1062          * @param string &$newLine
1063          * @return bool
1064          */
1065         public function streamStatementEnd( &$sql, &$newLine ) {
1066                 if ( strtoupper( substr( $newLine, 0, 9 ) ) == 'DELIMITER' ) {
1067                         preg_match( '/^DELIMITER\s+(\S+)/', $newLine, $m );
1068                         $this->delimiter = $m[1];
1069                         $newLine = '';
1070                 }
1071
1072                 return parent::streamStatementEnd( $sql, $newLine );
1073         }
1074
1075         /**
1076          * Check to see if a named lock is available. This is non-blocking.
1077          *
1078          * @param string $lockName Name of lock to poll
1079          * @param string $method Name of method calling us
1080          * @return bool
1081          * @since 1.20
1082          */
1083         public function lockIsFree( $lockName, $method ) {
1084                 $encName = $this->addQuotes( $this->makeLockName( $lockName ) );
1085                 $result = $this->query( "SELECT IS_FREE_LOCK($encName) AS lockstatus", $method );
1086                 $row = $this->fetchObject( $result );
1087
1088                 return ( $row->lockstatus == 1 );
1089         }
1090
1091         /**
1092          * @param string $lockName
1093          * @param string $method
1094          * @param int $timeout
1095          * @return bool
1096          */
1097         public function lock( $lockName, $method, $timeout = 5 ) {
1098                 $encName = $this->addQuotes( $this->makeLockName( $lockName ) );
1099                 $result = $this->query( "SELECT GET_LOCK($encName, $timeout) AS lockstatus", $method );
1100                 $row = $this->fetchObject( $result );
1101
1102                 if ( $row->lockstatus == 1 ) {
1103                         parent::lock( $lockName, $method, $timeout ); // record
1104                         return true;
1105                 }
1106
1107                 $this->queryLogger->info( __METHOD__ . " failed to acquire lock '{lockname}'",
1108                         [ 'lockname' => $lockName ] );
1109
1110                 return false;
1111         }
1112
1113         /**
1114          * FROM MYSQL DOCS:
1115          * https://dev.mysql.com/doc/refman/5.0/en/miscellaneous-functions.html#function_release-lock
1116          * @param string $lockName
1117          * @param string $method
1118          * @return bool
1119          */
1120         public function unlock( $lockName, $method ) {
1121                 $encName = $this->addQuotes( $this->makeLockName( $lockName ) );
1122                 $result = $this->query( "SELECT RELEASE_LOCK($encName) as lockstatus", $method );
1123                 $row = $this->fetchObject( $result );
1124
1125                 if ( $row->lockstatus == 1 ) {
1126                         parent::unlock( $lockName, $method ); // record
1127                         return true;
1128                 }
1129
1130                 $this->queryLogger->warning( __METHOD__ . " failed to release lock '$lockName'\n" );
1131
1132                 return false;
1133         }
1134
1135         private function makeLockName( $lockName ) {
1136                 // https://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html#function_get-lock
1137                 // Newer version enforce a 64 char length limit.
1138                 return ( strlen( $lockName ) > 64 ) ? sha1( $lockName ) : $lockName;
1139         }
1140
1141         public function namedLocksEnqueue() {
1142                 return true;
1143         }
1144
1145         public function tableLocksHaveTransactionScope() {
1146                 return false; // tied to TCP connection
1147         }
1148
1149         protected function doLockTables( array $read, array $write, $method ) {
1150                 $items = [];
1151                 foreach ( $write as $table ) {
1152                         $items[] = $this->tableName( $table ) . ' WRITE';
1153                 }
1154                 foreach ( $read as $table ) {
1155                         $items[] = $this->tableName( $table ) . ' READ';
1156                 }
1157
1158                 $sql = "LOCK TABLES " . implode( ',', $items );
1159                 $this->query( $sql, $method );
1160
1161                 return true;
1162         }
1163
1164         protected function doUnlockTables( $method ) {
1165                 $this->query( "UNLOCK TABLES", $method );
1166
1167                 return true;
1168         }
1169
1170         /**
1171          * @param bool $value
1172          */
1173         public function setBigSelects( $value = true ) {
1174                 if ( $value === 'default' ) {
1175                         if ( $this->mDefaultBigSelects === null ) {
1176                                 # Function hasn't been called before so it must already be set to the default
1177                                 return;
1178                         } else {
1179                                 $value = $this->mDefaultBigSelects;
1180                         }
1181                 } elseif ( $this->mDefaultBigSelects === null ) {
1182                         $this->mDefaultBigSelects =
1183                                 (bool)$this->selectField( false, '@@sql_big_selects', '', __METHOD__ );
1184                 }
1185                 $encValue = $value ? '1' : '0';
1186                 $this->query( "SET sql_big_selects=$encValue", __METHOD__ );
1187         }
1188
1189         /**
1190          * DELETE where the condition is a join. MySql uses multi-table deletes.
1191          * @param string $delTable
1192          * @param string $joinTable
1193          * @param string $delVar
1194          * @param string $joinVar
1195          * @param array|string $conds
1196          * @param bool|string $fname
1197          * @throws DBUnexpectedError
1198          * @return bool|ResultWrapper
1199          */
1200         public function deleteJoin(
1201                 $delTable, $joinTable, $delVar, $joinVar, $conds, $fname = __METHOD__
1202         ) {
1203                 if ( !$conds ) {
1204                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
1205                 }
1206
1207                 $delTable = $this->tableName( $delTable );
1208                 $joinTable = $this->tableName( $joinTable );
1209                 $sql = "DELETE $delTable FROM $delTable, $joinTable WHERE $delVar=$joinVar ";
1210
1211                 if ( $conds != '*' ) {
1212                         $sql .= ' AND ' . $this->makeList( $conds, self::LIST_AND );
1213                 }
1214
1215                 return $this->query( $sql, $fname );
1216         }
1217
1218         /**
1219          * @param string $table
1220          * @param array $rows
1221          * @param array $uniqueIndexes
1222          * @param array $set
1223          * @param string $fname
1224          * @return bool
1225          */
1226         public function upsert( $table, array $rows, array $uniqueIndexes,
1227                 array $set, $fname = __METHOD__
1228         ) {
1229                 if ( !count( $rows ) ) {
1230                         return true; // nothing to do
1231                 }
1232
1233                 if ( !is_array( reset( $rows ) ) ) {
1234                         $rows = [ $rows ];
1235                 }
1236
1237                 $table = $this->tableName( $table );
1238                 $columns = array_keys( $rows[0] );
1239
1240                 $sql = "INSERT INTO $table (" . implode( ',', $columns ) . ') VALUES ';
1241                 $rowTuples = [];
1242                 foreach ( $rows as $row ) {
1243                         $rowTuples[] = '(' . $this->makeList( $row ) . ')';
1244                 }
1245                 $sql .= implode( ',', $rowTuples );
1246                 $sql .= " ON DUPLICATE KEY UPDATE " . $this->makeList( $set, self::LIST_SET );
1247
1248                 return (bool)$this->query( $sql, $fname );
1249         }
1250
1251         /**
1252          * Determines how long the server has been up
1253          *
1254          * @return int
1255          */
1256         public function getServerUptime() {
1257                 $vars = $this->getMysqlStatus( 'Uptime' );
1258
1259                 return (int)$vars['Uptime'];
1260         }
1261
1262         /**
1263          * Determines if the last failure was due to a deadlock
1264          *
1265          * @return bool
1266          */
1267         public function wasDeadlock() {
1268                 return $this->lastErrno() == 1213;
1269         }
1270
1271         /**
1272          * Determines if the last failure was due to a lock timeout
1273          *
1274          * @return bool
1275          */
1276         public function wasLockTimeout() {
1277                 return $this->lastErrno() == 1205;
1278         }
1279
1280         public function wasErrorReissuable() {
1281                 return $this->lastErrno() == 2013 || $this->lastErrno() == 2006;
1282         }
1283
1284         /**
1285          * Determines if the last failure was due to the database being read-only.
1286          *
1287          * @return bool
1288          */
1289         public function wasReadOnlyError() {
1290                 return $this->lastErrno() == 1223 ||
1291                         ( $this->lastErrno() == 1290 && strpos( $this->lastError(), '--read-only' ) !== false );
1292         }
1293
1294         public function wasConnectionError( $errno ) {
1295                 return $errno == 2013 || $errno == 2006;
1296         }
1297
1298         /**
1299          * @param string $oldName
1300          * @param string $newName
1301          * @param bool $temporary
1302          * @param string $fname
1303          * @return bool
1304          */
1305         public function duplicateTableStructure(
1306                 $oldName, $newName, $temporary = false, $fname = __METHOD__
1307         ) {
1308                 $tmp = $temporary ? 'TEMPORARY ' : '';
1309                 $newName = $this->addIdentifierQuotes( $newName );
1310                 $oldName = $this->addIdentifierQuotes( $oldName );
1311                 $query = "CREATE $tmp TABLE $newName (LIKE $oldName)";
1312
1313                 return $this->query( $query, $fname );
1314         }
1315
1316         /**
1317          * List all tables on the database
1318          *
1319          * @param string $prefix Only show tables with this prefix, e.g. mw_
1320          * @param string $fname Calling function name
1321          * @return array
1322          */
1323         public function listTables( $prefix = null, $fname = __METHOD__ ) {
1324                 $result = $this->query( "SHOW TABLES", $fname );
1325
1326                 $endArray = [];
1327
1328                 foreach ( $result as $table ) {
1329                         $vars = get_object_vars( $table );
1330                         $table = array_pop( $vars );
1331
1332                         if ( !$prefix || strpos( $table, $prefix ) === 0 ) {
1333                                 $endArray[] = $table;
1334                         }
1335                 }
1336
1337                 return $endArray;
1338         }
1339
1340         /**
1341          * @param string $tableName
1342          * @param string $fName
1343          * @return bool|ResultWrapper
1344          */
1345         public function dropTable( $tableName, $fName = __METHOD__ ) {
1346                 if ( !$this->tableExists( $tableName, $fName ) ) {
1347                         return false;
1348                 }
1349
1350                 return $this->query( "DROP TABLE IF EXISTS " . $this->tableName( $tableName ), $fName );
1351         }
1352
1353         /**
1354          * Get status information from SHOW STATUS in an associative array
1355          *
1356          * @param string $which
1357          * @return array
1358          */
1359         private function getMysqlStatus( $which = "%" ) {
1360                 $res = $this->query( "SHOW STATUS LIKE '{$which}'" );
1361                 $status = [];
1362
1363                 foreach ( $res as $row ) {
1364                         $status[$row->Variable_name] = $row->Value;
1365                 }
1366
1367                 return $status;
1368         }
1369
1370         /**
1371          * Lists VIEWs in the database
1372          *
1373          * @param string $prefix Only show VIEWs with this prefix, eg.
1374          * unit_test_, or $wgDBprefix. Default: null, would return all views.
1375          * @param string $fname Name of calling function
1376          * @return array
1377          * @since 1.22
1378          */
1379         public function listViews( $prefix = null, $fname = __METHOD__ ) {
1380                 // The name of the column containing the name of the VIEW
1381                 $propertyName = 'Tables_in_' . $this->mDBname;
1382
1383                 // Query for the VIEWS
1384                 $res = $this->query( 'SHOW FULL TABLES WHERE TABLE_TYPE = "VIEW"' );
1385                 $allViews = [];
1386                 foreach ( $res as $row ) {
1387                         array_push( $allViews, $row->$propertyName );
1388                 }
1389
1390                 if ( is_null( $prefix ) || $prefix === '' ) {
1391                         return $allViews;
1392                 }
1393
1394                 $filteredViews = [];
1395                 foreach ( $allViews as $viewName ) {
1396                         // Does the name of this VIEW start with the table-prefix?
1397                         if ( strpos( $viewName, $prefix ) === 0 ) {
1398                                 array_push( $filteredViews, $viewName );
1399                         }
1400                 }
1401
1402                 return $filteredViews;
1403         }
1404
1405         /**
1406          * Differentiates between a TABLE and a VIEW.
1407          *
1408          * @param string $name Name of the TABLE/VIEW to test
1409          * @param string $prefix
1410          * @return bool
1411          * @since 1.22
1412          */
1413         public function isView( $name, $prefix = null ) {
1414                 return in_array( $name, $this->listViews( $prefix ) );
1415         }
1416
1417         /**
1418          * Allows for index remapping in queries where this is not consistent across DBMS
1419          *
1420          * @param string $index
1421          * @return string
1422          */
1423         protected function indexName( $index ) {
1424                 /**
1425                  * When SQLite indexes were introduced in r45764, it was noted that
1426                  * SQLite requires index names to be unique within the whole database,
1427                  * not just within a schema. As discussed in CR r45819, to avoid the
1428                  * need for a schema change on existing installations, the indexes
1429                  * were implicitly mapped from the new names to the old names.
1430                  *
1431                  * This mapping can be removed if DB patches are introduced to alter
1432                  * the relevant tables in existing installations. Note that because
1433                  * this index mapping applies to table creation, even new installations
1434                  * of MySQL have the old names (except for installations created during
1435                  * a period where this mapping was inappropriately removed, see
1436                  * T154872).
1437                  */
1438                 $renamed = [
1439                         'ar_usertext_timestamp' => 'usertext_timestamp',
1440                         'un_user_id' => 'user_id',
1441                         'un_user_ip' => 'user_ip',
1442                 ];
1443
1444                 if ( isset( $renamed[$index] ) ) {
1445                         return $renamed[$index];
1446                 } else {
1447                         return $index;
1448                 }
1449         }
1450 }
1451
1452 class_alias( DatabaseMysqlBase::class, 'DatabaseMysqlBase' );