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