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 Wikimedia;
  28 use InvalidArgumentException;
  29 use Exception;
  30 use RuntimeException;
  31 use stdClass;
  32
  33 /**
  34  * Database abstraction object for MySQL.
  35  * Defines methods independent on used MySQL extension.
  36  *
  37  * @ingroup Database
  38  * @since 1.22
  39  * @see Database
  40  */
  41 abstract class DatabaseMysqlBase extends Database {
  42         /** @var MysqlMasterPos */
  43         protected $lastKnownReplicaPos;
  44         /** @var string Method to detect replica DB lag */
  45         protected $lagDetectionMethod;
  46         /** @var array Method to detect replica DB lag */
  47         protected $lagDetectionOptions = [];
  48         /** @var bool bool Whether to use GTID methods */
  49         protected $useGTIDs = false;
  50         /** @var string|null */
  51         protected $sslKeyPath;
  52         /** @var string|null */
  53         protected $sslCertPath;
  54         /** @var string|null */
  55         protected $sslCAFile;
  56         /** @var string|null */
  57         protected $sslCAPath;
  58         /** @var string[]|null */
  59         protected $sslCiphers;
  60         /** @var string sql_mode value to send on connection */
  61         protected $sqlMode;
  62         /** @var bool Use experimental UTF-8 transmission encoding */
  63         protected $utf8Mode;
  64         /** @var bool|null */
  65         protected $defaultBigSelects = null;
  66
  67         /** @var string|null */
  68         private $serverVersion = null;
  69         /** @var bool|null */
  70         private $insertSelectIsSafe = null;
  71         /** @var stdClass|null */
  72         private $replicationInfoRow = null;
  73
  74         // Cache getServerId() for 24 hours
  75         const SERVER_ID_CACHE_TTL = 86400;
  76
  77         /** @var float Warn if lag estimates are made for transactions older than this many seconds */
  78         const LAG_STALE_WARN_THRESHOLD = 0.100;
  79
  80         /**
  81          * Additional $params include:
  82          *   - lagDetectionMethod : set to one of (Seconds_Behind_Master,pt-heartbeat).
  83          *       pt-heartbeat assumes the table is at heartbeat.heartbeat
  84          *       and uses UTC timestamps in the heartbeat.ts column.
  85          *       (https://www.percona.com/doc/percona-toolkit/2.2/pt-heartbeat.html)
  86          *   - lagDetectionOptions : if using pt-heartbeat, this can be set to an array map to change
  87          *       the default behavior. Normally, the heartbeat row with the server
  88          *       ID of this server's master will be used. Set the "conds" field to
  89          *       override the query conditions, e.g. ['shard' => 's1'].
  90          *   - useGTIDs : use GTID methods like MASTER_GTID_WAIT() when possible.
  91          *   - insertSelectIsSafe : force that native INSERT SELECT is or is not safe [default: null]
  92          *   - sslKeyPath : path to key file [default: null]
  93          *   - sslCertPath : path to certificate file [default: null]
  94          *   - sslCAFile: path to a single certificate authority PEM file [default: null]
  95          *   - sslCAPath : parth to certificate authority PEM directory [default: null]
  96          *   - sslCiphers : array list of allowable ciphers [default: null]
  97          * @param array $params
  98          */
  99         function __construct( array $params ) {
 100                 $this->lagDetectionMethod = $params['lagDetectionMethod'] ?? 'Seconds_Behind_Master';
 101                 $this->lagDetectionOptions = $params['lagDetectionOptions'] ?? [];
 102                 $this->useGTIDs = !empty( $params['useGTIDs' ] );
 103                 foreach ( [ 'KeyPath', 'CertPath', 'CAFile', 'CAPath', 'Ciphers' ] as $name ) {
 104                         $var = "ssl{$name}";
 105                         if ( isset( $params[$var] ) ) {
 106                                 $this->$var = $params[$var];
 107                         }
 108                 }
 109                 $this->sqlMode = $params['sqlMode'] ?? null;
 110                 $this->utf8Mode = !empty( $params['utf8Mode'] );
 111                 $this->insertSelectIsSafe = isset( $params['insertSelectIsSafe'] )
 112                         ? (bool)$params['insertSelectIsSafe'] : null;
 113
 114                 parent::__construct( $params );
 115         }
 116
 117         /**
 118          * @return string
 119          */
 120         public function getType() {
 121                 return 'mysql';
 122         }
 123
 124         protected function open( $server, $user, $password, $dbName, $schema, $tablePrefix ) {
 125                 # Close/unset connection handle
 126                 $this->close();
 127
 128                 $this->server = $server;
 129                 $this->user = $user;
 130                 $this->password = $password;
 131
 132                 $this->installErrorHandler();
 133                 try {
 134                         $this->conn = $this->mysqlConnect( $this->server, $dbName );
 135                 } catch ( Exception $ex ) {
 136                         $this->restoreErrorHandler();
 137                         throw $ex;
 138                 }
 139                 $error = $this->restoreErrorHandler();
 140
 141                 # Always log connection errors
 142                 if ( !$this->conn ) {
 143                         $error = $error ?: $this->lastError();
 144                         $this->connLogger->error(
 145                                 "Error connecting to {db_server}: {error}",
 146                                 $this->getLogContext( [
 147                                         'method' => __METHOD__,
 148                                         'error' => $error,
 149                                 ] )
 150                         );
 151                         $this->connLogger->debug( "DB connection error\n" .
 152                                 "Server: $server, User: $user, Password: " .
 153                                 substr( $password, 0, 3 ) . "..., error: " . $error . "\n" );
 154
 155                         throw new DBConnectionError( $this, $error );
 156                 }
 157
 158                 if ( strlen( $dbName ) ) {
 159                         $this->selectDomain( new DatabaseDomain( $dbName, null, $tablePrefix ) );
 160                 } else {
 161                         $this->currentDomain = new DatabaseDomain( null, null, $tablePrefix );
 162                 }
 163
 164                 // Tell the server what we're communicating with
 165                 if ( !$this->connectInitCharset() ) {
 166                         $error = $this->lastError();
 167                         $this->queryLogger->error(
 168                                 "Error setting character set: {error}",
 169                                 $this->getLogContext( [
 170                                         'method' => __METHOD__,
 171                                         'error' => $this->lastError(),
 172                                 ] )
 173                         );
 174                         throw new DBConnectionError( $this, "Error setting character set: $error" );
 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->connectionVariables 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                                 $error = $this->lastError();
 198                                 $this->queryLogger->error(
 199                                         'Error setting MySQL variables on server {db_server}: {error}',
 200                                         $this->getLogContext( [
 201                                                 'method' => __METHOD__,
 202                                                 'error' => $error,
 203                                         ] )
 204                                 );
 205                                 throw new DBConnectionError( $this, "Error setting MySQL variables: $error" );
 206                         }
 207                 }
 208
 209                 $this->opened = true;
 210
 211                 return true;
 212         }
 213
 214         /**
 215          * Set the character set information right after connection
 216          * @return bool
 217          */
 218         protected function connectInitCharset() {
 219                 if ( $this->utf8Mode ) {
 220                         // Tell the server we're communicating with it in UTF-8.
 221                         // This may engage various charset conversions.
 222                         return $this->mysqlSetCharset( 'utf8' );
 223                 } else {
 224                         return $this->mysqlSetCharset( 'binary' );
 225                 }
 226         }
 227
 228         protected function doSelectDomain( DatabaseDomain $domain ) {
 229                 if ( $domain->getSchema() !== null ) {
 230                         throw new DBExpectedError( $this, __CLASS__ . ": domain schemas are not supported." );
 231                 }
 232
 233                 $database = $domain->getDatabase();
 234                 // A null database means "don't care" so leave it as is and update the table prefix
 235                 if ( $database === null ) {
 236                         $this->currentDomain = new DatabaseDomain(
 237                                 $this->currentDomain->getDatabase(),
 238                                 null,
 239                                 $domain->getTablePrefix()
 240                         );
 241
 242                         return true;
 243                 }
 244
 245                 if ( $database !== $this->getDBname() ) {
 246                         $sql = 'USE ' . $this->addIdentifierQuotes( $database );
 247                         list( $res, $err, $errno ) =
 248                                 $this->executeQuery( $sql, __METHOD__, self::QUERY_IGNORE_DBO_TRX );
 249
 250                         if ( $res === false ) {
 251                                 $this->reportQueryError( $err, $errno, $sql, __METHOD__ );
 252                                 return false; // unreachable
 253                         }
 254                 }
 255
 256                 // Update that domain fields on success (no exception thrown)
 257                 $this->currentDomain = $domain;
 258
 259                 return true;
 260         }
 261
 262         /**
 263          * Open a connection to a MySQL server
 264          *
 265          * @param string $realServer
 266          * @param string|null $dbName
 267          * @return mixed Raw connection
 268          * @throws DBConnectionError
 269          */
 270         abstract protected function mysqlConnect( $realServer, $dbName );
 271
 272         /**
 273          * Set the character set of the MySQL link
 274          *
 275          * @param string $charset
 276          * @return bool
 277          */
 278         abstract protected function mysqlSetCharset( $charset );
 279
 280         /**
 281          * @param IResultWrapper|resource $res
 282          * @throws DBUnexpectedError
 283          */
 284         public function freeResult( $res ) {
 285                 if ( $res instanceof ResultWrapper ) {
 286                         $res = $res->result;
 287                 }
 288                 Wikimedia\suppressWarnings();
 289                 $ok = $this->mysqlFreeResult( $res );
 290                 Wikimedia\restoreWarnings();
 291                 if ( !$ok ) {
 292                         throw new DBUnexpectedError( $this, "Unable to free MySQL result" );
 293                 }
 294         }
 295
 296         /**
 297          * Free result memory
 298          *
 299          * @param resource $res Raw result
 300          * @return bool
 301          */
 302         abstract protected function mysqlFreeResult( $res );
 303
 304         /**
 305          * @param IResultWrapper|resource $res
 306          * @return stdClass|bool
 307          * @throws DBUnexpectedError
 308          */
 309         public function fetchObject( $res ) {
 310                 if ( $res instanceof ResultWrapper ) {
 311                         $res = $res->result;
 312                 }
 313                 Wikimedia\suppressWarnings();
 314                 $row = $this->mysqlFetchObject( $res );
 315                 Wikimedia\restoreWarnings();
 316
 317                 $errno = $this->lastErrno();
 318                 // Unfortunately, mysql_fetch_object 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_object 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 fetchObject(): ' . htmlspecialchars( $this->lastError() )
 326                         );
 327                 }
 328
 329                 return $row;
 330         }
 331
 332         /**
 333          * Fetch a result row as an object
 334          *
 335          * @param resource $res Raw result
 336          * @return stdClass
 337          */
 338         abstract protected function mysqlFetchObject( $res );
 339
 340         /**
 341          * @param IResultWrapper|resource $res
 342          * @return array|bool
 343          * @throws DBUnexpectedError
 344          */
 345         public function fetchRow( $res ) {
 346                 if ( $res instanceof ResultWrapper ) {
 347                         $res = $res->result;
 348                 }
 349                 Wikimedia\suppressWarnings();
 350                 $row = $this->mysqlFetchArray( $res );
 351                 Wikimedia\restoreWarnings();
 352
 353                 $errno = $this->lastErrno();
 354                 // Unfortunately, mysql_fetch_array does not reset the last errno.
 355                 // Only check for CR_SERVER_LOST and CR_UNKNOWN_ERROR, as
 356                 // these are the only errors mysql_fetch_array can cause.
 357                 // See https://dev.mysql.com/doc/refman/5.0/en/mysql-fetch-row.html.
 358                 if ( $errno == 2000 || $errno == 2013 ) {
 359                         throw new DBUnexpectedError(
 360                                 $this,
 361                                 'Error in fetchRow(): ' . htmlspecialchars( $this->lastError() )
 362                         );
 363                 }
 364
 365                 return $row;
 366         }
 367
 368         /**
 369          * Fetch a result row as an associative and numeric array
 370          *
 371          * @param resource $res Raw result
 372          * @return array|false
 373          */
 374         abstract protected function mysqlFetchArray( $res );
 375
 376         /**
 377          * @throws DBUnexpectedError
 378          * @param IResultWrapper|resource $res
 379          * @return int
 380          */
 381         function numRows( $res ) {
 382                 if ( $res instanceof ResultWrapper ) {
 383                         $res = $res->result;
 384                 }
 385                 Wikimedia\suppressWarnings();
 386                 $n = !is_bool( $res ) ? $this->mysqlNumRows( $res ) : 0;
 387                 Wikimedia\restoreWarnings();
 388
 389                 // Unfortunately, mysql_num_rows does not reset the last errno.
 390                 // We are not checking for any errors here, since
 391                 // there are no errors mysql_num_rows can cause.
 392                 // See https://dev.mysql.com/doc/refman/5.0/en/mysql-fetch-row.html.
 393                 // See https://phabricator.wikimedia.org/T44430
 394                 return $n;
 395         }
 396
 397         /**
 398          * Get number of rows in result
 399          *
 400          * @param resource $res Raw result
 401          * @return int
 402          */
 403         abstract protected function mysqlNumRows( $res );
 404
 405         /**
 406          * @param IResultWrapper|resource $res
 407          * @return int
 408          */
 409         public function numFields( $res ) {
 410                 if ( $res instanceof ResultWrapper ) {
 411                         $res = $res->result;
 412                 }
 413
 414                 return $this->mysqlNumFields( $res );
 415         }
 416
 417         /**
 418          * Get number of fields in result
 419          *
 420          * @param resource $res Raw result
 421          * @return int
 422          */
 423         abstract protected function mysqlNumFields( $res );
 424
 425         /**
 426          * @param IResultWrapper|resource $res
 427          * @param int $n
 428          * @return string
 429          */
 430         public function fieldName( $res, $n ) {
 431                 if ( $res instanceof ResultWrapper ) {
 432                         $res = $res->result;
 433                 }
 434
 435                 return $this->mysqlFieldName( $res, $n );
 436         }
 437
 438         /**
 439          * Get the name of the specified field in a result
 440          *
 441          * @param IResultWrapper|resource $res
 442          * @param int $n
 443          * @return string
 444          */
 445         abstract protected function mysqlFieldName( $res, $n );
 446
 447         /**
 448          * mysql_field_type() wrapper
 449          * @param IResultWrapper|resource $res
 450          * @param int $n
 451          * @return string
 452          */
 453         public function fieldType( $res, $n ) {
 454                 if ( $res instanceof ResultWrapper ) {
 455                         $res = $res->result;
 456                 }
 457
 458                 return $this->mysqlFieldType( $res, $n );
 459         }
 460
 461         /**
 462          * Get the type of the specified field in a result
 463          *
 464          * @param IResultWrapper|resource $res
 465          * @param int $n
 466          * @return string
 467          */
 468         abstract protected function mysqlFieldType( $res, $n );
 469
 470         /**
 471          * @param IResultWrapper|resource $res
 472          * @param int $row
 473          * @return bool
 474          */
 475         public function dataSeek( $res, $row ) {
 476                 if ( $res instanceof ResultWrapper ) {
 477                         $res = $res->result;
 478                 }
 479
 480                 return $this->mysqlDataSeek( $res, $row );
 481         }
 482
 483         /**
 484          * Move internal result pointer
 485          *
 486          * @param IResultWrapper|resource $res
 487          * @param int $row
 488          * @return bool
 489          */
 490         abstract protected function mysqlDataSeek( $res, $row );
 491
 492         /**
 493          * @return string
 494          */
 495         public function lastError() {
 496                 if ( $this->conn ) {
 497                         # Even if it's non-zero, it can still be invalid
 498                         Wikimedia\suppressWarnings();
 499                         $error = $this->mysqlError( $this->conn );
 500                         if ( !$error ) {
 501                                 $error = $this->mysqlError();
 502                         }
 503                         Wikimedia\restoreWarnings();
 504                 } else {
 505                         $error = $this->mysqlError();
 506                 }
 507                 if ( $error ) {
 508                         $error .= ' (' . $this->server . ')';
 509                 }
 510
 511                 return $error;
 512         }
 513
 514         /**
 515          * Returns the text of the error message from previous MySQL operation
 516          *
 517          * @param resource|null $conn Raw connection
 518          * @return string
 519          */
 520         abstract protected function mysqlError( $conn = null );
 521
 522         protected function wasQueryTimeout( $error, $errno ) {
 523                 // https://dev.mysql.com/doc/refman/8.0/en/client-error-reference.html
 524                 // https://phabricator.wikimedia.org/T170638
 525                 return in_array( $errno, [ 2062, 3024 ] );
 526         }
 527
 528         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
 529                 $this->nativeReplace( $table, $rows, $fname );
 530         }
 531
 532         protected function isInsertSelectSafe( array $insertOptions, array $selectOptions ) {
 533                 $row = $this->getReplicationSafetyInfo();
 534                 // For row-based-replication, the resulting changes will be relayed, not the query
 535                 if ( $row->binlog_format === 'ROW' ) {
 536                         return true;
 537                 }
 538                 // LIMIT requires ORDER BY on a unique key or it is non-deterministic
 539                 if ( isset( $selectOptions['LIMIT'] ) ) {
 540                         return false;
 541                 }
 542                 // In MySQL, an INSERT SELECT is only replication safe with row-based
 543                 // replication or if innodb_autoinc_lock_mode is 0. When those
 544                 // conditions aren't met, use non-native mode.
 545                 // While we could try to determine if the insert is safe anyway by
 546                 // checking if the target table has an auto-increment column that
 547                 // isn't set in $varMap, that seems unlikely to be worth the extra
 548                 // complexity.
 549                 return (
 550                         in_array( 'NO_AUTO_COLUMNS', $insertOptions ) ||
 551                         (int)$row->innodb_autoinc_lock_mode === 0
 552                 );
 553         }
 554
 555         /**
 556          * @return stdClass Process cached row
 557          */
 558         protected function getReplicationSafetyInfo() {
 559                 if ( $this->replicationInfoRow === null ) {
 560                         $this->replicationInfoRow = $this->selectRow(
 561                                 false,
 562                                 [
 563                                         'innodb_autoinc_lock_mode' => '@@innodb_autoinc_lock_mode',
 564                                         'binlog_format' => '@@binlog_format',
 565                                 ],
 566                                 [],
 567                                 __METHOD__
 568                         );
 569                 }
 570
 571                 return $this->replicationInfoRow;
 572         }
 573
 574         /**
 575          * Estimate rows in dataset
 576          * Returns estimated count, based on EXPLAIN output
 577          * Takes same arguments as Database::select()
 578          *
 579          * @param string|array $table
 580          * @param string|array $var
 581          * @param string|array $conds
 582          * @param string $fname
 583          * @param string|array $options
 584          * @param array $join_conds
 585          * @return bool|int
 586          */
 587         public function estimateRowCount( $table, $var = '*', $conds = '',
 588                 $fname = __METHOD__, $options = [], $join_conds = []
 589         ) {
 590                 $conds = $this->normalizeConditions( $conds, $fname );
 591                 $column = $this->extractSingleFieldFromList( $var );
 592                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
 593                         $conds[] = "$column IS NOT NULL";
 594                 }
 595
 596                 $options['EXPLAIN'] = true;
 597                 $res = $this->select( $table, $var, $conds, $fname, $options, $join_conds );
 598                 if ( $res === false ) {
 599                         return false;
 600                 }
 601                 if ( !$this->numRows( $res ) ) {
 602                         return 0;
 603                 }
 604
 605                 $rows = 1;
 606                 foreach ( $res as $plan ) {
 607                         $rows *= $plan->rows > 0 ? $plan->rows : 1; // avoid resetting to zero
 608                 }
 609
 610                 return (int)$rows;
 611         }
 612
 613         public function tableExists( $table, $fname = __METHOD__ ) {
 614                 // Split database and table into proper variables as Database::tableName() returns
 615                 // shared tables prefixed with their database, which do not work in SHOW TABLES statements
 616                 list( $database, , $prefix, $table ) = $this->qualifiedTableComponents( $table );
 617                 $tableName = "{$prefix}{$table}";
 618
 619                 if ( isset( $this->sessionTempTables[$tableName] ) ) {
 620                         return true; // already known to exist and won't show in SHOW TABLES anyway
 621                 }
 622
 623                 // We can't use buildLike() here, because it specifies an escape character
 624                 // other than the backslash, which is the only one supported by SHOW TABLES
 625                 $encLike = $this->escapeLikeInternal( $tableName, '\\' );
 626
 627                 // If the database has been specified (such as for shared tables), use "FROM"
 628                 if ( $database !== '' ) {
 629                         $encDatabase = $this->addIdentifierQuotes( $database );
 630                         $query = "SHOW TABLES FROM $encDatabase LIKE '$encLike'";
 631                 } else {
 632                         $query = "SHOW TABLES LIKE '$encLike'";
 633                 }
 634
 635                 return $this->query( $query, $fname )->numRows() > 0;
 636         }
 637
 638         /**
 639          * @param string $table
 640          * @param string $field
 641          * @return bool|MySQLField
 642          */
 643         public function fieldInfo( $table, $field ) {
 644                 $table = $this->tableName( $table );
 645                 $res = $this->query( "SELECT * FROM $table LIMIT 1", __METHOD__, true );
 646                 if ( !$res ) {
 647                         return false;
 648                 }
 649                 $n = $this->mysqlNumFields( $res->result );
 650                 for ( $i = 0; $i < $n; $i++ ) {
 651                         $meta = $this->mysqlFetchField( $res->result, $i );
 652                         if ( $field == $meta->name ) {
 653                                 return new MySQLField( $meta );
 654                         }
 655                 }
 656
 657                 return false;
 658         }
 659
 660         /**
 661          * Get column information from a result
 662          *
 663          * @param resource $res Raw result
 664          * @param int $n
 665          * @return stdClass
 666          */
 667         abstract protected function mysqlFetchField( $res, $n );
 668
 669         /**
 670          * Get information about an index into an object
 671          * Returns false if the index does not exist
 672          *
 673          * @param string $table
 674          * @param string $index
 675          * @param string $fname
 676          * @return bool|array|null False or null on failure
 677          */
 678         public function indexInfo( $table, $index, $fname = __METHOD__ ) {
 679                 # SHOW INDEX works in MySQL 3.23.58, but SHOW INDEXES does not.
 680                 # SHOW INDEX should work for 3.x and up:
 681                 # https://dev.mysql.com/doc/mysql/en/SHOW_INDEX.html
 682                 $table = $this->tableName( $table );
 683                 $index = $this->indexName( $index );
 684
 685                 $sql = 'SHOW INDEX FROM ' . $table;
 686                 $res = $this->query( $sql, $fname );
 687
 688                 if ( !$res ) {
 689                         return null;
 690                 }
 691
 692                 $result = [];
 693
 694                 foreach ( $res as $row ) {
 695                         if ( $row->Key_name == $index ) {
 696                                 $result[] = $row;
 697                         }
 698                 }
 699
 700                 return $result ?: false;
 701         }
 702
 703         /**
 704          * @param string $s
 705          * @return string
 706          */
 707         public function strencode( $s ) {
 708                 return $this->mysqlRealEscapeString( $s );
 709         }
 710
 711         /**
 712          * @param string $s
 713          * @return mixed
 714          */
 715         abstract protected function mysqlRealEscapeString( $s );
 716
 717         public function addQuotes( $s ) {
 718                 if ( is_bool( $s ) ) {
 719                         // Parent would transform to int, which does not play nice with MySQL type juggling.
 720                         // When searching for an int in a string column, the strings are cast to int, which
 721                         // means false would match any string not starting with a number.
 722                         $s = (string)(int)$s;
 723                 }
 724                 return parent::addQuotes( $s );
 725         }
 726
 727         /**
 728          * MySQL uses `backticks` for identifier quoting instead of the sql standard "double quotes".
 729          *
 730          * @param string $s
 731          * @return string
 732          */
 733         public function addIdentifierQuotes( $s ) {
 734                 // Characters in the range \u0001-\uFFFF are valid in a quoted identifier
 735                 // Remove NUL bytes and escape backticks by doubling
 736                 return '`' . str_replace( [ "\0", '`' ], [ '', '``' ], $s ) . '`';
 737         }
 738
 739         /**
 740          * @param string $name
 741          * @return bool
 742          */
 743         public function isQuotedIdentifier( $name ) {
 744                 return strlen( $name ) && $name[0] == '`' && substr( $name, -1, 1 ) == '`';
 745         }
 746
 747         protected function doGetLag() {
 748                 if ( $this->getLagDetectionMethod() === 'pt-heartbeat' ) {
 749                         return $this->getLagFromPtHeartbeat();
 750                 } else {
 751                         return $this->getLagFromSlaveStatus();
 752                 }
 753         }
 754
 755         /**
 756          * @return string
 757          */
 758         protected function getLagDetectionMethod() {
 759                 return $this->lagDetectionMethod;
 760         }
 761
 762         /**
 763          * @return bool|int
 764          */
 765         protected function getLagFromSlaveStatus() {
 766                 $res = $this->query( 'SHOW SLAVE STATUS', __METHOD__ );
 767                 $row = $res ? $res->fetchObject() : false;
 768                 // If the server is not replicating, there will be no row
 769                 if ( $row && strval( $row->Seconds_Behind_Master ) !== '' ) {
 770                         return intval( $row->Seconds_Behind_Master );
 771                 }
 772
 773                 return false;
 774         }
 775
 776         /**
 777          * @return bool|float
 778          */
 779         protected function getLagFromPtHeartbeat() {
 780                 $options = $this->lagDetectionOptions;
 781
 782                 $currentTrxInfo = $this->getRecordedTransactionLagStatus();
 783                 if ( $currentTrxInfo ) {
 784                         // There is an active transaction and the initial lag was already queried
 785                         $staleness = microtime( true ) - $currentTrxInfo['since'];
 786                         if ( $staleness > self::LAG_STALE_WARN_THRESHOLD ) {
 787                                 // Avoid returning higher and higher lag value due to snapshot age
 788                                 // given that the isolation level will typically be REPEATABLE-READ
 789                                 $this->queryLogger->warning(
 790                                         "Using cached lag value for {db_server} due to active transaction",
 791                                         $this->getLogContext( [
 792                                                 'method' => __METHOD__,
 793                                                 'age' => $staleness,
 794                                                 'trace' => ( new RuntimeException() )->getTraceAsString()
 795                                         ] )
 796                                 );
 797                         }
 798
 799                         return $currentTrxInfo['lag'];
 800                 }
 801
 802                 if ( isset( $options['conds'] ) ) {
 803                         // Best method for multi-DC setups: use logical channel names
 804                         $data = $this->getHeartbeatData( $options['conds'] );
 805                 } else {
 806                         // Standard method: use master server ID (works with stock pt-heartbeat)
 807                         $masterInfo = $this->getMasterServerInfo();
 808                         if ( !$masterInfo ) {
 809                                 $this->queryLogger->error(
 810                                         "Unable to query master of {db_server} for server ID",
 811                                         $this->getLogContext( [
 812                                                 'method' => __METHOD__
 813                                         ] )
 814                                 );
 815
 816                                 return false; // could not get master server ID
 817                         }
 818
 819                         $conds = [ 'server_id' => intval( $masterInfo['serverId'] ) ];
 820                         $data = $this->getHeartbeatData( $conds );
 821                 }
 822
 823                 list( $time, $nowUnix ) = $data;
 824                 if ( $time !== null ) {
 825                         // @time is in ISO format like "2015-09-25T16:48:10.000510"
 826                         $dateTime = new DateTime( $time, new DateTimeZone( 'UTC' ) );
 827                         $timeUnix = (int)$dateTime->format( 'U' ) + $dateTime->format( 'u' ) / 1e6;
 828
 829                         return max( $nowUnix - $timeUnix, 0.0 );
 830                 }
 831
 832                 $this->queryLogger->error(
 833                         "Unable to find pt-heartbeat row for {db_server}",
 834                         $this->getLogContext( [
 835                                 'method' => __METHOD__
 836                         ] )
 837                 );
 838
 839                 return false;
 840         }
 841
 842         protected function getMasterServerInfo() {
 843                 $cache = $this->srvCache;
 844                 $key = $cache->makeGlobalKey(
 845                         'mysql',
 846                         'master-info',
 847                         // Using one key for all cluster replica DBs is preferable
 848                         $this->getLBInfo( 'clusterMasterHost' ) ?: $this->getServer()
 849                 );
 850                 $fname = __METHOD__;
 851
 852                 return $cache->getWithSetCallback(
 853                         $key,
 854                         $cache::TTL_INDEFINITE,
 855                         function () use ( $cache, $key, $fname ) {
 856                                 // Get and leave a lock key in place for a short period
 857                                 if ( !$cache->lock( $key, 0, 10 ) ) {
 858                                         return false; // avoid master connection spike slams
 859                                 }
 860
 861                                 $conn = $this->getLazyMasterHandle();
 862                                 if ( !$conn ) {
 863                                         return false; // something is misconfigured
 864                                 }
 865
 866                                 // Connect to and query the master; catch errors to avoid outages
 867                                 try {
 868                                         $res = $conn->query( 'SELECT @@server_id AS id', $fname );
 869                                         $row = $res ? $res->fetchObject() : false;
 870                                         $id = $row ? (int)$row->id : 0;
 871                                 } catch ( DBError $e ) {
 872                                         $id = 0;
 873                                 }
 874
 875                                 // Cache the ID if it was retrieved
 876                                 return $id ? [ 'serverId' => $id, 'asOf' => time() ] : false;
 877                         }
 878                 );
 879         }
 880
 881         /**
 882          * @param array $conds WHERE clause conditions to find a row
 883          * @return array (heartbeat `ts` column value or null, UNIX timestamp) for the newest beat
 884          * @see https://www.percona.com/doc/percona-toolkit/2.1/pt-heartbeat.html
 885          */
 886         protected function getHeartbeatData( array $conds ) {
 887                 // Query time and trip time are not counted
 888                 $nowUnix = microtime( true );
 889                 // Do not bother starting implicit transactions here
 890                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
 891                 try {
 892                         $whereSQL = $this->makeList( $conds, self::LIST_AND );
 893                         // Use ORDER BY for channel based queries since that field might not be UNIQUE.
 894                         // Note: this would use "TIMESTAMPDIFF(MICROSECOND,ts,UTC_TIMESTAMP(6))" but the
 895                         // percision field is not supported in MySQL <= 5.5.
 896                         $res = $this->query(
 897                                 "SELECT ts FROM heartbeat.heartbeat WHERE $whereSQL ORDER BY ts DESC LIMIT 1",
 898                                 __METHOD__
 899                         );
 900                         $row = $res ? $res->fetchObject() : false;
 901                 } finally {
 902                         $this->restoreFlags();
 903                 }
 904
 905                 return [ $row ? $row->ts : null, $nowUnix ];
 906         }
 907
 908         protected function getApproximateLagStatus() {
 909                 if ( $this->getLagDetectionMethod() === 'pt-heartbeat' ) {
 910                         // Disable caching since this is fast enough and we don't wan't
 911                         // to be *too* pessimistic by having both the cache TTL and the
 912                         // pt-heartbeat interval count as lag in getSessionLagStatus()
 913                         return parent::getApproximateLagStatus();
 914                 }
 915
 916                 $key = $this->srvCache->makeGlobalKey( 'mysql-lag', $this->getServer() );
 917                 $approxLag = $this->srvCache->get( $key );
 918                 if ( !$approxLag ) {
 919                         $approxLag = parent::getApproximateLagStatus();
 920                         $this->srvCache->set( $key, $approxLag, 1 );
 921                 }
 922
 923                 return $approxLag;
 924         }
 925
 926         public function masterPosWait( DBMasterPos $pos, $timeout ) {
 927                 if ( !( $pos instanceof MySQLMasterPos ) ) {
 928                         throw new InvalidArgumentException( "Position not an instance of MySQLMasterPos" );
 929                 }
 930
 931                 if ( $this->getLBInfo( 'is static' ) === true ) {
 932                         return 0; // this is a copy of a read-only dataset with no master DB
 933                 } elseif ( $this->lastKnownReplicaPos && $this->lastKnownReplicaPos->hasReached( $pos ) ) {
 934                         return 0; // already reached this point for sure
 935                 }
 936
 937                 // Call doQuery() directly, to avoid opening a transaction if DBO_TRX is set
 938                 if ( $pos->getGTIDs() ) {
 939                         // Ignore GTIDs from domains exclusive to the master DB (presumably inactive)
 940                         $rpos = $this->getReplicaPos();
 941                         $gtidsWait = $rpos ? MySQLMasterPos::getCommonDomainGTIDs( $pos, $rpos ) : [];
 942                         if ( !$gtidsWait ) {
 943                                 $this->queryLogger->error(
 944                                         "No GTIDs with the same domain between master ($pos) and replica ($rpos)",
 945                                         $this->getLogContext( [
 946                                                 'method' => __METHOD__,
 947                                         ] )
 948                                 );
 949
 950                                 return -1; // $pos is from the wrong cluster?
 951                         }
 952                         // Wait on the GTID set (MariaDB only)
 953                         $gtidArg = $this->addQuotes( implode( ',', $gtidsWait ) );
 954                         if ( strpos( $gtidArg, ':' ) !== false ) {
 955                                 // MySQL GTIDs, e.g "source_id:transaction_id"
 956                                 $sql = "SELECT WAIT_FOR_EXECUTED_GTID_SET($gtidArg, $timeout)";
 957                         } else {
 958                                 // MariaDB GTIDs, e.g."domain:server:sequence"
 959                                 $sql = "SELECT MASTER_GTID_WAIT($gtidArg, $timeout)";
 960                         }
 961                 } else {
 962                         // Wait on the binlog coordinates
 963                         $encFile = $this->addQuotes( $pos->getLogFile() );
 964                         $encPos = intval( $pos->getLogPosition()[$pos::CORD_EVENT] );
 965                         $sql = "SELECT MASTER_POS_WAIT($encFile, $encPos, $timeout)";
 966                 }
 967
 968                 list( $res, $err ) = $this->executeQuery( $sql, __METHOD__, self::QUERY_IGNORE_DBO_TRX );
 969                 $row = $res ? $this->fetchRow( $res ) : false;
 970                 if ( !$row ) {
 971                         throw new DBExpectedError( $this, "Replication wait failed: {$err}" );
 972                 }
 973
 974                 // Result can be NULL (error), -1 (timeout), or 0+ per the MySQL manual
 975                 $status = ( $row[0] !== null ) ? intval( $row[0] ) : null;
 976                 if ( $status === null ) {
 977                         if ( !$pos->getGTIDs() ) {
 978                                 // T126436: jobs programmed to wait on master positions might be referencing
 979                                 // binlogs with an old master hostname; this makes MASTER_POS_WAIT() return null.
 980                                 // Try to detect this case and treat the replica DB as having reached the given
 981                                 // position (any master switchover already requires that the new master be caught
 982                                 // up before the switch).
 983                                 $replicationPos = $this->getReplicaPos();
 984                                 if ( $replicationPos && !$replicationPos->channelsMatch( $pos ) ) {
 985                                         $this->lastKnownReplicaPos = $replicationPos;
 986                                         $status = 0;
 987                                 }
 988                         }
 989                 } elseif ( $status >= 0 ) {
 990                         // Remember that this position was reached to save queries next time
 991                         $this->lastKnownReplicaPos = $pos;
 992                 }
 993
 994                 return $status;
 995         }
 996
 997         /**
 998          * Get the position of the master from SHOW SLAVE STATUS
 999          *
1000          * @return MySQLMasterPos|bool
1001          */
1002         public function getReplicaPos() {
1003                 $now = microtime( true ); // as-of-time *before* fetching GTID variables
1004
1005                 if ( $this->useGTIDs() ) {
1006                         // Try to use GTIDs, fallbacking to binlog positions if not possible
1007                         $data = $this->getServerGTIDs( __METHOD__ );
1008                         // Use gtid_slave_pos for MariaDB and gtid_executed for MySQL
1009                         foreach ( [ 'gtid_slave_pos', 'gtid_executed' ] as $name ) {
1010                                 if ( isset( $data[$name] ) && strlen( $data[$name] ) ) {
1011                                         return new MySQLMasterPos( $data[$name], $now );
1012                                 }
1013                         }
1014                 }
1015
1016                 $data = $this->getServerRoleStatus( 'SLAVE', __METHOD__ );
1017                 if ( $data && strlen( $data['Relay_Master_Log_File'] ) ) {
1018                         return new MySQLMasterPos(
1019                                 "{$data['Relay_Master_Log_File']}/{$data['Exec_Master_Log_Pos']}",
1020                                 $now
1021                         );
1022                 }
1023
1024                 return false;
1025         }
1026
1027         /**
1028          * Get the position of the master from SHOW MASTER STATUS
1029          *
1030          * @return MySQLMasterPos|bool
1031          */
1032         public function getMasterPos() {
1033                 $now = microtime( true ); // as-of-time *before* fetching GTID variables
1034
1035                 $pos = false;
1036                 if ( $this->useGTIDs() ) {
1037                         // Try to use GTIDs, fallbacking to binlog positions if not possible
1038                         $data = $this->getServerGTIDs( __METHOD__ );
1039                         // Use gtid_binlog_pos for MariaDB and gtid_executed for MySQL
1040                         foreach ( [ 'gtid_binlog_pos', 'gtid_executed' ] as $name ) {
1041                                 if ( isset( $data[$name] ) && strlen( $data[$name] ) ) {
1042                                         $pos = new MySQLMasterPos( $data[$name], $now );
1043                                         break;
1044                                 }
1045                         }
1046                         // Filter domains that are inactive or not relevant to the session
1047                         if ( $pos ) {
1048                                 $pos->setActiveOriginServerId( $this->getServerId() );
1049                                 $pos->setActiveOriginServerUUID( $this->getServerUUID() );
1050                                 if ( isset( $data['gtid_domain_id'] ) ) {
1051                                         $pos->setActiveDomain( $data['gtid_domain_id'] );
1052                                 }
1053                         }
1054                 }
1055
1056                 if ( !$pos ) {
1057                         $data = $this->getServerRoleStatus( 'MASTER', __METHOD__ );
1058                         if ( $data && strlen( $data['File'] ) ) {
1059                                 $pos = new MySQLMasterPos( "{$data['File']}/{$data['Position']}", $now );
1060                         }
1061                 }
1062
1063                 return $pos;
1064         }
1065
1066         /**
1067          * @return int
1068          * @throws DBQueryError If the variable doesn't exist for some reason
1069          */
1070         protected function getServerId() {
1071                 $fname = __METHOD__;
1072                 return $this->srvCache->getWithSetCallback(
1073                         $this->srvCache->makeGlobalKey( 'mysql-server-id', $this->getServer() ),
1074                         self::SERVER_ID_CACHE_TTL,
1075                         function () use ( $fname ) {
1076                                 $res = $this->query( "SELECT @@server_id AS id", $fname );
1077                                 return intval( $this->fetchObject( $res )->id );
1078                         }
1079                 );
1080         }
1081
1082         /**
1083          * @return string|null
1084          */
1085         protected function getServerUUID() {
1086                 return $this->srvCache->getWithSetCallback(
1087                         $this->srvCache->makeGlobalKey( 'mysql-server-uuid', $this->getServer() ),
1088                         self::SERVER_ID_CACHE_TTL,
1089                         function () {
1090                                 $res = $this->query( "SHOW GLOBAL VARIABLES LIKE 'server_uuid'" );
1091                                 $row = $this->fetchObject( $res );
1092
1093                                 return $row ? $row->Value : null;
1094                         }
1095                 );
1096         }
1097
1098         /**
1099          * @param string $fname
1100          * @return string[]
1101          */
1102         protected function getServerGTIDs( $fname = __METHOD__ ) {
1103                 $map = [];
1104                 // Get global-only variables like gtid_executed
1105                 $res = $this->query( "SHOW GLOBAL VARIABLES LIKE 'gtid_%'", $fname );
1106                 foreach ( $res as $row ) {
1107                         $map[$row->Variable_name] = $row->Value;
1108                 }
1109                 // Get session-specific (e.g. gtid_domain_id since that is were writes will log)
1110                 $res = $this->query( "SHOW SESSION VARIABLES LIKE 'gtid_%'", $fname );
1111                 foreach ( $res as $row ) {
1112                         $map[$row->Variable_name] = $row->Value;
1113                 }
1114
1115                 return $map;
1116         }
1117
1118         /**
1119          * @param string $role One of "MASTER"/"SLAVE"
1120          * @param string $fname
1121          * @return string[] Latest available server status row
1122          */
1123         protected function getServerRoleStatus( $role, $fname = __METHOD__ ) {
1124                 return $this->query( "SHOW $role STATUS", $fname )->fetchRow() ?: [];
1125         }
1126
1127         public function serverIsReadOnly() {
1128                 $res = $this->query( "SHOW GLOBAL VARIABLES LIKE 'read_only'", __METHOD__ );
1129                 $row = $this->fetchObject( $res );
1130
1131                 return $row ? ( strtolower( $row->Value ) === 'on' ) : false;
1132         }
1133
1134         /**
1135          * @param string $index
1136          * @return string
1137          */
1138         function useIndexClause( $index ) {
1139                 return "FORCE INDEX (" . $this->indexName( $index ) . ")";
1140         }
1141
1142         /**
1143          * @param string $index
1144          * @return string
1145          */
1146         function ignoreIndexClause( $index ) {
1147                 return "IGNORE INDEX (" . $this->indexName( $index ) . ")";
1148         }
1149
1150         /**
1151          * @return string
1152          */
1153         function lowPriorityOption() {
1154                 return 'LOW_PRIORITY';
1155         }
1156
1157         /**
1158          * @return string
1159          */
1160         public function getSoftwareLink() {
1161                 // MariaDB includes its name in its version string; this is how MariaDB's version of
1162                 // the mysql command-line client identifies MariaDB servers (see mariadb_connection()
1163                 // in libmysql/libmysql.c).
1164                 $version = $this->getServerVersion();
1165                 if ( strpos( $version, 'MariaDB' ) !== false || strpos( $version, '-maria-' ) !== false ) {
1166                         return '[{{int:version-db-mariadb-url}} MariaDB]';
1167                 }
1168
1169                 // Percona Server's version suffix is not very distinctive, and @@version_comment
1170                 // doesn't give the necessary info for source builds, so assume the server is MySQL.
1171                 // (Even Percona's version of mysql doesn't try to make the distinction.)
1172                 return '[{{int:version-db-mysql-url}} MySQL]';
1173         }
1174
1175         /**
1176          * @return string
1177          */
1178         public function getServerVersion() {
1179                 // Not using mysql_get_server_info() or similar for consistency: in the handshake,
1180                 // MariaDB 10 adds the prefix "5.5.5-", and only some newer client libraries strip
1181                 // it off (see RPL_VERSION_HACK in include/mysql_com.h).
1182                 if ( $this->serverVersion === null ) {
1183                         $this->serverVersion = $this->selectField( '', 'VERSION()', '', __METHOD__ );
1184                 }
1185                 return $this->serverVersion;
1186         }
1187
1188         /**
1189          * @param array $options
1190          */
1191         public function setSessionOptions( array $options ) {
1192                 if ( isset( $options['connTimeout'] ) ) {
1193                         $timeout = (int)$options['connTimeout'];
1194                         $this->query( "SET net_read_timeout=$timeout" );
1195                         $this->query( "SET net_write_timeout=$timeout" );
1196                 }
1197         }
1198
1199         /**
1200          * @param string &$sql
1201          * @param string &$newLine
1202          * @return bool
1203          */
1204         public function streamStatementEnd( &$sql, &$newLine ) {
1205                 if ( strtoupper( substr( $newLine, 0, 9 ) ) == 'DELIMITER' ) {
1206                         preg_match( '/^DELIMITER\s+(\S+)/', $newLine, $m );
1207                         $this->delimiter = $m[1];
1208                         $newLine = '';
1209                 }
1210
1211                 return parent::streamStatementEnd( $sql, $newLine );
1212         }
1213
1214         /**
1215          * Check to see if a named lock is available. This is non-blocking.
1216          *
1217          * @param string $lockName Name of lock to poll
1218          * @param string $method Name of method calling us
1219          * @return bool
1220          * @since 1.20
1221          */
1222         public function lockIsFree( $lockName, $method ) {
1223                 if ( !parent::lockIsFree( $lockName, $method ) ) {
1224                         return false; // already held
1225                 }
1226
1227                 $encName = $this->addQuotes( $this->makeLockName( $lockName ) );
1228                 $result = $this->query( "SELECT IS_FREE_LOCK($encName) AS lockstatus", $method );
1229                 $row = $this->fetchObject( $result );
1230
1231                 return ( $row->lockstatus == 1 );
1232         }
1233
1234         /**
1235          * @param string $lockName
1236          * @param string $method
1237          * @param int $timeout
1238          * @return bool
1239          */
1240         public function lock( $lockName, $method, $timeout = 5 ) {
1241                 $encName = $this->addQuotes( $this->makeLockName( $lockName ) );
1242                 $result = $this->query( "SELECT GET_LOCK($encName, $timeout) AS lockstatus", $method );
1243                 $row = $this->fetchObject( $result );
1244
1245                 if ( $row->lockstatus == 1 ) {
1246                         parent::lock( $lockName, $method, $timeout ); // record
1247                         return true;
1248                 }
1249
1250                 $this->queryLogger->info( __METHOD__ . " failed to acquire lock '{lockname}'",
1251                         [ 'lockname' => $lockName ] );
1252
1253                 return false;
1254         }
1255
1256         /**
1257          * FROM MYSQL DOCS:
1258          * https://dev.mysql.com/doc/refman/5.0/en/miscellaneous-functions.html#function_release-lock
1259          * @param string $lockName
1260          * @param string $method
1261          * @return bool
1262          */
1263         public function unlock( $lockName, $method ) {
1264                 $encName = $this->addQuotes( $this->makeLockName( $lockName ) );
1265                 $result = $this->query( "SELECT RELEASE_LOCK($encName) as lockstatus", $method );
1266                 $row = $this->fetchObject( $result );
1267
1268                 if ( $row->lockstatus == 1 ) {
1269                         parent::unlock( $lockName, $method ); // record
1270                         return true;
1271                 }
1272
1273                 $this->queryLogger->warning( __METHOD__ . " failed to release lock '$lockName'\n" );
1274
1275                 return false;
1276         }
1277
1278         private function makeLockName( $lockName ) {
1279                 // https://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html#function_get-lock
1280                 // Newer version enforce a 64 char length limit.
1281                 return ( strlen( $lockName ) > 64 ) ? sha1( $lockName ) : $lockName;
1282         }
1283
1284         public function namedLocksEnqueue() {
1285                 return true;
1286         }
1287
1288         public function tableLocksHaveTransactionScope() {
1289                 return false; // tied to TCP connection
1290         }
1291
1292         protected function doLockTables( array $read, array $write, $method ) {
1293                 $items = [];
1294                 foreach ( $write as $table ) {
1295                         $items[] = $this->tableName( $table ) . ' WRITE';
1296                 }
1297                 foreach ( $read as $table ) {
1298                         $items[] = $this->tableName( $table ) . ' READ';
1299                 }
1300
1301                 $sql = "LOCK TABLES " . implode( ',', $items );
1302                 $this->query( $sql, $method );
1303
1304                 return true;
1305         }
1306
1307         protected function doUnlockTables( $method ) {
1308                 $this->query( "UNLOCK TABLES", $method );
1309
1310                 return true;
1311         }
1312
1313         /**
1314          * @param bool $value
1315          */
1316         public function setBigSelects( $value = true ) {
1317                 if ( $value === 'default' ) {
1318                         if ( $this->defaultBigSelects === null ) {
1319                                 # Function hasn't been called before so it must already be set to the default
1320                                 return;
1321                         } else {
1322                                 $value = $this->defaultBigSelects;
1323                         }
1324                 } elseif ( $this->defaultBigSelects === null ) {
1325                         $this->defaultBigSelects =
1326                                 (bool)$this->selectField( false, '@@sql_big_selects', '', __METHOD__ );
1327                 }
1328                 $encValue = $value ? '1' : '0';
1329                 $this->query( "SET sql_big_selects=$encValue", __METHOD__ );
1330         }
1331
1332         /**
1333          * DELETE where the condition is a join. MySql uses multi-table deletes.
1334          * @param string $delTable
1335          * @param string $joinTable
1336          * @param string $delVar
1337          * @param string $joinVar
1338          * @param array|string $conds
1339          * @param bool|string $fname
1340          * @throws DBUnexpectedError
1341          */
1342         public function deleteJoin(
1343                 $delTable, $joinTable, $delVar, $joinVar, $conds, $fname = __METHOD__
1344         ) {
1345                 if ( !$conds ) {
1346                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
1347                 }
1348
1349                 $delTable = $this->tableName( $delTable );
1350                 $joinTable = $this->tableName( $joinTable );
1351                 $sql = "DELETE $delTable FROM $delTable, $joinTable WHERE $delVar=$joinVar ";
1352
1353                 if ( $conds != '*' ) {
1354                         $sql .= ' AND ' . $this->makeList( $conds, self::LIST_AND );
1355                 }
1356
1357                 $this->query( $sql, $fname );
1358         }
1359
1360         public function upsert(
1361                 $table, array $rows, $uniqueIndexes, array $set, $fname = __METHOD__
1362         ) {
1363                 if ( $rows === [] ) {
1364                         return true; // nothing to do
1365                 }
1366
1367                 if ( !is_array( reset( $rows ) ) ) {
1368                         $rows = [ $rows ];
1369                 }
1370
1371                 $table = $this->tableName( $table );
1372                 $columns = array_keys( $rows[0] );
1373
1374                 $sql = "INSERT INTO $table (" . implode( ',', $columns ) . ') VALUES ';
1375                 $rowTuples = [];
1376                 foreach ( $rows as $row ) {
1377                         $rowTuples[] = '(' . $this->makeList( $row ) . ')';
1378                 }
1379                 $sql .= implode( ',', $rowTuples );
1380                 $sql .= " ON DUPLICATE KEY UPDATE " . $this->makeList( $set, self::LIST_SET );
1381
1382                 $this->query( $sql, $fname );
1383
1384                 return true;
1385         }
1386
1387         /**
1388          * Determines how long the server has been up
1389          *
1390          * @return int
1391          */
1392         public function getServerUptime() {
1393                 $vars = $this->getMysqlStatus( 'Uptime' );
1394
1395                 return (int)$vars['Uptime'];
1396         }
1397
1398         /**
1399          * Determines if the last failure was due to a deadlock
1400          *
1401          * @return bool
1402          */
1403         public function wasDeadlock() {
1404                 return $this->lastErrno() == 1213;
1405         }
1406
1407         /**
1408          * Determines if the last failure was due to a lock timeout
1409          *
1410          * @return bool
1411          */
1412         public function wasLockTimeout() {
1413                 return $this->lastErrno() == 1205;
1414         }
1415
1416         /**
1417          * Determines if the last failure was due to the database being read-only.
1418          *
1419          * @return bool
1420          */
1421         public function wasReadOnlyError() {
1422                 return $this->lastErrno() == 1223 ||
1423                         ( $this->lastErrno() == 1290 && strpos( $this->lastError(), '--read-only' ) !== false );
1424         }
1425
1426         public function wasConnectionError( $errno ) {
1427                 return $errno == 2013 || $errno == 2006;
1428         }
1429
1430         protected function wasKnownStatementRollbackError() {
1431                 $errno = $this->lastErrno();
1432
1433                 if ( $errno === 1205 ) { // lock wait timeout
1434                         // Note that this is uncached to avoid stale values of SET is used
1435                         $row = $this->selectRow(
1436                                 false,
1437                                 [ 'innodb_rollback_on_timeout' => '@@innodb_rollback_on_timeout' ],
1438                                 [],
1439                                 __METHOD__
1440                         );
1441                         // https://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
1442                         // https://dev.mysql.com/doc/refman/5.5/en/innodb-parameters.html
1443                         return $row->innodb_rollback_on_timeout ? false : true;
1444                 }
1445
1446                 // See https://dev.mysql.com/doc/refman/5.5/en/error-messages-server.html
1447                 return in_array( $errno, [ 1022, 1062, 1216, 1217, 1137, 1146, 1051, 1054 ], true );
1448         }
1449
1450         /**
1451          * @param string $oldName
1452          * @param string $newName
1453          * @param bool $temporary
1454          * @param string $fname
1455          * @return bool
1456          */
1457         public function duplicateTableStructure(
1458                 $oldName, $newName, $temporary = false, $fname = __METHOD__
1459         ) {
1460                 $tmp = $temporary ? 'TEMPORARY ' : '';
1461                 $newName = $this->addIdentifierQuotes( $newName );
1462                 $oldName = $this->addIdentifierQuotes( $oldName );
1463                 $query = "CREATE $tmp TABLE $newName (LIKE $oldName)";
1464
1465                 return $this->query( $query, $fname, $this::QUERY_PSEUDO_PERMANENT );
1466         }
1467
1468         /**
1469          * List all tables on the database
1470          *
1471          * @param string|null $prefix Only show tables with this prefix, e.g. mw_
1472          * @param string $fname Calling function name
1473          * @return array
1474          */
1475         public function listTables( $prefix = null, $fname = __METHOD__ ) {
1476                 $result = $this->query( "SHOW TABLES", $fname );
1477
1478                 $endArray = [];
1479
1480                 foreach ( $result as $table ) {
1481                         $vars = get_object_vars( $table );
1482                         $table = array_pop( $vars );
1483
1484                         if ( !$prefix || strpos( $table, $prefix ) === 0 ) {
1485                                 $endArray[] = $table;
1486                         }
1487                 }
1488
1489                 return $endArray;
1490         }
1491
1492         /**
1493          * @param string $tableName
1494          * @param string $fName
1495          * @return bool|IResultWrapper
1496          */
1497         public function dropTable( $tableName, $fName = __METHOD__ ) {
1498                 if ( !$this->tableExists( $tableName, $fName ) ) {
1499                         return false;
1500                 }
1501
1502                 return $this->query( "DROP TABLE IF EXISTS " . $this->tableName( $tableName ), $fName );
1503         }
1504
1505         /**
1506          * Get status information from SHOW STATUS in an associative array
1507          *
1508          * @param string $which
1509          * @return array
1510          */
1511         private function getMysqlStatus( $which = "%" ) {
1512                 $res = $this->query( "SHOW STATUS LIKE '{$which}'" );
1513                 $status = [];
1514
1515                 foreach ( $res as $row ) {
1516                         $status[$row->Variable_name] = $row->Value;
1517                 }
1518
1519                 return $status;
1520         }
1521
1522         /**
1523          * Lists VIEWs in the database
1524          *
1525          * @param string|null $prefix Only show VIEWs with this prefix, eg.
1526          * unit_test_, or $wgDBprefix. Default: null, would return all views.
1527          * @param string $fname Name of calling function
1528          * @return array
1529          * @since 1.22
1530          */
1531         public function listViews( $prefix = null, $fname = __METHOD__ ) {
1532                 // The name of the column containing the name of the VIEW
1533                 $propertyName = 'Tables_in_' . $this->getDBname();
1534
1535                 // Query for the VIEWS
1536                 $res = $this->query( 'SHOW FULL TABLES WHERE TABLE_TYPE = "VIEW"' );
1537                 $allViews = [];
1538                 foreach ( $res as $row ) {
1539                         array_push( $allViews, $row->$propertyName );
1540                 }
1541
1542                 if ( is_null( $prefix ) || $prefix === '' ) {
1543                         return $allViews;
1544                 }
1545
1546                 $filteredViews = [];
1547                 foreach ( $allViews as $viewName ) {
1548                         // Does the name of this VIEW start with the table-prefix?
1549                         if ( strpos( $viewName, $prefix ) === 0 ) {
1550                                 array_push( $filteredViews, $viewName );
1551                         }
1552                 }
1553
1554                 return $filteredViews;
1555         }
1556
1557         /**
1558          * Differentiates between a TABLE and a VIEW.
1559          *
1560          * @param string $name Name of the TABLE/VIEW to test
1561          * @param string|null $prefix
1562          * @return bool
1563          * @since 1.22
1564          */
1565         public function isView( $name, $prefix = null ) {
1566                 return in_array( $name, $this->listViews( $prefix ) );
1567         }
1568
1569         protected function isTransactableQuery( $sql ) {
1570                 return parent::isTransactableQuery( $sql ) &&
1571                         !preg_match( '/^SELECT\s+(GET|RELEASE|IS_FREE)_LOCK\(/', $sql );
1572         }
1573
1574         public function buildStringCast( $field ) {
1575                 return "CAST( $field AS BINARY )";
1576         }
1577
1578         /**
1579          * @param string $field Field or column to cast
1580          * @return string
1581          */
1582         public function buildIntegerCast( $field ) {
1583                 return 'CAST( ' . $field . ' AS SIGNED )';
1584         }
1585
1586         /*
1587          * @return bool Whether GTID support is used (mockable for testing)
1588          */
1589         protected function useGTIDs() {
1590                 return $this->useGTIDs;
1591         }
1592 }
1593
1594 /**
1595  * @deprecated since 1.29
1596  */
1597 class_alias( DatabaseMysqlBase::class, 'DatabaseMysqlBase' );