includes/libs/rdbms/database/DatabasePostgres.php

   1 <?php
   2 /**
   3  * This is the Postgres 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 Wikimedia\Timestamp\ConvertibleTimestamp;
  26 use Wikimedia\WaitConditionLoop;
  27 use Wikimedia;
  28 use Exception;
  29
  30 /**
  31  * @ingroup Database
  32  */
  33 class DatabasePostgres extends Database {
  34         /** @var int|bool */
  35         protected $port;
  36
  37         /** @var resource */
  38         protected $lastResultHandle = null;
  39
  40         /** @var float|string */
  41         private $numericVersion = null;
  42         /** @var string Connect string to open a PostgreSQL connection */
  43         private $connectString;
  44         /** @var string */
  45         private $coreSchema;
  46         /** @var string[] Map of (reserved table name => alternate table name) */
  47         private $keywordTableMap = [];
  48
  49         /**
  50          * @see Database::__construct()
  51          * @param array $params Additional parameters include:
  52          *   - keywordTableMap : Map of reserved table names to alternative table names to use
  53          */
  54         public function __construct( array $params ) {
  55                 $this->port = isset( $params['port'] ) ? $params['port'] : false;
  56                 $this->keywordTableMap = isset( $params['keywordTableMap'] )
  57                         ? $params['keywordTableMap']
  58                         : [];
  59
  60                 parent::__construct( $params );
  61         }
  62
  63         public function getType() {
  64                 return 'postgres';
  65         }
  66
  67         public function implicitGroupby() {
  68                 return false;
  69         }
  70
  71         public function implicitOrderby() {
  72                 return false;
  73         }
  74
  75         public function hasConstraint( $name ) {
  76                 $conn = $this->getBindingHandle();
  77
  78                 $sql = "SELECT 1 FROM pg_catalog.pg_constraint c, pg_catalog.pg_namespace n " .
  79                         "WHERE c.connamespace = n.oid AND conname = '" .
  80                         pg_escape_string( $conn, $name ) . "' AND n.nspname = '" .
  81                         pg_escape_string( $conn, $this->getCoreSchema() ) . "'";
  82                 $res = $this->doQuery( $sql );
  83
  84                 return $this->numRows( $res );
  85         }
  86
  87         public function open( $server, $user, $password, $dbName ) {
  88                 # Test for Postgres support, to avoid suppressed fatal error
  89                 if ( !function_exists( 'pg_connect' ) ) {
  90                         throw new DBConnectionError(
  91                                 $this,
  92                                 "Postgres functions missing, have you compiled PHP with the --with-pgsql\n" .
  93                                 "option? (Note: if you recently installed PHP, you may need to restart your\n" .
  94                                 "webserver and database)\n"
  95                         );
  96                 }
  97
  98                 $this->server = $server;
  99                 $this->user = $user;
 100                 $this->password = $password;
 101                 $this->dbName = $dbName;
 102
 103                 $connectVars = [
 104                         // pg_connect() user $user as the default database. Since a database is *required*,
 105                         // at least pick a "don't care" database that is more likely to exist. This case
 106                         // arrises when LoadBalancer::getConnection( $i, [], '' ) is used.
 107                         'dbname' => strlen( $dbName ) ? $dbName : 'postgres',
 108                         'user' => $user,
 109                         'password' => $password
 110                 ];
 111                 if ( $server != false && $server != '' ) {
 112                         $connectVars['host'] = $server;
 113                 }
 114                 if ( (int)$this->port > 0 ) {
 115                         $connectVars['port'] = (int)$this->port;
 116                 }
 117                 if ( $this->flags & self::DBO_SSL ) {
 118                         $connectVars['sslmode'] = 1;
 119                 }
 120
 121                 $this->connectString = $this->makeConnectionString( $connectVars );
 122                 $this->close();
 123                 $this->installErrorHandler();
 124
 125                 try {
 126                         // Use new connections to let LoadBalancer/LBFactory handle reuse
 127                         $this->conn = pg_connect( $this->connectString, PGSQL_CONNECT_FORCE_NEW );
 128                 } catch ( Exception $ex ) {
 129                         $this->restoreErrorHandler();
 130                         throw $ex;
 131                 }
 132
 133                 $phpError = $this->restoreErrorHandler();
 134
 135                 if ( !$this->conn ) {
 136                         $this->queryLogger->debug(
 137                                 "DB connection error\n" .
 138                                 "Server: $server, Database: $dbName, User: $user, Password: " .
 139                                 substr( $password, 0, 3 ) . "...\n"
 140                         );
 141                         $this->queryLogger->debug( $this->lastError() . "\n" );
 142                         throw new DBConnectionError( $this, str_replace( "\n", ' ', $phpError ) );
 143                 }
 144
 145                 $this->opened = true;
 146
 147                 # If called from the command-line (e.g. importDump), only show errors
 148                 if ( $this->cliMode ) {
 149                         $this->doQuery( "SET client_min_messages = 'ERROR'" );
 150                 }
 151
 152                 $this->query( "SET client_encoding='UTF8'", __METHOD__ );
 153                 $this->query( "SET datestyle = 'ISO, YMD'", __METHOD__ );
 154                 $this->query( "SET timezone = 'GMT'", __METHOD__ );
 155                 $this->query( "SET standard_conforming_strings = on", __METHOD__ );
 156                 $this->query( "SET bytea_output = 'escape'", __METHOD__ ); // PHP bug 53127
 157
 158                 $this->determineCoreSchema( $this->schema );
 159                 // The schema to be used is now in the search path; no need for explicit qualification
 160                 $this->schema = '';
 161
 162                 return $this->conn;
 163         }
 164
 165         public function databasesAreIndependent() {
 166                 return true;
 167         }
 168
 169         /**
 170          * Postgres doesn't support selectDB in the same way MySQL does. So if the
 171          * DB name doesn't match the open connection, open a new one
 172          * @param string $db
 173          * @return bool
 174          * @throws DBUnexpectedError
 175          */
 176         public function selectDB( $db ) {
 177                 if ( $this->dbName !== $db ) {
 178                         return (bool)$this->open( $this->server, $this->user, $this->password, $db );
 179                 } else {
 180                         return true;
 181                 }
 182         }
 183
 184         /**
 185          * @param string[] $vars
 186          * @return string
 187          */
 188         private function makeConnectionString( $vars ) {
 189                 $s = '';
 190                 foreach ( $vars as $name => $value ) {
 191                         $s .= "$name='" . str_replace( "'", "\\'", $value ) . "' ";
 192                 }
 193
 194                 return $s;
 195         }
 196
 197         protected function closeConnection() {
 198                 return $this->conn ? pg_close( $this->conn ) : true;
 199         }
 200
 201         protected function isTransactableQuery( $sql ) {
 202                 return parent::isTransactableQuery( $sql ) &&
 203                         !preg_match( '/^SELECT\s+pg_(try_|)advisory_\w+\(/', $sql );
 204         }
 205
 206         public function doQuery( $sql ) {
 207                 $conn = $this->getBindingHandle();
 208
 209                 $sql = mb_convert_encoding( $sql, 'UTF-8' );
 210                 // Clear previously left over PQresult
 211                 while ( $res = pg_get_result( $conn ) ) {
 212                         pg_free_result( $res );
 213                 }
 214                 if ( pg_send_query( $conn, $sql ) === false ) {
 215                         throw new DBUnexpectedError( $this, "Unable to post new query to PostgreSQL\n" );
 216                 }
 217                 $this->lastResultHandle = pg_get_result( $conn );
 218                 if ( pg_result_error( $this->lastResultHandle ) ) {
 219                         return false;
 220                 }
 221
 222                 return $this->lastResultHandle;
 223         }
 224
 225         protected function dumpError() {
 226                 $diags = [
 227                         PGSQL_DIAG_SEVERITY,
 228                         PGSQL_DIAG_SQLSTATE,
 229                         PGSQL_DIAG_MESSAGE_PRIMARY,
 230                         PGSQL_DIAG_MESSAGE_DETAIL,
 231                         PGSQL_DIAG_MESSAGE_HINT,
 232                         PGSQL_DIAG_STATEMENT_POSITION,
 233                         PGSQL_DIAG_INTERNAL_POSITION,
 234                         PGSQL_DIAG_INTERNAL_QUERY,
 235                         PGSQL_DIAG_CONTEXT,
 236                         PGSQL_DIAG_SOURCE_FILE,
 237                         PGSQL_DIAG_SOURCE_LINE,
 238                         PGSQL_DIAG_SOURCE_FUNCTION
 239                 ];
 240                 foreach ( $diags as $d ) {
 241                         $this->queryLogger->debug( sprintf( "PgSQL ERROR(%d): %s\n",
 242                                 $d, pg_result_error_field( $this->lastResultHandle, $d ) ) );
 243                 }
 244         }
 245
 246         public function freeResult( $res ) {
 247                 if ( $res instanceof ResultWrapper ) {
 248                         $res = $res->result;
 249                 }
 250                 Wikimedia\suppressWarnings();
 251                 $ok = pg_free_result( $res );
 252                 Wikimedia\restoreWarnings();
 253                 if ( !$ok ) {
 254                         throw new DBUnexpectedError( $this, "Unable to free Postgres result\n" );
 255                 }
 256         }
 257
 258         public function fetchObject( $res ) {
 259                 if ( $res instanceof ResultWrapper ) {
 260                         $res = $res->result;
 261                 }
 262                 Wikimedia\suppressWarnings();
 263                 $row = pg_fetch_object( $res );
 264                 Wikimedia\restoreWarnings();
 265                 # @todo FIXME: HACK HACK HACK HACK debug
 266
 267                 # @todo hashar: not sure if the following test really trigger if the object
 268                 #          fetching failed.
 269                 $conn = $this->getBindingHandle();
 270                 if ( pg_last_error( $conn ) ) {
 271                         throw new DBUnexpectedError(
 272                                 $this,
 273                                 'SQL error: ' . htmlspecialchars( pg_last_error( $conn ) )
 274                         );
 275                 }
 276
 277                 return $row;
 278         }
 279
 280         public function fetchRow( $res ) {
 281                 if ( $res instanceof ResultWrapper ) {
 282                         $res = $res->result;
 283                 }
 284                 Wikimedia\suppressWarnings();
 285                 $row = pg_fetch_array( $res );
 286                 Wikimedia\restoreWarnings();
 287
 288                 $conn = $this->getBindingHandle();
 289                 if ( pg_last_error( $conn ) ) {
 290                         throw new DBUnexpectedError(
 291                                 $this,
 292                                 'SQL error: ' . htmlspecialchars( pg_last_error( $conn ) )
 293                         );
 294                 }
 295
 296                 return $row;
 297         }
 298
 299         public function numRows( $res ) {
 300                 if ( $res instanceof ResultWrapper ) {
 301                         $res = $res->result;
 302                 }
 303                 Wikimedia\suppressWarnings();
 304                 $n = pg_num_rows( $res );
 305                 Wikimedia\restoreWarnings();
 306
 307                 $conn = $this->getBindingHandle();
 308                 if ( pg_last_error( $conn ) ) {
 309                         throw new DBUnexpectedError(
 310                                 $this,
 311                                 'SQL error: ' . htmlspecialchars( pg_last_error( $conn ) )
 312                         );
 313                 }
 314
 315                 return $n;
 316         }
 317
 318         public function numFields( $res ) {
 319                 if ( $res instanceof ResultWrapper ) {
 320                         $res = $res->result;
 321                 }
 322
 323                 return pg_num_fields( $res );
 324         }
 325
 326         public function fieldName( $res, $n ) {
 327                 if ( $res instanceof ResultWrapper ) {
 328                         $res = $res->result;
 329                 }
 330
 331                 return pg_field_name( $res, $n );
 332         }
 333
 334         public function insertId() {
 335                 $res = $this->query( "SELECT lastval()" );
 336                 $row = $this->fetchRow( $res );
 337                 return is_null( $row[0] ) ? null : (int)$row[0];
 338         }
 339
 340         public function dataSeek( $res, $row ) {
 341                 if ( $res instanceof ResultWrapper ) {
 342                         $res = $res->result;
 343                 }
 344
 345                 return pg_result_seek( $res, $row );
 346         }
 347
 348         public function lastError() {
 349                 if ( $this->conn ) {
 350                         if ( $this->lastResultHandle ) {
 351                                 return pg_result_error( $this->lastResultHandle );
 352                         } else {
 353                                 return pg_last_error();
 354                         }
 355                 }
 356
 357                 return $this->getLastPHPError() ?: 'No database connection';
 358         }
 359
 360         public function lastErrno() {
 361                 if ( $this->lastResultHandle ) {
 362                         return pg_result_error_field( $this->lastResultHandle, PGSQL_DIAG_SQLSTATE );
 363                 } else {
 364                         return false;
 365                 }
 366         }
 367
 368         protected function fetchAffectedRowCount() {
 369                 if ( !$this->lastResultHandle ) {
 370                         return 0;
 371                 }
 372
 373                 return pg_affected_rows( $this->lastResultHandle );
 374         }
 375
 376         /**
 377          * Estimate rows in dataset
 378          * Returns estimated count, based on EXPLAIN output
 379          * This is not necessarily an accurate estimate, so use sparingly
 380          * Returns -1 if count cannot be found
 381          * Takes same arguments as Database::select()
 382          *
 383          * @param string $table
 384          * @param string $var
 385          * @param string $conds
 386          * @param string $fname
 387          * @param array $options
 388          * @param array $join_conds
 389          * @return int
 390          */
 391         public function estimateRowCount( $table, $var = '*', $conds = '',
 392                 $fname = __METHOD__, $options = [], $join_conds = []
 393         ) {
 394                 $conds = $this->normalizeConditions( $conds, $fname );
 395                 $column = $this->extractSingleFieldFromList( $var );
 396                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
 397                         $conds[] = "$column IS NOT NULL";
 398                 }
 399
 400                 $options['EXPLAIN'] = true;
 401                 $res = $this->select( $table, $var, $conds, $fname, $options, $join_conds );
 402                 $rows = -1;
 403                 if ( $res ) {
 404                         $row = $this->fetchRow( $res );
 405                         $count = [];
 406                         if ( preg_match( '/rows=(\d+)/', $row[0], $count ) ) {
 407                                 $rows = (int)$count[1];
 408                         }
 409                 }
 410
 411                 return $rows;
 412         }
 413
 414         public function indexInfo( $table, $index, $fname = __METHOD__ ) {
 415                 $sql = "SELECT indexname FROM pg_indexes WHERE tablename='$table'";
 416                 $res = $this->query( $sql, $fname );
 417                 if ( !$res ) {
 418                         return null;
 419                 }
 420                 foreach ( $res as $row ) {
 421                         if ( $row->indexname == $this->indexName( $index ) ) {
 422                                 return $row;
 423                         }
 424                 }
 425
 426                 return false;
 427         }
 428
 429         public function indexAttributes( $index, $schema = false ) {
 430                 if ( $schema === false ) {
 431                         $schema = $this->getCoreSchema();
 432                 }
 433                 /*
 434                  * A subquery would be not needed if we didn't care about the order
 435                  * of attributes, but we do
 436                  */
 437                 $sql = <<<__INDEXATTR__
 438
 439                         SELECT opcname,
 440                                 attname,
 441                                 i.indoption[s.g] as option,
 442                                 pg_am.amname
 443                         FROM
 444                                 (SELECT generate_series(array_lower(isub.indkey,1), array_upper(isub.indkey,1)) AS g
 445                                         FROM
 446                                                 pg_index isub
 447                                         JOIN pg_class cis
 448                                                 ON cis.oid=isub.indexrelid
 449                                         JOIN pg_namespace ns
 450                                                 ON cis.relnamespace = ns.oid
 451                                         WHERE cis.relname='$index' AND ns.nspname='$schema') AS s,
 452                                 pg_attribute,
 453                                 pg_opclass opcls,
 454                                 pg_am,
 455                                 pg_class ci
 456                                 JOIN pg_index i
 457                                         ON ci.oid=i.indexrelid
 458                                 JOIN pg_class ct
 459                                         ON ct.oid = i.indrelid
 460                                 JOIN pg_namespace n
 461                                         ON ci.relnamespace = n.oid
 462                                 WHERE
 463                                         ci.relname='$index' AND n.nspname='$schema'
 464                                         AND     attrelid = ct.oid
 465                                         AND     i.indkey[s.g] = attnum
 466                                         AND     i.indclass[s.g] = opcls.oid
 467                                         AND     pg_am.oid = opcls.opcmethod
 468 __INDEXATTR__;
 469                 $res = $this->query( $sql, __METHOD__ );
 470                 $a = [];
 471                 if ( $res ) {
 472                         foreach ( $res as $row ) {
 473                                 $a[] = [
 474                                         $row->attname,
 475                                         $row->opcname,
 476                                         $row->amname,
 477                                         $row->option ];
 478                         }
 479                 } else {
 480                         return null;
 481                 }
 482
 483                 return $a;
 484         }
 485
 486         public function indexUnique( $table, $index, $fname = __METHOD__ ) {
 487                 $sql = "SELECT indexname FROM pg_indexes WHERE tablename='{$table}'" .
 488                         " AND indexdef LIKE 'CREATE UNIQUE%(" .
 489                         $this->strencode( $this->indexName( $index ) ) .
 490                         ")'";
 491                 $res = $this->query( $sql, $fname );
 492                 if ( !$res ) {
 493                         return null;
 494                 }
 495
 496                 return $res->numRows() > 0;
 497         }
 498
 499         public function selectSQLText(
 500                 $table, $vars, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
 501         ) {
 502                 if ( is_string( $options ) ) {
 503                         $options = [ $options ];
 504                 }
 505
 506                 // Change the FOR UPDATE option as necessary based on the join conditions. Then pass
 507                 // to the parent function to get the actual SQL text.
 508                 // In Postgres when using FOR UPDATE, only the main table and tables that are inner joined
 509                 // can be locked. That means tables in an outer join cannot be FOR UPDATE locked. Trying to
 510                 // do so causes a DB error. This wrapper checks which tables can be locked and adjusts it
 511                 // accordingly.
 512                 // MySQL uses "ORDER BY NULL" as an optimization hint, but that is illegal in PostgreSQL.
 513                 if ( is_array( $options ) ) {
 514                         $forUpdateKey = array_search( 'FOR UPDATE', $options, true );
 515                         if ( $forUpdateKey !== false && $join_conds ) {
 516                                 unset( $options[$forUpdateKey] );
 517                                 $options['FOR UPDATE'] = [];
 518
 519                                 $toCheck = $table;
 520                                 reset( $toCheck );
 521                                 while ( $toCheck ) {
 522                                         $alias = key( $toCheck );
 523                                         $name = $toCheck[$alias];
 524                                         unset( $toCheck[$alias] );
 525
 526                                         $hasAlias = !is_numeric( $alias );
 527                                         if ( !$hasAlias && is_string( $name ) ) {
 528                                                 $alias = $name;
 529                                         }
 530
 531                                         if ( !isset( $join_conds[$alias] ) ||
 532                                                 !preg_match( '/^(?:LEFT|RIGHT|FULL)(?: OUTER)? JOIN$/i', $join_conds[$alias][0] )
 533                                         ) {
 534                                                 if ( is_array( $name ) ) {
 535                                                         // It's a parenthesized group, process all the tables inside the group.
 536                                                         $toCheck = array_merge( $toCheck, $name );
 537                                                 } else {
 538                                                         // Quote alias names so $this->tableName() won't mangle them
 539                                                         $options['FOR UPDATE'][] = $hasAlias ? $this->addIdentifierQuotes( $alias ) : $alias;
 540                                                 }
 541                                         }
 542                                 }
 543                         }
 544
 545                         if ( isset( $options['ORDER BY'] ) && $options['ORDER BY'] == 'NULL' ) {
 546                                 unset( $options['ORDER BY'] );
 547                         }
 548                 }
 549
 550                 return parent::selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
 551         }
 552
 553         /** @inheritDoc */
 554         public function insert( $table, $args, $fname = __METHOD__, $options = [] ) {
 555                 if ( !count( $args ) ) {
 556                         return true;
 557                 }
 558
 559                 $table = $this->tableName( $table );
 560                 if ( !isset( $this->numericVersion ) ) {
 561                         $this->getServerVersion();
 562                 }
 563
 564                 if ( !is_array( $options ) ) {
 565                         $options = [ $options ];
 566                 }
 567
 568                 if ( isset( $args[0] ) && is_array( $args[0] ) ) {
 569                         $rows = $args;
 570                         $keys = array_keys( $args[0] );
 571                 } else {
 572                         $rows = [ $args ];
 573                         $keys = array_keys( $args );
 574                 }
 575
 576                 $ignore = in_array( 'IGNORE', $options );
 577
 578                 $sql = "INSERT INTO $table (" . implode( ',', $keys ) . ') VALUES ';
 579
 580                 if ( $this->numericVersion >= 9.5 || !$ignore ) {
 581                         // No IGNORE or our PG has "ON CONFLICT DO NOTHING"
 582                         $first = true;
 583                         foreach ( $rows as $row ) {
 584                                 if ( $first ) {
 585                                         $first = false;
 586                                 } else {
 587                                         $sql .= ',';
 588                                 }
 589                                 $sql .= '(' . $this->makeList( $row ) . ')';
 590                         }
 591                         if ( $ignore ) {
 592                                 $sql .= ' ON CONFLICT DO NOTHING';
 593                         }
 594                         $this->query( $sql, $fname );
 595                 } else {
 596                         // Emulate IGNORE by doing each row individually, with savepoints
 597                         // to roll back as necessary.
 598                         $numrowsinserted = 0;
 599
 600                         $tok = $this->startAtomic( "$fname (outer)", self::ATOMIC_CANCELABLE );
 601                         try {
 602                                 foreach ( $rows as $row ) {
 603                                         $tempsql = $sql;
 604                                         $tempsql .= '(' . $this->makeList( $row ) . ')';
 605
 606                                         $this->startAtomic( "$fname (inner)", self::ATOMIC_CANCELABLE );
 607                                         try {
 608                                                 $this->query( $tempsql, $fname );
 609                                                 $this->endAtomic( "$fname (inner)" );
 610                                                 $numrowsinserted++;
 611                                         } catch ( DBQueryError $e ) {
 612                                                 $this->cancelAtomic( "$fname (inner)" );
 613                                                 // Our IGNORE is supposed to ignore duplicate key errors, but not others.
 614                                                 // (even though MySQL's version apparently ignores all errors)
 615                                                 if ( $e->errno !== '23505' ) {
 616                                                         throw $e;
 617                                                 }
 618                                         }
 619                                 }
 620                         } catch ( Exception $e ) {
 621                                 $this->cancelAtomic( "$fname (outer)", $tok );
 622                                 throw $e;
 623                         }
 624                         $this->endAtomic( "$fname (outer)" );
 625
 626                         // Set the affected row count for the whole operation
 627                         $this->affectedRowCount = $numrowsinserted;
 628                 }
 629
 630                 return true;
 631         }
 632
 633         /**
 634          * INSERT SELECT wrapper
 635          * $varMap must be an associative array of the form [ 'dest1' => 'source1', ... ]
 636          * Source items may be literals rather then field names, but strings should
 637          * be quoted with Database::addQuotes()
 638          * $conds may be "*" to copy the whole table
 639          * srcTable may be an array of tables.
 640          * @todo FIXME: Implement this a little better (seperate select/insert)?
 641          *
 642          * @param string $destTable
 643          * @param array|string $srcTable
 644          * @param array $varMap
 645          * @param array $conds
 646          * @param string $fname
 647          * @param array $insertOptions
 648          * @param array $selectOptions
 649          * @param array $selectJoinConds
 650          * @return bool
 651          */
 652         public function nativeInsertSelect(
 653                 $destTable, $srcTable, $varMap, $conds, $fname = __METHOD__,
 654                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
 655         ) {
 656                 if ( !is_array( $insertOptions ) ) {
 657                         $insertOptions = [ $insertOptions ];
 658                 }
 659
 660                 if ( in_array( 'IGNORE', $insertOptions ) ) {
 661                         if ( $this->getServerVersion() >= 9.5 ) {
 662                                 // Use ON CONFLICT DO NOTHING if we have it for IGNORE
 663                                 $destTable = $this->tableName( $destTable );
 664
 665                                 $selectSql = $this->selectSQLText(
 666                                         $srcTable,
 667                                         array_values( $varMap ),
 668                                         $conds,
 669                                         $fname,
 670                                         $selectOptions,
 671                                         $selectJoinConds
 672                                 );
 673
 674                                 $sql = "INSERT INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ') ' .
 675                                         $selectSql . ' ON CONFLICT DO NOTHING';
 676
 677                                 return $this->query( $sql, $fname );
 678                         } else {
 679                                 // IGNORE and we don't have ON CONFLICT DO NOTHING, so just use the non-native version
 680                                 return $this->nonNativeInsertSelect(
 681                                         $destTable, $srcTable, $varMap, $conds, $fname,
 682                                         $insertOptions, $selectOptions, $selectJoinConds
 683                                 );
 684                         }
 685                 }
 686
 687                 return parent::nativeInsertSelect( $destTable, $srcTable, $varMap, $conds, $fname,
 688                         $insertOptions, $selectOptions, $selectJoinConds );
 689         }
 690
 691         public function tableName( $name, $format = 'quoted' ) {
 692                 // Replace reserved words with better ones
 693                 $name = $this->remappedTableName( $name );
 694
 695                 return parent::tableName( $name, $format );
 696         }
 697
 698         /**
 699          * @param string $name
 700          * @return string Value of $name or remapped name if $name is a reserved keyword
 701          */
 702         public function remappedTableName( $name ) {
 703                 return isset( $this->keywordTableMap[$name] ) ? $this->keywordTableMap[$name] : $name;
 704         }
 705
 706         /**
 707          * @param string $name
 708          * @param string $format
 709          * @return string Qualified and encoded (if requested) table name
 710          */
 711         public function realTableName( $name, $format = 'quoted' ) {
 712                 return parent::tableName( $name, $format );
 713         }
 714
 715         public function nextSequenceValue( $seqName ) {
 716                 return new NextSequenceValue;
 717         }
 718
 719         /**
 720          * Return the current value of a sequence. Assumes it has been nextval'ed in this session.
 721          *
 722          * @param string $seqName
 723          * @return int
 724          */
 725         public function currentSequenceValue( $seqName ) {
 726                 $safeseq = str_replace( "'", "''", $seqName );
 727                 $res = $this->query( "SELECT currval('$safeseq')" );
 728                 $row = $this->fetchRow( $res );
 729                 $currval = $row[0];
 730
 731                 return $currval;
 732         }
 733
 734         public function textFieldSize( $table, $field ) {
 735                 $table = $this->tableName( $table );
 736                 $sql = "SELECT t.typname as ftype,a.atttypmod as size
 737                         FROM pg_class c, pg_attribute a, pg_type t
 738                         WHERE relname='$table' AND a.attrelid=c.oid AND
 739                                 a.atttypid=t.oid and a.attname='$field'";
 740                 $res = $this->query( $sql );
 741                 $row = $this->fetchObject( $res );
 742                 if ( $row->ftype == 'varchar' ) {
 743                         $size = $row->size - 4;
 744                 } else {
 745                         $size = $row->size;
 746                 }
 747
 748                 return $size;
 749         }
 750
 751         public function limitResult( $sql, $limit, $offset = false ) {
 752                 return "$sql LIMIT $limit " . ( is_numeric( $offset ) ? " OFFSET {$offset} " : '' );
 753         }
 754
 755         public function wasDeadlock() {
 756                 // https://www.postgresql.org/docs/9.2/static/errcodes-appendix.html
 757                 return $this->lastErrno() === '40P01';
 758         }
 759
 760         public function wasLockTimeout() {
 761                 // https://www.postgresql.org/docs/9.2/static/errcodes-appendix.html
 762                 return $this->lastErrno() === '55P03';
 763         }
 764
 765         public function wasConnectionError( $errno ) {
 766                 // https://www.postgresql.org/docs/9.2/static/errcodes-appendix.html
 767                 static $codes = [ '08000', '08003', '08006', '08001', '08004', '57P01', '57P03', '53300' ];
 768
 769                 return in_array( $errno, $codes, true );
 770         }
 771
 772         protected function wasKnownStatementRollbackError() {
 773                 return false; // transaction has to be rolled-back from error state
 774         }
 775
 776         public function duplicateTableStructure(
 777                 $oldName, $newName, $temporary = false, $fname = __METHOD__
 778         ) {
 779                 $newName = $this->addIdentifierQuotes( $newName );
 780                 $oldName = $this->addIdentifierQuotes( $oldName );
 781
 782                 return $this->query( 'CREATE ' . ( $temporary ? 'TEMPORARY ' : '' ) . " TABLE $newName " .
 783                         "(LIKE $oldName INCLUDING DEFAULTS INCLUDING INDEXES)", $fname );
 784         }
 785
 786         public function listTables( $prefix = null, $fname = __METHOD__ ) {
 787                 $eschema = $this->addQuotes( $this->getCoreSchema() );
 788                 $result = $this->query(
 789                         "SELECT tablename FROM pg_tables WHERE schemaname = $eschema", $fname );
 790                 $endArray = [];
 791
 792                 foreach ( $result as $table ) {
 793                         $vars = get_object_vars( $table );
 794                         $table = array_pop( $vars );
 795                         if ( !$prefix || strpos( $table, $prefix ) === 0 ) {
 796                                 $endArray[] = $table;
 797                         }
 798                 }
 799
 800                 return $endArray;
 801         }
 802
 803         public function timestamp( $ts = 0 ) {
 804                 $ct = new ConvertibleTimestamp( $ts );
 805
 806                 return $ct->getTimestamp( TS_POSTGRES );
 807         }
 808
 809         /**
 810          * Posted by cc[plus]php[at]c2se[dot]com on 25-Mar-2009 09:12
 811          * to https://secure.php.net/manual/en/ref.pgsql.php
 812          *
 813          * Parsing a postgres array can be a tricky problem, he's my
 814          * take on this, it handles multi-dimensional arrays plus
 815          * escaping using a nasty regexp to determine the limits of each
 816          * data-item.
 817          *
 818          * This should really be handled by PHP PostgreSQL module
 819          *
 820          * @since 1.19
 821          * @param string $text Postgreql array returned in a text form like {a,b}
 822          * @param string[] $output
 823          * @param int|bool $limit
 824          * @param int $offset
 825          * @return string[]
 826          */
 827         private function pg_array_parse( $text, &$output, $limit = false, $offset = 1 ) {
 828                 if ( false === $limit ) {
 829                         $limit = strlen( $text ) - 1;
 830                         $output = [];
 831                 }
 832                 if ( '{}' == $text ) {
 833                         return $output;
 834                 }
 835                 do {
 836                         if ( '{' != $text[$offset] ) {
 837                                 preg_match( "/(\\{?\"([^\"\\\\]|\\\\.)*\"|[^,{}]+)+([,}]+)/",
 838                                         $text, $match, 0, $offset );
 839                                 $offset += strlen( $match[0] );
 840                                 $output[] = ( '"' != $match[1][0]
 841                                         ? $match[1]
 842                                         : stripcslashes( substr( $match[1], 1, -1 ) ) );
 843                                 if ( '},' == $match[3] ) {
 844                                         return $output;
 845                                 }
 846                         } else {
 847                                 $offset = $this->pg_array_parse( $text, $output, $limit, $offset + 1 );
 848                         }
 849                 } while ( $limit > $offset );
 850
 851                 return $output;
 852         }
 853
 854         public function aggregateValue( $valuedata, $valuename = 'value' ) {
 855                 return $valuedata;
 856         }
 857
 858         public function getSoftwareLink() {
 859                 return '[{{int:version-db-postgres-url}} PostgreSQL]';
 860         }
 861
 862         /**
 863          * Return current schema (executes SELECT current_schema())
 864          * Needs transaction
 865          *
 866          * @since 1.19
 867          * @return string Default schema for the current session
 868          */
 869         public function getCurrentSchema() {
 870                 $res = $this->query( "SELECT current_schema()", __METHOD__ );
 871                 $row = $this->fetchRow( $res );
 872
 873                 return $row[0];
 874         }
 875
 876         /**
 877          * Return list of schemas which are accessible without schema name
 878          * This is list does not contain magic keywords like "$user"
 879          * Needs transaction
 880          *
 881          * @see getSearchPath()
 882          * @see setSearchPath()
 883          * @since 1.19
 884          * @return array List of actual schemas for the current sesson
 885          */
 886         public function getSchemas() {
 887                 $res = $this->query( "SELECT current_schemas(false)", __METHOD__ );
 888                 $row = $this->fetchRow( $res );
 889                 $schemas = [];
 890
 891                 /* PHP pgsql support does not support array type, "{a,b}" string is returned */
 892
 893                 return $this->pg_array_parse( $row[0], $schemas );
 894         }
 895
 896         /**
 897          * Return search patch for schemas
 898          * This is different from getSchemas() since it contain magic keywords
 899          * (like "$user").
 900          * Needs transaction
 901          *
 902          * @since 1.19
 903          * @return array How to search for table names schemas for the current user
 904          */
 905         public function getSearchPath() {
 906                 $res = $this->query( "SHOW search_path", __METHOD__ );
 907                 $row = $this->fetchRow( $res );
 908
 909                 /* PostgreSQL returns SHOW values as strings */
 910
 911                 return explode( ",", $row[0] );
 912         }
 913
 914         /**
 915          * Update search_path, values should already be sanitized
 916          * Values may contain magic keywords like "$user"
 917          * @since 1.19
 918          *
 919          * @param array $search_path List of schemas to be searched by default
 920          */
 921         private function setSearchPath( $search_path ) {
 922                 $this->query( "SET search_path = " . implode( ", ", $search_path ) );
 923         }
 924
 925         /**
 926          * Determine default schema for the current application
 927          * Adjust this session schema search path if desired schema exists
 928          * and is not alread there.
 929          *
 930          * We need to have name of the core schema stored to be able
 931          * to query database metadata.
 932          *
 933          * This will be also called by the installer after the schema is created
 934          *
 935          * @since 1.19
 936          *
 937          * @param string $desiredSchema
 938          */
 939         public function determineCoreSchema( $desiredSchema ) {
 940                 $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
 941                 if ( $this->schemaExists( $desiredSchema ) ) {
 942                         if ( in_array( $desiredSchema, $this->getSchemas() ) ) {
 943                                 $this->coreSchema = $desiredSchema;
 944                                 $this->queryLogger->debug(
 945                                         "Schema \"" . $desiredSchema . "\" already in the search path\n" );
 946                         } else {
 947                                 /**
 948                                  * Prepend our schema (e.g. 'mediawiki') in front
 949                                  * of the search path
 950                                  * Fixes T17816
 951                                  */
 952                                 $search_path = $this->getSearchPath();
 953                                 array_unshift( $search_path,
 954                                         $this->addIdentifierQuotes( $desiredSchema ) );
 955                                 $this->setSearchPath( $search_path );
 956                                 $this->coreSchema = $desiredSchema;
 957                                 $this->queryLogger->debug(
 958                                         "Schema \"" . $desiredSchema . "\" added to the search path\n" );
 959                         }
 960                 } else {
 961                         $this->coreSchema = $this->getCurrentSchema();
 962                         $this->queryLogger->debug(
 963                                 "Schema \"" . $desiredSchema . "\" not found, using current \"" .
 964                                 $this->coreSchema . "\"\n" );
 965                 }
 966                 /* Commit SET otherwise it will be rollbacked on error or IGNORE SELECT */
 967                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
 968         }
 969
 970         /**
 971          * Return schema name for core application tables
 972          *
 973          * @since 1.19
 974          * @return string Core schema name
 975          */
 976         public function getCoreSchema() {
 977                 return $this->coreSchema;
 978         }
 979
 980         public function getServerVersion() {
 981                 if ( !isset( $this->numericVersion ) ) {
 982                         $conn = $this->getBindingHandle();
 983                         $versionInfo = pg_version( $conn );
 984                         if ( version_compare( $versionInfo['client'], '7.4.0', 'lt' ) ) {
 985                                 // Old client, abort install
 986                                 $this->numericVersion = '7.3 or earlier';
 987                         } elseif ( isset( $versionInfo['server'] ) ) {
 988                                 // Normal client
 989                                 $this->numericVersion = $versionInfo['server'];
 990                         } else {
 991                                 // T18937: broken pgsql extension from PHP<5.3
 992                                 $this->numericVersion = pg_parameter_status( $conn, 'server_version' );
 993                         }
 994                 }
 995
 996                 return $this->numericVersion;
 997         }
 998
 999         /**
1000          * Query whether a given relation exists (in the given schema, or the
1001          * default mw one if not given)
1002          * @param string $table
1003          * @param array|string $types
1004          * @param bool|string $schema
1005          * @return bool
1006          */
1007         private function relationExists( $table, $types, $schema = false ) {
1008                 if ( !is_array( $types ) ) {
1009                         $types = [ $types ];
1010                 }
1011                 if ( $schema === false ) {
1012                         $schema = $this->getCoreSchema();
1013                 }
1014                 $table = $this->realTableName( $table, 'raw' );
1015                 $etable = $this->addQuotes( $table );
1016                 $eschema = $this->addQuotes( $schema );
1017                 $sql = "SELECT 1 FROM pg_catalog.pg_class c, pg_catalog.pg_namespace n "
1018                         . "WHERE c.relnamespace = n.oid AND c.relname = $etable AND n.nspname = $eschema "
1019                         . "AND c.relkind IN ('" . implode( "','", $types ) . "')";
1020                 $res = $this->query( $sql );
1021                 $count = $res ? $res->numRows() : 0;
1022
1023                 return (bool)$count;
1024         }
1025
1026         /**
1027          * For backward compatibility, this function checks both tables and views.
1028          * @param string $table
1029          * @param string $fname
1030          * @param bool|string $schema
1031          * @return bool
1032          */
1033         public function tableExists( $table, $fname = __METHOD__, $schema = false ) {
1034                 return $this->relationExists( $table, [ 'r', 'v' ], $schema );
1035         }
1036
1037         public function sequenceExists( $sequence, $schema = false ) {
1038                 return $this->relationExists( $sequence, 'S', $schema );
1039         }
1040
1041         public function triggerExists( $table, $trigger ) {
1042                 $q = <<<SQL
1043         SELECT 1 FROM pg_class, pg_namespace, pg_trigger
1044                 WHERE relnamespace=pg_namespace.oid AND relkind='r'
1045                         AND tgrelid=pg_class.oid
1046                         AND nspname=%s AND relname=%s AND tgname=%s
1047 SQL;
1048                 $res = $this->query(
1049                         sprintf(
1050                                 $q,
1051                                 $this->addQuotes( $this->getCoreSchema() ),
1052                                 $this->addQuotes( $table ),
1053                                 $this->addQuotes( $trigger )
1054                         )
1055                 );
1056                 if ( !$res ) {
1057                         return null;
1058                 }
1059                 $rows = $res->numRows();
1060
1061                 return $rows;
1062         }
1063
1064         public function ruleExists( $table, $rule ) {
1065                 $exists = $this->selectField( 'pg_rules', 'rulename',
1066                         [
1067                                 'rulename' => $rule,
1068                                 'tablename' => $table,
1069                                 'schemaname' => $this->getCoreSchema()
1070                         ]
1071                 );
1072
1073                 return $exists === $rule;
1074         }
1075
1076         public function constraintExists( $table, $constraint ) {
1077                 $sql = sprintf( "SELECT 1 FROM information_schema.table_constraints " .
1078                         "WHERE constraint_schema = %s AND table_name = %s AND constraint_name = %s",
1079                         $this->addQuotes( $this->getCoreSchema() ),
1080                         $this->addQuotes( $table ),
1081                         $this->addQuotes( $constraint )
1082                 );
1083                 $res = $this->query( $sql );
1084                 if ( !$res ) {
1085                         return null;
1086                 }
1087                 $rows = $res->numRows();
1088
1089                 return $rows;
1090         }
1091
1092         /**
1093          * Query whether a given schema exists. Returns true if it does, false if it doesn't.
1094          * @param string $schema
1095          * @return bool
1096          */
1097         public function schemaExists( $schema ) {
1098                 if ( !strlen( $schema ) ) {
1099                         return false; // short-circuit
1100                 }
1101
1102                 $exists = $this->selectField(
1103                         '"pg_catalog"."pg_namespace"', 1, [ 'nspname' => $schema ], __METHOD__ );
1104
1105                 return (bool)$exists;
1106         }
1107
1108         /**
1109          * Returns true if a given role (i.e. user) exists, false otherwise.
1110          * @param string $roleName
1111          * @return bool
1112          */
1113         public function roleExists( $roleName ) {
1114                 $exists = $this->selectField( '"pg_catalog"."pg_roles"', 1,
1115                         [ 'rolname' => $roleName ], __METHOD__ );
1116
1117                 return (bool)$exists;
1118         }
1119
1120         /**
1121          * @param string $table
1122          * @param string $field
1123          * @return PostgresField|null
1124          */
1125         public function fieldInfo( $table, $field ) {
1126                 return PostgresField::fromText( $this, $table, $field );
1127         }
1128
1129         /**
1130          * pg_field_type() wrapper
1131          * @param ResultWrapper|resource $res ResultWrapper or PostgreSQL query result resource
1132          * @param int $index Field number, starting from 0
1133          * @return string
1134          */
1135         public function fieldType( $res, $index ) {
1136                 if ( $res instanceof ResultWrapper ) {
1137                         $res = $res->result;
1138                 }
1139
1140                 return pg_field_type( $res, $index );
1141         }
1142
1143         public function encodeBlob( $b ) {
1144                 return new PostgresBlob( pg_escape_bytea( $b ) );
1145         }
1146
1147         public function decodeBlob( $b ) {
1148                 if ( $b instanceof PostgresBlob ) {
1149                         $b = $b->fetch();
1150                 } elseif ( $b instanceof Blob ) {
1151                         return $b->fetch();
1152                 }
1153
1154                 return pg_unescape_bytea( $b );
1155         }
1156
1157         public function strencode( $s ) {
1158                 // Should not be called by us
1159                 return pg_escape_string( $this->getBindingHandle(), (string)$s );
1160         }
1161
1162         public function addQuotes( $s ) {
1163                 $conn = $this->getBindingHandle();
1164
1165                 if ( is_null( $s ) ) {
1166                         return 'NULL';
1167                 } elseif ( is_bool( $s ) ) {
1168                         return intval( $s );
1169                 } elseif ( $s instanceof Blob ) {
1170                         if ( $s instanceof PostgresBlob ) {
1171                                 $s = $s->fetch();
1172                         } else {
1173                                 $s = pg_escape_bytea( $conn, $s->fetch() );
1174                         }
1175                         return "'$s'";
1176                 } elseif ( $s instanceof NextSequenceValue ) {
1177                         return 'DEFAULT';
1178                 }
1179
1180                 return "'" . pg_escape_string( $conn, (string)$s ) . "'";
1181         }
1182
1183         public function makeSelectOptions( $options ) {
1184                 $preLimitTail = $postLimitTail = '';
1185                 $startOpts = $useIndex = $ignoreIndex = '';
1186
1187                 $noKeyOptions = [];
1188                 foreach ( $options as $key => $option ) {
1189                         if ( is_numeric( $key ) ) {
1190                                 $noKeyOptions[$option] = true;
1191                         }
1192                 }
1193
1194                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1195
1196                 $preLimitTail .= $this->makeOrderBy( $options );
1197
1198                 if ( isset( $options['FOR UPDATE'] ) ) {
1199                         $postLimitTail .= ' FOR UPDATE OF ' .
1200                                 implode( ', ', array_map( [ $this, 'tableName' ], $options['FOR UPDATE'] ) );
1201                 } elseif ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1202                         $postLimitTail .= ' FOR UPDATE';
1203                 }
1204
1205                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1206                         $startOpts .= 'DISTINCT';
1207                 }
1208
1209                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1210         }
1211
1212         public function getDBname() {
1213                 return $this->dbName;
1214         }
1215
1216         public function getServer() {
1217                 return $this->server;
1218         }
1219
1220         public function buildConcat( $stringList ) {
1221                 return implode( ' || ', $stringList );
1222         }
1223
1224         public function buildGroupConcatField(
1225                 $delimiter, $table, $field, $conds = '', $options = [], $join_conds = []
1226         ) {
1227                 $fld = "array_to_string(array_agg($field)," . $this->addQuotes( $delimiter ) . ')';
1228
1229                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1230         }
1231
1232         public function buildStringCast( $field ) {
1233                 return $field . '::text';
1234         }
1235
1236         public function streamStatementEnd( &$sql, &$newLine ) {
1237                 # Allow dollar quoting for function declarations
1238                 if ( substr( $newLine, 0, 4 ) == '$mw$' ) {
1239                         if ( $this->delimiter ) {
1240                                 $this->delimiter = false;
1241                         } else {
1242                                 $this->delimiter = ';';
1243                         }
1244                 }
1245
1246                 return parent::streamStatementEnd( $sql, $newLine );
1247         }
1248
1249         public function doLockTables( array $read, array $write, $method ) {
1250                 $tablesWrite = [];
1251                 foreach ( $write as $table ) {
1252                         $tablesWrite[] = $this->tableName( $table );
1253                 }
1254                 $tablesRead = [];
1255                 foreach ( $read as $table ) {
1256                         $tablesRead[] = $this->tableName( $table );
1257                 }
1258
1259                 // Acquire locks for the duration of the current transaction...
1260                 if ( $tablesWrite ) {
1261                         $this->query(
1262                                 'LOCK TABLE ONLY ' . implode( ',', $tablesWrite ) . ' IN EXCLUSIVE MODE',
1263                                 $method
1264                         );
1265                 }
1266                 if ( $tablesRead ) {
1267                         $this->query(
1268                                 'LOCK TABLE ONLY ' . implode( ',', $tablesRead ) . ' IN SHARE MODE',
1269                                 $method
1270                         );
1271                 }
1272
1273                 return true;
1274         }
1275
1276         public function lockIsFree( $lockName, $method ) {
1277                 if ( !parent::lockIsFree( $lockName, $method ) ) {
1278                         return false; // already held
1279                 }
1280                 // http://www.postgresql.org/docs/9.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1281                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1282                 $result = $this->query( "SELECT (CASE(pg_try_advisory_lock($key))
1283                         WHEN 'f' THEN 'f' ELSE pg_advisory_unlock($key) END) AS lockstatus", $method );
1284                 $row = $this->fetchObject( $result );
1285
1286                 return ( $row->lockstatus === 't' );
1287         }
1288
1289         public function lock( $lockName, $method, $timeout = 5 ) {
1290                 // http://www.postgresql.org/docs/9.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1291                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1292                 $loop = new WaitConditionLoop(
1293                         function () use ( $lockName, $key, $timeout, $method ) {
1294                                 $res = $this->query( "SELECT pg_try_advisory_lock($key) AS lockstatus", $method );
1295                                 $row = $this->fetchObject( $res );
1296                                 if ( $row->lockstatus === 't' ) {
1297                                         parent::lock( $lockName, $method, $timeout ); // record
1298                                         return true;
1299                                 }
1300
1301                                 return WaitConditionLoop::CONDITION_CONTINUE;
1302                         },
1303                         $timeout
1304                 );
1305
1306                 return ( $loop->invoke() === $loop::CONDITION_REACHED );
1307         }
1308
1309         public function unlock( $lockName, $method ) {
1310                 // http://www.postgresql.org/docs/9.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1311                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1312                 $result = $this->query( "SELECT pg_advisory_unlock($key) as lockstatus", $method );
1313                 $row = $this->fetchObject( $result );
1314
1315                 if ( $row->lockstatus === 't' ) {
1316                         parent::unlock( $lockName, $method ); // record
1317                         return true;
1318                 }
1319
1320                 $this->queryLogger->debug( __METHOD__ . " failed to release lock\n" );
1321
1322                 return false;
1323         }
1324
1325         public function serverIsReadOnly() {
1326                 $res = $this->query( "SHOW default_transaction_read_only", __METHOD__ );
1327                 $row = $this->fetchObject( $res );
1328
1329                 return $row ? ( strtolower( $row->default_transaction_read_only ) === 'on' ) : false;
1330         }
1331
1332         /**
1333          * @param string $lockName
1334          * @return string Integer
1335          */
1336         private function bigintFromLockName( $lockName ) {
1337                 return \Wikimedia\base_convert( substr( sha1( $lockName ), 0, 15 ), 16, 10 );
1338         }
1339 }
1340
1341 class_alias( DatabasePostgres::class, 'DatabasePostgres' );