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 MediaWiki;
  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 $mLastResult = null;
  39         /** @var int The number of rows affected as an integer */
  40         protected $mAffectedRows = null;
  41
  42         /** @var float|string */
  43         private $numericVersion = null;
  44         /** @var string Connect string to open a PostgreSQL connection */
  45         private $connectString;
  46         /** @var string */
  47         private $mCoreSchema;
  48         /** @var string[] Map of (reserved table name => alternate table name) */
  49         private $keywordTableMap = [];
  50
  51         /**
  52          * @see Database::__construct()
  53          * @param array $params Additional parameters include:
  54          *   - keywordTableMap : Map of reserved table names to alternative table names to use
  55          */
  56         public function __construct( array $params ) {
  57                 $this->port = isset( $params['port'] ) ? $params['port'] : false;
  58                 $this->keywordTableMap = isset( $params['keywordTableMap'] )
  59                         ? $params['keywordTableMap']
  60                         : [];
  61
  62                 parent::__construct( $params );
  63         }
  64
  65         public function getType() {
  66                 return 'postgres';
  67         }
  68
  69         public function implicitGroupby() {
  70                 return false;
  71         }
  72
  73         public function implicitOrderby() {
  74                 return false;
  75         }
  76
  77         public function hasConstraint( $name ) {
  78                 $conn = $this->getBindingHandle();
  79
  80                 $sql = "SELECT 1 FROM pg_catalog.pg_constraint c, pg_catalog.pg_namespace n " .
  81                         "WHERE c.connamespace = n.oid AND conname = '" .
  82                         pg_escape_string( $conn, $name ) . "' AND n.nspname = '" .
  83                         pg_escape_string( $conn, $this->getCoreSchema() ) . "'";
  84                 $res = $this->doQuery( $sql );
  85
  86                 return $this->numRows( $res );
  87         }
  88
  89         public function open( $server, $user, $password, $dbName ) {
  90                 # Test for Postgres support, to avoid suppressed fatal error
  91                 if ( !function_exists( 'pg_connect' ) ) {
  92                         throw new DBConnectionError(
  93                                 $this,
  94                                 "Postgres functions missing, have you compiled PHP with the --with-pgsql\n" .
  95                                 "option? (Note: if you recently installed PHP, you may need to restart your\n" .
  96                                 "webserver and database)\n"
  97                         );
  98                 }
  99
 100                 $this->mServer = $server;
 101                 $this->mUser = $user;
 102                 $this->mPassword = $password;
 103                 $this->mDBname = $dbName;
 104
 105                 $connectVars = [
 106                         // pg_connect() user $user as the default database. Since a database is *required*,
 107                         // at least pick a "don't care" database that is more likely to exist. This case
 108                         // arrises when LoadBalancer::getConnection( $i, [], '' ) is used.
 109                         'dbname' => strlen( $dbName ) ? $dbName : 'postgres',
 110                         'user' => $user,
 111                         'password' => $password
 112                 ];
 113                 if ( $server != false && $server != '' ) {
 114                         $connectVars['host'] = $server;
 115                 }
 116                 if ( (int)$this->port > 0 ) {
 117                         $connectVars['port'] = (int)$this->port;
 118                 }
 119                 if ( $this->mFlags & self::DBO_SSL ) {
 120                         $connectVars['sslmode'] = 1;
 121                 }
 122
 123                 $this->connectString = $this->makeConnectionString( $connectVars );
 124                 $this->close();
 125                 $this->installErrorHandler();
 126
 127                 try {
 128                         // Use new connections to let LoadBalancer/LBFactory handle reuse
 129                         $this->mConn = pg_connect( $this->connectString, PGSQL_CONNECT_FORCE_NEW );
 130                 } catch ( Exception $ex ) {
 131                         $this->restoreErrorHandler();
 132                         throw $ex;
 133                 }
 134
 135                 $phpError = $this->restoreErrorHandler();
 136
 137                 if ( !$this->mConn ) {
 138                         $this->queryLogger->debug(
 139                                 "DB connection error\n" .
 140                                 "Server: $server, Database: $dbName, User: $user, Password: " .
 141                                 substr( $password, 0, 3 ) . "...\n"
 142                         );
 143                         $this->queryLogger->debug( $this->lastError() . "\n" );
 144                         throw new DBConnectionError( $this, str_replace( "\n", ' ', $phpError ) );
 145                 }
 146
 147                 $this->mOpened = true;
 148
 149                 # If called from the command-line (e.g. importDump), only show errors
 150                 if ( $this->cliMode ) {
 151                         $this->doQuery( "SET client_min_messages = 'ERROR'" );
 152                 }
 153
 154                 $this->query( "SET client_encoding='UTF8'", __METHOD__ );
 155                 $this->query( "SET datestyle = 'ISO, YMD'", __METHOD__ );
 156                 $this->query( "SET timezone = 'GMT'", __METHOD__ );
 157                 $this->query( "SET standard_conforming_strings = on", __METHOD__ );
 158                 if ( $this->getServerVersion() >= 9.0 ) {
 159                         $this->query( "SET bytea_output = 'escape'", __METHOD__ ); // PHP bug 53127
 160                 }
 161
 162                 $this->determineCoreSchema( $this->mSchema );
 163                 // The schema to be used is now in the search path; no need for explicit qualification
 164                 $this->mSchema = '';
 165
 166                 return $this->mConn;
 167         }
 168
 169         public function databasesAreIndependent() {
 170                 return true;
 171         }
 172
 173         /**
 174          * Postgres doesn't support selectDB in the same way MySQL does. So if the
 175          * DB name doesn't match the open connection, open a new one
 176          * @param string $db
 177          * @return bool
 178          * @throws DBUnexpectedError
 179          */
 180         public function selectDB( $db ) {
 181                 if ( $this->mDBname !== $db ) {
 182                         return (bool)$this->open( $this->mServer, $this->mUser, $this->mPassword, $db );
 183                 } else {
 184                         return true;
 185                 }
 186         }
 187
 188         /**
 189          * @param string[] $vars
 190          * @return string
 191          */
 192         private function makeConnectionString( $vars ) {
 193                 $s = '';
 194                 foreach ( $vars as $name => $value ) {
 195                         $s .= "$name='" . str_replace( "'", "\\'", $value ) . "' ";
 196                 }
 197
 198                 return $s;
 199         }
 200
 201         protected function closeConnection() {
 202                 return $this->mConn ? pg_close( $this->mConn ) : true;
 203         }
 204
 205         public function doQuery( $sql ) {
 206                 $conn = $this->getBindingHandle();
 207
 208                 $sql = mb_convert_encoding( $sql, 'UTF-8' );
 209                 // Clear previously left over PQresult
 210                 while ( $res = pg_get_result( $conn ) ) {
 211                         pg_free_result( $res );
 212                 }
 213                 if ( pg_send_query( $conn, $sql ) === false ) {
 214                         throw new DBUnexpectedError( $this, "Unable to post new query to PostgreSQL\n" );
 215                 }
 216                 $this->mLastResult = pg_get_result( $conn );
 217                 $this->mAffectedRows = null;
 218                 if ( pg_result_error( $this->mLastResult ) ) {
 219                         return false;
 220                 }
 221
 222                 return $this->mLastResult;
 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->mLastResult, $d ) ) );
 243                 }
 244         }
 245
 246         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
 247                 if ( $tempIgnore ) {
 248                         /* Check for constraint violation */
 249                         if ( $errno === '23505' ) {
 250                                 parent::reportQueryError( $error, $errno, $sql, $fname, $tempIgnore );
 251
 252                                 return;
 253                         }
 254                 }
 255                 /* Transaction stays in the ERROR state until rolled back */
 256                 if ( $this->mTrxLevel ) {
 257                         // Throw away the transaction state, then raise the error as normal.
 258                         // Note that if this connection is managed by LBFactory, it's already expected
 259                         // that the other transactions LBFactory manages will be rolled back.
 260                         $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
 261                 }
 262                 parent::reportQueryError( $error, $errno, $sql, $fname, false );
 263         }
 264
 265         public function freeResult( $res ) {
 266                 if ( $res instanceof ResultWrapper ) {
 267                         $res = $res->result;
 268                 }
 269                 MediaWiki\suppressWarnings();
 270                 $ok = pg_free_result( $res );
 271                 MediaWiki\restoreWarnings();
 272                 if ( !$ok ) {
 273                         throw new DBUnexpectedError( $this, "Unable to free Postgres result\n" );
 274                 }
 275         }
 276
 277         public function fetchObject( $res ) {
 278                 if ( $res instanceof ResultWrapper ) {
 279                         $res = $res->result;
 280                 }
 281                 MediaWiki\suppressWarnings();
 282                 $row = pg_fetch_object( $res );
 283                 MediaWiki\restoreWarnings();
 284                 # @todo FIXME: HACK HACK HACK HACK debug
 285
 286                 # @todo hashar: not sure if the following test really trigger if the object
 287                 #          fetching failed.
 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 fetchRow( $res ) {
 300                 if ( $res instanceof ResultWrapper ) {
 301                         $res = $res->result;
 302                 }
 303                 MediaWiki\suppressWarnings();
 304                 $row = pg_fetch_array( $res );
 305                 MediaWiki\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 $row;
 316         }
 317
 318         public function numRows( $res ) {
 319                 if ( $res instanceof ResultWrapper ) {
 320                         $res = $res->result;
 321                 }
 322                 MediaWiki\suppressWarnings();
 323                 $n = pg_num_rows( $res );
 324                 MediaWiki\restoreWarnings();
 325
 326                 $conn = $this->getBindingHandle();
 327                 if ( pg_last_error( $conn ) ) {
 328                         throw new DBUnexpectedError(
 329                                 $this,
 330                                 'SQL error: ' . htmlspecialchars( pg_last_error( $conn ) )
 331                         );
 332                 }
 333
 334                 return $n;
 335         }
 336
 337         public function numFields( $res ) {
 338                 if ( $res instanceof ResultWrapper ) {
 339                         $res = $res->result;
 340                 }
 341
 342                 return pg_num_fields( $res );
 343         }
 344
 345         public function fieldName( $res, $n ) {
 346                 if ( $res instanceof ResultWrapper ) {
 347                         $res = $res->result;
 348                 }
 349
 350                 return pg_field_name( $res, $n );
 351         }
 352
 353         public function insertId() {
 354                 $res = $this->query( "SELECT lastval()" );
 355                 $row = $this->fetchRow( $res );
 356                 return is_null( $row[0] ) ? null : (int)$row[0];
 357         }
 358
 359         public function dataSeek( $res, $row ) {
 360                 if ( $res instanceof ResultWrapper ) {
 361                         $res = $res->result;
 362                 }
 363
 364                 return pg_result_seek( $res, $row );
 365         }
 366
 367         public function lastError() {
 368                 if ( $this->mConn ) {
 369                         if ( $this->mLastResult ) {
 370                                 return pg_result_error( $this->mLastResult );
 371                         } else {
 372                                 return pg_last_error();
 373                         }
 374                 }
 375
 376                 return $this->getLastPHPError() ?: 'No database connection';
 377         }
 378
 379         public function lastErrno() {
 380                 if ( $this->mLastResult ) {
 381                         return pg_result_error_field( $this->mLastResult, PGSQL_DIAG_SQLSTATE );
 382                 } else {
 383                         return false;
 384                 }
 385         }
 386
 387         public function affectedRows() {
 388                 if ( !is_null( $this->mAffectedRows ) ) {
 389                         // Forced result for simulated queries
 390                         return $this->mAffectedRows;
 391                 }
 392                 if ( empty( $this->mLastResult ) ) {
 393                         return 0;
 394                 }
 395
 396                 return pg_affected_rows( $this->mLastResult );
 397         }
 398
 399         /**
 400          * Estimate rows in dataset
 401          * Returns estimated count, based on EXPLAIN output
 402          * This is not necessarily an accurate estimate, so use sparingly
 403          * Returns -1 if count cannot be found
 404          * Takes same arguments as Database::select()
 405          *
 406          * @param string $table
 407          * @param string $vars
 408          * @param string $conds
 409          * @param string $fname
 410          * @param array $options
 411          * @return int
 412          */
 413         public function estimateRowCount( $table, $vars = '*', $conds = '',
 414                 $fname = __METHOD__, $options = []
 415         ) {
 416                 $options['EXPLAIN'] = true;
 417                 $res = $this->select( $table, $vars, $conds, $fname, $options );
 418                 $rows = -1;
 419                 if ( $res ) {
 420                         $row = $this->fetchRow( $res );
 421                         $count = [];
 422                         if ( preg_match( '/rows=(\d+)/', $row[0], $count ) ) {
 423                                 $rows = (int)$count[1];
 424                         }
 425                 }
 426
 427                 return $rows;
 428         }
 429
 430         public function indexInfo( $table, $index, $fname = __METHOD__ ) {
 431                 $sql = "SELECT indexname FROM pg_indexes WHERE tablename='$table'";
 432                 $res = $this->query( $sql, $fname );
 433                 if ( !$res ) {
 434                         return null;
 435                 }
 436                 foreach ( $res as $row ) {
 437                         if ( $row->indexname == $this->indexName( $index ) ) {
 438                                 return $row;
 439                         }
 440                 }
 441
 442                 return false;
 443         }
 444
 445         public function indexAttributes( $index, $schema = false ) {
 446                 if ( $schema === false ) {
 447                         $schema = $this->getCoreSchema();
 448                 }
 449                 /*
 450                  * A subquery would be not needed if we didn't care about the order
 451                  * of attributes, but we do
 452                  */
 453                 $sql = <<<__INDEXATTR__
 454
 455                         SELECT opcname,
 456                                 attname,
 457                                 i.indoption[s.g] as option,
 458                                 pg_am.amname
 459                         FROM
 460                                 (SELECT generate_series(array_lower(isub.indkey,1), array_upper(isub.indkey,1)) AS g
 461                                         FROM
 462                                                 pg_index isub
 463                                         JOIN pg_class cis
 464                                                 ON cis.oid=isub.indexrelid
 465                                         JOIN pg_namespace ns
 466                                                 ON cis.relnamespace = ns.oid
 467                                         WHERE cis.relname='$index' AND ns.nspname='$schema') AS s,
 468                                 pg_attribute,
 469                                 pg_opclass opcls,
 470                                 pg_am,
 471                                 pg_class ci
 472                                 JOIN pg_index i
 473                                         ON ci.oid=i.indexrelid
 474                                 JOIN pg_class ct
 475                                         ON ct.oid = i.indrelid
 476                                 JOIN pg_namespace n
 477                                         ON ci.relnamespace = n.oid
 478                                 WHERE
 479                                         ci.relname='$index' AND n.nspname='$schema'
 480                                         AND     attrelid = ct.oid
 481                                         AND     i.indkey[s.g] = attnum
 482                                         AND     i.indclass[s.g] = opcls.oid
 483                                         AND     pg_am.oid = opcls.opcmethod
 484 __INDEXATTR__;
 485                 $res = $this->query( $sql, __METHOD__ );
 486                 $a = [];
 487                 if ( $res ) {
 488                         foreach ( $res as $row ) {
 489                                 $a[] = [
 490                                         $row->attname,
 491                                         $row->opcname,
 492                                         $row->amname,
 493                                         $row->option ];
 494                         }
 495                 } else {
 496                         return null;
 497                 }
 498
 499                 return $a;
 500         }
 501
 502         public function indexUnique( $table, $index, $fname = __METHOD__ ) {
 503                 $sql = "SELECT indexname FROM pg_indexes WHERE tablename='{$table}'" .
 504                         " AND indexdef LIKE 'CREATE UNIQUE%(" .
 505                         $this->strencode( $this->indexName( $index ) ) .
 506                         ")'";
 507                 $res = $this->query( $sql, $fname );
 508                 if ( !$res ) {
 509                         return null;
 510                 }
 511
 512                 return $res->numRows() > 0;
 513         }
 514
 515         public function selectSQLText(
 516                 $table, $vars, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
 517         ) {
 518                 if ( is_string( $options ) ) {
 519                         $options = [ $options ];
 520                 }
 521
 522                 // Change the FOR UPDATE option as necessary based on the join conditions. Then pass
 523                 // to the parent function to get the actual SQL text.
 524                 // In Postgres when using FOR UPDATE, only the main table and tables that are inner joined
 525                 // can be locked. That means tables in an outer join cannot be FOR UPDATE locked. Trying to
 526                 // do so causes a DB error. This wrapper checks which tables can be locked and adjusts it
 527                 // accordingly.
 528                 // MySQL uses "ORDER BY NULL" as an optimization hint, but that is illegal in PostgreSQL.
 529                 if ( is_array( $options ) ) {
 530                         $forUpdateKey = array_search( 'FOR UPDATE', $options, true );
 531                         if ( $forUpdateKey !== false && $join_conds ) {
 532                                 unset( $options[$forUpdateKey] );
 533                                 $options['FOR UPDATE'] = [];
 534
 535                                 // All tables not in $join_conds are good
 536                                 foreach ( $table as $alias => $name ) {
 537                                         if ( is_numeric( $alias ) ) {
 538                                                 $alias = $name;
 539                                         }
 540                                         if ( !isset( $join_conds[$alias] ) ) {
 541                                                 $options['FOR UPDATE'][] = $alias;
 542                                         }
 543                                 }
 544
 545                                 foreach ( $join_conds as $table_cond => $join_cond ) {
 546                                         if ( 0 === preg_match( '/^(?:LEFT|RIGHT|FULL)(?: OUTER)? JOIN$/i', $join_cond[0] ) ) {
 547                                                 $options['FOR UPDATE'][] = $table_cond;
 548                                         }
 549                                 }
 550
 551                                 // Quote alias names so $this->tableName() won't mangle them
 552                                 $options['FOR UPDATE'] = array_map( function ( $name ) use ( $table ) {
 553                                         return isset( $table[$name] ) ? $this->addIdentifierQuotes( $name ) : $name;
 554                                 }, $options['FOR UPDATE'] );
 555                         }
 556
 557                         if ( isset( $options['ORDER BY'] ) && $options['ORDER BY'] == 'NULL' ) {
 558                                 unset( $options['ORDER BY'] );
 559                         }
 560                 }
 561
 562                 return parent::selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
 563         }
 564
 565         /**
 566          * INSERT wrapper, inserts an array into a table
 567          *
 568          * $args may be a single associative array, or an array of these with numeric keys,
 569          * for multi-row insert (Postgres version 8.2 and above only).
 570          *
 571          * @param string $table Name of the table to insert to.
 572          * @param array $args Items to insert into the table.
 573          * @param string $fname Name of the function, for profiling
 574          * @param array|string $options String or array. Valid options: IGNORE
 575          * @return bool Success of insert operation. IGNORE always returns true.
 576          */
 577         public function insert( $table, $args, $fname = __METHOD__, $options = [] ) {
 578                 if ( !count( $args ) ) {
 579                         return true;
 580                 }
 581
 582                 $table = $this->tableName( $table );
 583                 if ( !isset( $this->numericVersion ) ) {
 584                         $this->getServerVersion();
 585                 }
 586
 587                 if ( !is_array( $options ) ) {
 588                         $options = [ $options ];
 589                 }
 590
 591                 if ( isset( $args[0] ) && is_array( $args[0] ) ) {
 592                         $multi = true;
 593                         $keys = array_keys( $args[0] );
 594                 } else {
 595                         $multi = false;
 596                         $keys = array_keys( $args );
 597                 }
 598
 599                 // If IGNORE is set, we use savepoints to emulate mysql's behavior
 600                 // @todo If PostgreSQL 9.5+, we could use ON CONFLICT DO NOTHING instead
 601                 $savepoint = $olde = null;
 602                 $numrowsinserted = 0;
 603                 if ( in_array( 'IGNORE', $options ) ) {
 604                         $savepoint = new SavepointPostgres( $this, 'mw', $this->queryLogger );
 605                         $olde = error_reporting( 0 );
 606                         // For future use, we may want to track the number of actual inserts
 607                         // Right now, insert (all writes) simply return true/false
 608                 }
 609
 610                 $sql = "INSERT INTO $table (" . implode( ',', $keys ) . ') VALUES ';
 611
 612                 if ( $multi ) {
 613                         if ( $this->numericVersion >= 8.2 && !$savepoint ) {
 614                                 $first = true;
 615                                 foreach ( $args as $row ) {
 616                                         if ( $first ) {
 617                                                 $first = false;
 618                                         } else {
 619                                                 $sql .= ',';
 620                                         }
 621                                         $sql .= '(' . $this->makeList( $row ) . ')';
 622                                 }
 623                                 $res = (bool)$this->query( $sql, $fname, $savepoint );
 624                         } else {
 625                                 $res = true;
 626                                 $origsql = $sql;
 627                                 foreach ( $args as $row ) {
 628                                         $tempsql = $origsql;
 629                                         $tempsql .= '(' . $this->makeList( $row ) . ')';
 630
 631                                         if ( $savepoint ) {
 632                                                 $savepoint->savepoint();
 633                                         }
 634
 635                                         $tempres = (bool)$this->query( $tempsql, $fname, $savepoint );
 636
 637                                         if ( $savepoint ) {
 638                                                 $bar = pg_result_error( $this->mLastResult );
 639                                                 if ( $bar != false ) {
 640                                                         $savepoint->rollback();
 641                                                 } else {
 642                                                         $savepoint->release();
 643                                                         $numrowsinserted++;
 644                                                 }
 645                                         }
 646
 647                                         // If any of them fail, we fail overall for this function call
 648                                         // Note that this will be ignored if IGNORE is set
 649                                         if ( !$tempres ) {
 650                                                 $res = false;
 651                                         }
 652                                 }
 653                         }
 654                 } else {
 655                         // Not multi, just a lone insert
 656                         if ( $savepoint ) {
 657                                 $savepoint->savepoint();
 658                         }
 659
 660                         $sql .= '(' . $this->makeList( $args ) . ')';
 661                         $res = (bool)$this->query( $sql, $fname, $savepoint );
 662                         if ( $savepoint ) {
 663                                 $bar = pg_result_error( $this->mLastResult );
 664                                 if ( $bar != false ) {
 665                                         $savepoint->rollback();
 666                                 } else {
 667                                         $savepoint->release();
 668                                         $numrowsinserted++;
 669                                 }
 670                         }
 671                 }
 672                 if ( $savepoint ) {
 673                         error_reporting( $olde );
 674                         $savepoint->commit();
 675
 676                         // Set the affected row count for the whole operation
 677                         $this->mAffectedRows = $numrowsinserted;
 678
 679                         // IGNORE always returns true
 680                         return true;
 681                 }
 682
 683                 return $res;
 684         }
 685
 686         /**
 687          * INSERT SELECT wrapper
 688          * $varMap must be an associative array of the form [ 'dest1' => 'source1', ... ]
 689          * Source items may be literals rather then field names, but strings should
 690          * be quoted with Database::addQuotes()
 691          * $conds may be "*" to copy the whole table
 692          * srcTable may be an array of tables.
 693          * @todo FIXME: Implement this a little better (seperate select/insert)?
 694          *
 695          * @param string $destTable
 696          * @param array|string $srcTable
 697          * @param array $varMap
 698          * @param array $conds
 699          * @param string $fname
 700          * @param array $insertOptions
 701          * @param array $selectOptions
 702          * @param array $selectJoinConds
 703          * @return bool
 704          */
 705         public function nativeInsertSelect(
 706                 $destTable, $srcTable, $varMap, $conds, $fname = __METHOD__,
 707                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
 708         ) {
 709                 if ( !is_array( $insertOptions ) ) {
 710                         $insertOptions = [ $insertOptions ];
 711                 }
 712
 713                 /*
 714                  * If IGNORE is set, use the non-native version.
 715                  * @todo If PostgreSQL 9.5+, we could use ON CONFLICT DO NOTHING
 716                  */
 717                 if ( in_array( 'IGNORE', $insertOptions ) ) {
 718                         return $this->nonNativeInsertSelect(
 719                                 $destTable, $srcTable, $varMap, $conds, $fname, $insertOptions, $selectOptions, $selectJoinConds
 720                         );
 721                 }
 722
 723                 return parent::nativeInsertSelect( $destTable, $srcTable, $varMap, $conds, $fname,
 724                         $insertOptions, $selectOptions, $selectJoinConds );
 725         }
 726
 727         public function tableName( $name, $format = 'quoted' ) {
 728                 // Replace reserved words with better ones
 729                 $name = $this->remappedTableName( $name );
 730
 731                 return parent::tableName( $name, $format );
 732         }
 733
 734         /**
 735          * @param string $name
 736          * @return string Value of $name or remapped name if $name is a reserved keyword
 737          */
 738         public function remappedTableName( $name ) {
 739                 return isset( $this->keywordTableMap[$name] ) ? $this->keywordTableMap[$name] : $name;
 740         }
 741
 742         /**
 743          * @param string $name
 744          * @param string $format
 745          * @return string Qualified and encoded (if requested) table name
 746          */
 747         public function realTableName( $name, $format = 'quoted' ) {
 748                 return parent::tableName( $name, $format );
 749         }
 750
 751         public function nextSequenceValue( $seqName ) {
 752                 return new NextSequenceValue;
 753         }
 754
 755         /**
 756          * Return the current value of a sequence. Assumes it has been nextval'ed in this session.
 757          *
 758          * @param string $seqName
 759          * @return int
 760          */
 761         public function currentSequenceValue( $seqName ) {
 762                 $safeseq = str_replace( "'", "''", $seqName );
 763                 $res = $this->query( "SELECT currval('$safeseq')" );
 764                 $row = $this->fetchRow( $res );
 765                 $currval = $row[0];
 766
 767                 return $currval;
 768         }
 769
 770         public function textFieldSize( $table, $field ) {
 771                 $table = $this->tableName( $table );
 772                 $sql = "SELECT t.typname as ftype,a.atttypmod as size
 773                         FROM pg_class c, pg_attribute a, pg_type t
 774                         WHERE relname='$table' AND a.attrelid=c.oid AND
 775                                 a.atttypid=t.oid and a.attname='$field'";
 776                 $res = $this->query( $sql );
 777                 $row = $this->fetchObject( $res );
 778                 if ( $row->ftype == 'varchar' ) {
 779                         $size = $row->size - 4;
 780                 } else {
 781                         $size = $row->size;
 782                 }
 783
 784                 return $size;
 785         }
 786
 787         public function limitResult( $sql, $limit, $offset = false ) {
 788                 return "$sql LIMIT $limit " . ( is_numeric( $offset ) ? " OFFSET {$offset} " : '' );
 789         }
 790
 791         public function wasDeadlock() {
 792                 return $this->lastErrno() == '40P01';
 793         }
 794
 795         public function duplicateTableStructure(
 796                 $oldName, $newName, $temporary = false, $fname = __METHOD__
 797         ) {
 798                 $newName = $this->addIdentifierQuotes( $newName );
 799                 $oldName = $this->addIdentifierQuotes( $oldName );
 800
 801                 return $this->query( 'CREATE ' . ( $temporary ? 'TEMPORARY ' : '' ) . " TABLE $newName " .
 802                         "(LIKE $oldName INCLUDING DEFAULTS INCLUDING INDEXES)", $fname );
 803         }
 804
 805         public function listTables( $prefix = null, $fname = __METHOD__ ) {
 806                 $eschema = $this->addQuotes( $this->getCoreSchema() );
 807                 $result = $this->query(
 808                         "SELECT tablename FROM pg_tables WHERE schemaname = $eschema", $fname );
 809                 $endArray = [];
 810
 811                 foreach ( $result as $table ) {
 812                         $vars = get_object_vars( $table );
 813                         $table = array_pop( $vars );
 814                         if ( !$prefix || strpos( $table, $prefix ) === 0 ) {
 815                                 $endArray[] = $table;
 816                         }
 817                 }
 818
 819                 return $endArray;
 820         }
 821
 822         public function timestamp( $ts = 0 ) {
 823                 $ct = new ConvertibleTimestamp( $ts );
 824
 825                 return $ct->getTimestamp( TS_POSTGRES );
 826         }
 827
 828         /**
 829          * Posted by cc[plus]php[at]c2se[dot]com on 25-Mar-2009 09:12
 830          * to https://secure.php.net/manual/en/ref.pgsql.php
 831          *
 832          * Parsing a postgres array can be a tricky problem, he's my
 833          * take on this, it handles multi-dimensional arrays plus
 834          * escaping using a nasty regexp to determine the limits of each
 835          * data-item.
 836          *
 837          * This should really be handled by PHP PostgreSQL module
 838          *
 839          * @since 1.19
 840          * @param string $text Postgreql array returned in a text form like {a,b}
 841          * @param string[] $output
 842          * @param int|bool $limit
 843          * @param int $offset
 844          * @return string[]
 845          */
 846         private function pg_array_parse( $text, &$output, $limit = false, $offset = 1 ) {
 847                 if ( false === $limit ) {
 848                         $limit = strlen( $text ) - 1;
 849                         $output = [];
 850                 }
 851                 if ( '{}' == $text ) {
 852                         return $output;
 853                 }
 854                 do {
 855                         if ( '{' != $text[$offset] ) {
 856                                 preg_match( "/(\\{?\"([^\"\\\\]|\\\\.)*\"|[^,{}]+)+([,}]+)/",
 857                                         $text, $match, 0, $offset );
 858                                 $offset += strlen( $match[0] );
 859                                 $output[] = ( '"' != $match[1][0]
 860                                         ? $match[1]
 861                                         : stripcslashes( substr( $match[1], 1, -1 ) ) );
 862                                 if ( '},' == $match[3] ) {
 863                                         return $output;
 864                                 }
 865                         } else {
 866                                 $offset = $this->pg_array_parse( $text, $output, $limit, $offset + 1 );
 867                         }
 868                 } while ( $limit > $offset );
 869
 870                 return $output;
 871         }
 872
 873         public function aggregateValue( $valuedata, $valuename = 'value' ) {
 874                 return $valuedata;
 875         }
 876
 877         public function getSoftwareLink() {
 878                 return '[{{int:version-db-postgres-url}} PostgreSQL]';
 879         }
 880
 881         /**
 882          * Return current schema (executes SELECT current_schema())
 883          * Needs transaction
 884          *
 885          * @since 1.19
 886          * @return string Default schema for the current session
 887          */
 888         public function getCurrentSchema() {
 889                 $res = $this->query( "SELECT current_schema()", __METHOD__ );
 890                 $row = $this->fetchRow( $res );
 891
 892                 return $row[0];
 893         }
 894
 895         /**
 896          * Return list of schemas which are accessible without schema name
 897          * This is list does not contain magic keywords like "$user"
 898          * Needs transaction
 899          *
 900          * @see getSearchPath()
 901          * @see setSearchPath()
 902          * @since 1.19
 903          * @return array List of actual schemas for the current sesson
 904          */
 905         public function getSchemas() {
 906                 $res = $this->query( "SELECT current_schemas(false)", __METHOD__ );
 907                 $row = $this->fetchRow( $res );
 908                 $schemas = [];
 909
 910                 /* PHP pgsql support does not support array type, "{a,b}" string is returned */
 911
 912                 return $this->pg_array_parse( $row[0], $schemas );
 913         }
 914
 915         /**
 916          * Return search patch for schemas
 917          * This is different from getSchemas() since it contain magic keywords
 918          * (like "$user").
 919          * Needs transaction
 920          *
 921          * @since 1.19
 922          * @return array How to search for table names schemas for the current user
 923          */
 924         public function getSearchPath() {
 925                 $res = $this->query( "SHOW search_path", __METHOD__ );
 926                 $row = $this->fetchRow( $res );
 927
 928                 /* PostgreSQL returns SHOW values as strings */
 929
 930                 return explode( ",", $row[0] );
 931         }
 932
 933         /**
 934          * Update search_path, values should already be sanitized
 935          * Values may contain magic keywords like "$user"
 936          * @since 1.19
 937          *
 938          * @param array $search_path List of schemas to be searched by default
 939          */
 940         private function setSearchPath( $search_path ) {
 941                 $this->query( "SET search_path = " . implode( ", ", $search_path ) );
 942         }
 943
 944         /**
 945          * Determine default schema for the current application
 946          * Adjust this session schema search path if desired schema exists
 947          * and is not alread there.
 948          *
 949          * We need to have name of the core schema stored to be able
 950          * to query database metadata.
 951          *
 952          * This will be also called by the installer after the schema is created
 953          *
 954          * @since 1.19
 955          *
 956          * @param string $desiredSchema
 957          */
 958         public function determineCoreSchema( $desiredSchema ) {
 959                 $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
 960                 if ( $this->schemaExists( $desiredSchema ) ) {
 961                         if ( in_array( $desiredSchema, $this->getSchemas() ) ) {
 962                                 $this->mCoreSchema = $desiredSchema;
 963                                 $this->queryLogger->debug(
 964                                         "Schema \"" . $desiredSchema . "\" already in the search path\n" );
 965                         } else {
 966                                 /**
 967                                  * Prepend our schema (e.g. 'mediawiki') in front
 968                                  * of the search path
 969                                  * Fixes T17816
 970                                  */
 971                                 $search_path = $this->getSearchPath();
 972                                 array_unshift( $search_path,
 973                                         $this->addIdentifierQuotes( $desiredSchema ) );
 974                                 $this->setSearchPath( $search_path );
 975                                 $this->mCoreSchema = $desiredSchema;
 976                                 $this->queryLogger->debug(
 977                                         "Schema \"" . $desiredSchema . "\" added to the search path\n" );
 978                         }
 979                 } else {
 980                         $this->mCoreSchema = $this->getCurrentSchema();
 981                         $this->queryLogger->debug(
 982                                 "Schema \"" . $desiredSchema . "\" not found, using current \"" .
 983                                 $this->mCoreSchema . "\"\n" );
 984                 }
 985                 /* Commit SET otherwise it will be rollbacked on error or IGNORE SELECT */
 986                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
 987         }
 988
 989         /**
 990          * Return schema name for core application tables
 991          *
 992          * @since 1.19
 993          * @return string Core schema name
 994          */
 995         public function getCoreSchema() {
 996                 return $this->mCoreSchema;
 997         }
 998
 999         public function getServerVersion() {
1000                 if ( !isset( $this->numericVersion ) ) {
1001                         $conn = $this->getBindingHandle();
1002                         $versionInfo = pg_version( $conn );
1003                         if ( version_compare( $versionInfo['client'], '7.4.0', 'lt' ) ) {
1004                                 // Old client, abort install
1005                                 $this->numericVersion = '7.3 or earlier';
1006                         } elseif ( isset( $versionInfo['server'] ) ) {
1007                                 // Normal client
1008                                 $this->numericVersion = $versionInfo['server'];
1009                         } else {
1010                                 // T18937: broken pgsql extension from PHP<5.3
1011                                 $this->numericVersion = pg_parameter_status( $conn, 'server_version' );
1012                         }
1013                 }
1014
1015                 return $this->numericVersion;
1016         }
1017
1018         /**
1019          * Query whether a given relation exists (in the given schema, or the
1020          * default mw one if not given)
1021          * @param string $table
1022          * @param array|string $types
1023          * @param bool|string $schema
1024          * @return bool
1025          */
1026         private function relationExists( $table, $types, $schema = false ) {
1027                 if ( !is_array( $types ) ) {
1028                         $types = [ $types ];
1029                 }
1030                 if ( $schema === false ) {
1031                         $schema = $this->getCoreSchema();
1032                 }
1033                 $table = $this->realTableName( $table, 'raw' );
1034                 $etable = $this->addQuotes( $table );
1035                 $eschema = $this->addQuotes( $schema );
1036                 $sql = "SELECT 1 FROM pg_catalog.pg_class c, pg_catalog.pg_namespace n "
1037                         . "WHERE c.relnamespace = n.oid AND c.relname = $etable AND n.nspname = $eschema "
1038                         . "AND c.relkind IN ('" . implode( "','", $types ) . "')";
1039                 $res = $this->query( $sql );
1040                 $count = $res ? $res->numRows() : 0;
1041
1042                 return (bool)$count;
1043         }
1044
1045         /**
1046          * For backward compatibility, this function checks both tables and views.
1047          * @param string $table
1048          * @param string $fname
1049          * @param bool|string $schema
1050          * @return bool
1051          */
1052         public function tableExists( $table, $fname = __METHOD__, $schema = false ) {
1053                 return $this->relationExists( $table, [ 'r', 'v' ], $schema );
1054         }
1055
1056         public function sequenceExists( $sequence, $schema = false ) {
1057                 return $this->relationExists( $sequence, 'S', $schema );
1058         }
1059
1060         public function triggerExists( $table, $trigger ) {
1061                 $q = <<<SQL
1062         SELECT 1 FROM pg_class, pg_namespace, pg_trigger
1063                 WHERE relnamespace=pg_namespace.oid AND relkind='r'
1064                         AND tgrelid=pg_class.oid
1065                         AND nspname=%s AND relname=%s AND tgname=%s
1066 SQL;
1067                 $res = $this->query(
1068                         sprintf(
1069                                 $q,
1070                                 $this->addQuotes( $this->getCoreSchema() ),
1071                                 $this->addQuotes( $table ),
1072                                 $this->addQuotes( $trigger )
1073                         )
1074                 );
1075                 if ( !$res ) {
1076                         return null;
1077                 }
1078                 $rows = $res->numRows();
1079
1080                 return $rows;
1081         }
1082
1083         public function ruleExists( $table, $rule ) {
1084                 $exists = $this->selectField( 'pg_rules', 'rulename',
1085                         [
1086                                 'rulename' => $rule,
1087                                 'tablename' => $table,
1088                                 'schemaname' => $this->getCoreSchema()
1089                         ]
1090                 );
1091
1092                 return $exists === $rule;
1093         }
1094
1095         public function constraintExists( $table, $constraint ) {
1096                 $sql = sprintf( "SELECT 1 FROM information_schema.table_constraints " .
1097                         "WHERE constraint_schema = %s AND table_name = %s AND constraint_name = %s",
1098                         $this->addQuotes( $this->getCoreSchema() ),
1099                         $this->addQuotes( $table ),
1100                         $this->addQuotes( $constraint )
1101                 );
1102                 $res = $this->query( $sql );
1103                 if ( !$res ) {
1104                         return null;
1105                 }
1106                 $rows = $res->numRows();
1107
1108                 return $rows;
1109         }
1110
1111         /**
1112          * Query whether a given schema exists. Returns true if it does, false if it doesn't.
1113          * @param string $schema
1114          * @return bool
1115          */
1116         public function schemaExists( $schema ) {
1117                 if ( !strlen( $schema ) ) {
1118                         return false; // short-circuit
1119                 }
1120
1121                 $exists = $this->selectField(
1122                         '"pg_catalog"."pg_namespace"', 1, [ 'nspname' => $schema ], __METHOD__ );
1123
1124                 return (bool)$exists;
1125         }
1126
1127         /**
1128          * Returns true if a given role (i.e. user) exists, false otherwise.
1129          * @param string $roleName
1130          * @return bool
1131          */
1132         public function roleExists( $roleName ) {
1133                 $exists = $this->selectField( '"pg_catalog"."pg_roles"', 1,
1134                         [ 'rolname' => $roleName ], __METHOD__ );
1135
1136                 return (bool)$exists;
1137         }
1138
1139         /**
1140          * @param string $table
1141          * @param string $field
1142          * @return PostgresField|null
1143          */
1144         public function fieldInfo( $table, $field ) {
1145                 return PostgresField::fromText( $this, $table, $field );
1146         }
1147
1148         /**
1149          * pg_field_type() wrapper
1150          * @param ResultWrapper|resource $res ResultWrapper or PostgreSQL query result resource
1151          * @param int $index Field number, starting from 0
1152          * @return string
1153          */
1154         public function fieldType( $res, $index ) {
1155                 if ( $res instanceof ResultWrapper ) {
1156                         $res = $res->result;
1157                 }
1158
1159                 return pg_field_type( $res, $index );
1160         }
1161
1162         public function encodeBlob( $b ) {
1163                 return new PostgresBlob( pg_escape_bytea( $b ) );
1164         }
1165
1166         public function decodeBlob( $b ) {
1167                 if ( $b instanceof PostgresBlob ) {
1168                         $b = $b->fetch();
1169                 } elseif ( $b instanceof Blob ) {
1170                         return $b->fetch();
1171                 }
1172
1173                 return pg_unescape_bytea( $b );
1174         }
1175
1176         public function strencode( $s ) {
1177                 // Should not be called by us
1178                 return pg_escape_string( $this->getBindingHandle(), $s );
1179         }
1180
1181         public function addQuotes( $s ) {
1182                 $conn = $this->getBindingHandle();
1183
1184                 if ( is_null( $s ) ) {
1185                         return 'NULL';
1186                 } elseif ( is_bool( $s ) ) {
1187                         return intval( $s );
1188                 } elseif ( $s instanceof Blob ) {
1189                         if ( $s instanceof PostgresBlob ) {
1190                                 $s = $s->fetch();
1191                         } else {
1192                                 $s = pg_escape_bytea( $conn, $s->fetch() );
1193                         }
1194                         return "'$s'";
1195                 } elseif ( $s instanceof NextSequenceValue ) {
1196                         return 'DEFAULT';
1197                 }
1198
1199                 return "'" . pg_escape_string( $conn, $s ) . "'";
1200         }
1201
1202         /**
1203          * Postgres specific version of replaceVars.
1204          * Calls the parent version in Database.php
1205          *
1206          * @param string $ins SQL string, read from a stream (usually tables.sql)
1207          * @return string SQL string
1208          */
1209         protected function replaceVars( $ins ) {
1210                 $ins = parent::replaceVars( $ins );
1211
1212                 if ( $this->numericVersion >= 8.3 ) {
1213                         // Thanks for not providing backwards-compatibility, 8.3
1214                         $ins = preg_replace( "/to_tsvector\s*\(\s*'default'\s*,/", 'to_tsvector(', $ins );
1215                 }
1216
1217                 if ( $this->numericVersion <= 8.1 ) { // Our minimum version
1218                         $ins = str_replace( 'USING gin', 'USING gist', $ins );
1219                 }
1220
1221                 return $ins;
1222         }
1223
1224         public function makeSelectOptions( $options ) {
1225                 $preLimitTail = $postLimitTail = '';
1226                 $startOpts = $useIndex = $ignoreIndex = '';
1227
1228                 $noKeyOptions = [];
1229                 foreach ( $options as $key => $option ) {
1230                         if ( is_numeric( $key ) ) {
1231                                 $noKeyOptions[$option] = true;
1232                         }
1233                 }
1234
1235                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1236
1237                 $preLimitTail .= $this->makeOrderBy( $options );
1238
1239                 if ( isset( $options['FOR UPDATE'] ) ) {
1240                         $postLimitTail .= ' FOR UPDATE OF ' .
1241                                 implode( ', ', array_map( [ $this, 'tableName' ], $options['FOR UPDATE'] ) );
1242                 } elseif ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1243                         $postLimitTail .= ' FOR UPDATE';
1244                 }
1245
1246                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1247                         $startOpts .= 'DISTINCT';
1248                 }
1249
1250                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1251         }
1252
1253         public function getDBname() {
1254                 return $this->mDBname;
1255         }
1256
1257         public function getServer() {
1258                 return $this->mServer;
1259         }
1260
1261         public function buildConcat( $stringList ) {
1262                 return implode( ' || ', $stringList );
1263         }
1264
1265         public function buildGroupConcatField(
1266                 $delimiter, $table, $field, $conds = '', $options = [], $join_conds = []
1267         ) {
1268                 $fld = "array_to_string(array_agg($field)," . $this->addQuotes( $delimiter ) . ')';
1269
1270                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1271         }
1272
1273         public function buildStringCast( $field ) {
1274                 return $field . '::text';
1275         }
1276
1277         public function streamStatementEnd( &$sql, &$newLine ) {
1278                 # Allow dollar quoting for function declarations
1279                 if ( substr( $newLine, 0, 4 ) == '$mw$' ) {
1280                         if ( $this->delimiter ) {
1281                                 $this->delimiter = false;
1282                         } else {
1283                                 $this->delimiter = ';';
1284                         }
1285                 }
1286
1287                 return parent::streamStatementEnd( $sql, $newLine );
1288         }
1289
1290         public function doLockTables( array $read, array $write, $method ) {
1291                 $tablesWrite = [];
1292                 foreach ( $write as $table ) {
1293                         $tablesWrite[] = $this->tableName( $table );
1294                 }
1295                 $tablesRead = [];
1296                 foreach ( $read as $table ) {
1297                         $tablesRead[] = $this->tableName( $table );
1298                 }
1299
1300                 // Acquire locks for the duration of the current transaction...
1301                 if ( $tablesWrite ) {
1302                         $this->query(
1303                                 'LOCK TABLE ONLY ' . implode( ',', $tablesWrite ) . ' IN EXCLUSIVE MODE',
1304                                 $method
1305                         );
1306                 }
1307                 if ( $tablesRead ) {
1308                         $this->query(
1309                                 'LOCK TABLE ONLY ' . implode( ',', $tablesRead ) . ' IN SHARE MODE',
1310                                 $method
1311                         );
1312                 }
1313
1314                 return true;
1315         }
1316
1317         public function lockIsFree( $lockName, $method ) {
1318                 // http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1319                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1320                 $result = $this->query( "SELECT (CASE(pg_try_advisory_lock($key))
1321                         WHEN 'f' THEN 'f' ELSE pg_advisory_unlock($key) END) AS lockstatus", $method );
1322                 $row = $this->fetchObject( $result );
1323
1324                 return ( $row->lockstatus === 't' );
1325         }
1326
1327         public function lock( $lockName, $method, $timeout = 5 ) {
1328                 // http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1329                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1330                 $loop = new WaitConditionLoop(
1331                         function () use ( $lockName, $key, $timeout, $method ) {
1332                                 $res = $this->query( "SELECT pg_try_advisory_lock($key) AS lockstatus", $method );
1333                                 $row = $this->fetchObject( $res );
1334                                 if ( $row->lockstatus === 't' ) {
1335                                         parent::lock( $lockName, $method, $timeout ); // record
1336                                         return true;
1337                                 }
1338
1339                                 return WaitConditionLoop::CONDITION_CONTINUE;
1340                         },
1341                         $timeout
1342                 );
1343
1344                 return ( $loop->invoke() === $loop::CONDITION_REACHED );
1345         }
1346
1347         public function unlock( $lockName, $method ) {
1348                 // http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1349                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1350                 $result = $this->query( "SELECT pg_advisory_unlock($key) as lockstatus", $method );
1351                 $row = $this->fetchObject( $result );
1352
1353                 if ( $row->lockstatus === 't' ) {
1354                         parent::unlock( $lockName, $method ); // record
1355                         return true;
1356                 }
1357
1358                 $this->queryLogger->debug( __METHOD__ . " failed to release lock\n" );
1359
1360                 return false;
1361         }
1362
1363         public function serverIsReadOnly() {
1364                 $res = $this->query( "SHOW default_transaction_read_only", __METHOD__ );
1365                 $row = $this->fetchObject( $res );
1366
1367                 return $row ? ( strtolower( $row->default_transaction_read_only ) === 'on' ) : false;
1368         }
1369
1370         /**
1371          * @param string $lockName
1372          * @return string Integer
1373          */
1374         private function bigintFromLockName( $lockName ) {
1375                 return \Wikimedia\base_convert( substr( sha1( $lockName ), 0, 15 ), 16, 10 );
1376         }
1377 }
1378
1379 class_alias( DatabasePostgres::class, 'DatabasePostgres' );