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 use Wikimedia\Timestamp\ConvertibleTimestamp;
  24 use Wikimedia\WaitConditionLoop;
  25 use Wikimedia\Rdbms\Blob;
  26 use Wikimedia\Rdbms\PostgresBlob;
  27 use Wikimedia\Rdbms\PostgresField;
  28
  29 /**
  30  * @ingroup Database
  31  */
  32 class DatabasePostgres extends Database {
  33         /** @var int|bool */
  34         protected $port;
  35
  36         /** @var resource */
  37         protected $mLastResult = null;
  38         /** @var int The number of rows affected as an integer */
  39         protected $mAffectedRows = null;
  40
  41         /** @var int */
  42         private $mInsertId = null;
  43         /** @var float|string */
  44         private $numericVersion = null;
  45         /** @var string Connect string to open a PostgreSQL connection */
  46         private $connectString;
  47         /** @var string */
  48         private $mCoreSchema;
  49         /** @var string[] Map of (reserved table name => alternate table name) */
  50         private $keywordTableMap = [];
  51
  52         /**
  53          * @see Database::__construct()
  54          * @param array $params Additional parameters include:
  55          *   - keywordTableMap : Map of reserved table names to alternative table names to use
  56          */
  57         public function __construct( array $params ) {
  58                 $this->port = isset( $params['port'] ) ? $params['port'] : false;
  59                 $this->keywordTableMap = isset( $params['keywordTableMap'] )
  60                         ? $params['keywordTableMap']
  61                         : [];
  62
  63                 parent::__construct( $params );
  64         }
  65
  66         public function getType() {
  67                 return 'postgres';
  68         }
  69
  70         public function implicitGroupby() {
  71                 return false;
  72         }
  73
  74         public function implicitOrderby() {
  75                 return false;
  76         }
  77
  78         public function hasConstraint( $name ) {
  79                 $conn = $this->getBindingHandle();
  80
  81                 $sql = "SELECT 1 FROM pg_catalog.pg_constraint c, pg_catalog.pg_namespace n " .
  82                         "WHERE c.connamespace = n.oid AND conname = '" .
  83                         pg_escape_string( $conn, $name ) . "' AND n.nspname = '" .
  84                         pg_escape_string( $conn, $this->getCoreSchema() ) . "'";
  85                 $res = $this->doQuery( $sql );
  86
  87                 return $this->numRows( $res );
  88         }
  89
  90         public function open( $server, $user, $password, $dbName ) {
  91                 # Test for Postgres support, to avoid suppressed fatal error
  92                 if ( !function_exists( 'pg_connect' ) ) {
  93                         throw new DBConnectionError(
  94                                 $this,
  95                                 "Postgres functions missing, have you compiled PHP with the --with-pgsql\n" .
  96                                 "option? (Note: if you recently installed PHP, you may need to restart your\n" .
  97                                 "webserver and database)\n"
  98                         );
  99                 }
 100
 101                 $this->mServer = $server;
 102                 $this->mUser = $user;
 103                 $this->mPassword = $password;
 104                 $this->mDBname = $dbName;
 105
 106                 $connectVars = [
 107                         'dbname' => $dbName,
 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->mFlags & 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->mConn = 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->mConn ) {
 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->mOpened = 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                 if ( $this->getServerVersion() >= 9.0 ) {
 157                         $this->query( "SET bytea_output = 'escape'", __METHOD__ ); // PHP bug 53127
 158                 }
 159
 160                 $this->determineCoreSchema( $this->mSchema );
 161                 // The schema to be used is now in the search path; no need for explicit qualification
 162                 $this->mSchema = '';
 163
 164                 return $this->mConn;
 165         }
 166
 167         /**
 168          * Postgres doesn't support selectDB in the same way MySQL does. So if the
 169          * DB name doesn't match the open connection, open a new one
 170          * @param string $db
 171          * @return bool
 172          */
 173         public function selectDB( $db ) {
 174                 if ( $this->mDBname !== $db ) {
 175                         return (bool)$this->open( $this->mServer, $this->mUser, $this->mPassword, $db );
 176                 } else {
 177                         return true;
 178                 }
 179         }
 180
 181         /**
 182          * @param string[] $vars
 183          * @return string
 184          */
 185         private function makeConnectionString( $vars ) {
 186                 $s = '';
 187                 foreach ( $vars as $name => $value ) {
 188                         $s .= "$name='" . str_replace( "'", "\\'", $value ) . "' ";
 189                 }
 190
 191                 return $s;
 192         }
 193
 194         protected function closeConnection() {
 195                 return $this->mConn ? pg_close( $this->mConn ) : true;
 196         }
 197
 198         public function doQuery( $sql ) {
 199                 $conn = $this->getBindingHandle();
 200
 201                 $sql = mb_convert_encoding( $sql, 'UTF-8' );
 202                 // Clear previously left over PQresult
 203                 while ( $res = pg_get_result( $conn ) ) {
 204                         pg_free_result( $res );
 205                 }
 206                 if ( pg_send_query( $conn, $sql ) === false ) {
 207                         throw new DBUnexpectedError( $this, "Unable to post new query to PostgreSQL\n" );
 208                 }
 209                 $this->mLastResult = pg_get_result( $conn );
 210                 $this->mAffectedRows = null;
 211                 if ( pg_result_error( $this->mLastResult ) ) {
 212                         return false;
 213                 }
 214
 215                 return $this->mLastResult;
 216         }
 217
 218         protected function dumpError() {
 219                 $diags = [
 220                         PGSQL_DIAG_SEVERITY,
 221                         PGSQL_DIAG_SQLSTATE,
 222                         PGSQL_DIAG_MESSAGE_PRIMARY,
 223                         PGSQL_DIAG_MESSAGE_DETAIL,
 224                         PGSQL_DIAG_MESSAGE_HINT,
 225                         PGSQL_DIAG_STATEMENT_POSITION,
 226                         PGSQL_DIAG_INTERNAL_POSITION,
 227                         PGSQL_DIAG_INTERNAL_QUERY,
 228                         PGSQL_DIAG_CONTEXT,
 229                         PGSQL_DIAG_SOURCE_FILE,
 230                         PGSQL_DIAG_SOURCE_LINE,
 231                         PGSQL_DIAG_SOURCE_FUNCTION
 232                 ];
 233                 foreach ( $diags as $d ) {
 234                         $this->queryLogger->debug( sprintf( "PgSQL ERROR(%d): %s\n",
 235                                 $d, pg_result_error_field( $this->mLastResult, $d ) ) );
 236                 }
 237         }
 238
 239         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
 240                 if ( $tempIgnore ) {
 241                         /* Check for constraint violation */
 242                         if ( $errno === '23505' ) {
 243                                 parent::reportQueryError( $error, $errno, $sql, $fname, $tempIgnore );
 244
 245                                 return;
 246                         }
 247                 }
 248                 /* Transaction stays in the ERROR state until rolled back */
 249                 if ( $this->mTrxLevel ) {
 250                         $this->rollback( __METHOD__ );
 251                 }
 252                 parent::reportQueryError( $error, $errno, $sql, $fname, false );
 253         }
 254
 255         public function freeResult( $res ) {
 256                 if ( $res instanceof ResultWrapper ) {
 257                         $res = $res->result;
 258                 }
 259                 MediaWiki\suppressWarnings();
 260                 $ok = pg_free_result( $res );
 261                 MediaWiki\restoreWarnings();
 262                 if ( !$ok ) {
 263                         throw new DBUnexpectedError( $this, "Unable to free Postgres result\n" );
 264                 }
 265         }
 266
 267         public function fetchObject( $res ) {
 268                 if ( $res instanceof ResultWrapper ) {
 269                         $res = $res->result;
 270                 }
 271                 MediaWiki\suppressWarnings();
 272                 $row = pg_fetch_object( $res );
 273                 MediaWiki\restoreWarnings();
 274                 # @todo FIXME: HACK HACK HACK HACK debug
 275
 276                 # @todo hashar: not sure if the following test really trigger if the object
 277                 #          fetching failed.
 278                 $conn = $this->getBindingHandle();
 279                 if ( pg_last_error( $conn ) ) {
 280                         throw new DBUnexpectedError(
 281                                 $this,
 282                                 'SQL error: ' . htmlspecialchars( pg_last_error( $conn ) )
 283                         );
 284                 }
 285
 286                 return $row;
 287         }
 288
 289         public function fetchRow( $res ) {
 290                 if ( $res instanceof ResultWrapper ) {
 291                         $res = $res->result;
 292                 }
 293                 MediaWiki\suppressWarnings();
 294                 $row = pg_fetch_array( $res );
 295                 MediaWiki\restoreWarnings();
 296
 297                 $conn = $this->getBindingHandle();
 298                 if ( pg_last_error( $conn ) ) {
 299                         throw new DBUnexpectedError(
 300                                 $this,
 301                                 'SQL error: ' . htmlspecialchars( pg_last_error( $conn ) )
 302                         );
 303                 }
 304
 305                 return $row;
 306         }
 307
 308         public function numRows( $res ) {
 309                 if ( $res instanceof ResultWrapper ) {
 310                         $res = $res->result;
 311                 }
 312                 MediaWiki\suppressWarnings();
 313                 $n = pg_num_rows( $res );
 314                 MediaWiki\restoreWarnings();
 315
 316                 $conn = $this->getBindingHandle();
 317                 if ( pg_last_error( $conn ) ) {
 318                         throw new DBUnexpectedError(
 319                                 $this,
 320                                 'SQL error: ' . htmlspecialchars( pg_last_error( $conn ) )
 321                         );
 322                 }
 323
 324                 return $n;
 325         }
 326
 327         public function numFields( $res ) {
 328                 if ( $res instanceof ResultWrapper ) {
 329                         $res = $res->result;
 330                 }
 331
 332                 return pg_num_fields( $res );
 333         }
 334
 335         public function fieldName( $res, $n ) {
 336                 if ( $res instanceof ResultWrapper ) {
 337                         $res = $res->result;
 338                 }
 339
 340                 return pg_field_name( $res, $n );
 341         }
 342
 343         /**
 344          * Return the result of the last call to nextSequenceValue();
 345          * This must be called after nextSequenceValue().
 346          *
 347          * @return int|null
 348          */
 349         public function insertId() {
 350                 return $this->mInsertId;
 351         }
 352
 353         public function dataSeek( $res, $row ) {
 354                 if ( $res instanceof ResultWrapper ) {
 355                         $res = $res->result;
 356                 }
 357
 358                 return pg_result_seek( $res, $row );
 359         }
 360
 361         public function lastError() {
 362                 if ( $this->mConn ) {
 363                         if ( $this->mLastResult ) {
 364                                 return pg_result_error( $this->mLastResult );
 365                         } else {
 366                                 return pg_last_error();
 367                         }
 368                 }
 369
 370                 return $this->getLastPHPError() ?: 'No database connection';
 371         }
 372
 373         public function lastErrno() {
 374                 if ( $this->mLastResult ) {
 375                         return pg_result_error_field( $this->mLastResult, PGSQL_DIAG_SQLSTATE );
 376                 } else {
 377                         return false;
 378                 }
 379         }
 380
 381         public function affectedRows() {
 382                 if ( !is_null( $this->mAffectedRows ) ) {
 383                         // Forced result for simulated queries
 384                         return $this->mAffectedRows;
 385                 }
 386                 if ( empty( $this->mLastResult ) ) {
 387                         return 0;
 388                 }
 389
 390                 return pg_affected_rows( $this->mLastResult );
 391         }
 392
 393         /**
 394          * Estimate rows in dataset
 395          * Returns estimated count, based on EXPLAIN output
 396          * This is not necessarily an accurate estimate, so use sparingly
 397          * Returns -1 if count cannot be found
 398          * Takes same arguments as Database::select()
 399          *
 400          * @param string $table
 401          * @param string $vars
 402          * @param string $conds
 403          * @param string $fname
 404          * @param array $options
 405          * @return int
 406          */
 407         public function estimateRowCount( $table, $vars = '*', $conds = '',
 408                 $fname = __METHOD__, $options = []
 409         ) {
 410                 $options['EXPLAIN'] = true;
 411                 $res = $this->select( $table, $vars, $conds, $fname, $options );
 412                 $rows = -1;
 413                 if ( $res ) {
 414                         $row = $this->fetchRow( $res );
 415                         $count = [];
 416                         if ( preg_match( '/rows=(\d+)/', $row[0], $count ) ) {
 417                                 $rows = (int)$count[1];
 418                         }
 419                 }
 420
 421                 return $rows;
 422         }
 423
 424         public function indexInfo( $table, $index, $fname = __METHOD__ ) {
 425                 $sql = "SELECT indexname FROM pg_indexes WHERE tablename='$table'";
 426                 $res = $this->query( $sql, $fname );
 427                 if ( !$res ) {
 428                         return null;
 429                 }
 430                 foreach ( $res as $row ) {
 431                         if ( $row->indexname == $this->indexName( $index ) ) {
 432                                 return $row;
 433                         }
 434                 }
 435
 436                 return false;
 437         }
 438
 439         public function indexAttributes( $index, $schema = false ) {
 440                 if ( $schema === false ) {
 441                         $schema = $this->getCoreSchema();
 442                 }
 443                 /*
 444                  * A subquery would be not needed if we didn't care about the order
 445                  * of attributes, but we do
 446                  */
 447                 $sql = <<<__INDEXATTR__
 448
 449                         SELECT opcname,
 450                                 attname,
 451                                 i.indoption[s.g] as option,
 452                                 pg_am.amname
 453                         FROM
 454                                 (SELECT generate_series(array_lower(isub.indkey,1), array_upper(isub.indkey,1)) AS g
 455                                         FROM
 456                                                 pg_index isub
 457                                         JOIN pg_class cis
 458                                                 ON cis.oid=isub.indexrelid
 459                                         JOIN pg_namespace ns
 460                                                 ON cis.relnamespace = ns.oid
 461                                         WHERE cis.relname='$index' AND ns.nspname='$schema') AS s,
 462                                 pg_attribute,
 463                                 pg_opclass opcls,
 464                                 pg_am,
 465                                 pg_class ci
 466                                 JOIN pg_index i
 467                                         ON ci.oid=i.indexrelid
 468                                 JOIN pg_class ct
 469                                         ON ct.oid = i.indrelid
 470                                 JOIN pg_namespace n
 471                                         ON ci.relnamespace = n.oid
 472                                 WHERE
 473                                         ci.relname='$index' AND n.nspname='$schema'
 474                                         AND     attrelid = ct.oid
 475                                         AND     i.indkey[s.g] = attnum
 476                                         AND     i.indclass[s.g] = opcls.oid
 477                                         AND     pg_am.oid = opcls.opcmethod
 478 __INDEXATTR__;
 479                 $res = $this->query( $sql, __METHOD__ );
 480                 $a = [];
 481                 if ( $res ) {
 482                         foreach ( $res as $row ) {
 483                                 $a[] = [
 484                                         $row->attname,
 485                                         $row->opcname,
 486                                         $row->amname,
 487                                         $row->option ];
 488                         }
 489                 } else {
 490                         return null;
 491                 }
 492
 493                 return $a;
 494         }
 495
 496         public function indexUnique( $table, $index, $fname = __METHOD__ ) {
 497                 $sql = "SELECT indexname FROM pg_indexes WHERE tablename='{$table}'" .
 498                         " AND indexdef LIKE 'CREATE UNIQUE%(" .
 499                         $this->strencode( $this->indexName( $index ) ) .
 500                         ")'";
 501                 $res = $this->query( $sql, $fname );
 502                 if ( !$res ) {
 503                         return null;
 504                 }
 505
 506                 return $res->numRows() > 0;
 507         }
 508
 509         public function selectSQLText(
 510                 $table, $vars, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
 511         ) {
 512                 // Change the FOR UPDATE option as necessary based on the join conditions. Then pass
 513                 // to the parent function to get the actual SQL text.
 514                 // In Postgres when using FOR UPDATE, only the main table and tables that are inner joined
 515                 // can be locked. That means tables in an outer join cannot be FOR UPDATE locked. Trying to
 516                 // do so causes a DB error. This wrapper checks which tables can be locked and adjusts it
 517                 // accordingly.
 518                 // MySQL uses "ORDER BY NULL" as an optimization hint, but that is illegal in PostgreSQL.
 519                 if ( is_array( $options ) ) {
 520                         $forUpdateKey = array_search( 'FOR UPDATE', $options, true );
 521                         if ( $forUpdateKey !== false && $join_conds ) {
 522                                 unset( $options[$forUpdateKey] );
 523
 524                                 foreach ( $join_conds as $table_cond => $join_cond ) {
 525                                         if ( 0 === preg_match( '/^(?:LEFT|RIGHT|FULL)(?: OUTER)? JOIN$/i', $join_cond[0] ) ) {
 526                                                 $options['FOR UPDATE'][] = $table_cond;
 527                                         }
 528                                 }
 529                         }
 530
 531                         if ( isset( $options['ORDER BY'] ) && $options['ORDER BY'] == 'NULL' ) {
 532                                 unset( $options['ORDER BY'] );
 533                         }
 534                 }
 535
 536                 return parent::selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
 537         }
 538
 539         /**
 540          * INSERT wrapper, inserts an array into a table
 541          *
 542          * $args may be a single associative array, or an array of these with numeric keys,
 543          * for multi-row insert (Postgres version 8.2 and above only).
 544          *
 545          * @param string $table Name of the table to insert to.
 546          * @param array $args Items to insert into the table.
 547          * @param string $fname Name of the function, for profiling
 548          * @param array|string $options String or array. Valid options: IGNORE
 549          * @return bool Success of insert operation. IGNORE always returns true.
 550          */
 551         public function insert( $table, $args, $fname = __METHOD__, $options = [] ) {
 552                 if ( !count( $args ) ) {
 553                         return true;
 554                 }
 555
 556                 $table = $this->tableName( $table );
 557                 if ( !isset( $this->numericVersion ) ) {
 558                         $this->getServerVersion();
 559                 }
 560
 561                 if ( !is_array( $options ) ) {
 562                         $options = [ $options ];
 563                 }
 564
 565                 if ( isset( $args[0] ) && is_array( $args[0] ) ) {
 566                         $multi = true;
 567                         $keys = array_keys( $args[0] );
 568                 } else {
 569                         $multi = false;
 570                         $keys = array_keys( $args );
 571                 }
 572
 573                 // If IGNORE is set, we use savepoints to emulate mysql's behavior
 574                 $savepoint = $olde = null;
 575                 $numrowsinserted = 0;
 576                 if ( in_array( 'IGNORE', $options ) ) {
 577                         $savepoint = new SavepointPostgres( $this, 'mw', $this->queryLogger );
 578                         $olde = error_reporting( 0 );
 579                         // For future use, we may want to track the number of actual inserts
 580                         // Right now, insert (all writes) simply return true/false
 581                 }
 582
 583                 $sql = "INSERT INTO $table (" . implode( ',', $keys ) . ') VALUES ';
 584
 585                 if ( $multi ) {
 586                         if ( $this->numericVersion >= 8.2 && !$savepoint ) {
 587                                 $first = true;
 588                                 foreach ( $args as $row ) {
 589                                         if ( $first ) {
 590                                                 $first = false;
 591                                         } else {
 592                                                 $sql .= ',';
 593                                         }
 594                                         $sql .= '(' . $this->makeList( $row ) . ')';
 595                                 }
 596                                 $res = (bool)$this->query( $sql, $fname, $savepoint );
 597                         } else {
 598                                 $res = true;
 599                                 $origsql = $sql;
 600                                 foreach ( $args as $row ) {
 601                                         $tempsql = $origsql;
 602                                         $tempsql .= '(' . $this->makeList( $row ) . ')';
 603
 604                                         if ( $savepoint ) {
 605                                                 $savepoint->savepoint();
 606                                         }
 607
 608                                         $tempres = (bool)$this->query( $tempsql, $fname, $savepoint );
 609
 610                                         if ( $savepoint ) {
 611                                                 $bar = pg_result_error( $this->mLastResult );
 612                                                 if ( $bar != false ) {
 613                                                         $savepoint->rollback();
 614                                                 } else {
 615                                                         $savepoint->release();
 616                                                         $numrowsinserted++;
 617                                                 }
 618                                         }
 619
 620                                         // If any of them fail, we fail overall for this function call
 621                                         // Note that this will be ignored if IGNORE is set
 622                                         if ( !$tempres ) {
 623                                                 $res = false;
 624                                         }
 625                                 }
 626                         }
 627                 } else {
 628                         // Not multi, just a lone insert
 629                         if ( $savepoint ) {
 630                                 $savepoint->savepoint();
 631                         }
 632
 633                         $sql .= '(' . $this->makeList( $args ) . ')';
 634                         $res = (bool)$this->query( $sql, $fname, $savepoint );
 635                         if ( $savepoint ) {
 636                                 $bar = pg_result_error( $this->mLastResult );
 637                                 if ( $bar != false ) {
 638                                         $savepoint->rollback();
 639                                 } else {
 640                                         $savepoint->release();
 641                                         $numrowsinserted++;
 642                                 }
 643                         }
 644                 }
 645                 if ( $savepoint ) {
 646                         error_reporting( $olde );
 647                         $savepoint->commit();
 648
 649                         // Set the affected row count for the whole operation
 650                         $this->mAffectedRows = $numrowsinserted;
 651
 652                         // IGNORE always returns true
 653                         return true;
 654                 }
 655
 656                 return $res;
 657         }
 658
 659         /**
 660          * INSERT SELECT wrapper
 661          * $varMap must be an associative array of the form [ 'dest1' => 'source1', ... ]
 662          * Source items may be literals rather then field names, but strings should
 663          * be quoted with Database::addQuotes()
 664          * $conds may be "*" to copy the whole table
 665          * srcTable may be an array of tables.
 666          * @todo FIXME: Implement this a little better (seperate select/insert)?
 667          *
 668          * @param string $destTable
 669          * @param array|string $srcTable
 670          * @param array $varMap
 671          * @param array $conds
 672          * @param string $fname
 673          * @param array $insertOptions
 674          * @param array $selectOptions
 675          * @return bool
 676          */
 677         public function nativeInsertSelect(
 678                 $destTable, $srcTable, $varMap, $conds, $fname = __METHOD__,
 679                 $insertOptions = [], $selectOptions = []
 680         ) {
 681                 $destTable = $this->tableName( $destTable );
 682
 683                 if ( !is_array( $insertOptions ) ) {
 684                         $insertOptions = [ $insertOptions ];
 685                 }
 686
 687                 /*
 688                  * If IGNORE is set, we use savepoints to emulate mysql's behavior
 689                  * Ignore LOW PRIORITY option, since it is MySQL-specific
 690                  */
 691                 $savepoint = $olde = null;
 692                 $numrowsinserted = 0;
 693                 if ( in_array( 'IGNORE', $insertOptions ) ) {
 694                         $savepoint = new SavepointPostgres( $this, 'mw', $this->queryLogger );
 695                         $olde = error_reporting( 0 );
 696                         $savepoint->savepoint();
 697                 }
 698
 699                 if ( !is_array( $selectOptions ) ) {
 700                         $selectOptions = [ $selectOptions ];
 701                 }
 702                 list( $startOpts, $useIndex, $tailOpts, $ignoreIndex ) =
 703                         $this->makeSelectOptions( $selectOptions );
 704                 if ( is_array( $srcTable ) ) {
 705                         $srcTable = implode( ',', array_map( [ $this, 'tableName' ], $srcTable ) );
 706                 } else {
 707                         $srcTable = $this->tableName( $srcTable );
 708                 }
 709
 710                 $sql = "INSERT INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
 711                         " SELECT $startOpts " . implode( ',', $varMap ) .
 712                         " FROM $srcTable $useIndex $ignoreIndex ";
 713
 714                 if ( $conds != '*' ) {
 715                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
 716                 }
 717
 718                 $sql .= " $tailOpts";
 719
 720                 $res = (bool)$this->query( $sql, $fname, $savepoint );
 721                 if ( $savepoint ) {
 722                         $bar = pg_result_error( $this->mLastResult );
 723                         if ( $bar != false ) {
 724                                 $savepoint->rollback();
 725                         } else {
 726                                 $savepoint->release();
 727                                 $numrowsinserted++;
 728                         }
 729                         error_reporting( $olde );
 730                         $savepoint->commit();
 731
 732                         // Set the affected row count for the whole operation
 733                         $this->mAffectedRows = $numrowsinserted;
 734
 735                         // IGNORE always returns true
 736                         return true;
 737                 }
 738
 739                 return $res;
 740         }
 741
 742         public function tableName( $name, $format = 'quoted' ) {
 743                 // Replace reserved words with better ones
 744                 $name = $this->remappedTableName( $name );
 745
 746                 return parent::tableName( $name, $format );
 747         }
 748
 749         /**
 750          * @param string $name
 751          * @return string Value of $name or remapped name if $name is a reserved keyword
 752          */
 753         public function remappedTableName( $name ) {
 754                 return isset( $this->keywordTableMap[$name] ) ? $this->keywordTableMap[$name] : $name;
 755         }
 756
 757         /**
 758          * @param string $name
 759          * @param string $format
 760          * @return string Qualified and encoded (if requested) table name
 761          */
 762         public function realTableName( $name, $format = 'quoted' ) {
 763                 return parent::tableName( $name, $format );
 764         }
 765
 766         public function nextSequenceValue( $seqName ) {
 767                 $safeseq = str_replace( "'", "''", $seqName );
 768                 $res = $this->query( "SELECT nextval('$safeseq')" );
 769                 $row = $this->fetchRow( $res );
 770                 $this->mInsertId = $row[0];
 771
 772                 return $this->mInsertId;
 773         }
 774
 775         /**
 776          * Return the current value of a sequence. Assumes it has been nextval'ed in this session.
 777          *
 778          * @param string $seqName
 779          * @return int
 780          */
 781         public function currentSequenceValue( $seqName ) {
 782                 $safeseq = str_replace( "'", "''", $seqName );
 783                 $res = $this->query( "SELECT currval('$safeseq')" );
 784                 $row = $this->fetchRow( $res );
 785                 $currval = $row[0];
 786
 787                 return $currval;
 788         }
 789
 790         public function textFieldSize( $table, $field ) {
 791                 $table = $this->tableName( $table );
 792                 $sql = "SELECT t.typname as ftype,a.atttypmod as size
 793                         FROM pg_class c, pg_attribute a, pg_type t
 794                         WHERE relname='$table' AND a.attrelid=c.oid AND
 795                                 a.atttypid=t.oid and a.attname='$field'";
 796                 $res = $this->query( $sql );
 797                 $row = $this->fetchObject( $res );
 798                 if ( $row->ftype == 'varchar' ) {
 799                         $size = $row->size - 4;
 800                 } else {
 801                         $size = $row->size;
 802                 }
 803
 804                 return $size;
 805         }
 806
 807         public function limitResult( $sql, $limit, $offset = false ) {
 808                 return "$sql LIMIT $limit " . ( is_numeric( $offset ) ? " OFFSET {$offset} " : '' );
 809         }
 810
 811         public function wasDeadlock() {
 812                 return $this->lastErrno() == '40P01';
 813         }
 814
 815         public function duplicateTableStructure(
 816                 $oldName, $newName, $temporary = false, $fname = __METHOD__
 817         ) {
 818                 $newName = $this->addIdentifierQuotes( $newName );
 819                 $oldName = $this->addIdentifierQuotes( $oldName );
 820
 821                 return $this->query( 'CREATE ' . ( $temporary ? 'TEMPORARY ' : '' ) . " TABLE $newName " .
 822                         "(LIKE $oldName INCLUDING DEFAULTS)", $fname );
 823         }
 824
 825         public function listTables( $prefix = null, $fname = __METHOD__ ) {
 826                 $eschema = $this->addQuotes( $this->getCoreSchema() );
 827                 $result = $this->query(
 828                         "SELECT tablename FROM pg_tables WHERE schemaname = $eschema", $fname );
 829                 $endArray = [];
 830
 831                 foreach ( $result as $table ) {
 832                         $vars = get_object_vars( $table );
 833                         $table = array_pop( $vars );
 834                         if ( !$prefix || strpos( $table, $prefix ) === 0 ) {
 835                                 $endArray[] = $table;
 836                         }
 837                 }
 838
 839                 return $endArray;
 840         }
 841
 842         public function timestamp( $ts = 0 ) {
 843                 $ct = new ConvertibleTimestamp( $ts );
 844
 845                 return $ct->getTimestamp( TS_POSTGRES );
 846         }
 847
 848         /**
 849          * Posted by cc[plus]php[at]c2se[dot]com on 25-Mar-2009 09:12
 850          * to https://secure.php.net/manual/en/ref.pgsql.php
 851          *
 852          * Parsing a postgres array can be a tricky problem, he's my
 853          * take on this, it handles multi-dimensional arrays plus
 854          * escaping using a nasty regexp to determine the limits of each
 855          * data-item.
 856          *
 857          * This should really be handled by PHP PostgreSQL module
 858          *
 859          * @since 1.19
 860          * @param string $text Postgreql array returned in a text form like {a,b}
 861          * @param string $output
 862          * @param int|bool $limit
 863          * @param int $offset
 864          * @return string
 865          */
 866         private function pg_array_parse( $text, &$output, $limit = false, $offset = 1 ) {
 867                 if ( false === $limit ) {
 868                         $limit = strlen( $text ) - 1;
 869                         $output = [];
 870                 }
 871                 if ( '{}' == $text ) {
 872                         return $output;
 873                 }
 874                 do {
 875                         if ( '{' != $text[$offset] ) {
 876                                 preg_match( "/(\\{?\"([^\"\\\\]|\\\\.)*\"|[^,{}]+)+([,}]+)/",
 877                                         $text, $match, 0, $offset );
 878                                 $offset += strlen( $match[0] );
 879                                 $output[] = ( '"' != $match[1][0]
 880                                         ? $match[1]
 881                                         : stripcslashes( substr( $match[1], 1, -1 ) ) );
 882                                 if ( '},' == $match[3] ) {
 883                                         return $output;
 884                                 }
 885                         } else {
 886                                 $offset = $this->pg_array_parse( $text, $output, $limit, $offset + 1 );
 887                         }
 888                 } while ( $limit > $offset );
 889
 890                 return $output;
 891         }
 892
 893         public function aggregateValue( $valuedata, $valuename = 'value' ) {
 894                 return $valuedata;
 895         }
 896
 897         public function getSoftwareLink() {
 898                 return '[{{int:version-db-postgres-url}} PostgreSQL]';
 899         }
 900
 901         /**
 902          * Return current schema (executes SELECT current_schema())
 903          * Needs transaction
 904          *
 905          * @since 1.19
 906          * @return string Default schema for the current session
 907          */
 908         public function getCurrentSchema() {
 909                 $res = $this->query( "SELECT current_schema()", __METHOD__ );
 910                 $row = $this->fetchRow( $res );
 911
 912                 return $row[0];
 913         }
 914
 915         /**
 916          * Return list of schemas which are accessible without schema name
 917          * This is list does not contain magic keywords like "$user"
 918          * Needs transaction
 919          *
 920          * @see getSearchPath()
 921          * @see setSearchPath()
 922          * @since 1.19
 923          * @return array List of actual schemas for the current sesson
 924          */
 925         public function getSchemas() {
 926                 $res = $this->query( "SELECT current_schemas(false)", __METHOD__ );
 927                 $row = $this->fetchRow( $res );
 928                 $schemas = [];
 929
 930                 /* PHP pgsql support does not support array type, "{a,b}" string is returned */
 931
 932                 return $this->pg_array_parse( $row[0], $schemas );
 933         }
 934
 935         /**
 936          * Return search patch for schemas
 937          * This is different from getSchemas() since it contain magic keywords
 938          * (like "$user").
 939          * Needs transaction
 940          *
 941          * @since 1.19
 942          * @return array How to search for table names schemas for the current user
 943          */
 944         public function getSearchPath() {
 945                 $res = $this->query( "SHOW search_path", __METHOD__ );
 946                 $row = $this->fetchRow( $res );
 947
 948                 /* PostgreSQL returns SHOW values as strings */
 949
 950                 return explode( ",", $row[0] );
 951         }
 952
 953         /**
 954          * Update search_path, values should already be sanitized
 955          * Values may contain magic keywords like "$user"
 956          * @since 1.19
 957          *
 958          * @param array $search_path List of schemas to be searched by default
 959          */
 960         private function setSearchPath( $search_path ) {
 961                 $this->query( "SET search_path = " . implode( ", ", $search_path ) );
 962         }
 963
 964         /**
 965          * Determine default schema for the current application
 966          * Adjust this session schema search path if desired schema exists
 967          * and is not alread there.
 968          *
 969          * We need to have name of the core schema stored to be able
 970          * to query database metadata.
 971          *
 972          * This will be also called by the installer after the schema is created
 973          *
 974          * @since 1.19
 975          *
 976          * @param string $desiredSchema
 977          */
 978         public function determineCoreSchema( $desiredSchema ) {
 979                 $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
 980                 if ( $this->schemaExists( $desiredSchema ) ) {
 981                         if ( in_array( $desiredSchema, $this->getSchemas() ) ) {
 982                                 $this->mCoreSchema = $desiredSchema;
 983                                 $this->queryLogger->debug(
 984                                         "Schema \"" . $desiredSchema . "\" already in the search path\n" );
 985                         } else {
 986                                 /**
 987                                  * Prepend our schema (e.g. 'mediawiki') in front
 988                                  * of the search path
 989                                  * Fixes T17816
 990                                  */
 991                                 $search_path = $this->getSearchPath();
 992                                 array_unshift( $search_path,
 993                                         $this->addIdentifierQuotes( $desiredSchema ) );
 994                                 $this->setSearchPath( $search_path );
 995                                 $this->mCoreSchema = $desiredSchema;
 996                                 $this->queryLogger->debug(
 997                                         "Schema \"" . $desiredSchema . "\" added to the search path\n" );
 998                         }
 999                 } else {
1000                         $this->mCoreSchema = $this->getCurrentSchema();
1001                         $this->queryLogger->debug(
1002                                 "Schema \"" . $desiredSchema . "\" not found, using current \"" .
1003                                 $this->mCoreSchema . "\"\n" );
1004                 }
1005                 /* Commit SET otherwise it will be rollbacked on error or IGNORE SELECT */
1006                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
1007         }
1008
1009         /**
1010          * Return schema name for core application tables
1011          *
1012          * @since 1.19
1013          * @return string Core schema name
1014          */
1015         public function getCoreSchema() {
1016                 return $this->mCoreSchema;
1017         }
1018
1019         public function getServerVersion() {
1020                 if ( !isset( $this->numericVersion ) ) {
1021                         $conn = $this->getBindingHandle();
1022                         $versionInfo = pg_version( $conn );
1023                         if ( version_compare( $versionInfo['client'], '7.4.0', 'lt' ) ) {
1024                                 // Old client, abort install
1025                                 $this->numericVersion = '7.3 or earlier';
1026                         } elseif ( isset( $versionInfo['server'] ) ) {
1027                                 // Normal client
1028                                 $this->numericVersion = $versionInfo['server'];
1029                         } else {
1030                                 // T18937: broken pgsql extension from PHP<5.3
1031                                 $this->numericVersion = pg_parameter_status( $conn, 'server_version' );
1032                         }
1033                 }
1034
1035                 return $this->numericVersion;
1036         }
1037
1038         /**
1039          * Query whether a given relation exists (in the given schema, or the
1040          * default mw one if not given)
1041          * @param string $table
1042          * @param array|string $types
1043          * @param bool|string $schema
1044          * @return bool
1045          */
1046         private function relationExists( $table, $types, $schema = false ) {
1047                 if ( !is_array( $types ) ) {
1048                         $types = [ $types ];
1049                 }
1050                 if ( $schema === false ) {
1051                         $schema = $this->getCoreSchema();
1052                 }
1053                 $etable = $this->addQuotes( $table );
1054                 $eschema = $this->addQuotes( $schema );
1055                 $sql = "SELECT 1 FROM pg_catalog.pg_class c, pg_catalog.pg_namespace n "
1056                         . "WHERE c.relnamespace = n.oid AND c.relname = $etable AND n.nspname = $eschema "
1057                         . "AND c.relkind IN ('" . implode( "','", $types ) . "')";
1058                 $res = $this->query( $sql );
1059                 $count = $res ? $res->numRows() : 0;
1060
1061                 return (bool)$count;
1062         }
1063
1064         /**
1065          * For backward compatibility, this function checks both tables and views.
1066          * @param string $table
1067          * @param string $fname
1068          * @param bool|string $schema
1069          * @return bool
1070          */
1071         public function tableExists( $table, $fname = __METHOD__, $schema = false ) {
1072                 return $this->relationExists( $table, [ 'r', 'v' ], $schema );
1073         }
1074
1075         public function sequenceExists( $sequence, $schema = false ) {
1076                 return $this->relationExists( $sequence, 'S', $schema );
1077         }
1078
1079         public function triggerExists( $table, $trigger ) {
1080                 $q = <<<SQL
1081         SELECT 1 FROM pg_class, pg_namespace, pg_trigger
1082                 WHERE relnamespace=pg_namespace.oid AND relkind='r'
1083                         AND tgrelid=pg_class.oid
1084                         AND nspname=%s AND relname=%s AND tgname=%s
1085 SQL;
1086                 $res = $this->query(
1087                         sprintf(
1088                                 $q,
1089                                 $this->addQuotes( $this->getCoreSchema() ),
1090                                 $this->addQuotes( $table ),
1091                                 $this->addQuotes( $trigger )
1092                         )
1093                 );
1094                 if ( !$res ) {
1095                         return null;
1096                 }
1097                 $rows = $res->numRows();
1098
1099                 return $rows;
1100         }
1101
1102         public function ruleExists( $table, $rule ) {
1103                 $exists = $this->selectField( 'pg_rules', 'rulename',
1104                         [
1105                                 'rulename' => $rule,
1106                                 'tablename' => $table,
1107                                 'schemaname' => $this->getCoreSchema()
1108                         ]
1109                 );
1110
1111                 return $exists === $rule;
1112         }
1113
1114         public function constraintExists( $table, $constraint ) {
1115                 $sql = sprintf( "SELECT 1 FROM information_schema.table_constraints " .
1116                         "WHERE constraint_schema = %s AND table_name = %s AND constraint_name = %s",
1117                         $this->addQuotes( $this->getCoreSchema() ),
1118                         $this->addQuotes( $table ),
1119                         $this->addQuotes( $constraint )
1120                 );
1121                 $res = $this->query( $sql );
1122                 if ( !$res ) {
1123                         return null;
1124                 }
1125                 $rows = $res->numRows();
1126
1127                 return $rows;
1128         }
1129
1130         /**
1131          * Query whether a given schema exists. Returns true if it does, false if it doesn't.
1132          * @param string $schema
1133          * @return bool
1134          */
1135         public function schemaExists( $schema ) {
1136                 if ( !strlen( $schema ) ) {
1137                         return false; // short-circuit
1138                 }
1139
1140                 $exists = $this->selectField(
1141                         '"pg_catalog"."pg_namespace"', 1, [ 'nspname' => $schema ], __METHOD__ );
1142
1143                 return (bool)$exists;
1144         }
1145
1146         /**
1147          * Returns true if a given role (i.e. user) exists, false otherwise.
1148          * @param string $roleName
1149          * @return bool
1150          */
1151         public function roleExists( $roleName ) {
1152                 $exists = $this->selectField( '"pg_catalog"."pg_roles"', 1,
1153                         [ 'rolname' => $roleName ], __METHOD__ );
1154
1155                 return (bool)$exists;
1156         }
1157
1158         /**
1159          * @var string $table
1160          * @var string $field
1161          * @return PostgresField|null
1162          */
1163         public function fieldInfo( $table, $field ) {
1164                 return PostgresField::fromText( $this, $table, $field );
1165         }
1166
1167         /**
1168          * pg_field_type() wrapper
1169          * @param ResultWrapper|resource $res ResultWrapper or PostgreSQL query result resource
1170          * @param int $index Field number, starting from 0
1171          * @return string
1172          */
1173         public function fieldType( $res, $index ) {
1174                 if ( $res instanceof ResultWrapper ) {
1175                         $res = $res->result;
1176                 }
1177
1178                 return pg_field_type( $res, $index );
1179         }
1180
1181         public function encodeBlob( $b ) {
1182                 return new PostgresBlob( pg_escape_bytea( $b ) );
1183         }
1184
1185         public function decodeBlob( $b ) {
1186                 if ( $b instanceof PostgresBlob ) {
1187                         $b = $b->fetch();
1188                 } elseif ( $b instanceof Blob ) {
1189                         return $b->fetch();
1190                 }
1191
1192                 return pg_unescape_bytea( $b );
1193         }
1194
1195         public function strencode( $s ) {
1196                 // Should not be called by us
1197                 return pg_escape_string( $this->getBindingHandle(), $s );
1198         }
1199
1200         public function addQuotes( $s ) {
1201                 $conn = $this->getBindingHandle();
1202
1203                 if ( is_null( $s ) ) {
1204                         return 'NULL';
1205                 } elseif ( is_bool( $s ) ) {
1206                         return intval( $s );
1207                 } elseif ( $s instanceof Blob ) {
1208                         if ( $s instanceof PostgresBlob ) {
1209                                 $s = $s->fetch();
1210                         } else {
1211                                 $s = pg_escape_bytea( $conn, $s->fetch() );
1212                         }
1213                         return "'$s'";
1214                 }
1215
1216                 return "'" . pg_escape_string( $conn, $s ) . "'";
1217         }
1218
1219         /**
1220          * Postgres specific version of replaceVars.
1221          * Calls the parent version in Database.php
1222          *
1223          * @param string $ins SQL string, read from a stream (usually tables.sql)
1224          * @return string SQL string
1225          */
1226         protected function replaceVars( $ins ) {
1227                 $ins = parent::replaceVars( $ins );
1228
1229                 if ( $this->numericVersion >= 8.3 ) {
1230                         // Thanks for not providing backwards-compatibility, 8.3
1231                         $ins = preg_replace( "/to_tsvector\s*\(\s*'default'\s*,/", 'to_tsvector(', $ins );
1232                 }
1233
1234                 if ( $this->numericVersion <= 8.1 ) { // Our minimum version
1235                         $ins = str_replace( 'USING gin', 'USING gist', $ins );
1236                 }
1237
1238                 return $ins;
1239         }
1240
1241         public function makeSelectOptions( $options ) {
1242                 $preLimitTail = $postLimitTail = '';
1243                 $startOpts = $useIndex = $ignoreIndex = '';
1244
1245                 $noKeyOptions = [];
1246                 foreach ( $options as $key => $option ) {
1247                         if ( is_numeric( $key ) ) {
1248                                 $noKeyOptions[$option] = true;
1249                         }
1250                 }
1251
1252                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1253
1254                 $preLimitTail .= $this->makeOrderBy( $options );
1255
1256                 if ( isset( $options['FOR UPDATE'] ) ) {
1257                         $postLimitTail .= ' FOR UPDATE OF ' .
1258                                 implode( ', ', array_map( [ $this, 'tableName' ], $options['FOR UPDATE'] ) );
1259                 } elseif ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1260                         $postLimitTail .= ' FOR UPDATE';
1261                 }
1262
1263                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1264                         $startOpts .= 'DISTINCT';
1265                 }
1266
1267                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1268         }
1269
1270         public function getDBname() {
1271                 return $this->mDBname;
1272         }
1273
1274         public function getServer() {
1275                 return $this->mServer;
1276         }
1277
1278         public function buildConcat( $stringList ) {
1279                 return implode( ' || ', $stringList );
1280         }
1281
1282         public function buildGroupConcatField(
1283                 $delimiter, $table, $field, $conds = '', $options = [], $join_conds = []
1284         ) {
1285                 $fld = "array_to_string(array_agg($field)," . $this->addQuotes( $delimiter ) . ')';
1286
1287                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1288         }
1289
1290         public function buildStringCast( $field ) {
1291                 return $field . '::text';
1292         }
1293
1294         public function streamStatementEnd( &$sql, &$newLine ) {
1295                 # Allow dollar quoting for function declarations
1296                 if ( substr( $newLine, 0, 4 ) == '$mw$' ) {
1297                         if ( $this->delimiter ) {
1298                                 $this->delimiter = false;
1299                         } else {
1300                                 $this->delimiter = ';';
1301                         }
1302                 }
1303
1304                 return parent::streamStatementEnd( $sql, $newLine );
1305         }
1306
1307         public function lockIsFree( $lockName, $method ) {
1308                 // http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1309                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1310                 $result = $this->query( "SELECT (CASE(pg_try_advisory_lock($key))
1311                         WHEN 'f' THEN 'f' ELSE pg_advisory_unlock($key) END) AS lockstatus", $method );
1312                 $row = $this->fetchObject( $result );
1313
1314                 return ( $row->lockstatus === 't' );
1315         }
1316
1317         public function lock( $lockName, $method, $timeout = 5 ) {
1318                 // http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1319                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1320                 $loop = new WaitConditionLoop(
1321                         function () use ( $lockName, $key, $timeout, $method ) {
1322                                 $res = $this->query( "SELECT pg_try_advisory_lock($key) AS lockstatus", $method );
1323                                 $row = $this->fetchObject( $res );
1324                                 if ( $row->lockstatus === 't' ) {
1325                                         parent::lock( $lockName, $method, $timeout ); // record
1326                                         return true;
1327                                 }
1328
1329                                 return WaitConditionLoop::CONDITION_CONTINUE;
1330                         },
1331                         $timeout
1332                 );
1333
1334                 return ( $loop->invoke() === $loop::CONDITION_REACHED );
1335         }
1336
1337         public function unlock( $lockName, $method ) {
1338                 // http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1339                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1340                 $result = $this->query( "SELECT pg_advisory_unlock($key) as lockstatus", $method );
1341                 $row = $this->fetchObject( $result );
1342
1343                 if ( $row->lockstatus === 't' ) {
1344                         parent::unlock( $lockName, $method ); // record
1345                         return true;
1346                 }
1347
1348                 $this->queryLogger->debug( __METHOD__ . " failed to release lock\n" );
1349
1350                 return false;
1351         }
1352
1353         /**
1354          * @param string $lockName
1355          * @return string Integer
1356          */
1357         private function bigintFromLockName( $lockName ) {
1358                 return Wikimedia\base_convert( substr( sha1( $lockName ), 0, 15 ), 16, 10 );
1359         }
1360 }