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 DBUnexpectedError;
  29 use DBConnectionError;
  30 use Exception;
  31
  32 /**
  33  * @ingroup Database
  34  */
  35 class DatabasePostgres extends Database {
  36         /** @var int|bool */
  37         protected $port;
  38
  39         /** @var resource */
  40         protected $mLastResult = null;
  41         /** @var int The number of rows affected as an integer */
  42         protected $mAffectedRows = null;
  43
  44         /** @var int */
  45         private $mInsertId = null;
  46         /** @var float|string */
  47         private $numericVersion = null;
  48         /** @var string Connect string to open a PostgreSQL connection */
  49         private $connectString;
  50         /** @var string */
  51         private $mCoreSchema;
  52         /** @var string[] Map of (reserved table name => alternate table name) */
  53         private $keywordTableMap = [];
  54
  55         /**
  56          * @see Database::__construct()
  57          * @param array $params Additional parameters include:
  58          *   - keywordTableMap : Map of reserved table names to alternative table names to use
  59          */
  60         public function __construct( array $params ) {
  61                 $this->port = isset( $params['port'] ) ? $params['port'] : false;
  62                 $this->keywordTableMap = isset( $params['keywordTableMap'] )
  63                         ? $params['keywordTableMap']
  64                         : [];
  65
  66                 parent::__construct( $params );
  67         }
  68
  69         public function getType() {
  70                 return 'postgres';
  71         }
  72
  73         public function implicitGroupby() {
  74                 return false;
  75         }
  76
  77         public function implicitOrderby() {
  78                 return false;
  79         }
  80
  81         public function hasConstraint( $name ) {
  82                 $conn = $this->getBindingHandle();
  83
  84                 $sql = "SELECT 1 FROM pg_catalog.pg_constraint c, pg_catalog.pg_namespace n " .
  85                         "WHERE c.connamespace = n.oid AND conname = '" .
  86                         pg_escape_string( $conn, $name ) . "' AND n.nspname = '" .
  87                         pg_escape_string( $conn, $this->getCoreSchema() ) . "'";
  88                 $res = $this->doQuery( $sql );
  89
  90                 return $this->numRows( $res );
  91         }
  92
  93         public function open( $server, $user, $password, $dbName ) {
  94                 # Test for Postgres support, to avoid suppressed fatal error
  95                 if ( !function_exists( 'pg_connect' ) ) {
  96                         throw new DBConnectionError(
  97                                 $this,
  98                                 "Postgres functions missing, have you compiled PHP with the --with-pgsql\n" .
  99                                 "option? (Note: if you recently installed PHP, you may need to restart your\n" .
 100                                 "webserver and database)\n"
 101                         );
 102                 }
 103
 104                 $this->mServer = $server;
 105                 $this->mUser = $user;
 106                 $this->mPassword = $password;
 107                 $this->mDBname = $dbName;
 108
 109                 $connectVars = [
 110                         'dbname' => $dbName,
 111                         'user' => $user,
 112                         'password' => $password
 113                 ];
 114                 if ( $server != false && $server != '' ) {
 115                         $connectVars['host'] = $server;
 116                 }
 117                 if ( (int)$this->port > 0 ) {
 118                         $connectVars['port'] = (int)$this->port;
 119                 }
 120                 if ( $this->mFlags & self::DBO_SSL ) {
 121                         $connectVars['sslmode'] = 1;
 122                 }
 123
 124                 $this->connectString = $this->makeConnectionString( $connectVars );
 125                 $this->close();
 126                 $this->installErrorHandler();
 127
 128                 try {
 129                         // Use new connections to let LoadBalancer/LBFactory handle reuse
 130                         $this->mConn = pg_connect( $this->connectString, PGSQL_CONNECT_FORCE_NEW );
 131                 } catch ( Exception $ex ) {
 132                         $this->restoreErrorHandler();
 133                         throw $ex;
 134                 }
 135
 136                 $phpError = $this->restoreErrorHandler();
 137
 138                 if ( !$this->mConn ) {
 139                         $this->queryLogger->debug(
 140                                 "DB connection error\n" .
 141                                 "Server: $server, Database: $dbName, User: $user, Password: " .
 142                                 substr( $password, 0, 3 ) . "...\n"
 143                         );
 144                         $this->queryLogger->debug( $this->lastError() . "\n" );
 145                         throw new DBConnectionError( $this, str_replace( "\n", ' ', $phpError ) );
 146                 }
 147
 148                 $this->mOpened = true;
 149
 150                 # If called from the command-line (e.g. importDump), only show errors
 151                 if ( $this->cliMode ) {
 152                         $this->doQuery( "SET client_min_messages = 'ERROR'" );
 153                 }
 154
 155                 $this->query( "SET client_encoding='UTF8'", __METHOD__ );
 156                 $this->query( "SET datestyle = 'ISO, YMD'", __METHOD__ );
 157                 $this->query( "SET timezone = 'GMT'", __METHOD__ );
 158                 $this->query( "SET standard_conforming_strings = on", __METHOD__ );
 159                 if ( $this->getServerVersion() >= 9.0 ) {
 160                         $this->query( "SET bytea_output = 'escape'", __METHOD__ ); // PHP bug 53127
 161                 }
 162
 163                 $this->determineCoreSchema( $this->mSchema );
 164                 // The schema to be used is now in the search path; no need for explicit qualification
 165                 $this->mSchema = '';
 166
 167                 return $this->mConn;
 168         }
 169
 170         /**
 171          * Postgres doesn't support selectDB in the same way MySQL does. So if the
 172          * DB name doesn't match the open connection, open a new one
 173          * @param string $db
 174          * @return bool
 175          */
 176         public function selectDB( $db ) {
 177                 if ( $this->mDBname !== $db ) {
 178                         return (bool)$this->open( $this->mServer, $this->mUser, $this->mPassword, $db );
 179                 } else {
 180                         return true;
 181                 }
 182         }
 183
 184         /**
 185          * @param string[] $vars
 186          * @return string
 187          */
 188         private function makeConnectionString( $vars ) {
 189                 $s = '';
 190                 foreach ( $vars as $name => $value ) {
 191                         $s .= "$name='" . str_replace( "'", "\\'", $value ) . "' ";
 192                 }
 193
 194                 return $s;
 195         }
 196
 197         protected function closeConnection() {
 198                 return $this->mConn ? pg_close( $this->mConn ) : true;
 199         }
 200
 201         public function doQuery( $sql ) {
 202                 $conn = $this->getBindingHandle();
 203
 204                 $sql = mb_convert_encoding( $sql, 'UTF-8' );
 205                 // Clear previously left over PQresult
 206                 while ( $res = pg_get_result( $conn ) ) {
 207                         pg_free_result( $res );
 208                 }
 209                 if ( pg_send_query( $conn, $sql ) === false ) {
 210                         throw new DBUnexpectedError( $this, "Unable to post new query to PostgreSQL\n" );
 211                 }
 212                 $this->mLastResult = pg_get_result( $conn );
 213                 $this->mAffectedRows = null;
 214                 if ( pg_result_error( $this->mLastResult ) ) {
 215                         return false;
 216                 }
 217
 218                 return $this->mLastResult;
 219         }
 220
 221         protected function dumpError() {
 222                 $diags = [
 223                         PGSQL_DIAG_SEVERITY,
 224                         PGSQL_DIAG_SQLSTATE,
 225                         PGSQL_DIAG_MESSAGE_PRIMARY,
 226                         PGSQL_DIAG_MESSAGE_DETAIL,
 227                         PGSQL_DIAG_MESSAGE_HINT,
 228                         PGSQL_DIAG_STATEMENT_POSITION,
 229                         PGSQL_DIAG_INTERNAL_POSITION,
 230                         PGSQL_DIAG_INTERNAL_QUERY,
 231                         PGSQL_DIAG_CONTEXT,
 232                         PGSQL_DIAG_SOURCE_FILE,
 233                         PGSQL_DIAG_SOURCE_LINE,
 234                         PGSQL_DIAG_SOURCE_FUNCTION
 235                 ];
 236                 foreach ( $diags as $d ) {
 237                         $this->queryLogger->debug( sprintf( "PgSQL ERROR(%d): %s\n",
 238                                 $d, pg_result_error_field( $this->mLastResult, $d ) ) );
 239                 }
 240         }
 241
 242         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
 243                 if ( $tempIgnore ) {
 244                         /* Check for constraint violation */
 245                         if ( $errno === '23505' ) {
 246                                 parent::reportQueryError( $error, $errno, $sql, $fname, $tempIgnore );
 247
 248                                 return;
 249                         }
 250                 }
 251                 /* Transaction stays in the ERROR state until rolled back */
 252                 if ( $this->mTrxLevel ) {
 253                         $this->rollback( __METHOD__ );
 254                 }
 255                 parent::reportQueryError( $error, $errno, $sql, $fname, false );
 256         }
 257
 258         public function freeResult( $res ) {
 259                 if ( $res instanceof ResultWrapper ) {
 260                         $res = $res->result;
 261                 }
 262                 MediaWiki\suppressWarnings();
 263                 $ok = pg_free_result( $res );
 264                 MediaWiki\restoreWarnings();
 265                 if ( !$ok ) {
 266                         throw new DBUnexpectedError( $this, "Unable to free Postgres result\n" );
 267                 }
 268         }
 269
 270         public function fetchObject( $res ) {
 271                 if ( $res instanceof ResultWrapper ) {
 272                         $res = $res->result;
 273                 }
 274                 MediaWiki\suppressWarnings();
 275                 $row = pg_fetch_object( $res );
 276                 MediaWiki\restoreWarnings();
 277                 # @todo FIXME: HACK HACK HACK HACK debug
 278
 279                 # @todo hashar: not sure if the following test really trigger if the object
 280                 #          fetching failed.
 281                 $conn = $this->getBindingHandle();
 282                 if ( pg_last_error( $conn ) ) {
 283                         throw new DBUnexpectedError(
 284                                 $this,
 285                                 'SQL error: ' . htmlspecialchars( pg_last_error( $conn ) )
 286                         );
 287                 }
 288
 289                 return $row;
 290         }
 291
 292         public function fetchRow( $res ) {
 293                 if ( $res instanceof ResultWrapper ) {
 294                         $res = $res->result;
 295                 }
 296                 MediaWiki\suppressWarnings();
 297                 $row = pg_fetch_array( $res );
 298                 MediaWiki\restoreWarnings();
 299
 300                 $conn = $this->getBindingHandle();
 301                 if ( pg_last_error( $conn ) ) {
 302                         throw new DBUnexpectedError(
 303                                 $this,
 304                                 'SQL error: ' . htmlspecialchars( pg_last_error( $conn ) )
 305                         );
 306                 }
 307
 308                 return $row;
 309         }
 310
 311         public function numRows( $res ) {
 312                 if ( $res instanceof ResultWrapper ) {
 313                         $res = $res->result;
 314                 }
 315                 MediaWiki\suppressWarnings();
 316                 $n = pg_num_rows( $res );
 317                 MediaWiki\restoreWarnings();
 318
 319                 $conn = $this->getBindingHandle();
 320                 if ( pg_last_error( $conn ) ) {
 321                         throw new DBUnexpectedError(
 322                                 $this,
 323                                 'SQL error: ' . htmlspecialchars( pg_last_error( $conn ) )
 324                         );
 325                 }
 326
 327                 return $n;
 328         }
 329
 330         public function numFields( $res ) {
 331                 if ( $res instanceof ResultWrapper ) {
 332                         $res = $res->result;
 333                 }
 334
 335                 return pg_num_fields( $res );
 336         }
 337
 338         public function fieldName( $res, $n ) {
 339                 if ( $res instanceof ResultWrapper ) {
 340                         $res = $res->result;
 341                 }
 342
 343                 return pg_field_name( $res, $n );
 344         }
 345
 346         /**
 347          * Return the result of the last call to nextSequenceValue();
 348          * This must be called after nextSequenceValue().
 349          *
 350          * @return int|null
 351          */
 352         public function insertId() {
 353                 return $this->mInsertId;
 354         }
 355
 356         public function dataSeek( $res, $row ) {
 357                 if ( $res instanceof ResultWrapper ) {
 358                         $res = $res->result;
 359                 }
 360
 361                 return pg_result_seek( $res, $row );
 362         }
 363
 364         public function lastError() {
 365                 if ( $this->mConn ) {
 366                         if ( $this->mLastResult ) {
 367                                 return pg_result_error( $this->mLastResult );
 368                         } else {
 369                                 return pg_last_error();
 370                         }
 371                 }
 372
 373                 return $this->getLastPHPError() ?: 'No database connection';
 374         }
 375
 376         public function lastErrno() {
 377                 if ( $this->mLastResult ) {
 378                         return pg_result_error_field( $this->mLastResult, PGSQL_DIAG_SQLSTATE );
 379                 } else {
 380                         return false;
 381                 }
 382         }
 383
 384         public function affectedRows() {
 385                 if ( !is_null( $this->mAffectedRows ) ) {
 386                         // Forced result for simulated queries
 387                         return $this->mAffectedRows;
 388                 }
 389                 if ( empty( $this->mLastResult ) ) {
 390                         return 0;
 391                 }
 392
 393                 return pg_affected_rows( $this->mLastResult );
 394         }
 395
 396         /**
 397          * Estimate rows in dataset
 398          * Returns estimated count, based on EXPLAIN output
 399          * This is not necessarily an accurate estimate, so use sparingly
 400          * Returns -1 if count cannot be found
 401          * Takes same arguments as Database::select()
 402          *
 403          * @param string $table
 404          * @param string $vars
 405          * @param string $conds
 406          * @param string $fname
 407          * @param array $options
 408          * @return int
 409          */
 410         public function estimateRowCount( $table, $vars = '*', $conds = '',
 411                 $fname = __METHOD__, $options = []
 412         ) {
 413                 $options['EXPLAIN'] = true;
 414                 $res = $this->select( $table, $vars, $conds, $fname, $options );
 415                 $rows = -1;
 416                 if ( $res ) {
 417                         $row = $this->fetchRow( $res );
 418                         $count = [];
 419                         if ( preg_match( '/rows=(\d+)/', $row[0], $count ) ) {
 420                                 $rows = (int)$count[1];
 421                         }
 422                 }
 423
 424                 return $rows;
 425         }
 426
 427         public function indexInfo( $table, $index, $fname = __METHOD__ ) {
 428                 $sql = "SELECT indexname FROM pg_indexes WHERE tablename='$table'";
 429                 $res = $this->query( $sql, $fname );
 430                 if ( !$res ) {
 431                         return null;
 432                 }
 433                 foreach ( $res as $row ) {
 434                         if ( $row->indexname == $this->indexName( $index ) ) {
 435                                 return $row;
 436                         }
 437                 }
 438
 439                 return false;
 440         }
 441
 442         public function indexAttributes( $index, $schema = false ) {
 443                 if ( $schema === false ) {
 444                         $schema = $this->getCoreSchema();
 445                 }
 446                 /*
 447                  * A subquery would be not needed if we didn't care about the order
 448                  * of attributes, but we do
 449                  */
 450                 $sql = <<<__INDEXATTR__
 451
 452                         SELECT opcname,
 453                                 attname,
 454                                 i.indoption[s.g] as option,
 455                                 pg_am.amname
 456                         FROM
 457                                 (SELECT generate_series(array_lower(isub.indkey,1), array_upper(isub.indkey,1)) AS g
 458                                         FROM
 459                                                 pg_index isub
 460                                         JOIN pg_class cis
 461                                                 ON cis.oid=isub.indexrelid
 462                                         JOIN pg_namespace ns
 463                                                 ON cis.relnamespace = ns.oid
 464                                         WHERE cis.relname='$index' AND ns.nspname='$schema') AS s,
 465                                 pg_attribute,
 466                                 pg_opclass opcls,
 467                                 pg_am,
 468                                 pg_class ci
 469                                 JOIN pg_index i
 470                                         ON ci.oid=i.indexrelid
 471                                 JOIN pg_class ct
 472                                         ON ct.oid = i.indrelid
 473                                 JOIN pg_namespace n
 474                                         ON ci.relnamespace = n.oid
 475                                 WHERE
 476                                         ci.relname='$index' AND n.nspname='$schema'
 477                                         AND     attrelid = ct.oid
 478                                         AND     i.indkey[s.g] = attnum
 479                                         AND     i.indclass[s.g] = opcls.oid
 480                                         AND     pg_am.oid = opcls.opcmethod
 481 __INDEXATTR__;
 482                 $res = $this->query( $sql, __METHOD__ );
 483                 $a = [];
 484                 if ( $res ) {
 485                         foreach ( $res as $row ) {
 486                                 $a[] = [
 487                                         $row->attname,
 488                                         $row->opcname,
 489                                         $row->amname,
 490                                         $row->option ];
 491                         }
 492                 } else {
 493                         return null;
 494                 }
 495
 496                 return $a;
 497         }
 498
 499         public function indexUnique( $table, $index, $fname = __METHOD__ ) {
 500                 $sql = "SELECT indexname FROM pg_indexes WHERE tablename='{$table}'" .
 501                         " AND indexdef LIKE 'CREATE UNIQUE%(" .
 502                         $this->strencode( $this->indexName( $index ) ) .
 503                         ")'";
 504                 $res = $this->query( $sql, $fname );
 505                 if ( !$res ) {
 506                         return null;
 507                 }
 508
 509                 return $res->numRows() > 0;
 510         }
 511
 512         public function selectSQLText(
 513                 $table, $vars, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
 514         ) {
 515                 // Change the FOR UPDATE option as necessary based on the join conditions. Then pass
 516                 // to the parent function to get the actual SQL text.
 517                 // In Postgres when using FOR UPDATE, only the main table and tables that are inner joined
 518                 // can be locked. That means tables in an outer join cannot be FOR UPDATE locked. Trying to
 519                 // do so causes a DB error. This wrapper checks which tables can be locked and adjusts it
 520                 // accordingly.
 521                 // MySQL uses "ORDER BY NULL" as an optimization hint, but that is illegal in PostgreSQL.
 522                 if ( is_array( $options ) ) {
 523                         $forUpdateKey = array_search( 'FOR UPDATE', $options, true );
 524                         if ( $forUpdateKey !== false && $join_conds ) {
 525                                 unset( $options[$forUpdateKey] );
 526
 527                                 foreach ( $join_conds as $table_cond => $join_cond ) {
 528                                         if ( 0 === preg_match( '/^(?:LEFT|RIGHT|FULL)(?: OUTER)? JOIN$/i', $join_cond[0] ) ) {
 529                                                 $options['FOR UPDATE'][] = $table_cond;
 530                                         }
 531                                 }
 532                         }
 533
 534                         if ( isset( $options['ORDER BY'] ) && $options['ORDER BY'] == 'NULL' ) {
 535                                 unset( $options['ORDER BY'] );
 536                         }
 537                 }
 538
 539                 return parent::selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
 540         }
 541
 542         /**
 543          * INSERT wrapper, inserts an array into a table
 544          *
 545          * $args may be a single associative array, or an array of these with numeric keys,
 546          * for multi-row insert (Postgres version 8.2 and above only).
 547          *
 548          * @param string $table Name of the table to insert to.
 549          * @param array $args Items to insert into the table.
 550          * @param string $fname Name of the function, for profiling
 551          * @param array|string $options String or array. Valid options: IGNORE
 552          * @return bool Success of insert operation. IGNORE always returns true.
 553          */
 554         public function insert( $table, $args, $fname = __METHOD__, $options = [] ) {
 555                 if ( !count( $args ) ) {
 556                         return true;
 557                 }
 558
 559                 $table = $this->tableName( $table );
 560                 if ( !isset( $this->numericVersion ) ) {
 561                         $this->getServerVersion();
 562                 }
 563
 564                 if ( !is_array( $options ) ) {
 565                         $options = [ $options ];
 566                 }
 567
 568                 if ( isset( $args[0] ) && is_array( $args[0] ) ) {
 569                         $multi = true;
 570                         $keys = array_keys( $args[0] );
 571                 } else {
 572                         $multi = false;
 573                         $keys = array_keys( $args );
 574                 }
 575
 576                 // If IGNORE is set, we use savepoints to emulate mysql's behavior
 577                 $savepoint = $olde = null;
 578                 $numrowsinserted = 0;
 579                 if ( in_array( 'IGNORE', $options ) ) {
 580                         $savepoint = new SavepointPostgres( $this, 'mw', $this->queryLogger );
 581                         $olde = error_reporting( 0 );
 582                         // For future use, we may want to track the number of actual inserts
 583                         // Right now, insert (all writes) simply return true/false
 584                 }
 585
 586                 $sql = "INSERT INTO $table (" . implode( ',', $keys ) . ') VALUES ';
 587
 588                 if ( $multi ) {
 589                         if ( $this->numericVersion >= 8.2 && !$savepoint ) {
 590                                 $first = true;
 591                                 foreach ( $args as $row ) {
 592                                         if ( $first ) {
 593                                                 $first = false;
 594                                         } else {
 595                                                 $sql .= ',';
 596                                         }
 597                                         $sql .= '(' . $this->makeList( $row ) . ')';
 598                                 }
 599                                 $res = (bool)$this->query( $sql, $fname, $savepoint );
 600                         } else {
 601                                 $res = true;
 602                                 $origsql = $sql;
 603                                 foreach ( $args as $row ) {
 604                                         $tempsql = $origsql;
 605                                         $tempsql .= '(' . $this->makeList( $row ) . ')';
 606
 607                                         if ( $savepoint ) {
 608                                                 $savepoint->savepoint();
 609                                         }
 610
 611                                         $tempres = (bool)$this->query( $tempsql, $fname, $savepoint );
 612
 613                                         if ( $savepoint ) {
 614                                                 $bar = pg_result_error( $this->mLastResult );
 615                                                 if ( $bar != false ) {
 616                                                         $savepoint->rollback();
 617                                                 } else {
 618                                                         $savepoint->release();
 619                                                         $numrowsinserted++;
 620                                                 }
 621                                         }
 622
 623                                         // If any of them fail, we fail overall for this function call
 624                                         // Note that this will be ignored if IGNORE is set
 625                                         if ( !$tempres ) {
 626                                                 $res = false;
 627                                         }
 628                                 }
 629                         }
 630                 } else {
 631                         // Not multi, just a lone insert
 632                         if ( $savepoint ) {
 633                                 $savepoint->savepoint();
 634                         }
 635
 636                         $sql .= '(' . $this->makeList( $args ) . ')';
 637                         $res = (bool)$this->query( $sql, $fname, $savepoint );
 638                         if ( $savepoint ) {
 639                                 $bar = pg_result_error( $this->mLastResult );
 640                                 if ( $bar != false ) {
 641                                         $savepoint->rollback();
 642                                 } else {
 643                                         $savepoint->release();
 644                                         $numrowsinserted++;
 645                                 }
 646                         }
 647                 }
 648                 if ( $savepoint ) {
 649                         error_reporting( $olde );
 650                         $savepoint->commit();
 651
 652                         // Set the affected row count for the whole operation
 653                         $this->mAffectedRows = $numrowsinserted;
 654
 655                         // IGNORE always returns true
 656                         return true;
 657                 }
 658
 659                 return $res;
 660         }
 661
 662         /**
 663          * INSERT SELECT wrapper
 664          * $varMap must be an associative array of the form [ 'dest1' => 'source1', ... ]
 665          * Source items may be literals rather then field names, but strings should
 666          * be quoted with Database::addQuotes()
 667          * $conds may be "*" to copy the whole table
 668          * srcTable may be an array of tables.
 669          * @todo FIXME: Implement this a little better (seperate select/insert)?
 670          *
 671          * @param string $destTable
 672          * @param array|string $srcTable
 673          * @param array $varMap
 674          * @param array $conds
 675          * @param string $fname
 676          * @param array $insertOptions
 677          * @param array $selectOptions
 678          * @return bool
 679          */
 680         public function nativeInsertSelect(
 681                 $destTable, $srcTable, $varMap, $conds, $fname = __METHOD__,
 682                 $insertOptions = [], $selectOptions = []
 683         ) {
 684                 $destTable = $this->tableName( $destTable );
 685
 686                 if ( !is_array( $insertOptions ) ) {
 687                         $insertOptions = [ $insertOptions ];
 688                 }
 689
 690                 /*
 691                  * If IGNORE is set, we use savepoints to emulate mysql's behavior
 692                  * Ignore LOW PRIORITY option, since it is MySQL-specific
 693                  */
 694                 $savepoint = $olde = null;
 695                 $numrowsinserted = 0;
 696                 if ( in_array( 'IGNORE', $insertOptions ) ) {
 697                         $savepoint = new SavepointPostgres( $this, 'mw', $this->queryLogger );
 698                         $olde = error_reporting( 0 );
 699                         $savepoint->savepoint();
 700                 }
 701
 702                 if ( !is_array( $selectOptions ) ) {
 703                         $selectOptions = [ $selectOptions ];
 704                 }
 705                 list( $startOpts, $useIndex, $tailOpts, $ignoreIndex ) =
 706                         $this->makeSelectOptions( $selectOptions );
 707                 if ( is_array( $srcTable ) ) {
 708                         $srcTable = implode( ',', array_map( [ $this, 'tableName' ], $srcTable ) );
 709                 } else {
 710                         $srcTable = $this->tableName( $srcTable );
 711                 }
 712
 713                 $sql = "INSERT INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
 714                         " SELECT $startOpts " . implode( ',', $varMap ) .
 715                         " FROM $srcTable $useIndex $ignoreIndex ";
 716
 717                 if ( $conds != '*' ) {
 718                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
 719                 }
 720
 721                 $sql .= " $tailOpts";
 722
 723                 $res = (bool)$this->query( $sql, $fname, $savepoint );
 724                 if ( $savepoint ) {
 725                         $bar = pg_result_error( $this->mLastResult );
 726                         if ( $bar != false ) {
 727                                 $savepoint->rollback();
 728                         } else {
 729                                 $savepoint->release();
 730                                 $numrowsinserted++;
 731                         }
 732                         error_reporting( $olde );
 733                         $savepoint->commit();
 734
 735                         // Set the affected row count for the whole operation
 736                         $this->mAffectedRows = $numrowsinserted;
 737
 738                         // IGNORE always returns true
 739                         return true;
 740                 }
 741
 742                 return $res;
 743         }
 744
 745         public function tableName( $name, $format = 'quoted' ) {
 746                 // Replace reserved words with better ones
 747                 $name = $this->remappedTableName( $name );
 748
 749                 return parent::tableName( $name, $format );
 750         }
 751
 752         /**
 753          * @param string $name
 754          * @return string Value of $name or remapped name if $name is a reserved keyword
 755          */
 756         public function remappedTableName( $name ) {
 757                 return isset( $this->keywordTableMap[$name] ) ? $this->keywordTableMap[$name] : $name;
 758         }
 759
 760         /**
 761          * @param string $name
 762          * @param string $format
 763          * @return string Qualified and encoded (if requested) table name
 764          */
 765         public function realTableName( $name, $format = 'quoted' ) {
 766                 return parent::tableName( $name, $format );
 767         }
 768
 769         public function nextSequenceValue( $seqName ) {
 770                 $safeseq = str_replace( "'", "''", $seqName );
 771                 $res = $this->query( "SELECT nextval('$safeseq')" );
 772                 $row = $this->fetchRow( $res );
 773                 $this->mInsertId = $row[0];
 774
 775                 return $this->mInsertId;
 776         }
 777
 778         /**
 779          * Return the current value of a sequence. Assumes it has been nextval'ed in this session.
 780          *
 781          * @param string $seqName
 782          * @return int
 783          */
 784         public function currentSequenceValue( $seqName ) {
 785                 $safeseq = str_replace( "'", "''", $seqName );
 786                 $res = $this->query( "SELECT currval('$safeseq')" );
 787                 $row = $this->fetchRow( $res );
 788                 $currval = $row[0];
 789
 790                 return $currval;
 791         }
 792
 793         public function textFieldSize( $table, $field ) {
 794                 $table = $this->tableName( $table );
 795                 $sql = "SELECT t.typname as ftype,a.atttypmod as size
 796                         FROM pg_class c, pg_attribute a, pg_type t
 797                         WHERE relname='$table' AND a.attrelid=c.oid AND
 798                                 a.atttypid=t.oid and a.attname='$field'";
 799                 $res = $this->query( $sql );
 800                 $row = $this->fetchObject( $res );
 801                 if ( $row->ftype == 'varchar' ) {
 802                         $size = $row->size - 4;
 803                 } else {
 804                         $size = $row->size;
 805                 }
 806
 807                 return $size;
 808         }
 809
 810         public function limitResult( $sql, $limit, $offset = false ) {
 811                 return "$sql LIMIT $limit " . ( is_numeric( $offset ) ? " OFFSET {$offset} " : '' );
 812         }
 813
 814         public function wasDeadlock() {
 815                 return $this->lastErrno() == '40P01';
 816         }
 817
 818         public function duplicateTableStructure(
 819                 $oldName, $newName, $temporary = false, $fname = __METHOD__
 820         ) {
 821                 $newName = $this->addIdentifierQuotes( $newName );
 822                 $oldName = $this->addIdentifierQuotes( $oldName );
 823
 824                 return $this->query( 'CREATE ' . ( $temporary ? 'TEMPORARY ' : '' ) . " TABLE $newName " .
 825                         "(LIKE $oldName INCLUDING DEFAULTS)", $fname );
 826         }
 827
 828         public function listTables( $prefix = null, $fname = __METHOD__ ) {
 829                 $eschema = $this->addQuotes( $this->getCoreSchema() );
 830                 $result = $this->query(
 831                         "SELECT tablename FROM pg_tables WHERE schemaname = $eschema", $fname );
 832                 $endArray = [];
 833
 834                 foreach ( $result as $table ) {
 835                         $vars = get_object_vars( $table );
 836                         $table = array_pop( $vars );
 837                         if ( !$prefix || strpos( $table, $prefix ) === 0 ) {
 838                                 $endArray[] = $table;
 839                         }
 840                 }
 841
 842                 return $endArray;
 843         }
 844
 845         public function timestamp( $ts = 0 ) {
 846                 $ct = new ConvertibleTimestamp( $ts );
 847
 848                 return $ct->getTimestamp( TS_POSTGRES );
 849         }
 850
 851         /**
 852          * Posted by cc[plus]php[at]c2se[dot]com on 25-Mar-2009 09:12
 853          * to https://secure.php.net/manual/en/ref.pgsql.php
 854          *
 855          * Parsing a postgres array can be a tricky problem, he's my
 856          * take on this, it handles multi-dimensional arrays plus
 857          * escaping using a nasty regexp to determine the limits of each
 858          * data-item.
 859          *
 860          * This should really be handled by PHP PostgreSQL module
 861          *
 862          * @since 1.19
 863          * @param string $text Postgreql array returned in a text form like {a,b}
 864          * @param string[] $output
 865          * @param int|bool $limit
 866          * @param int $offset
 867          * @return string[]
 868          */
 869         private function pg_array_parse( $text, &$output, $limit = false, $offset = 1 ) {
 870                 if ( false === $limit ) {
 871                         $limit = strlen( $text ) - 1;
 872                         $output = [];
 873                 }
 874                 if ( '{}' == $text ) {
 875                         return $output;
 876                 }
 877                 do {
 878                         if ( '{' != $text[$offset] ) {
 879                                 preg_match( "/(\\{?\"([^\"\\\\]|\\\\.)*\"|[^,{}]+)+([,}]+)/",
 880                                         $text, $match, 0, $offset );
 881                                 $offset += strlen( $match[0] );
 882                                 $output[] = ( '"' != $match[1][0]
 883                                         ? $match[1]
 884                                         : stripcslashes( substr( $match[1], 1, -1 ) ) );
 885                                 if ( '},' == $match[3] ) {
 886                                         return $output;
 887                                 }
 888                         } else {
 889                                 $offset = $this->pg_array_parse( $text, $output, $limit, $offset + 1 );
 890                         }
 891                 } while ( $limit > $offset );
 892
 893                 return $output;
 894         }
 895
 896         public function aggregateValue( $valuedata, $valuename = 'value' ) {
 897                 return $valuedata;
 898         }
 899
 900         public function getSoftwareLink() {
 901                 return '[{{int:version-db-postgres-url}} PostgreSQL]';
 902         }
 903
 904         /**
 905          * Return current schema (executes SELECT current_schema())
 906          * Needs transaction
 907          *
 908          * @since 1.19
 909          * @return string Default schema for the current session
 910          */
 911         public function getCurrentSchema() {
 912                 $res = $this->query( "SELECT current_schema()", __METHOD__ );
 913                 $row = $this->fetchRow( $res );
 914
 915                 return $row[0];
 916         }
 917
 918         /**
 919          * Return list of schemas which are accessible without schema name
 920          * This is list does not contain magic keywords like "$user"
 921          * Needs transaction
 922          *
 923          * @see getSearchPath()
 924          * @see setSearchPath()
 925          * @since 1.19
 926          * @return array List of actual schemas for the current sesson
 927          */
 928         public function getSchemas() {
 929                 $res = $this->query( "SELECT current_schemas(false)", __METHOD__ );
 930                 $row = $this->fetchRow( $res );
 931                 $schemas = [];
 932
 933                 /* PHP pgsql support does not support array type, "{a,b}" string is returned */
 934
 935                 return $this->pg_array_parse( $row[0], $schemas );
 936         }
 937
 938         /**
 939          * Return search patch for schemas
 940          * This is different from getSchemas() since it contain magic keywords
 941          * (like "$user").
 942          * Needs transaction
 943          *
 944          * @since 1.19
 945          * @return array How to search for table names schemas for the current user
 946          */
 947         public function getSearchPath() {
 948                 $res = $this->query( "SHOW search_path", __METHOD__ );
 949                 $row = $this->fetchRow( $res );
 950
 951                 /* PostgreSQL returns SHOW values as strings */
 952
 953                 return explode( ",", $row[0] );
 954         }
 955
 956         /**
 957          * Update search_path, values should already be sanitized
 958          * Values may contain magic keywords like "$user"
 959          * @since 1.19
 960          *
 961          * @param array $search_path List of schemas to be searched by default
 962          */
 963         private function setSearchPath( $search_path ) {
 964                 $this->query( "SET search_path = " . implode( ", ", $search_path ) );
 965         }
 966
 967         /**
 968          * Determine default schema for the current application
 969          * Adjust this session schema search path if desired schema exists
 970          * and is not alread there.
 971          *
 972          * We need to have name of the core schema stored to be able
 973          * to query database metadata.
 974          *
 975          * This will be also called by the installer after the schema is created
 976          *
 977          * @since 1.19
 978          *
 979          * @param string $desiredSchema
 980          */
 981         public function determineCoreSchema( $desiredSchema ) {
 982                 $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
 983                 if ( $this->schemaExists( $desiredSchema ) ) {
 984                         if ( in_array( $desiredSchema, $this->getSchemas() ) ) {
 985                                 $this->mCoreSchema = $desiredSchema;
 986                                 $this->queryLogger->debug(
 987                                         "Schema \"" . $desiredSchema . "\" already in the search path\n" );
 988                         } else {
 989                                 /**
 990                                  * Prepend our schema (e.g. 'mediawiki') in front
 991                                  * of the search path
 992                                  * Fixes T17816
 993                                  */
 994                                 $search_path = $this->getSearchPath();
 995                                 array_unshift( $search_path,
 996                                         $this->addIdentifierQuotes( $desiredSchema ) );
 997                                 $this->setSearchPath( $search_path );
 998                                 $this->mCoreSchema = $desiredSchema;
 999                                 $this->queryLogger->debug(
1000                                         "Schema \"" . $desiredSchema . "\" added to the search path\n" );
1001                         }
1002                 } else {
1003                         $this->mCoreSchema = $this->getCurrentSchema();
1004                         $this->queryLogger->debug(
1005                                 "Schema \"" . $desiredSchema . "\" not found, using current \"" .
1006                                 $this->mCoreSchema . "\"\n" );
1007                 }
1008                 /* Commit SET otherwise it will be rollbacked on error or IGNORE SELECT */
1009                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
1010         }
1011
1012         /**
1013          * Return schema name for core application tables
1014          *
1015          * @since 1.19
1016          * @return string Core schema name
1017          */
1018         public function getCoreSchema() {
1019                 return $this->mCoreSchema;
1020         }
1021
1022         public function getServerVersion() {
1023                 if ( !isset( $this->numericVersion ) ) {
1024                         $conn = $this->getBindingHandle();
1025                         $versionInfo = pg_version( $conn );
1026                         if ( version_compare( $versionInfo['client'], '7.4.0', 'lt' ) ) {
1027                                 // Old client, abort install
1028                                 $this->numericVersion = '7.3 or earlier';
1029                         } elseif ( isset( $versionInfo['server'] ) ) {
1030                                 // Normal client
1031                                 $this->numericVersion = $versionInfo['server'];
1032                         } else {
1033                                 // T18937: broken pgsql extension from PHP<5.3
1034                                 $this->numericVersion = pg_parameter_status( $conn, 'server_version' );
1035                         }
1036                 }
1037
1038                 return $this->numericVersion;
1039         }
1040
1041         /**
1042          * Query whether a given relation exists (in the given schema, or the
1043          * default mw one if not given)
1044          * @param string $table
1045          * @param array|string $types
1046          * @param bool|string $schema
1047          * @return bool
1048          */
1049         private function relationExists( $table, $types, $schema = false ) {
1050                 if ( !is_array( $types ) ) {
1051                         $types = [ $types ];
1052                 }
1053                 if ( $schema === false ) {
1054                         $schema = $this->getCoreSchema();
1055                 }
1056                 $etable = $this->addQuotes( $table );
1057                 $eschema = $this->addQuotes( $schema );
1058                 $sql = "SELECT 1 FROM pg_catalog.pg_class c, pg_catalog.pg_namespace n "
1059                         . "WHERE c.relnamespace = n.oid AND c.relname = $etable AND n.nspname = $eschema "
1060                         . "AND c.relkind IN ('" . implode( "','", $types ) . "')";
1061                 $res = $this->query( $sql );
1062                 $count = $res ? $res->numRows() : 0;
1063
1064                 return (bool)$count;
1065         }
1066
1067         /**
1068          * For backward compatibility, this function checks both tables and views.
1069          * @param string $table
1070          * @param string $fname
1071          * @param bool|string $schema
1072          * @return bool
1073          */
1074         public function tableExists( $table, $fname = __METHOD__, $schema = false ) {
1075                 return $this->relationExists( $table, [ 'r', 'v' ], $schema );
1076         }
1077
1078         public function sequenceExists( $sequence, $schema = false ) {
1079                 return $this->relationExists( $sequence, 'S', $schema );
1080         }
1081
1082         public function triggerExists( $table, $trigger ) {
1083                 $q = <<<SQL
1084         SELECT 1 FROM pg_class, pg_namespace, pg_trigger
1085                 WHERE relnamespace=pg_namespace.oid AND relkind='r'
1086                         AND tgrelid=pg_class.oid
1087                         AND nspname=%s AND relname=%s AND tgname=%s
1088 SQL;
1089                 $res = $this->query(
1090                         sprintf(
1091                                 $q,
1092                                 $this->addQuotes( $this->getCoreSchema() ),
1093                                 $this->addQuotes( $table ),
1094                                 $this->addQuotes( $trigger )
1095                         )
1096                 );
1097                 if ( !$res ) {
1098                         return null;
1099                 }
1100                 $rows = $res->numRows();
1101
1102                 return $rows;
1103         }
1104
1105         public function ruleExists( $table, $rule ) {
1106                 $exists = $this->selectField( 'pg_rules', 'rulename',
1107                         [
1108                                 'rulename' => $rule,
1109                                 'tablename' => $table,
1110                                 'schemaname' => $this->getCoreSchema()
1111                         ]
1112                 );
1113
1114                 return $exists === $rule;
1115         }
1116
1117         public function constraintExists( $table, $constraint ) {
1118                 $sql = sprintf( "SELECT 1 FROM information_schema.table_constraints " .
1119                         "WHERE constraint_schema = %s AND table_name = %s AND constraint_name = %s",
1120                         $this->addQuotes( $this->getCoreSchema() ),
1121                         $this->addQuotes( $table ),
1122                         $this->addQuotes( $constraint )
1123                 );
1124                 $res = $this->query( $sql );
1125                 if ( !$res ) {
1126                         return null;
1127                 }
1128                 $rows = $res->numRows();
1129
1130                 return $rows;
1131         }
1132
1133         /**
1134          * Query whether a given schema exists. Returns true if it does, false if it doesn't.
1135          * @param string $schema
1136          * @return bool
1137          */
1138         public function schemaExists( $schema ) {
1139                 if ( !strlen( $schema ) ) {
1140                         return false; // short-circuit
1141                 }
1142
1143                 $exists = $this->selectField(
1144                         '"pg_catalog"."pg_namespace"', 1, [ 'nspname' => $schema ], __METHOD__ );
1145
1146                 return (bool)$exists;
1147         }
1148
1149         /**
1150          * Returns true if a given role (i.e. user) exists, false otherwise.
1151          * @param string $roleName
1152          * @return bool
1153          */
1154         public function roleExists( $roleName ) {
1155                 $exists = $this->selectField( '"pg_catalog"."pg_roles"', 1,
1156                         [ 'rolname' => $roleName ], __METHOD__ );
1157
1158                 return (bool)$exists;
1159         }
1160
1161         /**
1162          * @var string $table
1163          * @var string $field
1164          * @return PostgresField|null
1165          */
1166         public function fieldInfo( $table, $field ) {
1167                 return PostgresField::fromText( $this, $table, $field );
1168         }
1169
1170         /**
1171          * pg_field_type() wrapper
1172          * @param ResultWrapper|resource $res ResultWrapper or PostgreSQL query result resource
1173          * @param int $index Field number, starting from 0
1174          * @return string
1175          */
1176         public function fieldType( $res, $index ) {
1177                 if ( $res instanceof ResultWrapper ) {
1178                         $res = $res->result;
1179                 }
1180
1181                 return pg_field_type( $res, $index );
1182         }
1183
1184         public function encodeBlob( $b ) {
1185                 return new PostgresBlob( pg_escape_bytea( $b ) );
1186         }
1187
1188         public function decodeBlob( $b ) {
1189                 if ( $b instanceof PostgresBlob ) {
1190                         $b = $b->fetch();
1191                 } elseif ( $b instanceof Blob ) {
1192                         return $b->fetch();
1193                 }
1194
1195                 return pg_unescape_bytea( $b );
1196         }
1197
1198         public function strencode( $s ) {
1199                 // Should not be called by us
1200                 return pg_escape_string( $this->getBindingHandle(), $s );
1201         }
1202
1203         public function addQuotes( $s ) {
1204                 $conn = $this->getBindingHandle();
1205
1206                 if ( is_null( $s ) ) {
1207                         return 'NULL';
1208                 } elseif ( is_bool( $s ) ) {
1209                         return intval( $s );
1210                 } elseif ( $s instanceof Blob ) {
1211                         if ( $s instanceof PostgresBlob ) {
1212                                 $s = $s->fetch();
1213                         } else {
1214                                 $s = pg_escape_bytea( $conn, $s->fetch() );
1215                         }
1216                         return "'$s'";
1217                 }
1218
1219                 return "'" . pg_escape_string( $conn, $s ) . "'";
1220         }
1221
1222         /**
1223          * Postgres specific version of replaceVars.
1224          * Calls the parent version in Database.php
1225          *
1226          * @param string $ins SQL string, read from a stream (usually tables.sql)
1227          * @return string SQL string
1228          */
1229         protected function replaceVars( $ins ) {
1230                 $ins = parent::replaceVars( $ins );
1231
1232                 if ( $this->numericVersion >= 8.3 ) {
1233                         // Thanks for not providing backwards-compatibility, 8.3
1234                         $ins = preg_replace( "/to_tsvector\s*\(\s*'default'\s*,/", 'to_tsvector(', $ins );
1235                 }
1236
1237                 if ( $this->numericVersion <= 8.1 ) { // Our minimum version
1238                         $ins = str_replace( 'USING gin', 'USING gist', $ins );
1239                 }
1240
1241                 return $ins;
1242         }
1243
1244         public function makeSelectOptions( $options ) {
1245                 $preLimitTail = $postLimitTail = '';
1246                 $startOpts = $useIndex = $ignoreIndex = '';
1247
1248                 $noKeyOptions = [];
1249                 foreach ( $options as $key => $option ) {
1250                         if ( is_numeric( $key ) ) {
1251                                 $noKeyOptions[$option] = true;
1252                         }
1253                 }
1254
1255                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1256
1257                 $preLimitTail .= $this->makeOrderBy( $options );
1258
1259                 if ( isset( $options['FOR UPDATE'] ) ) {
1260                         $postLimitTail .= ' FOR UPDATE OF ' .
1261                                 implode( ', ', array_map( [ $this, 'tableName' ], $options['FOR UPDATE'] ) );
1262                 } elseif ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1263                         $postLimitTail .= ' FOR UPDATE';
1264                 }
1265
1266                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1267                         $startOpts .= 'DISTINCT';
1268                 }
1269
1270                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1271         }
1272
1273         public function getDBname() {
1274                 return $this->mDBname;
1275         }
1276
1277         public function getServer() {
1278                 return $this->mServer;
1279         }
1280
1281         public function buildConcat( $stringList ) {
1282                 return implode( ' || ', $stringList );
1283         }
1284
1285         public function buildGroupConcatField(
1286                 $delimiter, $table, $field, $conds = '', $options = [], $join_conds = []
1287         ) {
1288                 $fld = "array_to_string(array_agg($field)," . $this->addQuotes( $delimiter ) . ')';
1289
1290                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1291         }
1292
1293         public function buildStringCast( $field ) {
1294                 return $field . '::text';
1295         }
1296
1297         public function streamStatementEnd( &$sql, &$newLine ) {
1298                 # Allow dollar quoting for function declarations
1299                 if ( substr( $newLine, 0, 4 ) == '$mw$' ) {
1300                         if ( $this->delimiter ) {
1301                                 $this->delimiter = false;
1302                         } else {
1303                                 $this->delimiter = ';';
1304                         }
1305                 }
1306
1307                 return parent::streamStatementEnd( $sql, $newLine );
1308         }
1309
1310         public function doLockTables( array $read, array $write, $method ) {
1311                 $tablesWrite = [];
1312                 foreach ( $write as $table ) {
1313                         $tablesWrite[] = $this->tableName( $table );
1314                 }
1315                 $tablesRead = [];
1316                 foreach ( $read as $table ) {
1317                         $tablesRead[] = $this->tableName( $table );
1318                 }
1319
1320                 // Acquire locks for the duration of the current transaction...
1321                 if ( $tablesWrite ) {
1322                         $this->query(
1323                                 'LOCK TABLE ONLY ' . implode( ',', $tablesWrite ) . ' IN EXCLUSIVE MODE',
1324                                 $method
1325                         );
1326                 }
1327                 if ( $tablesRead ) {
1328                         $this->query(
1329                                 'LOCK TABLE ONLY ' . implode( ',', $tablesRead ) . ' IN SHARE MODE',
1330                                 $method
1331                         );
1332                 }
1333
1334                 return true;
1335         }
1336
1337         public function lockIsFree( $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 = $this->query( "SELECT (CASE(pg_try_advisory_lock($key))
1341                         WHEN 'f' THEN 'f' ELSE pg_advisory_unlock($key) END) AS lockstatus", $method );
1342                 $row = $this->fetchObject( $result );
1343
1344                 return ( $row->lockstatus === 't' );
1345         }
1346
1347         public function lock( $lockName, $method, $timeout = 5 ) {
1348                 // http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1349                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1350                 $loop = new WaitConditionLoop(
1351                         function () use ( $lockName, $key, $timeout, $method ) {
1352                                 $res = $this->query( "SELECT pg_try_advisory_lock($key) AS lockstatus", $method );
1353                                 $row = $this->fetchObject( $res );
1354                                 if ( $row->lockstatus === 't' ) {
1355                                         parent::lock( $lockName, $method, $timeout ); // record
1356                                         return true;
1357                                 }
1358
1359                                 return WaitConditionLoop::CONDITION_CONTINUE;
1360                         },
1361                         $timeout
1362                 );
1363
1364                 return ( $loop->invoke() === $loop::CONDITION_REACHED );
1365         }
1366
1367         public function unlock( $lockName, $method ) {
1368                 // http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1369                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1370                 $result = $this->query( "SELECT pg_advisory_unlock($key) as lockstatus", $method );
1371                 $row = $this->fetchObject( $result );
1372
1373                 if ( $row->lockstatus === 't' ) {
1374                         parent::unlock( $lockName, $method ); // record
1375                         return true;
1376                 }
1377
1378                 $this->queryLogger->debug( __METHOD__ . " failed to release lock\n" );
1379
1380                 return false;
1381         }
1382
1383         /**
1384          * @param string $lockName
1385          * @return string Integer
1386          */
1387         private function bigintFromLockName( $lockName ) {
1388                 return \Wikimedia\base_convert( substr( sha1( $lockName ), 0, 15 ), 16, 10 );
1389         }
1390 }
1391
1392 class_alias( DatabasePostgres::class, 'DatabasePostgres' );