includes/libs/rdbms/database/DatabasePostgres.php

   1 <?php
   2 /**
   3  * This is the Postgres database abstraction layer.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @ingroup Database
  22  */
  23 namespace Wikimedia\Rdbms;
  24
  25 use Wikimedia\Timestamp\ConvertibleTimestamp;
  26 use Wikimedia\WaitConditionLoop;
  27 use MediaWiki;
  28 use Exception;
  29
  30 /**
  31  * @ingroup Database
  32  */
  33 class DatabasePostgres extends Database {
  34         /** @var int|bool */
  35         protected $port;
  36
  37         /** @var resource */
  38         protected $mLastResult = null;
  39         /** @var int The number of rows affected as an integer */
  40         protected $mAffectedRows = null;
  41
  42         /** @var int */
  43         private $mInsertId = null;
  44         /** @var float|string */
  45         private $numericVersion = null;
  46         /** @var string Connect string to open a PostgreSQL connection */
  47         private $connectString;
  48         /** @var string */
  49         private $mCoreSchema;
  50         /** @var string[] Map of (reserved table name => alternate table name) */
  51         private $keywordTableMap = [];
  52
  53         /**
  54          * @see Database::__construct()
  55          * @param array $params Additional parameters include:
  56          *   - keywordTableMap : Map of reserved table names to alternative table names to use
  57          */
  58         public function __construct( array $params ) {
  59                 $this->port = isset( $params['port'] ) ? $params['port'] : false;
  60                 $this->keywordTableMap = isset( $params['keywordTableMap'] )
  61                         ? $params['keywordTableMap']
  62                         : [];
  63
  64                 parent::__construct( $params );
  65         }
  66
  67         public function getType() {
  68                 return 'postgres';
  69         }
  70
  71         public function implicitGroupby() {
  72                 return false;
  73         }
  74
  75         public function implicitOrderby() {
  76                 return false;
  77         }
  78
  79         public function hasConstraint( $name ) {
  80                 $conn = $this->getBindingHandle();
  81
  82                 $sql = "SELECT 1 FROM pg_catalog.pg_constraint c, pg_catalog.pg_namespace n " .
  83                         "WHERE c.connamespace = n.oid AND conname = '" .
  84                         pg_escape_string( $conn, $name ) . "' AND n.nspname = '" .
  85                         pg_escape_string( $conn, $this->getCoreSchema() ) . "'";
  86                 $res = $this->doQuery( $sql );
  87
  88                 return $this->numRows( $res );
  89         }
  90
  91         public function open( $server, $user, $password, $dbName ) {
  92                 # Test for Postgres support, to avoid suppressed fatal error
  93                 if ( !function_exists( 'pg_connect' ) ) {
  94                         throw new DBConnectionError(
  95                                 $this,
  96                                 "Postgres functions missing, have you compiled PHP with the --with-pgsql\n" .
  97                                 "option? (Note: if you recently installed PHP, you may need to restart your\n" .
  98                                 "webserver and database)\n"
  99                         );
 100                 }
 101
 102                 $this->mServer = $server;
 103                 $this->mUser = $user;
 104                 $this->mPassword = $password;
 105                 $this->mDBname = $dbName;
 106
 107                 $connectVars = [
 108                         // pg_connect() user $user as the default database. Since a database is *required*,
 109                         // at least pick a "don't care" database that is more likely to exist. This case
 110                         // arrises when LoadBalancer::getConnection( $i, [], '' ) is used.
 111                         'dbname' => strlen( $dbName ) ? $dbName : 'postgres',
 112                         'user' => $user,
 113                         'password' => $password
 114                 ];
 115                 if ( $server != false && $server != '' ) {
 116                         $connectVars['host'] = $server;
 117                 }
 118                 if ( (int)$this->port > 0 ) {
 119                         $connectVars['port'] = (int)$this->port;
 120                 }
 121                 if ( $this->mFlags & self::DBO_SSL ) {
 122                         $connectVars['sslmode'] = 1;
 123                 }
 124
 125                 $this->connectString = $this->makeConnectionString( $connectVars );
 126                 $this->close();
 127                 $this->installErrorHandler();
 128
 129                 try {
 130                         // Use new connections to let LoadBalancer/LBFactory handle reuse
 131                         $this->mConn = pg_connect( $this->connectString, PGSQL_CONNECT_FORCE_NEW );
 132                 } catch ( Exception $ex ) {
 133                         $this->restoreErrorHandler();
 134                         throw $ex;
 135                 }
 136
 137                 $phpError = $this->restoreErrorHandler();
 138
 139                 if ( !$this->mConn ) {
 140                         $this->queryLogger->debug(
 141                                 "DB connection error\n" .
 142                                 "Server: $server, Database: $dbName, User: $user, Password: " .
 143                                 substr( $password, 0, 3 ) . "...\n"
 144                         );
 145                         $this->queryLogger->debug( $this->lastError() . "\n" );
 146                         throw new DBConnectionError( $this, str_replace( "\n", ' ', $phpError ) );
 147                 }
 148
 149                 $this->mOpened = true;
 150
 151                 # If called from the command-line (e.g. importDump), only show errors
 152                 if ( $this->cliMode ) {
 153                         $this->doQuery( "SET client_min_messages = 'ERROR'" );
 154                 }
 155
 156                 $this->query( "SET client_encoding='UTF8'", __METHOD__ );
 157                 $this->query( "SET datestyle = 'ISO, YMD'", __METHOD__ );
 158                 $this->query( "SET timezone = 'GMT'", __METHOD__ );
 159                 $this->query( "SET standard_conforming_strings = on", __METHOD__ );
 160                 if ( $this->getServerVersion() >= 9.0 ) {
 161                         $this->query( "SET bytea_output = 'escape'", __METHOD__ ); // PHP bug 53127
 162                 }
 163
 164                 $this->determineCoreSchema( $this->mSchema );
 165                 // The schema to be used is now in the search path; no need for explicit qualification
 166                 $this->mSchema = '';
 167
 168                 return $this->mConn;
 169         }
 170
 171         public function databasesAreIndependent() {
 172                 return true;
 173         }
 174
 175         /**
 176          * Postgres doesn't support selectDB in the same way MySQL does. So if the
 177          * DB name doesn't match the open connection, open a new one
 178          * @param string $db
 179          * @return bool
 180          * @throws DBUnexpectedError
 181          */
 182         public function selectDB( $db ) {
 183                 if ( $this->mDBname !== $db ) {
 184                         return (bool)$this->open( $this->mServer, $this->mUser, $this->mPassword, $db );
 185                 } else {
 186                         return true;
 187                 }
 188         }
 189
 190         /**
 191          * @param string[] $vars
 192          * @return string
 193          */
 194         private function makeConnectionString( $vars ) {
 195                 $s = '';
 196                 foreach ( $vars as $name => $value ) {
 197                         $s .= "$name='" . str_replace( "'", "\\'", $value ) . "' ";
 198                 }
 199
 200                 return $s;
 201         }
 202
 203         protected function closeConnection() {
 204                 return $this->mConn ? pg_close( $this->mConn ) : true;
 205         }
 206
 207         public function doQuery( $sql ) {
 208                 $conn = $this->getBindingHandle();
 209
 210                 $sql = mb_convert_encoding( $sql, 'UTF-8' );
 211                 // Clear previously left over PQresult
 212                 while ( $res = pg_get_result( $conn ) ) {
 213                         pg_free_result( $res );
 214                 }
 215                 if ( pg_send_query( $conn, $sql ) === false ) {
 216                         throw new DBUnexpectedError( $this, "Unable to post new query to PostgreSQL\n" );
 217                 }
 218                 $this->mLastResult = pg_get_result( $conn );
 219                 $this->mAffectedRows = null;
 220                 if ( pg_result_error( $this->mLastResult ) ) {
 221                         return false;
 222                 }
 223
 224                 return $this->mLastResult;
 225         }
 226
 227         protected function dumpError() {
 228                 $diags = [
 229                         PGSQL_DIAG_SEVERITY,
 230                         PGSQL_DIAG_SQLSTATE,
 231                         PGSQL_DIAG_MESSAGE_PRIMARY,
 232                         PGSQL_DIAG_MESSAGE_DETAIL,
 233                         PGSQL_DIAG_MESSAGE_HINT,
 234                         PGSQL_DIAG_STATEMENT_POSITION,
 235                         PGSQL_DIAG_INTERNAL_POSITION,
 236                         PGSQL_DIAG_INTERNAL_QUERY,
 237                         PGSQL_DIAG_CONTEXT,
 238                         PGSQL_DIAG_SOURCE_FILE,
 239                         PGSQL_DIAG_SOURCE_LINE,
 240                         PGSQL_DIAG_SOURCE_FUNCTION
 241                 ];
 242                 foreach ( $diags as $d ) {
 243                         $this->queryLogger->debug( sprintf( "PgSQL ERROR(%d): %s\n",
 244                                 $d, pg_result_error_field( $this->mLastResult, $d ) ) );
 245                 }
 246         }
 247
 248         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
 249                 if ( $tempIgnore ) {
 250                         /* Check for constraint violation */
 251                         if ( $errno === '23505' ) {
 252                                 parent::reportQueryError( $error, $errno, $sql, $fname, $tempIgnore );
 253
 254                                 return;
 255                         }
 256                 }
 257                 /* Transaction stays in the ERROR state until rolled back */
 258                 if ( $this->mTrxLevel ) {
 259                         $this->rollback( __METHOD__ );
 260                 }
 261                 parent::reportQueryError( $error, $errno, $sql, $fname, false );
 262         }
 263
 264         public function freeResult( $res ) {
 265                 if ( $res instanceof ResultWrapper ) {
 266                         $res = $res->result;
 267                 }
 268                 MediaWiki\suppressWarnings();
 269                 $ok = pg_free_result( $res );
 270                 MediaWiki\restoreWarnings();
 271                 if ( !$ok ) {
 272                         throw new DBUnexpectedError( $this, "Unable to free Postgres result\n" );
 273                 }
 274         }
 275
 276         public function fetchObject( $res ) {
 277                 if ( $res instanceof ResultWrapper ) {
 278                         $res = $res->result;
 279                 }
 280                 MediaWiki\suppressWarnings();
 281                 $row = pg_fetch_object( $res );
 282                 MediaWiki\restoreWarnings();
 283                 # @todo FIXME: HACK HACK HACK HACK debug
 284
 285                 # @todo hashar: not sure if the following test really trigger if the object
 286                 #          fetching failed.
 287                 $conn = $this->getBindingHandle();
 288                 if ( pg_last_error( $conn ) ) {
 289                         throw new DBUnexpectedError(
 290                                 $this,
 291                                 'SQL error: ' . htmlspecialchars( pg_last_error( $conn ) )
 292                         );
 293                 }
 294
 295                 return $row;
 296         }
 297
 298         public function fetchRow( $res ) {
 299                 if ( $res instanceof ResultWrapper ) {
 300                         $res = $res->result;
 301                 }
 302                 MediaWiki\suppressWarnings();
 303                 $row = pg_fetch_array( $res );
 304                 MediaWiki\restoreWarnings();
 305
 306                 $conn = $this->getBindingHandle();
 307                 if ( pg_last_error( $conn ) ) {
 308                         throw new DBUnexpectedError(
 309                                 $this,
 310                                 'SQL error: ' . htmlspecialchars( pg_last_error( $conn ) )
 311                         );
 312                 }
 313
 314                 return $row;
 315         }
 316
 317         public function numRows( $res ) {
 318                 if ( $res instanceof ResultWrapper ) {
 319                         $res = $res->result;
 320                 }
 321                 MediaWiki\suppressWarnings();
 322                 $n = pg_num_rows( $res );
 323                 MediaWiki\restoreWarnings();
 324
 325                 $conn = $this->getBindingHandle();
 326                 if ( pg_last_error( $conn ) ) {
 327                         throw new DBUnexpectedError(
 328                                 $this,
 329                                 'SQL error: ' . htmlspecialchars( pg_last_error( $conn ) )
 330                         );
 331                 }
 332
 333                 return $n;
 334         }
 335
 336         public function numFields( $res ) {
 337                 if ( $res instanceof ResultWrapper ) {
 338                         $res = $res->result;
 339                 }
 340
 341                 return pg_num_fields( $res );
 342         }
 343
 344         public function fieldName( $res, $n ) {
 345                 if ( $res instanceof ResultWrapper ) {
 346                         $res = $res->result;
 347                 }
 348
 349                 return pg_field_name( $res, $n );
 350         }
 351
 352         /**
 353          * Return the result of the last call to nextSequenceValue();
 354          * This must be called after nextSequenceValue().
 355          *
 356          * @return int|null
 357          */
 358         public function insertId() {
 359                 return $this->mInsertId;
 360         }
 361
 362         public function dataSeek( $res, $row ) {
 363                 if ( $res instanceof ResultWrapper ) {
 364                         $res = $res->result;
 365                 }
 366
 367                 return pg_result_seek( $res, $row );
 368         }
 369
 370         public function lastError() {
 371                 if ( $this->mConn ) {
 372                         if ( $this->mLastResult ) {
 373                                 return pg_result_error( $this->mLastResult );
 374                         } else {
 375                                 return pg_last_error();
 376                         }
 377                 }
 378
 379                 return $this->getLastPHPError() ?: 'No database connection';
 380         }
 381
 382         public function lastErrno() {
 383                 if ( $this->mLastResult ) {
 384                         return pg_result_error_field( $this->mLastResult, PGSQL_DIAG_SQLSTATE );
 385                 } else {
 386                         return false;
 387                 }
 388         }
 389
 390         public function affectedRows() {
 391                 if ( !is_null( $this->mAffectedRows ) ) {
 392                         // Forced result for simulated queries
 393                         return $this->mAffectedRows;
 394                 }
 395                 if ( empty( $this->mLastResult ) ) {
 396                         return 0;
 397                 }
 398
 399                 return pg_affected_rows( $this->mLastResult );
 400         }
 401
 402         /**
 403          * Estimate rows in dataset
 404          * Returns estimated count, based on EXPLAIN output
 405          * This is not necessarily an accurate estimate, so use sparingly
 406          * Returns -1 if count cannot be found
 407          * Takes same arguments as Database::select()
 408          *
 409          * @param string $table
 410          * @param string $vars
 411          * @param string $conds
 412          * @param string $fname
 413          * @param array $options
 414          * @return int
 415          */
 416         public function estimateRowCount( $table, $vars = '*', $conds = '',
 417                 $fname = __METHOD__, $options = []
 418         ) {
 419                 $options['EXPLAIN'] = true;
 420                 $res = $this->select( $table, $vars, $conds, $fname, $options );
 421                 $rows = -1;
 422                 if ( $res ) {
 423                         $row = $this->fetchRow( $res );
 424                         $count = [];
 425                         if ( preg_match( '/rows=(\d+)/', $row[0], $count ) ) {
 426                                 $rows = (int)$count[1];
 427                         }
 428                 }
 429
 430                 return $rows;
 431         }
 432
 433         public function indexInfo( $table, $index, $fname = __METHOD__ ) {
 434                 $sql = "SELECT indexname FROM pg_indexes WHERE tablename='$table'";
 435                 $res = $this->query( $sql, $fname );
 436                 if ( !$res ) {
 437                         return null;
 438                 }
 439                 foreach ( $res as $row ) {
 440                         if ( $row->indexname == $this->indexName( $index ) ) {
 441                                 return $row;
 442                         }
 443                 }
 444
 445                 return false;
 446         }
 447
 448         public function indexAttributes( $index, $schema = false ) {
 449                 if ( $schema === false ) {
 450                         $schema = $this->getCoreSchema();
 451                 }
 452                 /*
 453                  * A subquery would be not needed if we didn't care about the order
 454                  * of attributes, but we do
 455                  */
 456                 $sql = <<<__INDEXATTR__
 457
 458                         SELECT opcname,
 459                                 attname,
 460                                 i.indoption[s.g] as option,
 461                                 pg_am.amname
 462                         FROM
 463                                 (SELECT generate_series(array_lower(isub.indkey,1), array_upper(isub.indkey,1)) AS g
 464                                         FROM
 465                                                 pg_index isub
 466                                         JOIN pg_class cis
 467                                                 ON cis.oid=isub.indexrelid
 468                                         JOIN pg_namespace ns
 469                                                 ON cis.relnamespace = ns.oid
 470                                         WHERE cis.relname='$index' AND ns.nspname='$schema') AS s,
 471                                 pg_attribute,
 472                                 pg_opclass opcls,
 473                                 pg_am,
 474                                 pg_class ci
 475                                 JOIN pg_index i
 476                                         ON ci.oid=i.indexrelid
 477                                 JOIN pg_class ct
 478                                         ON ct.oid = i.indrelid
 479                                 JOIN pg_namespace n
 480                                         ON ci.relnamespace = n.oid
 481                                 WHERE
 482                                         ci.relname='$index' AND n.nspname='$schema'
 483                                         AND     attrelid = ct.oid
 484                                         AND     i.indkey[s.g] = attnum
 485                                         AND     i.indclass[s.g] = opcls.oid
 486                                         AND     pg_am.oid = opcls.opcmethod
 487 __INDEXATTR__;
 488                 $res = $this->query( $sql, __METHOD__ );
 489                 $a = [];
 490                 if ( $res ) {
 491                         foreach ( $res as $row ) {
 492                                 $a[] = [
 493                                         $row->attname,
 494                                         $row->opcname,
 495                                         $row->amname,
 496                                         $row->option ];
 497                         }
 498                 } else {
 499                         return null;
 500                 }
 501
 502                 return $a;
 503         }
 504
 505         public function indexUnique( $table, $index, $fname = __METHOD__ ) {
 506                 $sql = "SELECT indexname FROM pg_indexes WHERE tablename='{$table}'" .
 507                         " AND indexdef LIKE 'CREATE UNIQUE%(" .
 508                         $this->strencode( $this->indexName( $index ) ) .
 509                         ")'";
 510                 $res = $this->query( $sql, $fname );
 511                 if ( !$res ) {
 512                         return null;
 513                 }
 514
 515                 return $res->numRows() > 0;
 516         }
 517
 518         public function selectSQLText(
 519                 $table, $vars, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
 520         ) {
 521                 // Change the FOR UPDATE option as necessary based on the join conditions. Then pass
 522                 // to the parent function to get the actual SQL text.
 523                 // In Postgres when using FOR UPDATE, only the main table and tables that are inner joined
 524                 // can be locked. That means tables in an outer join cannot be FOR UPDATE locked. Trying to
 525                 // do so causes a DB error. This wrapper checks which tables can be locked and adjusts it
 526                 // accordingly.
 527                 // MySQL uses "ORDER BY NULL" as an optimization hint, but that is illegal in PostgreSQL.
 528                 if ( is_array( $options ) ) {
 529                         $forUpdateKey = array_search( 'FOR UPDATE', $options, true );
 530                         if ( $forUpdateKey !== false && $join_conds ) {
 531                                 unset( $options[$forUpdateKey] );
 532
 533                                 foreach ( $join_conds as $table_cond => $join_cond ) {
 534                                         if ( 0 === preg_match( '/^(?:LEFT|RIGHT|FULL)(?: OUTER)? JOIN$/i', $join_cond[0] ) ) {
 535                                                 $options['FOR UPDATE'][] = $table_cond;
 536                                         }
 537                                 }
 538                         }
 539
 540                         if ( isset( $options['ORDER BY'] ) && $options['ORDER BY'] == 'NULL' ) {
 541                                 unset( $options['ORDER BY'] );
 542                         }
 543                 }
 544
 545                 return parent::selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
 546         }
 547
 548         /**
 549          * INSERT wrapper, inserts an array into a table
 550          *
 551          * $args may be a single associative array, or an array of these with numeric keys,
 552          * for multi-row insert (Postgres version 8.2 and above only).
 553          *
 554          * @param string $table Name of the table to insert to.
 555          * @param array $args Items to insert into the table.
 556          * @param string $fname Name of the function, for profiling
 557          * @param array|string $options String or array. Valid options: IGNORE
 558          * @return bool Success of insert operation. IGNORE always returns true.
 559          */
 560         public function insert( $table, $args, $fname = __METHOD__, $options = [] ) {
 561                 if ( !count( $args ) ) {
 562                         return true;
 563                 }
 564
 565                 $table = $this->tableName( $table );
 566                 if ( !isset( $this->numericVersion ) ) {
 567                         $this->getServerVersion();
 568                 }
 569
 570                 if ( !is_array( $options ) ) {
 571                         $options = [ $options ];
 572                 }
 573
 574                 if ( isset( $args[0] ) && is_array( $args[0] ) ) {
 575                         $multi = true;
 576                         $keys = array_keys( $args[0] );
 577                 } else {
 578                         $multi = false;
 579                         $keys = array_keys( $args );
 580                 }
 581
 582                 // If IGNORE is set, we use savepoints to emulate mysql's behavior
 583                 $savepoint = $olde = null;
 584                 $numrowsinserted = 0;
 585                 if ( in_array( 'IGNORE', $options ) ) {
 586                         $savepoint = new SavepointPostgres( $this, 'mw', $this->queryLogger );
 587                         $olde = error_reporting( 0 );
 588                         // For future use, we may want to track the number of actual inserts
 589                         // Right now, insert (all writes) simply return true/false
 590                 }
 591
 592                 $sql = "INSERT INTO $table (" . implode( ',', $keys ) . ') VALUES ';
 593
 594                 if ( $multi ) {
 595                         if ( $this->numericVersion >= 8.2 && !$savepoint ) {
 596                                 $first = true;
 597                                 foreach ( $args as $row ) {
 598                                         if ( $first ) {
 599                                                 $first = false;
 600                                         } else {
 601                                                 $sql .= ',';
 602                                         }
 603                                         $sql .= '(' . $this->makeList( $row ) . ')';
 604                                 }
 605                                 $res = (bool)$this->query( $sql, $fname, $savepoint );
 606                         } else {
 607                                 $res = true;
 608                                 $origsql = $sql;
 609                                 foreach ( $args as $row ) {
 610                                         $tempsql = $origsql;
 611                                         $tempsql .= '(' . $this->makeList( $row ) . ')';
 612
 613                                         if ( $savepoint ) {
 614                                                 $savepoint->savepoint();
 615                                         }
 616
 617                                         $tempres = (bool)$this->query( $tempsql, $fname, $savepoint );
 618
 619                                         if ( $savepoint ) {
 620                                                 $bar = pg_result_error( $this->mLastResult );
 621                                                 if ( $bar != false ) {
 622                                                         $savepoint->rollback();
 623                                                 } else {
 624                                                         $savepoint->release();
 625                                                         $numrowsinserted++;
 626                                                 }
 627                                         }
 628
 629                                         // If any of them fail, we fail overall for this function call
 630                                         // Note that this will be ignored if IGNORE is set
 631                                         if ( !$tempres ) {
 632                                                 $res = false;
 633                                         }
 634                                 }
 635                         }
 636                 } else {
 637                         // Not multi, just a lone insert
 638                         if ( $savepoint ) {
 639                                 $savepoint->savepoint();
 640                         }
 641
 642                         $sql .= '(' . $this->makeList( $args ) . ')';
 643                         $res = (bool)$this->query( $sql, $fname, $savepoint );
 644                         if ( $savepoint ) {
 645                                 $bar = pg_result_error( $this->mLastResult );
 646                                 if ( $bar != false ) {
 647                                         $savepoint->rollback();
 648                                 } else {
 649                                         $savepoint->release();
 650                                         $numrowsinserted++;
 651                                 }
 652                         }
 653                 }
 654                 if ( $savepoint ) {
 655                         error_reporting( $olde );
 656                         $savepoint->commit();
 657
 658                         // Set the affected row count for the whole operation
 659                         $this->mAffectedRows = $numrowsinserted;
 660
 661                         // IGNORE always returns true
 662                         return true;
 663                 }
 664
 665                 return $res;
 666         }
 667
 668         /**
 669          * INSERT SELECT wrapper
 670          * $varMap must be an associative array of the form [ 'dest1' => 'source1', ... ]
 671          * Source items may be literals rather then field names, but strings should
 672          * be quoted with Database::addQuotes()
 673          * $conds may be "*" to copy the whole table
 674          * srcTable may be an array of tables.
 675          * @todo FIXME: Implement this a little better (seperate select/insert)?
 676          *
 677          * @param string $destTable
 678          * @param array|string $srcTable
 679          * @param array $varMap
 680          * @param array $conds
 681          * @param string $fname
 682          * @param array $insertOptions
 683          * @param array $selectOptions
 684          * @return bool
 685          */
 686         public function nativeInsertSelect(
 687                 $destTable, $srcTable, $varMap, $conds, $fname = __METHOD__,
 688                 $insertOptions = [], $selectOptions = []
 689         ) {
 690                 $destTable = $this->tableName( $destTable );
 691
 692                 if ( !is_array( $insertOptions ) ) {
 693                         $insertOptions = [ $insertOptions ];
 694                 }
 695
 696                 /*
 697                  * If IGNORE is set, we use savepoints to emulate mysql's behavior
 698                  * Ignore LOW PRIORITY option, since it is MySQL-specific
 699                  */
 700                 $savepoint = $olde = null;
 701                 $numrowsinserted = 0;
 702                 if ( in_array( 'IGNORE', $insertOptions ) ) {
 703                         $savepoint = new SavepointPostgres( $this, 'mw', $this->queryLogger );
 704                         $olde = error_reporting( 0 );
 705                         $savepoint->savepoint();
 706                 }
 707
 708                 if ( !is_array( $selectOptions ) ) {
 709                         $selectOptions = [ $selectOptions ];
 710                 }
 711                 list( $startOpts, $useIndex, $tailOpts, $ignoreIndex ) =
 712                         $this->makeSelectOptions( $selectOptions );
 713                 if ( is_array( $srcTable ) ) {
 714                         $srcTable = implode( ',', array_map( [ $this, 'tableName' ], $srcTable ) );
 715                 } else {
 716                         $srcTable = $this->tableName( $srcTable );
 717                 }
 718
 719                 $sql = "INSERT INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
 720                         " SELECT $startOpts " . implode( ',', $varMap ) .
 721                         " FROM $srcTable $useIndex $ignoreIndex ";
 722
 723                 if ( $conds != '*' ) {
 724                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
 725                 }
 726
 727                 $sql .= " $tailOpts";
 728
 729                 $res = (bool)$this->query( $sql, $fname, $savepoint );
 730                 if ( $savepoint ) {
 731                         $bar = pg_result_error( $this->mLastResult );
 732                         if ( $bar != false ) {
 733                                 $savepoint->rollback();
 734                         } else {
 735                                 $savepoint->release();
 736                                 $numrowsinserted++;
 737                         }
 738                         error_reporting( $olde );
 739                         $savepoint->commit();
 740
 741                         // Set the affected row count for the whole operation
 742                         $this->mAffectedRows = $numrowsinserted;
 743
 744                         // IGNORE always returns true
 745                         return true;
 746                 }
 747
 748                 return $res;
 749         }
 750
 751         public function tableName( $name, $format = 'quoted' ) {
 752                 // Replace reserved words with better ones
 753                 $name = $this->remappedTableName( $name );
 754
 755                 return parent::tableName( $name, $format );
 756         }
 757
 758         /**
 759          * @param string $name
 760          * @return string Value of $name or remapped name if $name is a reserved keyword
 761          */
 762         public function remappedTableName( $name ) {
 763                 return isset( $this->keywordTableMap[$name] ) ? $this->keywordTableMap[$name] : $name;
 764         }
 765
 766         /**
 767          * @param string $name
 768          * @param string $format
 769          * @return string Qualified and encoded (if requested) table name
 770          */
 771         public function realTableName( $name, $format = 'quoted' ) {
 772                 return parent::tableName( $name, $format );
 773         }
 774
 775         public function nextSequenceValue( $seqName ) {
 776                 $safeseq = str_replace( "'", "''", $seqName );
 777                 $res = $this->query( "SELECT nextval('$safeseq')" );
 778                 $row = $this->fetchRow( $res );
 779                 $this->mInsertId = $row[0];
 780
 781                 return $this->mInsertId;
 782         }
 783
 784         /**
 785          * Return the current value of a sequence. Assumes it has been nextval'ed in this session.
 786          *
 787          * @param string $seqName
 788          * @return int
 789          */
 790         public function currentSequenceValue( $seqName ) {
 791                 $safeseq = str_replace( "'", "''", $seqName );
 792                 $res = $this->query( "SELECT currval('$safeseq')" );
 793                 $row = $this->fetchRow( $res );
 794                 $currval = $row[0];
 795
 796                 return $currval;
 797         }
 798
 799         public function textFieldSize( $table, $field ) {
 800                 $table = $this->tableName( $table );
 801                 $sql = "SELECT t.typname as ftype,a.atttypmod as size
 802                         FROM pg_class c, pg_attribute a, pg_type t
 803                         WHERE relname='$table' AND a.attrelid=c.oid AND
 804                                 a.atttypid=t.oid and a.attname='$field'";
 805                 $res = $this->query( $sql );
 806                 $row = $this->fetchObject( $res );
 807                 if ( $row->ftype == 'varchar' ) {
 808                         $size = $row->size - 4;
 809                 } else {
 810                         $size = $row->size;
 811                 }
 812
 813                 return $size;
 814         }
 815
 816         public function limitResult( $sql, $limit, $offset = false ) {
 817                 return "$sql LIMIT $limit " . ( is_numeric( $offset ) ? " OFFSET {$offset} " : '' );
 818         }
 819
 820         public function wasDeadlock() {
 821                 return $this->lastErrno() == '40P01';
 822         }
 823
 824         public function duplicateTableStructure(
 825                 $oldName, $newName, $temporary = false, $fname = __METHOD__
 826         ) {
 827                 $newName = $this->addIdentifierQuotes( $newName );
 828                 $oldName = $this->addIdentifierQuotes( $oldName );
 829
 830                 return $this->query( 'CREATE ' . ( $temporary ? 'TEMPORARY ' : '' ) . " TABLE $newName " .
 831                         "(LIKE $oldName INCLUDING DEFAULTS INCLUDING INDEXES)", $fname );
 832         }
 833
 834         public function listTables( $prefix = null, $fname = __METHOD__ ) {
 835                 $eschema = $this->addQuotes( $this->getCoreSchema() );
 836                 $result = $this->query(
 837                         "SELECT tablename FROM pg_tables WHERE schemaname = $eschema", $fname );
 838                 $endArray = [];
 839
 840                 foreach ( $result as $table ) {
 841                         $vars = get_object_vars( $table );
 842                         $table = array_pop( $vars );
 843                         if ( !$prefix || strpos( $table, $prefix ) === 0 ) {
 844                                 $endArray[] = $table;
 845                         }
 846                 }
 847
 848                 return $endArray;
 849         }
 850
 851         public function timestamp( $ts = 0 ) {
 852                 $ct = new ConvertibleTimestamp( $ts );
 853
 854                 return $ct->getTimestamp( TS_POSTGRES );
 855         }
 856
 857         /**
 858          * Posted by cc[plus]php[at]c2se[dot]com on 25-Mar-2009 09:12
 859          * to https://secure.php.net/manual/en/ref.pgsql.php
 860          *
 861          * Parsing a postgres array can be a tricky problem, he's my
 862          * take on this, it handles multi-dimensional arrays plus
 863          * escaping using a nasty regexp to determine the limits of each
 864          * data-item.
 865          *
 866          * This should really be handled by PHP PostgreSQL module
 867          *
 868          * @since 1.19
 869          * @param string $text Postgreql array returned in a text form like {a,b}
 870          * @param string[] $output
 871          * @param int|bool $limit
 872          * @param int $offset
 873          * @return string[]
 874          */
 875         private function pg_array_parse( $text, &$output, $limit = false, $offset = 1 ) {
 876                 if ( false === $limit ) {
 877                         $limit = strlen( $text ) - 1;
 878                         $output = [];
 879                 }
 880                 if ( '{}' == $text ) {
 881                         return $output;
 882                 }
 883                 do {
 884                         if ( '{' != $text[$offset] ) {
 885                                 preg_match( "/(\\{?\"([^\"\\\\]|\\\\.)*\"|[^,{}]+)+([,}]+)/",
 886                                         $text, $match, 0, $offset );
 887                                 $offset += strlen( $match[0] );
 888                                 $output[] = ( '"' != $match[1][0]
 889                                         ? $match[1]
 890                                         : stripcslashes( substr( $match[1], 1, -1 ) ) );
 891                                 if ( '},' == $match[3] ) {
 892                                         return $output;
 893                                 }
 894                         } else {
 895                                 $offset = $this->pg_array_parse( $text, $output, $limit, $offset + 1 );
 896                         }
 897                 } while ( $limit > $offset );
 898
 899                 return $output;
 900         }
 901
 902         public function aggregateValue( $valuedata, $valuename = 'value' ) {
 903                 return $valuedata;
 904         }
 905
 906         public function getSoftwareLink() {
 907                 return '[{{int:version-db-postgres-url}} PostgreSQL]';
 908         }
 909
 910         /**
 911          * Return current schema (executes SELECT current_schema())
 912          * Needs transaction
 913          *
 914          * @since 1.19
 915          * @return string Default schema for the current session
 916          */
 917         public function getCurrentSchema() {
 918                 $res = $this->query( "SELECT current_schema()", __METHOD__ );
 919                 $row = $this->fetchRow( $res );
 920
 921                 return $row[0];
 922         }
 923
 924         /**
 925          * Return list of schemas which are accessible without schema name
 926          * This is list does not contain magic keywords like "$user"
 927          * Needs transaction
 928          *
 929          * @see getSearchPath()
 930          * @see setSearchPath()
 931          * @since 1.19
 932          * @return array List of actual schemas for the current sesson
 933          */
 934         public function getSchemas() {
 935                 $res = $this->query( "SELECT current_schemas(false)", __METHOD__ );
 936                 $row = $this->fetchRow( $res );
 937                 $schemas = [];
 938
 939                 /* PHP pgsql support does not support array type, "{a,b}" string is returned */
 940
 941                 return $this->pg_array_parse( $row[0], $schemas );
 942         }
 943
 944         /**
 945          * Return search patch for schemas
 946          * This is different from getSchemas() since it contain magic keywords
 947          * (like "$user").
 948          * Needs transaction
 949          *
 950          * @since 1.19
 951          * @return array How to search for table names schemas for the current user
 952          */
 953         public function getSearchPath() {
 954                 $res = $this->query( "SHOW search_path", __METHOD__ );
 955                 $row = $this->fetchRow( $res );
 956
 957                 /* PostgreSQL returns SHOW values as strings */
 958
 959                 return explode( ",", $row[0] );
 960         }
 961
 962         /**
 963          * Update search_path, values should already be sanitized
 964          * Values may contain magic keywords like "$user"
 965          * @since 1.19
 966          *
 967          * @param array $search_path List of schemas to be searched by default
 968          */
 969         private function setSearchPath( $search_path ) {
 970                 $this->query( "SET search_path = " . implode( ", ", $search_path ) );
 971         }
 972
 973         /**
 974          * Determine default schema for the current application
 975          * Adjust this session schema search path if desired schema exists
 976          * and is not alread there.
 977          *
 978          * We need to have name of the core schema stored to be able
 979          * to query database metadata.
 980          *
 981          * This will be also called by the installer after the schema is created
 982          *
 983          * @since 1.19
 984          *
 985          * @param string $desiredSchema
 986          */
 987         public function determineCoreSchema( $desiredSchema ) {
 988                 $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
 989                 if ( $this->schemaExists( $desiredSchema ) ) {
 990                         if ( in_array( $desiredSchema, $this->getSchemas() ) ) {
 991                                 $this->mCoreSchema = $desiredSchema;
 992                                 $this->queryLogger->debug(
 993                                         "Schema \"" . $desiredSchema . "\" already in the search path\n" );
 994                         } else {
 995                                 /**
 996                                  * Prepend our schema (e.g. 'mediawiki') in front
 997                                  * of the search path
 998                                  * Fixes T17816
 999                                  */
1000                                 $search_path = $this->getSearchPath();
1001                                 array_unshift( $search_path,
1002                                         $this->addIdentifierQuotes( $desiredSchema ) );
1003                                 $this->setSearchPath( $search_path );
1004                                 $this->mCoreSchema = $desiredSchema;
1005                                 $this->queryLogger->debug(
1006                                         "Schema \"" . $desiredSchema . "\" added to the search path\n" );
1007                         }
1008                 } else {
1009                         $this->mCoreSchema = $this->getCurrentSchema();
1010                         $this->queryLogger->debug(
1011                                 "Schema \"" . $desiredSchema . "\" not found, using current \"" .
1012                                 $this->mCoreSchema . "\"\n" );
1013                 }
1014                 /* Commit SET otherwise it will be rollbacked on error or IGNORE SELECT */
1015                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
1016         }
1017
1018         /**
1019          * Return schema name for core application tables
1020          *
1021          * @since 1.19
1022          * @return string Core schema name
1023          */
1024         public function getCoreSchema() {
1025                 return $this->mCoreSchema;
1026         }
1027
1028         public function getServerVersion() {
1029                 if ( !isset( $this->numericVersion ) ) {
1030                         $conn = $this->getBindingHandle();
1031                         $versionInfo = pg_version( $conn );
1032                         if ( version_compare( $versionInfo['client'], '7.4.0', 'lt' ) ) {
1033                                 // Old client, abort install
1034                                 $this->numericVersion = '7.3 or earlier';
1035                         } elseif ( isset( $versionInfo['server'] ) ) {
1036                                 // Normal client
1037                                 $this->numericVersion = $versionInfo['server'];
1038                         } else {
1039                                 // T18937: broken pgsql extension from PHP<5.3
1040                                 $this->numericVersion = pg_parameter_status( $conn, 'server_version' );
1041                         }
1042                 }
1043
1044                 return $this->numericVersion;
1045         }
1046
1047         /**
1048          * Query whether a given relation exists (in the given schema, or the
1049          * default mw one if not given)
1050          * @param string $table
1051          * @param array|string $types
1052          * @param bool|string $schema
1053          * @return bool
1054          */
1055         private function relationExists( $table, $types, $schema = false ) {
1056                 if ( !is_array( $types ) ) {
1057                         $types = [ $types ];
1058                 }
1059                 if ( $schema === false ) {
1060                         $schema = $this->getCoreSchema();
1061                 }
1062                 $etable = $this->addQuotes( $table );
1063                 $eschema = $this->addQuotes( $schema );
1064                 $sql = "SELECT 1 FROM pg_catalog.pg_class c, pg_catalog.pg_namespace n "
1065                         . "WHERE c.relnamespace = n.oid AND c.relname = $etable AND n.nspname = $eschema "
1066                         . "AND c.relkind IN ('" . implode( "','", $types ) . "')";
1067                 $res = $this->query( $sql );
1068                 $count = $res ? $res->numRows() : 0;
1069
1070                 return (bool)$count;
1071         }
1072
1073         /**
1074          * For backward compatibility, this function checks both tables and views.
1075          * @param string $table
1076          * @param string $fname
1077          * @param bool|string $schema
1078          * @return bool
1079          */
1080         public function tableExists( $table, $fname = __METHOD__, $schema = false ) {
1081                 return $this->relationExists( $table, [ 'r', 'v' ], $schema );
1082         }
1083
1084         public function sequenceExists( $sequence, $schema = false ) {
1085                 return $this->relationExists( $sequence, 'S', $schema );
1086         }
1087
1088         public function triggerExists( $table, $trigger ) {
1089                 $q = <<<SQL
1090         SELECT 1 FROM pg_class, pg_namespace, pg_trigger
1091                 WHERE relnamespace=pg_namespace.oid AND relkind='r'
1092                         AND tgrelid=pg_class.oid
1093                         AND nspname=%s AND relname=%s AND tgname=%s
1094 SQL;
1095                 $res = $this->query(
1096                         sprintf(
1097                                 $q,
1098                                 $this->addQuotes( $this->getCoreSchema() ),
1099                                 $this->addQuotes( $table ),
1100                                 $this->addQuotes( $trigger )
1101                         )
1102                 );
1103                 if ( !$res ) {
1104                         return null;
1105                 }
1106                 $rows = $res->numRows();
1107
1108                 return $rows;
1109         }
1110
1111         public function ruleExists( $table, $rule ) {
1112                 $exists = $this->selectField( 'pg_rules', 'rulename',
1113                         [
1114                                 'rulename' => $rule,
1115                                 'tablename' => $table,
1116                                 'schemaname' => $this->getCoreSchema()
1117                         ]
1118                 );
1119
1120                 return $exists === $rule;
1121         }
1122
1123         public function constraintExists( $table, $constraint ) {
1124                 $sql = sprintf( "SELECT 1 FROM information_schema.table_constraints " .
1125                         "WHERE constraint_schema = %s AND table_name = %s AND constraint_name = %s",
1126                         $this->addQuotes( $this->getCoreSchema() ),
1127                         $this->addQuotes( $table ),
1128                         $this->addQuotes( $constraint )
1129                 );
1130                 $res = $this->query( $sql );
1131                 if ( !$res ) {
1132                         return null;
1133                 }
1134                 $rows = $res->numRows();
1135
1136                 return $rows;
1137         }
1138
1139         /**
1140          * Query whether a given schema exists. Returns true if it does, false if it doesn't.
1141          * @param string $schema
1142          * @return bool
1143          */
1144         public function schemaExists( $schema ) {
1145                 if ( !strlen( $schema ) ) {
1146                         return false; // short-circuit
1147                 }
1148
1149                 $exists = $this->selectField(
1150                         '"pg_catalog"."pg_namespace"', 1, [ 'nspname' => $schema ], __METHOD__ );
1151
1152                 return (bool)$exists;
1153         }
1154
1155         /**
1156          * Returns true if a given role (i.e. user) exists, false otherwise.
1157          * @param string $roleName
1158          * @return bool
1159          */
1160         public function roleExists( $roleName ) {
1161                 $exists = $this->selectField( '"pg_catalog"."pg_roles"', 1,
1162                         [ 'rolname' => $roleName ], __METHOD__ );
1163
1164                 return (bool)$exists;
1165         }
1166
1167         /**
1168          * @var string $table
1169          * @var string $field
1170          * @return PostgresField|null
1171          */
1172         public function fieldInfo( $table, $field ) {
1173                 return PostgresField::fromText( $this, $table, $field );
1174         }
1175
1176         /**
1177          * pg_field_type() wrapper
1178          * @param ResultWrapper|resource $res ResultWrapper or PostgreSQL query result resource
1179          * @param int $index Field number, starting from 0
1180          * @return string
1181          */
1182         public function fieldType( $res, $index ) {
1183                 if ( $res instanceof ResultWrapper ) {
1184                         $res = $res->result;
1185                 }
1186
1187                 return pg_field_type( $res, $index );
1188         }
1189
1190         public function encodeBlob( $b ) {
1191                 return new PostgresBlob( pg_escape_bytea( $b ) );
1192         }
1193
1194         public function decodeBlob( $b ) {
1195                 if ( $b instanceof PostgresBlob ) {
1196                         $b = $b->fetch();
1197                 } elseif ( $b instanceof Blob ) {
1198                         return $b->fetch();
1199                 }
1200
1201                 return pg_unescape_bytea( $b );
1202         }
1203
1204         public function strencode( $s ) {
1205                 // Should not be called by us
1206                 return pg_escape_string( $this->getBindingHandle(), $s );
1207         }
1208
1209         public function addQuotes( $s ) {
1210                 $conn = $this->getBindingHandle();
1211
1212                 if ( is_null( $s ) ) {
1213                         return 'NULL';
1214                 } elseif ( is_bool( $s ) ) {
1215                         return intval( $s );
1216                 } elseif ( $s instanceof Blob ) {
1217                         if ( $s instanceof PostgresBlob ) {
1218                                 $s = $s->fetch();
1219                         } else {
1220                                 $s = pg_escape_bytea( $conn, $s->fetch() );
1221                         }
1222                         return "'$s'";
1223                 }
1224
1225                 return "'" . pg_escape_string( $conn, $s ) . "'";
1226         }
1227
1228         /**
1229          * Postgres specific version of replaceVars.
1230          * Calls the parent version in Database.php
1231          *
1232          * @param string $ins SQL string, read from a stream (usually tables.sql)
1233          * @return string SQL string
1234          */
1235         protected function replaceVars( $ins ) {
1236                 $ins = parent::replaceVars( $ins );
1237
1238                 if ( $this->numericVersion >= 8.3 ) {
1239                         // Thanks for not providing backwards-compatibility, 8.3
1240                         $ins = preg_replace( "/to_tsvector\s*\(\s*'default'\s*,/", 'to_tsvector(', $ins );
1241                 }
1242
1243                 if ( $this->numericVersion <= 8.1 ) { // Our minimum version
1244                         $ins = str_replace( 'USING gin', 'USING gist', $ins );
1245                 }
1246
1247                 return $ins;
1248         }
1249
1250         public function makeSelectOptions( $options ) {
1251                 $preLimitTail = $postLimitTail = '';
1252                 $startOpts = $useIndex = $ignoreIndex = '';
1253
1254                 $noKeyOptions = [];
1255                 foreach ( $options as $key => $option ) {
1256                         if ( is_numeric( $key ) ) {
1257                                 $noKeyOptions[$option] = true;
1258                         }
1259                 }
1260
1261                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1262
1263                 $preLimitTail .= $this->makeOrderBy( $options );
1264
1265                 if ( isset( $options['FOR UPDATE'] ) ) {
1266                         $postLimitTail .= ' FOR UPDATE OF ' .
1267                                 implode( ', ', array_map( [ $this, 'tableName' ], $options['FOR UPDATE'] ) );
1268                 } elseif ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1269                         $postLimitTail .= ' FOR UPDATE';
1270                 }
1271
1272                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1273                         $startOpts .= 'DISTINCT';
1274                 }
1275
1276                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1277         }
1278
1279         public function getDBname() {
1280                 return $this->mDBname;
1281         }
1282
1283         public function getServer() {
1284                 return $this->mServer;
1285         }
1286
1287         public function buildConcat( $stringList ) {
1288                 return implode( ' || ', $stringList );
1289         }
1290
1291         public function buildGroupConcatField(
1292                 $delimiter, $table, $field, $conds = '', $options = [], $join_conds = []
1293         ) {
1294                 $fld = "array_to_string(array_agg($field)," . $this->addQuotes( $delimiter ) . ')';
1295
1296                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1297         }
1298
1299         public function buildStringCast( $field ) {
1300                 return $field . '::text';
1301         }
1302
1303         public function streamStatementEnd( &$sql, &$newLine ) {
1304                 # Allow dollar quoting for function declarations
1305                 if ( substr( $newLine, 0, 4 ) == '$mw$' ) {
1306                         if ( $this->delimiter ) {
1307                                 $this->delimiter = false;
1308                         } else {
1309                                 $this->delimiter = ';';
1310                         }
1311                 }
1312
1313                 return parent::streamStatementEnd( $sql, $newLine );
1314         }
1315
1316         public function doLockTables( array $read, array $write, $method ) {
1317                 $tablesWrite = [];
1318                 foreach ( $write as $table ) {
1319                         $tablesWrite[] = $this->tableName( $table );
1320                 }
1321                 $tablesRead = [];
1322                 foreach ( $read as $table ) {
1323                         $tablesRead[] = $this->tableName( $table );
1324                 }
1325
1326                 // Acquire locks for the duration of the current transaction...
1327                 if ( $tablesWrite ) {
1328                         $this->query(
1329                                 'LOCK TABLE ONLY ' . implode( ',', $tablesWrite ) . ' IN EXCLUSIVE MODE',
1330                                 $method
1331                         );
1332                 }
1333                 if ( $tablesRead ) {
1334                         $this->query(
1335                                 'LOCK TABLE ONLY ' . implode( ',', $tablesRead ) . ' IN SHARE MODE',
1336                                 $method
1337                         );
1338                 }
1339
1340                 return true;
1341         }
1342
1343         public function lockIsFree( $lockName, $method ) {
1344                 // http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1345                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1346                 $result = $this->query( "SELECT (CASE(pg_try_advisory_lock($key))
1347                         WHEN 'f' THEN 'f' ELSE pg_advisory_unlock($key) END) AS lockstatus", $method );
1348                 $row = $this->fetchObject( $result );
1349
1350                 return ( $row->lockstatus === 't' );
1351         }
1352
1353         public function lock( $lockName, $method, $timeout = 5 ) {
1354                 // http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1355                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1356                 $loop = new WaitConditionLoop(
1357                         function () use ( $lockName, $key, $timeout, $method ) {
1358                                 $res = $this->query( "SELECT pg_try_advisory_lock($key) AS lockstatus", $method );
1359                                 $row = $this->fetchObject( $res );
1360                                 if ( $row->lockstatus === 't' ) {
1361                                         parent::lock( $lockName, $method, $timeout ); // record
1362                                         return true;
1363                                 }
1364
1365                                 return WaitConditionLoop::CONDITION_CONTINUE;
1366                         },
1367                         $timeout
1368                 );
1369
1370                 return ( $loop->invoke() === $loop::CONDITION_REACHED );
1371         }
1372
1373         public function unlock( $lockName, $method ) {
1374                 // http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1375                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1376                 $result = $this->query( "SELECT pg_advisory_unlock($key) as lockstatus", $method );
1377                 $row = $this->fetchObject( $result );
1378
1379                 if ( $row->lockstatus === 't' ) {
1380                         parent::unlock( $lockName, $method ); // record
1381                         return true;
1382                 }
1383
1384                 $this->queryLogger->debug( __METHOD__ . " failed to release lock\n" );
1385
1386                 return false;
1387         }
1388
1389         /**
1390          * @param string $lockName
1391          * @return string Integer
1392          */
1393         private function bigintFromLockName( $lockName ) {
1394                 return \Wikimedia\base_convert( substr( sha1( $lockName ), 0, 15 ), 16, 10 );
1395         }
1396 }
1397
1398 class_alias( DatabasePostgres::class, 'DatabasePostgres' );