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
  24 /**
  25  * @ingroup Database
  26  */
  27 class DatabasePostgres extends DatabaseBase {
  28         /** @var int|bool */
  29         protected $port;
  30
  31         /** @var resource */
  32         protected $mLastResult = null;
  33         /** @var int The number of rows affected as an integer */
  34         protected $mAffectedRows = null;
  35
  36         /** @var int */
  37         private $mInsertId = null;
  38         /** @var float|string */
  39         private $numericVersion = null;
  40         /** @var string Connect string to open a PostgreSQL connection */
  41         private $connectString;
  42         /** @var string */
  43         private $mCoreSchema;
  44
  45         public function __construct( array $params ) {
  46                 $this->port = isset( $params['port'] ) ? $params['port'] : false;
  47                 parent::__construct( $params );
  48         }
  49
  50         function getType() {
  51                 return 'postgres';
  52         }
  53
  54         function implicitGroupby() {
  55                 return false;
  56         }
  57
  58         function implicitOrderby() {
  59                 return false;
  60         }
  61
  62         function hasConstraint( $name ) {
  63                 $sql = "SELECT 1 FROM pg_catalog.pg_constraint c, pg_catalog.pg_namespace n " .
  64                         "WHERE c.connamespace = n.oid AND conname = '" .
  65                         pg_escape_string( $this->mConn, $name ) . "' AND n.nspname = '" .
  66                         pg_escape_string( $this->mConn, $this->getCoreSchema() ) . "'";
  67                 $res = $this->doQuery( $sql );
  68
  69                 return $this->numRows( $res );
  70         }
  71
  72         /**
  73          * Usually aborts on failure
  74          * @param string $server
  75          * @param string $user
  76          * @param string $password
  77          * @param string $dbName
  78          * @throws DBConnectionError|Exception
  79          * @return resource|bool|null
  80          */
  81         function open( $server, $user, $password, $dbName ) {
  82                 # Test for Postgres support, to avoid suppressed fatal error
  83                 if ( !function_exists( 'pg_connect' ) ) {
  84                         throw new DBConnectionError(
  85                                 $this,
  86                                 "Postgres functions missing, have you compiled PHP with the --with-pgsql\n" .
  87                                 "option? (Note: if you recently installed PHP, you may need to restart your\n" .
  88                                 "webserver and database)\n"
  89                         );
  90                 }
  91
  92                 if ( !strlen( $user ) ) { # e.g. the class is being loaded
  93                         return null;
  94                 }
  95
  96                 $this->mServer = $server;
  97                 $this->mUser = $user;
  98                 $this->mPassword = $password;
  99                 $this->mDBname = $dbName;
 100
 101                 $connectVars = [
 102                         'dbname' => $dbName,
 103                         'user' => $user,
 104                         'password' => $password
 105                 ];
 106                 if ( $server != false && $server != '' ) {
 107                         $connectVars['host'] = $server;
 108                 }
 109                 if ( (int)$this->port > 0 ) {
 110                         $connectVars['port'] = (int)$this->port;
 111                 }
 112                 if ( $this->mFlags & self::DBO_SSL ) {
 113                         $connectVars['sslmode'] = 1;
 114                 }
 115
 116                 $this->connectString = $this->makeConnectionString( $connectVars );
 117                 $this->close();
 118                 $this->installErrorHandler();
 119
 120                 try {
 121                         $this->mConn = pg_connect( $this->connectString );
 122                 } catch ( Exception $ex ) {
 123                         $this->restoreErrorHandler();
 124                         throw $ex;
 125                 }
 126
 127                 $phpError = $this->restoreErrorHandler();
 128
 129                 if ( !$this->mConn ) {
 130                         $this->queryLogger->debug( "DB connection error\n" );
 131                         $this->queryLogger->debug(
 132                                 "Server: $server, Database: $dbName, User: $user, Password: " .
 133                                 substr( $password, 0, 3 ) . "...\n" );
 134                         $this->queryLogger->debug( $this->lastError() . "\n" );
 135                         throw new DBConnectionError( $this, str_replace( "\n", ' ', $phpError ) );
 136                 }
 137
 138                 $this->mOpened = true;
 139
 140                 # If called from the command-line (e.g. importDump), only show errors
 141                 if ( $this->cliMode ) {
 142                         $this->doQuery( "SET client_min_messages = 'ERROR'" );
 143                 }
 144
 145                 $this->query( "SET client_encoding='UTF8'", __METHOD__ );
 146                 $this->query( "SET datestyle = 'ISO, YMD'", __METHOD__ );
 147                 $this->query( "SET timezone = 'GMT'", __METHOD__ );
 148                 $this->query( "SET standard_conforming_strings = on", __METHOD__ );
 149                 if ( $this->getServerVersion() >= 9.0 ) {
 150                         $this->query( "SET bytea_output = 'escape'", __METHOD__ ); // PHP bug 53127
 151                 }
 152
 153                 $this->determineCoreSchema( $this->mSchema );
 154
 155                 return $this->mConn;
 156         }
 157
 158         /**
 159          * Postgres doesn't support selectDB in the same way MySQL does. So if the
 160          * DB name doesn't match the open connection, open a new one
 161          * @param string $db
 162          * @return bool
 163          */
 164         function selectDB( $db ) {
 165                 if ( $this->mDBname !== $db ) {
 166                         return (bool)$this->open( $this->mServer, $this->mUser, $this->mPassword, $db );
 167                 } else {
 168                         return true;
 169                 }
 170         }
 171
 172         function makeConnectionString( $vars ) {
 173                 $s = '';
 174                 foreach ( $vars as $name => $value ) {
 175                         $s .= "$name='" . str_replace( "'", "\\'", $value ) . "' ";
 176                 }
 177
 178                 return $s;
 179         }
 180
 181         /**
 182          * Closes a database connection, if it is open
 183          * Returns success, true if already closed
 184          * @return bool
 185          */
 186         protected function closeConnection() {
 187                 return pg_close( $this->mConn );
 188         }
 189
 190         public function doQuery( $sql ) {
 191                 $sql = mb_convert_encoding( $sql, 'UTF-8' );
 192                 // Clear previously left over PQresult
 193                 while ( $res = pg_get_result( $this->mConn ) ) {
 194                         pg_free_result( $res );
 195                 }
 196                 if ( pg_send_query( $this->mConn, $sql ) === false ) {
 197                         throw new DBUnexpectedError( $this, "Unable to post new query to PostgreSQL\n" );
 198                 }
 199                 $this->mLastResult = pg_get_result( $this->mConn );
 200                 $this->mAffectedRows = null;
 201                 if ( pg_result_error( $this->mLastResult ) ) {
 202                         return false;
 203                 }
 204
 205                 return $this->mLastResult;
 206         }
 207
 208         protected function dumpError() {
 209                 $diags = [
 210                         PGSQL_DIAG_SEVERITY,
 211                         PGSQL_DIAG_SQLSTATE,
 212                         PGSQL_DIAG_MESSAGE_PRIMARY,
 213                         PGSQL_DIAG_MESSAGE_DETAIL,
 214                         PGSQL_DIAG_MESSAGE_HINT,
 215                         PGSQL_DIAG_STATEMENT_POSITION,
 216                         PGSQL_DIAG_INTERNAL_POSITION,
 217                         PGSQL_DIAG_INTERNAL_QUERY,
 218                         PGSQL_DIAG_CONTEXT,
 219                         PGSQL_DIAG_SOURCE_FILE,
 220                         PGSQL_DIAG_SOURCE_LINE,
 221                         PGSQL_DIAG_SOURCE_FUNCTION
 222                 ];
 223                 foreach ( $diags as $d ) {
 224                         $this->queryLogger->debug( sprintf( "PgSQL ERROR(%d): %s\n",
 225                                 $d, pg_result_error_field( $this->mLastResult, $d ) ) );
 226                 }
 227         }
 228
 229         function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
 230                 if ( $tempIgnore ) {
 231                         /* Check for constraint violation */
 232                         if ( $errno === '23505' ) {
 233                                 parent::reportQueryError( $error, $errno, $sql, $fname, $tempIgnore );
 234
 235                                 return;
 236                         }
 237                 }
 238                 /* Transaction stays in the ERROR state until rolled back */
 239                 if ( $this->mTrxLevel ) {
 240                         $ignore = $this->ignoreErrors( true );
 241                         $this->rollback( __METHOD__ );
 242                         $this->ignoreErrors( $ignore );
 243                 }
 244                 parent::reportQueryError( $error, $errno, $sql, $fname, false );
 245         }
 246
 247         function queryIgnore( $sql, $fname = __METHOD__ ) {
 248                 return $this->query( $sql, $fname, true );
 249         }
 250
 251         /**
 252          * @param stdClass|ResultWrapper $res
 253          * @throws DBUnexpectedError
 254          */
 255         function freeResult( $res ) {
 256                 if ( $res instanceof ResultWrapper ) {
 257                         $res = $res->result;
 258                 }
 259                 MediaWiki\suppressWarnings();
 260                 $ok = pg_free_result( $res );
 261                 MediaWiki\restoreWarnings();
 262                 if ( !$ok ) {
 263                         throw new DBUnexpectedError( $this, "Unable to free Postgres result\n" );
 264                 }
 265         }
 266
 267         /**
 268          * @param ResultWrapper|stdClass $res
 269          * @return stdClass
 270          * @throws DBUnexpectedError
 271          */
 272         function fetchObject( $res ) {
 273                 if ( $res instanceof ResultWrapper ) {
 274                         $res = $res->result;
 275                 }
 276                 MediaWiki\suppressWarnings();
 277                 $row = pg_fetch_object( $res );
 278                 MediaWiki\restoreWarnings();
 279                 # @todo FIXME: HACK HACK HACK HACK debug
 280
 281                 # @todo hashar: not sure if the following test really trigger if the object
 282                 #          fetching failed.
 283                 if ( pg_last_error( $this->mConn ) ) {
 284                         throw new DBUnexpectedError(
 285                                 $this,
 286                                 'SQL error: ' . htmlspecialchars( pg_last_error( $this->mConn ) )
 287                         );
 288                 }
 289
 290                 return $row;
 291         }
 292
 293         function fetchRow( $res ) {
 294                 if ( $res instanceof ResultWrapper ) {
 295                         $res = $res->result;
 296                 }
 297                 MediaWiki\suppressWarnings();
 298                 $row = pg_fetch_array( $res );
 299                 MediaWiki\restoreWarnings();
 300                 if ( pg_last_error( $this->mConn ) ) {
 301                         throw new DBUnexpectedError(
 302                                 $this,
 303                                 'SQL error: ' . htmlspecialchars( pg_last_error( $this->mConn ) )
 304                         );
 305                 }
 306
 307                 return $row;
 308         }
 309
 310         function numRows( $res ) {
 311                 if ( $res instanceof ResultWrapper ) {
 312                         $res = $res->result;
 313                 }
 314                 MediaWiki\suppressWarnings();
 315                 $n = pg_num_rows( $res );
 316                 MediaWiki\restoreWarnings();
 317                 if ( pg_last_error( $this->mConn ) ) {
 318                         throw new DBUnexpectedError(
 319                                 $this,
 320                                 'SQL error: ' . htmlspecialchars( pg_last_error( $this->mConn ) )
 321                         );
 322                 }
 323
 324                 return $n;
 325         }
 326
 327         function numFields( $res ) {
 328                 if ( $res instanceof ResultWrapper ) {
 329                         $res = $res->result;
 330                 }
 331
 332                 return pg_num_fields( $res );
 333         }
 334
 335         function fieldName( $res, $n ) {
 336                 if ( $res instanceof ResultWrapper ) {
 337                         $res = $res->result;
 338                 }
 339
 340                 return pg_field_name( $res, $n );
 341         }
 342
 343         /**
 344          * Return the result of the last call to nextSequenceValue();
 345          * This must be called after nextSequenceValue().
 346          *
 347          * @return int|null
 348          */
 349         function insertId() {
 350                 return $this->mInsertId;
 351         }
 352
 353         /**
 354          * @param mixed $res
 355          * @param int $row
 356          * @return bool
 357          */
 358         function dataSeek( $res, $row ) {
 359                 if ( $res instanceof ResultWrapper ) {
 360                         $res = $res->result;
 361                 }
 362
 363                 return pg_result_seek( $res, $row );
 364         }
 365
 366         function lastError() {
 367                 if ( $this->mConn ) {
 368                         if ( $this->mLastResult ) {
 369                                 return pg_result_error( $this->mLastResult );
 370                         } else {
 371                                 return pg_last_error();
 372                         }
 373                 } else {
 374                         return 'No database connection';
 375                 }
 376         }
 377
 378         function lastErrno() {
 379                 if ( $this->mLastResult ) {
 380                         return pg_result_error_field( $this->mLastResult, PGSQL_DIAG_SQLSTATE );
 381                 } else {
 382                         return false;
 383                 }
 384         }
 385
 386         function affectedRows() {
 387                 if ( !is_null( $this->mAffectedRows ) ) {
 388                         // Forced result for simulated queries
 389                         return $this->mAffectedRows;
 390                 }
 391                 if ( empty( $this->mLastResult ) ) {
 392                         return 0;
 393                 }
 394
 395                 return pg_affected_rows( $this->mLastResult );
 396         }
 397
 398         /**
 399          * Estimate rows in dataset
 400          * Returns estimated count, based on EXPLAIN output
 401          * This is not necessarily an accurate estimate, so use sparingly
 402          * Returns -1 if count cannot be found
 403          * Takes same arguments as Database::select()
 404          *
 405          * @param string $table
 406          * @param string $vars
 407          * @param string $conds
 408          * @param string $fname
 409          * @param array $options
 410          * @return int
 411          */
 412         function estimateRowCount( $table, $vars = '*', $conds = '',
 413                 $fname = __METHOD__, $options = []
 414         ) {
 415                 $options['EXPLAIN'] = true;
 416                 $res = $this->select( $table, $vars, $conds, $fname, $options );
 417                 $rows = -1;
 418                 if ( $res ) {
 419                         $row = $this->fetchRow( $res );
 420                         $count = [];
 421                         if ( preg_match( '/rows=(\d+)/', $row[0], $count ) ) {
 422                                 $rows = (int)$count[1];
 423                         }
 424                 }
 425
 426                 return $rows;
 427         }
 428
 429         /**
 430          * Returns information about an index
 431          * If errors are explicitly ignored, returns NULL on failure
 432          *
 433          * @param string $table
 434          * @param string $index
 435          * @param string $fname
 436          * @return bool|null
 437          */
 438         function indexInfo( $table, $index, $fname = __METHOD__ ) {
 439                 $sql = "SELECT indexname FROM pg_indexes WHERE tablename='$table'";
 440                 $res = $this->query( $sql, $fname );
 441                 if ( !$res ) {
 442                         return null;
 443                 }
 444                 foreach ( $res as $row ) {
 445                         if ( $row->indexname == $this->indexName( $index ) ) {
 446                                 return $row;
 447                         }
 448                 }
 449
 450                 return false;
 451         }
 452
 453         /**
 454          * Returns is of attributes used in index
 455          *
 456          * @since 1.19
 457          * @param string $index
 458          * @param bool|string $schema
 459          * @return array
 460          */
 461         function indexAttributes( $index, $schema = false ) {
 462                 if ( $schema === false ) {
 463                         $schema = $this->getCoreSchema();
 464                 }
 465                 /*
 466                  * A subquery would be not needed if we didn't care about the order
 467                  * of attributes, but we do
 468                  */
 469                 $sql = <<<__INDEXATTR__
 470
 471                         SELECT opcname,
 472                                 attname,
 473                                 i.indoption[s.g] as option,
 474                                 pg_am.amname
 475                         FROM
 476                                 (SELECT generate_series(array_lower(isub.indkey,1), array_upper(isub.indkey,1)) AS g
 477                                         FROM
 478                                                 pg_index isub
 479                                         JOIN pg_class cis
 480                                                 ON cis.oid=isub.indexrelid
 481                                         JOIN pg_namespace ns
 482                                                 ON cis.relnamespace = ns.oid
 483                                         WHERE cis.relname='$index' AND ns.nspname='$schema') AS s,
 484                                 pg_attribute,
 485                                 pg_opclass opcls,
 486                                 pg_am,
 487                                 pg_class ci
 488                                 JOIN pg_index i
 489                                         ON ci.oid=i.indexrelid
 490                                 JOIN pg_class ct
 491                                         ON ct.oid = i.indrelid
 492                                 JOIN pg_namespace n
 493                                         ON ci.relnamespace = n.oid
 494                                 WHERE
 495                                         ci.relname='$index' AND n.nspname='$schema'
 496                                         AND     attrelid = ct.oid
 497                                         AND     i.indkey[s.g] = attnum
 498                                         AND     i.indclass[s.g] = opcls.oid
 499                                         AND     pg_am.oid = opcls.opcmethod
 500 __INDEXATTR__;
 501                 $res = $this->query( $sql, __METHOD__ );
 502                 $a = [];
 503                 if ( $res ) {
 504                         foreach ( $res as $row ) {
 505                                 $a[] = [
 506                                         $row->attname,
 507                                         $row->opcname,
 508                                         $row->amname,
 509                                         $row->option ];
 510                         }
 511                 } else {
 512                         return null;
 513                 }
 514
 515                 return $a;
 516         }
 517
 518         function indexUnique( $table, $index, $fname = __METHOD__ ) {
 519                 $sql = "SELECT indexname FROM pg_indexes WHERE tablename='{$table}'" .
 520                         " AND indexdef LIKE 'CREATE UNIQUE%(" .
 521                         $this->strencode( $this->indexName( $index ) ) .
 522                         ")'";
 523                 $res = $this->query( $sql, $fname );
 524                 if ( !$res ) {
 525                         return null;
 526                 }
 527
 528                 return $res->numRows() > 0;
 529         }
 530
 531         function selectSQLText(
 532                 $table, $vars, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
 533         ) {
 534                 // Change the FOR UPDATE option as necessary based on the join conditions. Then pass
 535                 // to the parent function to get the actual SQL text.
 536                 // In Postgres when using FOR UPDATE, only the main table and tables that are inner joined
 537                 // can be locked. That means tables in an outer join cannot be FOR UPDATE locked. Trying to
 538                 // do so causes a DB error. This wrapper checks which tables can be locked and adjusts it
 539                 // accordingly.
 540                 // MySQL uses "ORDER BY NULL" as an optimization hint, but that is illegal in PostgreSQL.
 541                 if ( is_array( $options ) ) {
 542                         $forUpdateKey = array_search( 'FOR UPDATE', $options, true );
 543                         if ( $forUpdateKey !== false && $join_conds ) {
 544                                 unset( $options[$forUpdateKey] );
 545
 546                                 foreach ( $join_conds as $table_cond => $join_cond ) {
 547                                         if ( 0 === preg_match( '/^(?:LEFT|RIGHT|FULL)(?: OUTER)? JOIN$/i', $join_cond[0] ) ) {
 548                                                 $options['FOR UPDATE'][] = $table_cond;
 549                                         }
 550                                 }
 551                         }
 552
 553                         if ( isset( $options['ORDER BY'] ) && $options['ORDER BY'] == 'NULL' ) {
 554                                 unset( $options['ORDER BY'] );
 555                         }
 556                 }
 557
 558                 return parent::selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
 559         }
 560
 561         /**
 562          * INSERT wrapper, inserts an array into a table
 563          *
 564          * $args may be a single associative array, or an array of these with numeric keys,
 565          * for multi-row insert (Postgres version 8.2 and above only).
 566          *
 567          * @param string $table Name of the table to insert to.
 568          * @param array $args Items to insert into the table.
 569          * @param string $fname Name of the function, for profiling
 570          * @param array|string $options String or array. Valid options: IGNORE
 571          * @return bool Success of insert operation. IGNORE always returns true.
 572          */
 573         function insert( $table, $args, $fname = __METHOD__, $options = [] ) {
 574                 if ( !count( $args ) ) {
 575                         return true;
 576                 }
 577
 578                 $table = $this->tableName( $table );
 579                 if ( !isset( $this->numericVersion ) ) {
 580                         $this->getServerVersion();
 581                 }
 582
 583                 if ( !is_array( $options ) ) {
 584                         $options = [ $options ];
 585                 }
 586
 587                 if ( isset( $args[0] ) && is_array( $args[0] ) ) {
 588                         $multi = true;
 589                         $keys = array_keys( $args[0] );
 590                 } else {
 591                         $multi = false;
 592                         $keys = array_keys( $args );
 593                 }
 594
 595                 // If IGNORE is set, we use savepoints to emulate mysql's behavior
 596                 $savepoint = $olde = null;
 597                 $numrowsinserted = 0;
 598                 if ( in_array( 'IGNORE', $options ) ) {
 599                         $savepoint = new SavepointPostgres( $this, 'mw', $this->queryLogger );
 600                         $olde = error_reporting( 0 );
 601                         // For future use, we may want to track the number of actual inserts
 602                         // Right now, insert (all writes) simply return true/false
 603                 }
 604
 605                 $sql = "INSERT INTO $table (" . implode( ',', $keys ) . ') VALUES ';
 606
 607                 if ( $multi ) {
 608                         if ( $this->numericVersion >= 8.2 && !$savepoint ) {
 609                                 $first = true;
 610                                 foreach ( $args as $row ) {
 611                                         if ( $first ) {
 612                                                 $first = false;
 613                                         } else {
 614                                                 $sql .= ',';
 615                                         }
 616                                         $sql .= '(' . $this->makeList( $row ) . ')';
 617                                 }
 618                                 $res = (bool)$this->query( $sql, $fname, $savepoint );
 619                         } else {
 620                                 $res = true;
 621                                 $origsql = $sql;
 622                                 foreach ( $args as $row ) {
 623                                         $tempsql = $origsql;
 624                                         $tempsql .= '(' . $this->makeList( $row ) . ')';
 625
 626                                         if ( $savepoint ) {
 627                                                 $savepoint->savepoint();
 628                                         }
 629
 630                                         $tempres = (bool)$this->query( $tempsql, $fname, $savepoint );
 631
 632                                         if ( $savepoint ) {
 633                                                 $bar = pg_result_error( $this->mLastResult );
 634                                                 if ( $bar != false ) {
 635                                                         $savepoint->rollback();
 636                                                 } else {
 637                                                         $savepoint->release();
 638                                                         $numrowsinserted++;
 639                                                 }
 640                                         }
 641
 642                                         // If any of them fail, we fail overall for this function call
 643                                         // Note that this will be ignored if IGNORE is set
 644                                         if ( !$tempres ) {
 645                                                 $res = false;
 646                                         }
 647                                 }
 648                         }
 649                 } else {
 650                         // Not multi, just a lone insert
 651                         if ( $savepoint ) {
 652                                 $savepoint->savepoint();
 653                         }
 654
 655                         $sql .= '(' . $this->makeList( $args ) . ')';
 656                         $res = (bool)$this->query( $sql, $fname, $savepoint );
 657                         if ( $savepoint ) {
 658                                 $bar = pg_result_error( $this->mLastResult );
 659                                 if ( $bar != false ) {
 660                                         $savepoint->rollback();
 661                                 } else {
 662                                         $savepoint->release();
 663                                         $numrowsinserted++;
 664                                 }
 665                         }
 666                 }
 667                 if ( $savepoint ) {
 668                         error_reporting( $olde );
 669                         $savepoint->commit();
 670
 671                         // Set the affected row count for the whole operation
 672                         $this->mAffectedRows = $numrowsinserted;
 673
 674                         // IGNORE always returns true
 675                         return true;
 676                 }
 677
 678                 return $res;
 679         }
 680
 681         /**
 682          * INSERT SELECT wrapper
 683          * $varMap must be an associative array of the form [ 'dest1' => 'source1', ... ]
 684          * Source items may be literals rather then field names, but strings should
 685          * be quoted with Database::addQuotes()
 686          * $conds may be "*" to copy the whole table
 687          * srcTable may be an array of tables.
 688          * @todo FIXME: Implement this a little better (seperate select/insert)?
 689          *
 690          * @param string $destTable
 691          * @param array|string $srcTable
 692          * @param array $varMap
 693          * @param array $conds
 694          * @param string $fname
 695          * @param array $insertOptions
 696          * @param array $selectOptions
 697          * @return bool
 698          */
 699         function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds, $fname = __METHOD__,
 700                 $insertOptions = [], $selectOptions = [] ) {
 701                 $destTable = $this->tableName( $destTable );
 702
 703                 if ( !is_array( $insertOptions ) ) {
 704                         $insertOptions = [ $insertOptions ];
 705                 }
 706
 707                 /*
 708                  * If IGNORE is set, we use savepoints to emulate mysql's behavior
 709                  * Ignore LOW PRIORITY option, since it is MySQL-specific
 710                  */
 711                 $savepoint = $olde = null;
 712                 $numrowsinserted = 0;
 713                 if ( in_array( 'IGNORE', $insertOptions ) ) {
 714                         $savepoint = new SavepointPostgres( $this, 'mw', $this->queryLogger );
 715                         $olde = error_reporting( 0 );
 716                         $savepoint->savepoint();
 717                 }
 718
 719                 if ( !is_array( $selectOptions ) ) {
 720                         $selectOptions = [ $selectOptions ];
 721                 }
 722                 list( $startOpts, $useIndex, $tailOpts, $ignoreIndex ) =
 723                         $this->makeSelectOptions( $selectOptions );
 724                 if ( is_array( $srcTable ) ) {
 725                         $srcTable = implode( ',', array_map( [ &$this, 'tableName' ], $srcTable ) );
 726                 } else {
 727                         $srcTable = $this->tableName( $srcTable );
 728                 }
 729
 730                 $sql = "INSERT INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
 731                         " SELECT $startOpts " . implode( ',', $varMap ) .
 732                         " FROM $srcTable $useIndex $ignoreIndex ";
 733
 734                 if ( $conds != '*' ) {
 735                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
 736                 }
 737
 738                 $sql .= " $tailOpts";
 739
 740                 $res = (bool)$this->query( $sql, $fname, $savepoint );
 741                 if ( $savepoint ) {
 742                         $bar = pg_result_error( $this->mLastResult );
 743                         if ( $bar != false ) {
 744                                 $savepoint->rollback();
 745                         } else {
 746                                 $savepoint->release();
 747                                 $numrowsinserted++;
 748                         }
 749                         error_reporting( $olde );
 750                         $savepoint->commit();
 751
 752                         // Set the affected row count for the whole operation
 753                         $this->mAffectedRows = $numrowsinserted;
 754
 755                         // IGNORE always returns true
 756                         return true;
 757                 }
 758
 759                 return $res;
 760         }
 761
 762         function tableName( $name, $format = 'quoted' ) {
 763                 # Replace reserved words with better ones
 764                 switch ( $name ) {
 765                         case 'user':
 766                                 return $this->realTableName( 'mwuser', $format );
 767                         case 'text':
 768                                 return $this->realTableName( 'pagecontent', $format );
 769                         default:
 770                                 return $this->realTableName( $name, $format );
 771                 }
 772         }
 773
 774         /* Don't cheat on installer */
 775         function realTableName( $name, $format = 'quoted' ) {
 776                 return parent::tableName( $name, $format );
 777         }
 778
 779         /**
 780          * Return the next in a sequence, save the value for retrieval via insertId()
 781          *
 782          * @param string $seqName
 783          * @return int|null
 784          */
 785         function nextSequenceValue( $seqName ) {
 786                 $safeseq = str_replace( "'", "''", $seqName );
 787                 $res = $this->query( "SELECT nextval('$safeseq')" );
 788                 $row = $this->fetchRow( $res );
 789                 $this->mInsertId = $row[0];
 790
 791                 return $this->mInsertId;
 792         }
 793
 794         /**
 795          * Return the current value of a sequence. Assumes it has been nextval'ed in this session.
 796          *
 797          * @param string $seqName
 798          * @return int
 799          */
 800         function currentSequenceValue( $seqName ) {
 801                 $safeseq = str_replace( "'", "''", $seqName );
 802                 $res = $this->query( "SELECT currval('$safeseq')" );
 803                 $row = $this->fetchRow( $res );
 804                 $currval = $row[0];
 805
 806                 return $currval;
 807         }
 808
 809         # Returns the size of a text field, or -1 for "unlimited"
 810         function textFieldSize( $table, $field ) {
 811                 $table = $this->tableName( $table );
 812                 $sql = "SELECT t.typname as ftype,a.atttypmod as size
 813                         FROM pg_class c, pg_attribute a, pg_type t
 814                         WHERE relname='$table' AND a.attrelid=c.oid AND
 815                                 a.atttypid=t.oid and a.attname='$field'";
 816                 $res = $this->query( $sql );
 817                 $row = $this->fetchObject( $res );
 818                 if ( $row->ftype == 'varchar' ) {
 819                         $size = $row->size - 4;
 820                 } else {
 821                         $size = $row->size;
 822                 }
 823
 824                 return $size;
 825         }
 826
 827         function limitResult( $sql, $limit, $offset = false ) {
 828                 return "$sql LIMIT $limit " . ( is_numeric( $offset ) ? " OFFSET {$offset} " : '' );
 829         }
 830
 831         function wasDeadlock() {
 832                 return $this->lastErrno() == '40P01';
 833         }
 834
 835         function duplicateTableStructure(
 836                 $oldName, $newName, $temporary = false, $fname = __METHOD__
 837         ) {
 838                 $newName = $this->addIdentifierQuotes( $newName );
 839                 $oldName = $this->addIdentifierQuotes( $oldName );
 840
 841                 return $this->query( 'CREATE ' . ( $temporary ? 'TEMPORARY ' : '' ) . " TABLE $newName " .
 842                         "(LIKE $oldName INCLUDING DEFAULTS)", $fname );
 843         }
 844
 845         function listTables( $prefix = null, $fname = __METHOD__ ) {
 846                 $eschema = $this->addQuotes( $this->getCoreSchema() );
 847                 $result = $this->query(
 848                         "SELECT tablename FROM pg_tables WHERE schemaname = $eschema", $fname );
 849                 $endArray = [];
 850
 851                 foreach ( $result as $table ) {
 852                         $vars = get_object_vars( $table );
 853                         $table = array_pop( $vars );
 854                         if ( !$prefix || strpos( $table, $prefix ) === 0 ) {
 855                                 $endArray[] = $table;
 856                         }
 857                 }
 858
 859                 return $endArray;
 860         }
 861
 862         function timestamp( $ts = 0 ) {
 863                 $ct = new ConvertibleTimestamp( $ts );
 864
 865                 return $ct->getTimestamp( TS_POSTGRES );
 866         }
 867
 868         /**
 869          * Posted by cc[plus]php[at]c2se[dot]com on 25-Mar-2009 09:12
 870          * to http://www.php.net/manual/en/ref.pgsql.php
 871          *
 872          * Parsing a postgres array can be a tricky problem, he's my
 873          * take on this, it handles multi-dimensional arrays plus
 874          * escaping using a nasty regexp to determine the limits of each
 875          * data-item.
 876          *
 877          * This should really be handled by PHP PostgreSQL module
 878          *
 879          * @since 1.19
 880          * @param string $text Postgreql array returned in a text form like {a,b}
 881          * @param string $output
 882          * @param int|bool $limit
 883          * @param int $offset
 884          * @return string
 885          */
 886         function pg_array_parse( $text, &$output, $limit = false, $offset = 1 ) {
 887                 if ( false === $limit ) {
 888                         $limit = strlen( $text ) - 1;
 889                         $output = [];
 890                 }
 891                 if ( '{}' == $text ) {
 892                         return $output;
 893                 }
 894                 do {
 895                         if ( '{' != $text[$offset] ) {
 896                                 preg_match( "/(\\{?\"([^\"\\\\]|\\\\.)*\"|[^,{}]+)+([,}]+)/",
 897                                         $text, $match, 0, $offset );
 898                                 $offset += strlen( $match[0] );
 899                                 $output[] = ( '"' != $match[1][0]
 900                                         ? $match[1]
 901                                         : stripcslashes( substr( $match[1], 1, -1 ) ) );
 902                                 if ( '},' == $match[3] ) {
 903                                         return $output;
 904                                 }
 905                         } else {
 906                                 $offset = $this->pg_array_parse( $text, $output, $limit, $offset + 1 );
 907                         }
 908                 } while ( $limit > $offset );
 909
 910                 return $output;
 911         }
 912
 913         /**
 914          * Return aggregated value function call
 915          * @param array $valuedata
 916          * @param string $valuename
 917          * @return array
 918          */
 919         public function aggregateValue( $valuedata, $valuename = 'value' ) {
 920                 return $valuedata;
 921         }
 922
 923         /**
 924          * @return string Wikitext of a link to the server software's web site
 925          */
 926         public function getSoftwareLink() {
 927                 return '[{{int:version-db-postgres-url}} PostgreSQL]';
 928         }
 929
 930         /**
 931          * Return current schema (executes SELECT current_schema())
 932          * Needs transaction
 933          *
 934          * @since 1.19
 935          * @return string Default schema for the current session
 936          */
 937         function getCurrentSchema() {
 938                 $res = $this->query( "SELECT current_schema()", __METHOD__ );
 939                 $row = $this->fetchRow( $res );
 940
 941                 return $row[0];
 942         }
 943
 944         /**
 945          * Return list of schemas which are accessible without schema name
 946          * This is list does not contain magic keywords like "$user"
 947          * Needs transaction
 948          *
 949          * @see getSearchPath()
 950          * @see setSearchPath()
 951          * @since 1.19
 952          * @return array List of actual schemas for the current sesson
 953          */
 954         function getSchemas() {
 955                 $res = $this->query( "SELECT current_schemas(false)", __METHOD__ );
 956                 $row = $this->fetchRow( $res );
 957                 $schemas = [];
 958
 959                 /* PHP pgsql support does not support array type, "{a,b}" string is returned */
 960
 961                 return $this->pg_array_parse( $row[0], $schemas );
 962         }
 963
 964         /**
 965          * Return search patch for schemas
 966          * This is different from getSchemas() since it contain magic keywords
 967          * (like "$user").
 968          * Needs transaction
 969          *
 970          * @since 1.19
 971          * @return array How to search for table names schemas for the current user
 972          */
 973         function getSearchPath() {
 974                 $res = $this->query( "SHOW search_path", __METHOD__ );
 975                 $row = $this->fetchRow( $res );
 976
 977                 /* PostgreSQL returns SHOW values as strings */
 978
 979                 return explode( ",", $row[0] );
 980         }
 981
 982         /**
 983          * Update search_path, values should already be sanitized
 984          * Values may contain magic keywords like "$user"
 985          * @since 1.19
 986          *
 987          * @param array $search_path List of schemas to be searched by default
 988          */
 989         function setSearchPath( $search_path ) {
 990                 $this->query( "SET search_path = " . implode( ", ", $search_path ) );
 991         }
 992
 993         /**
 994          * Determine default schema for the current application
 995          * Adjust this session schema search path if desired schema exists
 996          * and is not alread there.
 997          *
 998          * We need to have name of the core schema stored to be able
 999          * to query database metadata.
1000          *
1001          * This will be also called by the installer after the schema is created
1002          *
1003          * @since 1.19
1004          *
1005          * @param string $desiredSchema
1006          */
1007         function determineCoreSchema( $desiredSchema ) {
1008                 $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
1009                 if ( $this->schemaExists( $desiredSchema ) ) {
1010                         if ( in_array( $desiredSchema, $this->getSchemas() ) ) {
1011                                 $this->mCoreSchema = $desiredSchema;
1012                                 $this->queryLogger->debug(
1013                                         "Schema \"" . $desiredSchema . "\" already in the search path\n" );
1014                         } else {
1015                                 /**
1016                                  * Prepend our schema (e.g. 'mediawiki') in front
1017                                  * of the search path
1018                                  * Fixes bug 15816
1019                                  */
1020                                 $search_path = $this->getSearchPath();
1021                                 array_unshift( $search_path,
1022                                         $this->addIdentifierQuotes( $desiredSchema ) );
1023                                 $this->setSearchPath( $search_path );
1024                                 $this->mCoreSchema = $desiredSchema;
1025                                 $this->queryLogger->debug(
1026                                         "Schema \"" . $desiredSchema . "\" added to the search path\n" );
1027                         }
1028                 } else {
1029                         $this->mCoreSchema = $this->getCurrentSchema();
1030                         $this->queryLogger->debug(
1031                                 "Schema \"" . $desiredSchema . "\" not found, using current \"" .
1032                                 $this->mCoreSchema . "\"\n" );
1033                 }
1034                 /* Commit SET otherwise it will be rollbacked on error or IGNORE SELECT */
1035                 $this->commit( __METHOD__ );
1036         }
1037
1038         /**
1039          * Return schema name for core application tables
1040          *
1041          * @since 1.19
1042          * @return string Core schema name
1043          */
1044         function getCoreSchema() {
1045                 return $this->mCoreSchema;
1046         }
1047
1048         /**
1049          * @return string Version information from the database
1050          */
1051         function getServerVersion() {
1052                 if ( !isset( $this->numericVersion ) ) {
1053                         $versionInfo = pg_version( $this->mConn );
1054                         if ( version_compare( $versionInfo['client'], '7.4.0', 'lt' ) ) {
1055                                 // Old client, abort install
1056                                 $this->numericVersion = '7.3 or earlier';
1057                         } elseif ( isset( $versionInfo['server'] ) ) {
1058                                 // Normal client
1059                                 $this->numericVersion = $versionInfo['server'];
1060                         } else {
1061                                 // Bug 16937: broken pgsql extension from PHP<5.3
1062                                 $this->numericVersion = pg_parameter_status( $this->mConn, 'server_version' );
1063                         }
1064                 }
1065
1066                 return $this->numericVersion;
1067         }
1068
1069         /**
1070          * Query whether a given relation exists (in the given schema, or the
1071          * default mw one if not given)
1072          * @param string $table
1073          * @param array|string $types
1074          * @param bool|string $schema
1075          * @return bool
1076          */
1077         function relationExists( $table, $types, $schema = false ) {
1078                 if ( !is_array( $types ) ) {
1079                         $types = [ $types ];
1080                 }
1081                 if ( !$schema ) {
1082                         $schema = $this->getCoreSchema();
1083                 }
1084                 $table = $this->realTableName( $table, 'raw' );
1085                 $etable = $this->addQuotes( $table );
1086                 $eschema = $this->addQuotes( $schema );
1087                 $sql = "SELECT 1 FROM pg_catalog.pg_class c, pg_catalog.pg_namespace n "
1088                         . "WHERE c.relnamespace = n.oid AND c.relname = $etable AND n.nspname = $eschema "
1089                         . "AND c.relkind IN ('" . implode( "','", $types ) . "')";
1090                 $res = $this->query( $sql );
1091                 $count = $res ? $res->numRows() : 0;
1092
1093                 return (bool)$count;
1094         }
1095
1096         /**
1097          * For backward compatibility, this function checks both tables and
1098          * views.
1099          * @param string $table
1100          * @param string $fname
1101          * @param bool|string $schema
1102          * @return bool
1103          */
1104         function tableExists( $table, $fname = __METHOD__, $schema = false ) {
1105                 return $this->relationExists( $table, [ 'r', 'v' ], $schema );
1106         }
1107
1108         function sequenceExists( $sequence, $schema = false ) {
1109                 return $this->relationExists( $sequence, 'S', $schema );
1110         }
1111
1112         function triggerExists( $table, $trigger ) {
1113                 $q = <<<SQL
1114         SELECT 1 FROM pg_class, pg_namespace, pg_trigger
1115                 WHERE relnamespace=pg_namespace.oid AND relkind='r'
1116                           AND tgrelid=pg_class.oid
1117                           AND nspname=%s AND relname=%s AND tgname=%s
1118 SQL;
1119                 $res = $this->query(
1120                         sprintf(
1121                                 $q,
1122                                 $this->addQuotes( $this->getCoreSchema() ),
1123                                 $this->addQuotes( $table ),
1124                                 $this->addQuotes( $trigger )
1125                         )
1126                 );
1127                 if ( !$res ) {
1128                         return null;
1129                 }
1130                 $rows = $res->numRows();
1131
1132                 return $rows;
1133         }
1134
1135         function ruleExists( $table, $rule ) {
1136                 $exists = $this->selectField( 'pg_rules', 'rulename',
1137                         [
1138                                 'rulename' => $rule,
1139                                 'tablename' => $table,
1140                                 'schemaname' => $this->getCoreSchema()
1141                         ]
1142                 );
1143
1144                 return $exists === $rule;
1145         }
1146
1147         function constraintExists( $table, $constraint ) {
1148                 $sql = sprintf( "SELECT 1 FROM information_schema.table_constraints " .
1149                         "WHERE constraint_schema = %s AND table_name = %s AND constraint_name = %s",
1150                         $this->addQuotes( $this->getCoreSchema() ),
1151                         $this->addQuotes( $table ),
1152                         $this->addQuotes( $constraint )
1153                 );
1154                 $res = $this->query( $sql );
1155                 if ( !$res ) {
1156                         return null;
1157                 }
1158                 $rows = $res->numRows();
1159
1160                 return $rows;
1161         }
1162
1163         /**
1164          * Query whether a given schema exists. Returns true if it does, false if it doesn't.
1165          * @param string $schema
1166          * @return bool
1167          */
1168         function schemaExists( $schema ) {
1169                 $exists = $this->selectField( '"pg_catalog"."pg_namespace"', 1,
1170                         [ 'nspname' => $schema ], __METHOD__ );
1171
1172                 return (bool)$exists;
1173         }
1174
1175         /**
1176          * Returns true if a given role (i.e. user) exists, false otherwise.
1177          * @param string $roleName
1178          * @return bool
1179          */
1180         function roleExists( $roleName ) {
1181                 $exists = $this->selectField( '"pg_catalog"."pg_roles"', 1,
1182                         [ 'rolname' => $roleName ], __METHOD__ );
1183
1184                 return (bool)$exists;
1185         }
1186
1187         /**
1188          * @var string $table
1189          * @var string $field
1190          * @return PostgresField|null
1191          */
1192         function fieldInfo( $table, $field ) {
1193                 return PostgresField::fromText( $this, $table, $field );
1194         }
1195
1196         /**
1197          * pg_field_type() wrapper
1198          * @param ResultWrapper|resource $res ResultWrapper or PostgreSQL query result resource
1199          * @param int $index Field number, starting from 0
1200          * @return string
1201          */
1202         function fieldType( $res, $index ) {
1203                 if ( $res instanceof ResultWrapper ) {
1204                         $res = $res->result;
1205                 }
1206
1207                 return pg_field_type( $res, $index );
1208         }
1209
1210         /**
1211          * @param string $b
1212          * @return Blob
1213          */
1214         function encodeBlob( $b ) {
1215                 return new PostgresBlob( pg_escape_bytea( $b ) );
1216         }
1217
1218         function decodeBlob( $b ) {
1219                 if ( $b instanceof PostgresBlob ) {
1220                         $b = $b->fetch();
1221                 } elseif ( $b instanceof Blob ) {
1222                         return $b->fetch();
1223                 }
1224
1225                 return pg_unescape_bytea( $b );
1226         }
1227
1228         function strencode( $s ) {
1229                 // Should not be called by us
1230
1231                 return pg_escape_string( $this->mConn, $s );
1232         }
1233
1234         /**
1235          * @param string|int|null|bool|Blob $s
1236          * @return string|int
1237          */
1238         function addQuotes( $s ) {
1239                 if ( is_null( $s ) ) {
1240                         return 'NULL';
1241                 } elseif ( is_bool( $s ) ) {
1242                         return intval( $s );
1243                 } elseif ( $s instanceof Blob ) {
1244                         if ( $s instanceof PostgresBlob ) {
1245                                 $s = $s->fetch();
1246                         } else {
1247                                 $s = pg_escape_bytea( $this->mConn, $s->fetch() );
1248                         }
1249                         return "'$s'";
1250                 }
1251
1252                 return "'" . pg_escape_string( $this->mConn, $s ) . "'";
1253         }
1254
1255         /**
1256          * Postgres specific version of replaceVars.
1257          * Calls the parent version in Database.php
1258          *
1259          * @param string $ins SQL string, read from a stream (usually tables.sql)
1260          * @return string SQL string
1261          */
1262         protected function replaceVars( $ins ) {
1263                 $ins = parent::replaceVars( $ins );
1264
1265                 if ( $this->numericVersion >= 8.3 ) {
1266                         // Thanks for not providing backwards-compatibility, 8.3
1267                         $ins = preg_replace( "/to_tsvector\s*\(\s*'default'\s*,/", 'to_tsvector(', $ins );
1268                 }
1269
1270                 if ( $this->numericVersion <= 8.1 ) { // Our minimum version
1271                         $ins = str_replace( 'USING gin', 'USING gist', $ins );
1272                 }
1273
1274                 return $ins;
1275         }
1276
1277         /**
1278          * Various select options
1279          *
1280          * @param array $options An associative array of options to be turned into
1281          *   an SQL query, valid keys are listed in the function.
1282          * @return array
1283          */
1284         function makeSelectOptions( $options ) {
1285                 $preLimitTail = $postLimitTail = '';
1286                 $startOpts = $useIndex = $ignoreIndex = '';
1287
1288                 $noKeyOptions = [];
1289                 foreach ( $options as $key => $option ) {
1290                         if ( is_numeric( $key ) ) {
1291                                 $noKeyOptions[$option] = true;
1292                         }
1293                 }
1294
1295                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1296
1297                 $preLimitTail .= $this->makeOrderBy( $options );
1298
1299                 // if ( isset( $options['LIMIT'] ) ) {
1300                 //      $tailOpts .= $this->limitResult( '', $options['LIMIT'],
1301                 //              isset( $options['OFFSET'] ) ? $options['OFFSET']
1302                 //              : false );
1303                 // }
1304
1305                 if ( isset( $options['FOR UPDATE'] ) ) {
1306                         $postLimitTail .= ' FOR UPDATE OF ' .
1307                                 implode( ', ', array_map( [ &$this, 'tableName' ], $options['FOR UPDATE'] ) );
1308                 } elseif ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1309                         $postLimitTail .= ' FOR UPDATE';
1310                 }
1311
1312                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1313                         $startOpts .= 'DISTINCT';
1314                 }
1315
1316                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1317         }
1318
1319         function getDBname() {
1320                 return $this->mDBname;
1321         }
1322
1323         function getServer() {
1324                 return $this->mServer;
1325         }
1326
1327         function buildConcat( $stringList ) {
1328                 return implode( ' || ', $stringList );
1329         }
1330
1331         public function buildGroupConcatField(
1332                 $delimiter, $table, $field, $conds = '', $options = [], $join_conds = []
1333         ) {
1334                 $fld = "array_to_string(array_agg($field)," . $this->addQuotes( $delimiter ) . ')';
1335
1336                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1337         }
1338
1339         /**
1340          * @param string $field Field or column to cast
1341          * @return string
1342          * @since 1.28
1343          */
1344         public function buildStringCast( $field ) {
1345                 return $field . '::text';
1346         }
1347
1348         public function streamStatementEnd( &$sql, &$newLine ) {
1349                 # Allow dollar quoting for function declarations
1350                 if ( substr( $newLine, 0, 4 ) == '$mw$' ) {
1351                         if ( $this->delimiter ) {
1352                                 $this->delimiter = false;
1353                         } else {
1354                                 $this->delimiter = ';';
1355                         }
1356                 }
1357
1358                 return parent::streamStatementEnd( $sql, $newLine );
1359         }
1360
1361         /**
1362          * Check to see if a named lock is available. This is non-blocking.
1363          * See http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1364          *
1365          * @param string $lockName Name of lock to poll
1366          * @param string $method Name of method calling us
1367          * @return bool
1368          * @since 1.20
1369          */
1370         public function lockIsFree( $lockName, $method ) {
1371                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1372                 $result = $this->query( "SELECT (CASE(pg_try_advisory_lock($key))
1373                         WHEN 'f' THEN 'f' ELSE pg_advisory_unlock($key) END) AS lockstatus", $method );
1374                 $row = $this->fetchObject( $result );
1375
1376                 return ( $row->lockstatus === 't' );
1377         }
1378
1379         /**
1380          * See http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1381          * @param string $lockName
1382          * @param string $method
1383          * @param int $timeout
1384          * @return bool
1385          */
1386         public function lock( $lockName, $method, $timeout = 5 ) {
1387                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1388                 $loop = new WaitConditionLoop(
1389                         function () use ( $lockName, $key, $timeout, $method ) {
1390                                 $res = $this->query( "SELECT pg_try_advisory_lock($key) AS lockstatus", $method );
1391                                 $row = $this->fetchObject( $res );
1392                                 if ( $row->lockstatus === 't' ) {
1393                                         parent::lock( $lockName, $method, $timeout ); // record
1394                                         return true;
1395                                 }
1396
1397                                 return WaitConditionLoop::CONDITION_CONTINUE;
1398                         },
1399                         $timeout
1400                 );
1401
1402                 return ( $loop->invoke() === $loop::CONDITION_REACHED );
1403         }
1404
1405         /**
1406          * See http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKSFROM
1407          * PG DOCS: http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1408          * @param string $lockName
1409          * @param string $method
1410          * @return bool
1411          */
1412         public function unlock( $lockName, $method ) {
1413                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1414                 $result = $this->query( "SELECT pg_advisory_unlock($key) as lockstatus", $method );
1415                 $row = $this->fetchObject( $result );
1416
1417                 if ( $row->lockstatus === 't' ) {
1418                         parent::unlock( $lockName, $method ); // record
1419                         return true;
1420                 }
1421
1422                 $this->queryLogger->debug( __METHOD__ . " failed to release lock\n" );
1423
1424                 return false;
1425         }
1426
1427         /**
1428          * @param string $lockName
1429          * @return string Integer
1430          */
1431         private function bigintFromLockName( $lockName ) {
1432                 return Wikimedia\base_convert( substr( sha1( $lockName ), 0, 15 ), 16, 10 );
1433         }
1434 }