includes/libs/rdbms/database/DatabasePostgres.php

   1 <?php
   2 /**
   3  * This is the Postgres database abstraction layer.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @ingroup Database
  22  */
  23 use Wikimedia\WaitConditionLoop;
  24
  25 /**
  26  * @ingroup Database
  27  */
  28 class DatabasePostgres extends Database {
  29         /** @var int|bool */
  30         protected $port;
  31
  32         /** @var resource */
  33         protected $mLastResult = null;
  34         /** @var int The number of rows affected as an integer */
  35         protected $mAffectedRows = null;
  36
  37         /** @var int */
  38         private $mInsertId = null;
  39         /** @var float|string */
  40         private $numericVersion = null;
  41         /** @var string Connect string to open a PostgreSQL connection */
  42         private $connectString;
  43         /** @var string */
  44         private $mCoreSchema;
  45
  46         public function __construct( array $params ) {
  47                 $this->port = isset( $params['port'] ) ? $params['port'] : false;
  48                 parent::__construct( $params );
  49         }
  50
  51         function getType() {
  52                 return 'postgres';
  53         }
  54
  55         function implicitGroupby() {
  56                 return false;
  57         }
  58
  59         function implicitOrderby() {
  60                 return false;
  61         }
  62
  63         function hasConstraint( $name ) {
  64                 $sql = "SELECT 1 FROM pg_catalog.pg_constraint c, pg_catalog.pg_namespace n " .
  65                         "WHERE c.connamespace = n.oid AND conname = '" .
  66                         pg_escape_string( $this->mConn, $name ) . "' AND n.nspname = '" .
  67                         pg_escape_string( $this->mConn, $this->getCoreSchema() ) . "'";
  68                 $res = $this->doQuery( $sql );
  69
  70                 return $this->numRows( $res );
  71         }
  72
  73         /**
  74          * Usually aborts on failure
  75          * @param string $server
  76          * @param string $user
  77          * @param string $password
  78          * @param string $dbName
  79          * @throws DBConnectionError|Exception
  80          * @return resource|bool|null
  81          */
  82         function open( $server, $user, $password, $dbName ) {
  83                 # Test for Postgres support, to avoid suppressed fatal error
  84                 if ( !function_exists( 'pg_connect' ) ) {
  85                         throw new DBConnectionError(
  86                                 $this,
  87                                 "Postgres functions missing, have you compiled PHP with the --with-pgsql\n" .
  88                                 "option? (Note: if you recently installed PHP, you may need to restart your\n" .
  89                                 "webserver and database)\n"
  90                         );
  91                 }
  92
  93                 if ( !strlen( $user ) ) { # e.g. the class is being loaded
  94                         return null;
  95                 }
  96
  97                 $this->mServer = $server;
  98                 $this->mUser = $user;
  99                 $this->mPassword = $password;
 100                 $this->mDBname = $dbName;
 101
 102                 $connectVars = [
 103                         'dbname' => $dbName,
 104                         'user' => $user,
 105                         'password' => $password
 106                 ];
 107                 if ( $server != false && $server != '' ) {
 108                         $connectVars['host'] = $server;
 109                 }
 110                 if ( (int)$this->port > 0 ) {
 111                         $connectVars['port'] = (int)$this->port;
 112                 }
 113                 if ( $this->mFlags & self::DBO_SSL ) {
 114                         $connectVars['sslmode'] = 1;
 115                 }
 116
 117                 $this->connectString = $this->makeConnectionString( $connectVars );
 118                 $this->close();
 119                 $this->installErrorHandler();
 120
 121                 try {
 122                         $this->mConn = pg_connect( $this->connectString );
 123                 } catch ( Exception $ex ) {
 124                         $this->restoreErrorHandler();
 125                         throw $ex;
 126                 }
 127
 128                 $phpError = $this->restoreErrorHandler();
 129
 130                 if ( !$this->mConn ) {
 131                         $this->queryLogger->debug( "DB connection error\n" );
 132                         $this->queryLogger->debug(
 133                                 "Server: $server, Database: $dbName, User: $user, Password: " .
 134                                 substr( $password, 0, 3 ) . "...\n" );
 135                         $this->queryLogger->debug( $this->lastError() . "\n" );
 136                         throw new DBConnectionError( $this, str_replace( "\n", ' ', $phpError ) );
 137                 }
 138
 139                 $this->mOpened = true;
 140
 141                 # If called from the command-line (e.g. importDump), only show errors
 142                 if ( $this->cliMode ) {
 143                         $this->doQuery( "SET client_min_messages = 'ERROR'" );
 144                 }
 145
 146                 $this->query( "SET client_encoding='UTF8'", __METHOD__ );
 147                 $this->query( "SET datestyle = 'ISO, YMD'", __METHOD__ );
 148                 $this->query( "SET timezone = 'GMT'", __METHOD__ );
 149                 $this->query( "SET standard_conforming_strings = on", __METHOD__ );
 150                 if ( $this->getServerVersion() >= 9.0 ) {
 151                         $this->query( "SET bytea_output = 'escape'", __METHOD__ ); // PHP bug 53127
 152                 }
 153
 154                 $this->determineCoreSchema( $this->mSchema );
 155
 156                 return $this->mConn;
 157         }
 158
 159         /**
 160          * Postgres doesn't support selectDB in the same way MySQL does. So if the
 161          * DB name doesn't match the open connection, open a new one
 162          * @param string $db
 163          * @return bool
 164          */
 165         function selectDB( $db ) {
 166                 if ( $this->mDBname !== $db ) {
 167                         return (bool)$this->open( $this->mServer, $this->mUser, $this->mPassword, $db );
 168                 } else {
 169                         return true;
 170                 }
 171         }
 172
 173         function makeConnectionString( $vars ) {
 174                 $s = '';
 175                 foreach ( $vars as $name => $value ) {
 176                         $s .= "$name='" . str_replace( "'", "\\'", $value ) . "' ";
 177                 }
 178
 179                 return $s;
 180         }
 181
 182         /**
 183          * Closes a database connection, if it is open
 184          * Returns success, true if already closed
 185          * @return bool
 186          */
 187         protected function closeConnection() {
 188                 return pg_close( $this->mConn );
 189         }
 190
 191         public function doQuery( $sql ) {
 192                 $sql = mb_convert_encoding( $sql, 'UTF-8' );
 193                 // Clear previously left over PQresult
 194                 while ( $res = pg_get_result( $this->mConn ) ) {
 195                         pg_free_result( $res );
 196                 }
 197                 if ( pg_send_query( $this->mConn, $sql ) === false ) {
 198                         throw new DBUnexpectedError( $this, "Unable to post new query to PostgreSQL\n" );
 199                 }
 200                 $this->mLastResult = pg_get_result( $this->mConn );
 201                 $this->mAffectedRows = null;
 202                 if ( pg_result_error( $this->mLastResult ) ) {
 203                         return false;
 204                 }
 205
 206                 return $this->mLastResult;
 207         }
 208
 209         protected function dumpError() {
 210                 $diags = [
 211                         PGSQL_DIAG_SEVERITY,
 212                         PGSQL_DIAG_SQLSTATE,
 213                         PGSQL_DIAG_MESSAGE_PRIMARY,
 214                         PGSQL_DIAG_MESSAGE_DETAIL,
 215                         PGSQL_DIAG_MESSAGE_HINT,
 216                         PGSQL_DIAG_STATEMENT_POSITION,
 217                         PGSQL_DIAG_INTERNAL_POSITION,
 218                         PGSQL_DIAG_INTERNAL_QUERY,
 219                         PGSQL_DIAG_CONTEXT,
 220                         PGSQL_DIAG_SOURCE_FILE,
 221                         PGSQL_DIAG_SOURCE_LINE,
 222                         PGSQL_DIAG_SOURCE_FUNCTION
 223                 ];
 224                 foreach ( $diags as $d ) {
 225                         $this->queryLogger->debug( sprintf( "PgSQL ERROR(%d): %s\n",
 226                                 $d, pg_result_error_field( $this->mLastResult, $d ) ) );
 227                 }
 228         }
 229
 230         function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
 231                 if ( $tempIgnore ) {
 232                         /* Check for constraint violation */
 233                         if ( $errno === '23505' ) {
 234                                 parent::reportQueryError( $error, $errno, $sql, $fname, $tempIgnore );
 235
 236                                 return;
 237                         }
 238                 }
 239                 /* Transaction stays in the ERROR state until rolled back */
 240                 if ( $this->mTrxLevel ) {
 241                         $ignore = $this->ignoreErrors( true );
 242                         $this->rollback( __METHOD__ );
 243                         $this->ignoreErrors( $ignore );
 244                 }
 245                 parent::reportQueryError( $error, $errno, $sql, $fname, false );
 246         }
 247
 248         function queryIgnore( $sql, $fname = __METHOD__ ) {
 249                 return $this->query( $sql, $fname, true );
 250         }
 251
 252         /**
 253          * @param stdClass|ResultWrapper $res
 254          * @throws DBUnexpectedError
 255          */
 256         function freeResult( $res ) {
 257                 if ( $res instanceof ResultWrapper ) {
 258                         $res = $res->result;
 259                 }
 260                 MediaWiki\suppressWarnings();
 261                 $ok = pg_free_result( $res );
 262                 MediaWiki\restoreWarnings();
 263                 if ( !$ok ) {
 264                         throw new DBUnexpectedError( $this, "Unable to free Postgres result\n" );
 265                 }
 266         }
 267
 268         /**
 269          * @param ResultWrapper|stdClass $res
 270          * @return stdClass
 271          * @throws DBUnexpectedError
 272          */
 273         function fetchObject( $res ) {
 274                 if ( $res instanceof ResultWrapper ) {
 275                         $res = $res->result;
 276                 }
 277                 MediaWiki\suppressWarnings();
 278                 $row = pg_fetch_object( $res );
 279                 MediaWiki\restoreWarnings();
 280                 # @todo FIXME: HACK HACK HACK HACK debug
 281
 282                 # @todo hashar: not sure if the following test really trigger if the object
 283                 #          fetching failed.
 284                 if ( pg_last_error( $this->mConn ) ) {
 285                         throw new DBUnexpectedError(
 286                                 $this,
 287                                 'SQL error: ' . htmlspecialchars( pg_last_error( $this->mConn ) )
 288                         );
 289                 }
 290
 291                 return $row;
 292         }
 293
 294         function fetchRow( $res ) {
 295                 if ( $res instanceof ResultWrapper ) {
 296                         $res = $res->result;
 297                 }
 298                 MediaWiki\suppressWarnings();
 299                 $row = pg_fetch_array( $res );
 300                 MediaWiki\restoreWarnings();
 301                 if ( pg_last_error( $this->mConn ) ) {
 302                         throw new DBUnexpectedError(
 303                                 $this,
 304                                 'SQL error: ' . htmlspecialchars( pg_last_error( $this->mConn ) )
 305                         );
 306                 }
 307
 308                 return $row;
 309         }
 310
 311         function numRows( $res ) {
 312                 if ( $res instanceof ResultWrapper ) {
 313                         $res = $res->result;
 314                 }
 315                 MediaWiki\suppressWarnings();
 316                 $n = pg_num_rows( $res );
 317                 MediaWiki\restoreWarnings();
 318                 if ( pg_last_error( $this->mConn ) ) {
 319                         throw new DBUnexpectedError(
 320                                 $this,
 321                                 'SQL error: ' . htmlspecialchars( pg_last_error( $this->mConn ) )
 322                         );
 323                 }
 324
 325                 return $n;
 326         }
 327
 328         function numFields( $res ) {
 329                 if ( $res instanceof ResultWrapper ) {
 330                         $res = $res->result;
 331                 }
 332
 333                 return pg_num_fields( $res );
 334         }
 335
 336         function fieldName( $res, $n ) {
 337                 if ( $res instanceof ResultWrapper ) {
 338                         $res = $res->result;
 339                 }
 340
 341                 return pg_field_name( $res, $n );
 342         }
 343
 344         /**
 345          * Return the result of the last call to nextSequenceValue();
 346          * This must be called after nextSequenceValue().
 347          *
 348          * @return int|null
 349          */
 350         function insertId() {
 351                 return $this->mInsertId;
 352         }
 353
 354         /**
 355          * @param mixed $res
 356          * @param int $row
 357          * @return bool
 358          */
 359         function dataSeek( $res, $row ) {
 360                 if ( $res instanceof ResultWrapper ) {
 361                         $res = $res->result;
 362                 }
 363
 364                 return pg_result_seek( $res, $row );
 365         }
 366
 367         function lastError() {
 368                 if ( $this->mConn ) {
 369                         if ( $this->mLastResult ) {
 370                                 return pg_result_error( $this->mLastResult );
 371                         } else {
 372                                 return pg_last_error();
 373                         }
 374                 } else {
 375                         return 'No database connection';
 376                 }
 377         }
 378
 379         function lastErrno() {
 380                 if ( $this->mLastResult ) {
 381                         return pg_result_error_field( $this->mLastResult, PGSQL_DIAG_SQLSTATE );
 382                 } else {
 383                         return false;
 384                 }
 385         }
 386
 387         function affectedRows() {
 388                 if ( !is_null( $this->mAffectedRows ) ) {
 389                         // Forced result for simulated queries
 390                         return $this->mAffectedRows;
 391                 }
 392                 if ( empty( $this->mLastResult ) ) {
 393                         return 0;
 394                 }
 395
 396                 return pg_affected_rows( $this->mLastResult );
 397         }
 398
 399         /**
 400          * Estimate rows in dataset
 401          * Returns estimated count, based on EXPLAIN output
 402          * This is not necessarily an accurate estimate, so use sparingly
 403          * Returns -1 if count cannot be found
 404          * Takes same arguments as Database::select()
 405          *
 406          * @param string $table
 407          * @param string $vars
 408          * @param string $conds
 409          * @param string $fname
 410          * @param array $options
 411          * @return int
 412          */
 413         function estimateRowCount( $table, $vars = '*', $conds = '',
 414                 $fname = __METHOD__, $options = []
 415         ) {
 416                 $options['EXPLAIN'] = true;
 417                 $res = $this->select( $table, $vars, $conds, $fname, $options );
 418                 $rows = -1;
 419                 if ( $res ) {
 420                         $row = $this->fetchRow( $res );
 421                         $count = [];
 422                         if ( preg_match( '/rows=(\d+)/', $row[0], $count ) ) {
 423                                 $rows = (int)$count[1];
 424                         }
 425                 }
 426
 427                 return $rows;
 428         }
 429
 430         /**
 431          * Returns information about an index
 432          * If errors are explicitly ignored, returns NULL on failure
 433          *
 434          * @param string $table
 435          * @param string $index
 436          * @param string $fname
 437          * @return bool|null
 438          */
 439         function indexInfo( $table, $index, $fname = __METHOD__ ) {
 440                 $sql = "SELECT indexname FROM pg_indexes WHERE tablename='$table'";
 441                 $res = $this->query( $sql, $fname );
 442                 if ( !$res ) {
 443                         return null;
 444                 }
 445                 foreach ( $res as $row ) {
 446                         if ( $row->indexname == $this->indexName( $index ) ) {
 447                                 return $row;
 448                         }
 449                 }
 450
 451                 return false;
 452         }
 453
 454         /**
 455          * Returns is of attributes used in index
 456          *
 457          * @since 1.19
 458          * @param string $index
 459          * @param bool|string $schema
 460          * @return array
 461          */
 462         function indexAttributes( $index, $schema = false ) {
 463                 if ( $schema === false ) {
 464                         $schema = $this->getCoreSchema();
 465                 }
 466                 /*
 467                  * A subquery would be not needed if we didn't care about the order
 468                  * of attributes, but we do
 469                  */
 470                 $sql = <<<__INDEXATTR__
 471
 472                         SELECT opcname,
 473                                 attname,
 474                                 i.indoption[s.g] as option,
 475                                 pg_am.amname
 476                         FROM
 477                                 (SELECT generate_series(array_lower(isub.indkey,1), array_upper(isub.indkey,1)) AS g
 478                                         FROM
 479                                                 pg_index isub
 480                                         JOIN pg_class cis
 481                                                 ON cis.oid=isub.indexrelid
 482                                         JOIN pg_namespace ns
 483                                                 ON cis.relnamespace = ns.oid
 484                                         WHERE cis.relname='$index' AND ns.nspname='$schema') AS s,
 485                                 pg_attribute,
 486                                 pg_opclass opcls,
 487                                 pg_am,
 488                                 pg_class ci
 489                                 JOIN pg_index i
 490                                         ON ci.oid=i.indexrelid
 491                                 JOIN pg_class ct
 492                                         ON ct.oid = i.indrelid
 493                                 JOIN pg_namespace n
 494                                         ON ci.relnamespace = n.oid
 495                                 WHERE
 496                                         ci.relname='$index' AND n.nspname='$schema'
 497                                         AND     attrelid = ct.oid
 498                                         AND     i.indkey[s.g] = attnum
 499                                         AND     i.indclass[s.g] = opcls.oid
 500                                         AND     pg_am.oid = opcls.opcmethod
 501 __INDEXATTR__;
 502                 $res = $this->query( $sql, __METHOD__ );
 503                 $a = [];
 504                 if ( $res ) {
 505                         foreach ( $res as $row ) {
 506                                 $a[] = [
 507                                         $row->attname,
 508                                         $row->opcname,
 509                                         $row->amname,
 510                                         $row->option ];
 511                         }
 512                 } else {
 513                         return null;
 514                 }
 515
 516                 return $a;
 517         }
 518
 519         function indexUnique( $table, $index, $fname = __METHOD__ ) {
 520                 $sql = "SELECT indexname FROM pg_indexes WHERE tablename='{$table}'" .
 521                         " AND indexdef LIKE 'CREATE UNIQUE%(" .
 522                         $this->strencode( $this->indexName( $index ) ) .
 523                         ")'";
 524                 $res = $this->query( $sql, $fname );
 525                 if ( !$res ) {
 526                         return null;
 527                 }
 528
 529                 return $res->numRows() > 0;
 530         }
 531
 532         function selectSQLText(
 533                 $table, $vars, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
 534         ) {
 535                 // Change the FOR UPDATE option as necessary based on the join conditions. Then pass
 536                 // to the parent function to get the actual SQL text.
 537                 // In Postgres when using FOR UPDATE, only the main table and tables that are inner joined
 538                 // can be locked. That means tables in an outer join cannot be FOR UPDATE locked. Trying to
 539                 // do so causes a DB error. This wrapper checks which tables can be locked and adjusts it
 540                 // accordingly.
 541                 // MySQL uses "ORDER BY NULL" as an optimization hint, but that is illegal in PostgreSQL.
 542                 if ( is_array( $options ) ) {
 543                         $forUpdateKey = array_search( 'FOR UPDATE', $options, true );
 544                         if ( $forUpdateKey !== false && $join_conds ) {
 545                                 unset( $options[$forUpdateKey] );
 546
 547                                 foreach ( $join_conds as $table_cond => $join_cond ) {
 548                                         if ( 0 === preg_match( '/^(?:LEFT|RIGHT|FULL)(?: OUTER)? JOIN$/i', $join_cond[0] ) ) {
 549                                                 $options['FOR UPDATE'][] = $table_cond;
 550                                         }
 551                                 }
 552                         }
 553
 554                         if ( isset( $options['ORDER BY'] ) && $options['ORDER BY'] == 'NULL' ) {
 555                                 unset( $options['ORDER BY'] );
 556                         }
 557                 }
 558
 559                 return parent::selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
 560         }
 561
 562         /**
 563          * INSERT wrapper, inserts an array into a table
 564          *
 565          * $args may be a single associative array, or an array of these with numeric keys,
 566          * for multi-row insert (Postgres version 8.2 and above only).
 567          *
 568          * @param string $table Name of the table to insert to.
 569          * @param array $args Items to insert into the table.
 570          * @param string $fname Name of the function, for profiling
 571          * @param array|string $options String or array. Valid options: IGNORE
 572          * @return bool Success of insert operation. IGNORE always returns true.
 573          */
 574         function insert( $table, $args, $fname = __METHOD__, $options = [] ) {
 575                 if ( !count( $args ) ) {
 576                         return true;
 577                 }
 578
 579                 $table = $this->tableName( $table );
 580                 if ( !isset( $this->numericVersion ) ) {
 581                         $this->getServerVersion();
 582                 }
 583
 584                 if ( !is_array( $options ) ) {
 585                         $options = [ $options ];
 586                 }
 587
 588                 if ( isset( $args[0] ) && is_array( $args[0] ) ) {
 589                         $multi = true;
 590                         $keys = array_keys( $args[0] );
 591                 } else {
 592                         $multi = false;
 593                         $keys = array_keys( $args );
 594                 }
 595
 596                 // If IGNORE is set, we use savepoints to emulate mysql's behavior
 597                 $savepoint = $olde = null;
 598                 $numrowsinserted = 0;
 599                 if ( in_array( 'IGNORE', $options ) ) {
 600                         $savepoint = new SavepointPostgres( $this, 'mw', $this->queryLogger );
 601                         $olde = error_reporting( 0 );
 602                         // For future use, we may want to track the number of actual inserts
 603                         // Right now, insert (all writes) simply return true/false
 604                 }
 605
 606                 $sql = "INSERT INTO $table (" . implode( ',', $keys ) . ') VALUES ';
 607
 608                 if ( $multi ) {
 609                         if ( $this->numericVersion >= 8.2 && !$savepoint ) {
 610                                 $first = true;
 611                                 foreach ( $args as $row ) {
 612                                         if ( $first ) {
 613                                                 $first = false;
 614                                         } else {
 615                                                 $sql .= ',';
 616                                         }
 617                                         $sql .= '(' . $this->makeList( $row ) . ')';
 618                                 }
 619                                 $res = (bool)$this->query( $sql, $fname, $savepoint );
 620                         } else {
 621                                 $res = true;
 622                                 $origsql = $sql;
 623                                 foreach ( $args as $row ) {
 624                                         $tempsql = $origsql;
 625                                         $tempsql .= '(' . $this->makeList( $row ) . ')';
 626
 627                                         if ( $savepoint ) {
 628                                                 $savepoint->savepoint();
 629                                         }
 630
 631                                         $tempres = (bool)$this->query( $tempsql, $fname, $savepoint );
 632
 633                                         if ( $savepoint ) {
 634                                                 $bar = pg_result_error( $this->mLastResult );
 635                                                 if ( $bar != false ) {
 636                                                         $savepoint->rollback();
 637                                                 } else {
 638                                                         $savepoint->release();
 639                                                         $numrowsinserted++;
 640                                                 }
 641                                         }
 642
 643                                         // If any of them fail, we fail overall for this function call
 644                                         // Note that this will be ignored if IGNORE is set
 645                                         if ( !$tempres ) {
 646                                                 $res = false;
 647                                         }
 648                                 }
 649                         }
 650                 } else {
 651                         // Not multi, just a lone insert
 652                         if ( $savepoint ) {
 653                                 $savepoint->savepoint();
 654                         }
 655
 656                         $sql .= '(' . $this->makeList( $args ) . ')';
 657                         $res = (bool)$this->query( $sql, $fname, $savepoint );
 658                         if ( $savepoint ) {
 659                                 $bar = pg_result_error( $this->mLastResult );
 660                                 if ( $bar != false ) {
 661                                         $savepoint->rollback();
 662                                 } else {
 663                                         $savepoint->release();
 664                                         $numrowsinserted++;
 665                                 }
 666                         }
 667                 }
 668                 if ( $savepoint ) {
 669                         error_reporting( $olde );
 670                         $savepoint->commit();
 671
 672                         // Set the affected row count for the whole operation
 673                         $this->mAffectedRows = $numrowsinserted;
 674
 675                         // IGNORE always returns true
 676                         return true;
 677                 }
 678
 679                 return $res;
 680         }
 681
 682         /**
 683          * INSERT SELECT wrapper
 684          * $varMap must be an associative array of the form [ 'dest1' => 'source1', ... ]
 685          * Source items may be literals rather then field names, but strings should
 686          * be quoted with Database::addQuotes()
 687          * $conds may be "*" to copy the whole table
 688          * srcTable may be an array of tables.
 689          * @todo FIXME: Implement this a little better (seperate select/insert)?
 690          *
 691          * @param string $destTable
 692          * @param array|string $srcTable
 693          * @param array $varMap
 694          * @param array $conds
 695          * @param string $fname
 696          * @param array $insertOptions
 697          * @param array $selectOptions
 698          * @return bool
 699          */
 700         function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds, $fname = __METHOD__,
 701                 $insertOptions = [], $selectOptions = [] ) {
 702                 $destTable = $this->tableName( $destTable );
 703
 704                 if ( !is_array( $insertOptions ) ) {
 705                         $insertOptions = [ $insertOptions ];
 706                 }
 707
 708                 /*
 709                  * If IGNORE is set, we use savepoints to emulate mysql's behavior
 710                  * Ignore LOW PRIORITY option, since it is MySQL-specific
 711                  */
 712                 $savepoint = $olde = null;
 713                 $numrowsinserted = 0;
 714                 if ( in_array( 'IGNORE', $insertOptions ) ) {
 715                         $savepoint = new SavepointPostgres( $this, 'mw', $this->queryLogger );
 716                         $olde = error_reporting( 0 );
 717                         $savepoint->savepoint();
 718                 }
 719
 720                 if ( !is_array( $selectOptions ) ) {
 721                         $selectOptions = [ $selectOptions ];
 722                 }
 723                 list( $startOpts, $useIndex, $tailOpts, $ignoreIndex ) =
 724                         $this->makeSelectOptions( $selectOptions );
 725                 if ( is_array( $srcTable ) ) {
 726                         $srcTable = implode( ',', array_map( [ &$this, 'tableName' ], $srcTable ) );
 727                 } else {
 728                         $srcTable = $this->tableName( $srcTable );
 729                 }
 730
 731                 $sql = "INSERT INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
 732                         " SELECT $startOpts " . implode( ',', $varMap ) .
 733                         " FROM $srcTable $useIndex $ignoreIndex ";
 734
 735                 if ( $conds != '*' ) {
 736                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
 737                 }
 738
 739                 $sql .= " $tailOpts";
 740
 741                 $res = (bool)$this->query( $sql, $fname, $savepoint );
 742                 if ( $savepoint ) {
 743                         $bar = pg_result_error( $this->mLastResult );
 744                         if ( $bar != false ) {
 745                                 $savepoint->rollback();
 746                         } else {
 747                                 $savepoint->release();
 748                                 $numrowsinserted++;
 749                         }
 750                         error_reporting( $olde );
 751                         $savepoint->commit();
 752
 753                         // Set the affected row count for the whole operation
 754                         $this->mAffectedRows = $numrowsinserted;
 755
 756                         // IGNORE always returns true
 757                         return true;
 758                 }
 759
 760                 return $res;
 761         }
 762
 763         function tableName( $name, $format = 'quoted' ) {
 764                 # Replace reserved words with better ones
 765                 switch ( $name ) {
 766                         case 'user':
 767                                 return $this->realTableName( 'mwuser', $format );
 768                         case 'text':
 769                                 return $this->realTableName( 'pagecontent', $format );
 770                         default:
 771                                 return $this->realTableName( $name, $format );
 772                 }
 773         }
 774
 775         /* Don't cheat on installer */
 776         function realTableName( $name, $format = 'quoted' ) {
 777                 return parent::tableName( $name, $format );
 778         }
 779
 780         /**
 781          * Return the next in a sequence, save the value for retrieval via insertId()
 782          *
 783          * @param string $seqName
 784          * @return int|null
 785          */
 786         function nextSequenceValue( $seqName ) {
 787                 $safeseq = str_replace( "'", "''", $seqName );
 788                 $res = $this->query( "SELECT nextval('$safeseq')" );
 789                 $row = $this->fetchRow( $res );
 790                 $this->mInsertId = $row[0];
 791
 792                 return $this->mInsertId;
 793         }
 794
 795         /**
 796          * Return the current value of a sequence. Assumes it has been nextval'ed in this session.
 797          *
 798          * @param string $seqName
 799          * @return int
 800          */
 801         function currentSequenceValue( $seqName ) {
 802                 $safeseq = str_replace( "'", "''", $seqName );
 803                 $res = $this->query( "SELECT currval('$safeseq')" );
 804                 $row = $this->fetchRow( $res );
 805                 $currval = $row[0];
 806
 807                 return $currval;
 808         }
 809
 810         # Returns the size of a text field, or -1 for "unlimited"
 811         function textFieldSize( $table, $field ) {
 812                 $table = $this->tableName( $table );
 813                 $sql = "SELECT t.typname as ftype,a.atttypmod as size
 814                         FROM pg_class c, pg_attribute a, pg_type t
 815                         WHERE relname='$table' AND a.attrelid=c.oid AND
 816                                 a.atttypid=t.oid and a.attname='$field'";
 817                 $res = $this->query( $sql );
 818                 $row = $this->fetchObject( $res );
 819                 if ( $row->ftype == 'varchar' ) {
 820                         $size = $row->size - 4;
 821                 } else {
 822                         $size = $row->size;
 823                 }
 824
 825                 return $size;
 826         }
 827
 828         function limitResult( $sql, $limit, $offset = false ) {
 829                 return "$sql LIMIT $limit " . ( is_numeric( $offset ) ? " OFFSET {$offset} " : '' );
 830         }
 831
 832         function wasDeadlock() {
 833                 return $this->lastErrno() == '40P01';
 834         }
 835
 836         function duplicateTableStructure(
 837                 $oldName, $newName, $temporary = false, $fname = __METHOD__
 838         ) {
 839                 $newName = $this->addIdentifierQuotes( $newName );
 840                 $oldName = $this->addIdentifierQuotes( $oldName );
 841
 842                 return $this->query( 'CREATE ' . ( $temporary ? 'TEMPORARY ' : '' ) . " TABLE $newName " .
 843                         "(LIKE $oldName INCLUDING DEFAULTS)", $fname );
 844         }
 845
 846         function listTables( $prefix = null, $fname = __METHOD__ ) {
 847                 $eschema = $this->addQuotes( $this->getCoreSchema() );
 848                 $result = $this->query(
 849                         "SELECT tablename FROM pg_tables WHERE schemaname = $eschema", $fname );
 850                 $endArray = [];
 851
 852                 foreach ( $result as $table ) {
 853                         $vars = get_object_vars( $table );
 854                         $table = array_pop( $vars );
 855                         if ( !$prefix || strpos( $table, $prefix ) === 0 ) {
 856                                 $endArray[] = $table;
 857                         }
 858                 }
 859
 860                 return $endArray;
 861         }
 862
 863         function timestamp( $ts = 0 ) {
 864                 $ct = new ConvertibleTimestamp( $ts );
 865
 866                 return $ct->getTimestamp( TS_POSTGRES );
 867         }
 868
 869         /**
 870          * Posted by cc[plus]php[at]c2se[dot]com on 25-Mar-2009 09:12
 871          * to http://www.php.net/manual/en/ref.pgsql.php
 872          *
 873          * Parsing a postgres array can be a tricky problem, he's my
 874          * take on this, it handles multi-dimensional arrays plus
 875          * escaping using a nasty regexp to determine the limits of each
 876          * data-item.
 877          *
 878          * This should really be handled by PHP PostgreSQL module
 879          *
 880          * @since 1.19
 881          * @param string $text Postgreql array returned in a text form like {a,b}
 882          * @param string $output
 883          * @param int|bool $limit
 884          * @param int $offset
 885          * @return string
 886          */
 887         function pg_array_parse( $text, &$output, $limit = false, $offset = 1 ) {
 888                 if ( false === $limit ) {
 889                         $limit = strlen( $text ) - 1;
 890                         $output = [];
 891                 }
 892                 if ( '{}' == $text ) {
 893                         return $output;
 894                 }
 895                 do {
 896                         if ( '{' != $text[$offset] ) {
 897                                 preg_match( "/(\\{?\"([^\"\\\\]|\\\\.)*\"|[^,{}]+)+([,}]+)/",
 898                                         $text, $match, 0, $offset );
 899                                 $offset += strlen( $match[0] );
 900                                 $output[] = ( '"' != $match[1][0]
 901                                         ? $match[1]
 902                                         : stripcslashes( substr( $match[1], 1, -1 ) ) );
 903                                 if ( '},' == $match[3] ) {
 904                                         return $output;
 905                                 }
 906                         } else {
 907                                 $offset = $this->pg_array_parse( $text, $output, $limit, $offset + 1 );
 908                         }
 909                 } while ( $limit > $offset );
 910
 911                 return $output;
 912         }
 913
 914         /**
 915          * Return aggregated value function call
 916          * @param array $valuedata
 917          * @param string $valuename
 918          * @return array
 919          */
 920         public function aggregateValue( $valuedata, $valuename = 'value' ) {
 921                 return $valuedata;
 922         }
 923
 924         /**
 925          * @return string Wikitext of a link to the server software's web site
 926          */
 927         public function getSoftwareLink() {
 928                 return '[{{int:version-db-postgres-url}} PostgreSQL]';
 929         }
 930
 931         /**
 932          * Return current schema (executes SELECT current_schema())
 933          * Needs transaction
 934          *
 935          * @since 1.19
 936          * @return string Default schema for the current session
 937          */
 938         function getCurrentSchema() {
 939                 $res = $this->query( "SELECT current_schema()", __METHOD__ );
 940                 $row = $this->fetchRow( $res );
 941
 942                 return $row[0];
 943         }
 944
 945         /**
 946          * Return list of schemas which are accessible without schema name
 947          * This is list does not contain magic keywords like "$user"
 948          * Needs transaction
 949          *
 950          * @see getSearchPath()
 951          * @see setSearchPath()
 952          * @since 1.19
 953          * @return array List of actual schemas for the current sesson
 954          */
 955         function getSchemas() {
 956                 $res = $this->query( "SELECT current_schemas(false)", __METHOD__ );
 957                 $row = $this->fetchRow( $res );
 958                 $schemas = [];
 959
 960                 /* PHP pgsql support does not support array type, "{a,b}" string is returned */
 961
 962                 return $this->pg_array_parse( $row[0], $schemas );
 963         }
 964
 965         /**
 966          * Return search patch for schemas
 967          * This is different from getSchemas() since it contain magic keywords
 968          * (like "$user").
 969          * Needs transaction
 970          *
 971          * @since 1.19
 972          * @return array How to search for table names schemas for the current user
 973          */
 974         function getSearchPath() {
 975                 $res = $this->query( "SHOW search_path", __METHOD__ );
 976                 $row = $this->fetchRow( $res );
 977
 978                 /* PostgreSQL returns SHOW values as strings */
 979
 980                 return explode( ",", $row[0] );
 981         }
 982
 983         /**
 984          * Update search_path, values should already be sanitized
 985          * Values may contain magic keywords like "$user"
 986          * @since 1.19
 987          *
 988          * @param array $search_path List of schemas to be searched by default
 989          */
 990         function setSearchPath( $search_path ) {
 991                 $this->query( "SET search_path = " . implode( ", ", $search_path ) );
 992         }
 993
 994         /**
 995          * Determine default schema for the current application
 996          * Adjust this session schema search path if desired schema exists
 997          * and is not alread there.
 998          *
 999          * We need to have name of the core schema stored to be able
1000          * to query database metadata.
1001          *
1002          * This will be also called by the installer after the schema is created
1003          *
1004          * @since 1.19
1005          *
1006          * @param string $desiredSchema
1007          */
1008         function determineCoreSchema( $desiredSchema ) {
1009                 $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
1010                 if ( $this->schemaExists( $desiredSchema ) ) {
1011                         if ( in_array( $desiredSchema, $this->getSchemas() ) ) {
1012                                 $this->mCoreSchema = $desiredSchema;
1013                                 $this->queryLogger->debug(
1014                                         "Schema \"" . $desiredSchema . "\" already in the search path\n" );
1015                         } else {
1016                                 /**
1017                                  * Prepend our schema (e.g. 'mediawiki') in front
1018                                  * of the search path
1019                                  * Fixes bug 15816
1020                                  */
1021                                 $search_path = $this->getSearchPath();
1022                                 array_unshift( $search_path,
1023                                         $this->addIdentifierQuotes( $desiredSchema ) );
1024                                 $this->setSearchPath( $search_path );
1025                                 $this->mCoreSchema = $desiredSchema;
1026                                 $this->queryLogger->debug(
1027                                         "Schema \"" . $desiredSchema . "\" added to the search path\n" );
1028                         }
1029                 } else {
1030                         $this->mCoreSchema = $this->getCurrentSchema();
1031                         $this->queryLogger->debug(
1032                                 "Schema \"" . $desiredSchema . "\" not found, using current \"" .
1033                                 $this->mCoreSchema . "\"\n" );
1034                 }
1035                 /* Commit SET otherwise it will be rollbacked on error or IGNORE SELECT */
1036                 $this->commit( __METHOD__ );
1037         }
1038
1039         /**
1040          * Return schema name for core application tables
1041          *
1042          * @since 1.19
1043          * @return string Core schema name
1044          */
1045         function getCoreSchema() {
1046                 return $this->mCoreSchema;
1047         }
1048
1049         /**
1050          * @return string Version information from the database
1051          */
1052         function getServerVersion() {
1053                 if ( !isset( $this->numericVersion ) ) {
1054                         $versionInfo = pg_version( $this->mConn );
1055                         if ( version_compare( $versionInfo['client'], '7.4.0', 'lt' ) ) {
1056                                 // Old client, abort install
1057                                 $this->numericVersion = '7.3 or earlier';
1058                         } elseif ( isset( $versionInfo['server'] ) ) {
1059                                 // Normal client
1060                                 $this->numericVersion = $versionInfo['server'];
1061                         } else {
1062                                 // Bug 16937: broken pgsql extension from PHP<5.3
1063                                 $this->numericVersion = pg_parameter_status( $this->mConn, 'server_version' );
1064                         }
1065                 }
1066
1067                 return $this->numericVersion;
1068         }
1069
1070         /**
1071          * Query whether a given relation exists (in the given schema, or the
1072          * default mw one if not given)
1073          * @param string $table
1074          * @param array|string $types
1075          * @param bool|string $schema
1076          * @return bool
1077          */
1078         function relationExists( $table, $types, $schema = false ) {
1079                 if ( !is_array( $types ) ) {
1080                         $types = [ $types ];
1081                 }
1082                 if ( !$schema ) {
1083                         $schema = $this->getCoreSchema();
1084                 }
1085                 $table = $this->realTableName( $table, 'raw' );
1086                 $etable = $this->addQuotes( $table );
1087                 $eschema = $this->addQuotes( $schema );
1088                 $sql = "SELECT 1 FROM pg_catalog.pg_class c, pg_catalog.pg_namespace n "
1089                         . "WHERE c.relnamespace = n.oid AND c.relname = $etable AND n.nspname = $eschema "
1090                         . "AND c.relkind IN ('" . implode( "','", $types ) . "')";
1091                 $res = $this->query( $sql );
1092                 $count = $res ? $res->numRows() : 0;
1093
1094                 return (bool)$count;
1095         }
1096
1097         /**
1098          * For backward compatibility, this function checks both tables and
1099          * views.
1100          * @param string $table
1101          * @param string $fname
1102          * @param bool|string $schema
1103          * @return bool
1104          */
1105         function tableExists( $table, $fname = __METHOD__, $schema = false ) {
1106                 return $this->relationExists( $table, [ 'r', 'v' ], $schema );
1107         }
1108
1109         function sequenceExists( $sequence, $schema = false ) {
1110                 return $this->relationExists( $sequence, 'S', $schema );
1111         }
1112
1113         function triggerExists( $table, $trigger ) {
1114                 $q = <<<SQL
1115         SELECT 1 FROM pg_class, pg_namespace, pg_trigger
1116                 WHERE relnamespace=pg_namespace.oid AND relkind='r'
1117                           AND tgrelid=pg_class.oid
1118                           AND nspname=%s AND relname=%s AND tgname=%s
1119 SQL;
1120                 $res = $this->query(
1121                         sprintf(
1122                                 $q,
1123                                 $this->addQuotes( $this->getCoreSchema() ),
1124                                 $this->addQuotes( $table ),
1125                                 $this->addQuotes( $trigger )
1126                         )
1127                 );
1128                 if ( !$res ) {
1129                         return null;
1130                 }
1131                 $rows = $res->numRows();
1132
1133                 return $rows;
1134         }
1135
1136         function ruleExists( $table, $rule ) {
1137                 $exists = $this->selectField( 'pg_rules', 'rulename',
1138                         [
1139                                 'rulename' => $rule,
1140                                 'tablename' => $table,
1141                                 'schemaname' => $this->getCoreSchema()
1142                         ]
1143                 );
1144
1145                 return $exists === $rule;
1146         }
1147
1148         function constraintExists( $table, $constraint ) {
1149                 $sql = sprintf( "SELECT 1 FROM information_schema.table_constraints " .
1150                         "WHERE constraint_schema = %s AND table_name = %s AND constraint_name = %s",
1151                         $this->addQuotes( $this->getCoreSchema() ),
1152                         $this->addQuotes( $table ),
1153                         $this->addQuotes( $constraint )
1154                 );
1155                 $res = $this->query( $sql );
1156                 if ( !$res ) {
1157                         return null;
1158                 }
1159                 $rows = $res->numRows();
1160
1161                 return $rows;
1162         }
1163
1164         /**
1165          * Query whether a given schema exists. Returns true if it does, false if it doesn't.
1166          * @param string $schema
1167          * @return bool
1168          */
1169         function schemaExists( $schema ) {
1170                 $exists = $this->selectField( '"pg_catalog"."pg_namespace"', 1,
1171                         [ 'nspname' => $schema ], __METHOD__ );
1172
1173                 return (bool)$exists;
1174         }
1175
1176         /**
1177          * Returns true if a given role (i.e. user) exists, false otherwise.
1178          * @param string $roleName
1179          * @return bool
1180          */
1181         function roleExists( $roleName ) {
1182                 $exists = $this->selectField( '"pg_catalog"."pg_roles"', 1,
1183                         [ 'rolname' => $roleName ], __METHOD__ );
1184
1185                 return (bool)$exists;
1186         }
1187
1188         /**
1189          * @var string $table
1190          * @var string $field
1191          * @return PostgresField|null
1192          */
1193         function fieldInfo( $table, $field ) {
1194                 return PostgresField::fromText( $this, $table, $field );
1195         }
1196
1197         /**
1198          * pg_field_type() wrapper
1199          * @param ResultWrapper|resource $res ResultWrapper or PostgreSQL query result resource
1200          * @param int $index Field number, starting from 0
1201          * @return string
1202          */
1203         function fieldType( $res, $index ) {
1204                 if ( $res instanceof ResultWrapper ) {
1205                         $res = $res->result;
1206                 }
1207
1208                 return pg_field_type( $res, $index );
1209         }
1210
1211         /**
1212          * @param string $b
1213          * @return Blob
1214          */
1215         function encodeBlob( $b ) {
1216                 return new PostgresBlob( pg_escape_bytea( $b ) );
1217         }
1218
1219         function decodeBlob( $b ) {
1220                 if ( $b instanceof PostgresBlob ) {
1221                         $b = $b->fetch();
1222                 } elseif ( $b instanceof Blob ) {
1223                         return $b->fetch();
1224                 }
1225
1226                 return pg_unescape_bytea( $b );
1227         }
1228
1229         function strencode( $s ) {
1230                 // Should not be called by us
1231
1232                 return pg_escape_string( $this->mConn, $s );
1233         }
1234
1235         /**
1236          * @param string|int|null|bool|Blob $s
1237          * @return string|int
1238          */
1239         function addQuotes( $s ) {
1240                 if ( is_null( $s ) ) {
1241                         return 'NULL';
1242                 } elseif ( is_bool( $s ) ) {
1243                         return intval( $s );
1244                 } elseif ( $s instanceof Blob ) {
1245                         if ( $s instanceof PostgresBlob ) {
1246                                 $s = $s->fetch();
1247                         } else {
1248                                 $s = pg_escape_bytea( $this->mConn, $s->fetch() );
1249                         }
1250                         return "'$s'";
1251                 }
1252
1253                 return "'" . pg_escape_string( $this->mConn, $s ) . "'";
1254         }
1255
1256         /**
1257          * Postgres specific version of replaceVars.
1258          * Calls the parent version in Database.php
1259          *
1260          * @param string $ins SQL string, read from a stream (usually tables.sql)
1261          * @return string SQL string
1262          */
1263         protected function replaceVars( $ins ) {
1264                 $ins = parent::replaceVars( $ins );
1265
1266                 if ( $this->numericVersion >= 8.3 ) {
1267                         // Thanks for not providing backwards-compatibility, 8.3
1268                         $ins = preg_replace( "/to_tsvector\s*\(\s*'default'\s*,/", 'to_tsvector(', $ins );
1269                 }
1270
1271                 if ( $this->numericVersion <= 8.1 ) { // Our minimum version
1272                         $ins = str_replace( 'USING gin', 'USING gist', $ins );
1273                 }
1274
1275                 return $ins;
1276         }
1277
1278         /**
1279          * Various select options
1280          *
1281          * @param array $options An associative array of options to be turned into
1282          *   an SQL query, valid keys are listed in the function.
1283          * @return array
1284          */
1285         function makeSelectOptions( $options ) {
1286                 $preLimitTail = $postLimitTail = '';
1287                 $startOpts = $useIndex = $ignoreIndex = '';
1288
1289                 $noKeyOptions = [];
1290                 foreach ( $options as $key => $option ) {
1291                         if ( is_numeric( $key ) ) {
1292                                 $noKeyOptions[$option] = true;
1293                         }
1294                 }
1295
1296                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1297
1298                 $preLimitTail .= $this->makeOrderBy( $options );
1299
1300                 // if ( isset( $options['LIMIT'] ) ) {
1301                 //      $tailOpts .= $this->limitResult( '', $options['LIMIT'],
1302                 //              isset( $options['OFFSET'] ) ? $options['OFFSET']
1303                 //              : false );
1304                 // }
1305
1306                 if ( isset( $options['FOR UPDATE'] ) ) {
1307                         $postLimitTail .= ' FOR UPDATE OF ' .
1308                                 implode( ', ', array_map( [ &$this, 'tableName' ], $options['FOR UPDATE'] ) );
1309                 } elseif ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1310                         $postLimitTail .= ' FOR UPDATE';
1311                 }
1312
1313                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1314                         $startOpts .= 'DISTINCT';
1315                 }
1316
1317                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1318         }
1319
1320         function getDBname() {
1321                 return $this->mDBname;
1322         }
1323
1324         function getServer() {
1325                 return $this->mServer;
1326         }
1327
1328         function buildConcat( $stringList ) {
1329                 return implode( ' || ', $stringList );
1330         }
1331
1332         public function buildGroupConcatField(
1333                 $delimiter, $table, $field, $conds = '', $options = [], $join_conds = []
1334         ) {
1335                 $fld = "array_to_string(array_agg($field)," . $this->addQuotes( $delimiter ) . ')';
1336
1337                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1338         }
1339
1340         /**
1341          * @param string $field Field or column to cast
1342          * @return string
1343          * @since 1.28
1344          */
1345         public function buildStringCast( $field ) {
1346                 return $field . '::text';
1347         }
1348
1349         public function streamStatementEnd( &$sql, &$newLine ) {
1350                 # Allow dollar quoting for function declarations
1351                 if ( substr( $newLine, 0, 4 ) == '$mw$' ) {
1352                         if ( $this->delimiter ) {
1353                                 $this->delimiter = false;
1354                         } else {
1355                                 $this->delimiter = ';';
1356                         }
1357                 }
1358
1359                 return parent::streamStatementEnd( $sql, $newLine );
1360         }
1361
1362         /**
1363          * Check to see if a named lock is available. This is non-blocking.
1364          * See http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1365          *
1366          * @param string $lockName Name of lock to poll
1367          * @param string $method Name of method calling us
1368          * @return bool
1369          * @since 1.20
1370          */
1371         public function lockIsFree( $lockName, $method ) {
1372                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1373                 $result = $this->query( "SELECT (CASE(pg_try_advisory_lock($key))
1374                         WHEN 'f' THEN 'f' ELSE pg_advisory_unlock($key) END) AS lockstatus", $method );
1375                 $row = $this->fetchObject( $result );
1376
1377                 return ( $row->lockstatus === 't' );
1378         }
1379
1380         /**
1381          * See http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1382          * @param string $lockName
1383          * @param string $method
1384          * @param int $timeout
1385          * @return bool
1386          */
1387         public function lock( $lockName, $method, $timeout = 5 ) {
1388                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1389                 $loop = new WaitConditionLoop(
1390                         function () use ( $lockName, $key, $timeout, $method ) {
1391                                 $res = $this->query( "SELECT pg_try_advisory_lock($key) AS lockstatus", $method );
1392                                 $row = $this->fetchObject( $res );
1393                                 if ( $row->lockstatus === 't' ) {
1394                                         parent::lock( $lockName, $method, $timeout ); // record
1395                                         return true;
1396                                 }
1397
1398                                 return WaitConditionLoop::CONDITION_CONTINUE;
1399                         },
1400                         $timeout
1401                 );
1402
1403                 return ( $loop->invoke() === $loop::CONDITION_REACHED );
1404         }
1405
1406         /**
1407          * See http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKSFROM
1408          * PG DOCS: http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1409          * @param string $lockName
1410          * @param string $method
1411          * @return bool
1412          */
1413         public function unlock( $lockName, $method ) {
1414                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1415                 $result = $this->query( "SELECT pg_advisory_unlock($key) as lockstatus", $method );
1416                 $row = $this->fetchObject( $result );
1417
1418                 if ( $row->lockstatus === 't' ) {
1419                         parent::unlock( $lockName, $method ); // record
1420                         return true;
1421                 }
1422
1423                 $this->queryLogger->debug( __METHOD__ . " failed to release lock\n" );
1424
1425                 return false;
1426         }
1427
1428         /**
1429          * @param string $lockName
1430          * @return string Integer
1431          */
1432         private function bigintFromLockName( $lockName ) {
1433                 return Wikimedia\base_convert( substr( sha1( $lockName ), 0, 15 ), 16, 10 );
1434         }
1435 }