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                 $conn = $this->getBindingHandle();
  65
  66                 $sql = "SELECT 1 FROM pg_catalog.pg_constraint c, pg_catalog.pg_namespace n " .
  67                         "WHERE c.connamespace = n.oid AND conname = '" .
  68                         pg_escape_string( $conn, $name ) . "' AND n.nspname = '" .
  69                         pg_escape_string( $conn, $this->getCoreSchema() ) . "'";
  70                 $res = $this->doQuery( $sql );
  71
  72                 return $this->numRows( $res );
  73         }
  74
  75         /**
  76          * Usually aborts on failure
  77          * @param string $server
  78          * @param string $user
  79          * @param string $password
  80          * @param string $dbName
  81          * @throws DBConnectionError|Exception
  82          * @return resource|bool|null
  83          */
  84         function open( $server, $user, $password, $dbName ) {
  85                 # Test for Postgres support, to avoid suppressed fatal error
  86                 if ( !function_exists( 'pg_connect' ) ) {
  87                         throw new DBConnectionError(
  88                                 $this,
  89                                 "Postgres functions missing, have you compiled PHP with the --with-pgsql\n" .
  90                                 "option? (Note: if you recently installed PHP, you may need to restart your\n" .
  91                                 "webserver and database)\n"
  92                         );
  93                 }
  94
  95                 $this->mServer = $server;
  96                 $this->mUser = $user;
  97                 $this->mPassword = $password;
  98                 $this->mDBname = $dbName;
  99
 100                 $connectVars = [
 101                         'dbname' => $dbName,
 102                         'user' => $user,
 103                         'password' => $password
 104                 ];
 105                 if ( $server != false && $server != '' ) {
 106                         $connectVars['host'] = $server;
 107                 }
 108                 if ( (int)$this->port > 0 ) {
 109                         $connectVars['port'] = (int)$this->port;
 110                 }
 111                 if ( $this->mFlags & self::DBO_SSL ) {
 112                         $connectVars['sslmode'] = 1;
 113                 }
 114
 115                 $this->connectString = $this->makeConnectionString( $connectVars );
 116                 $this->close();
 117                 $this->installErrorHandler();
 118
 119                 try {
 120                         // Use new connections to let LoadBalancer/LBFactory handle reuse
 121                         $this->mConn = pg_connect( $this->connectString, PGSQL_CONNECT_FORCE_NEW );
 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(
 131                                 "DB connection error\n" .
 132                                 "Server: $server, Database: $dbName, User: $user, Password: " .
 133                                 substr( $password, 0, 3 ) . "...\n"
 134                         );
 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                 // The schema to be used is now in the search path; no need for explicit qualification
 156                 $this->mSchema = null;
 157
 158                 return $this->mConn;
 159         }
 160
 161         /**
 162          * Postgres doesn't support selectDB in the same way MySQL does. So if the
 163          * DB name doesn't match the open connection, open a new one
 164          * @param string $db
 165          * @return bool
 166          */
 167         function selectDB( $db ) {
 168                 if ( $this->mDBname !== $db ) {
 169                         return (bool)$this->open( $this->mServer, $this->mUser, $this->mPassword, $db );
 170                 } else {
 171                         return true;
 172                 }
 173         }
 174
 175         function makeConnectionString( $vars ) {
 176                 $s = '';
 177                 foreach ( $vars as $name => $value ) {
 178                         $s .= "$name='" . str_replace( "'", "\\'", $value ) . "' ";
 179                 }
 180
 181                 return $s;
 182         }
 183
 184         /**
 185          * Closes a database connection, if it is open
 186          * Returns success, true if already closed
 187          * @return bool
 188          */
 189         protected function closeConnection() {
 190                 return $this->mConn ? pg_close( $this->mConn ) : true;
 191         }
 192
 193         public function doQuery( $sql ) {
 194                 $conn = $this->getBindingHandle();
 195
 196                 $sql = mb_convert_encoding( $sql, 'UTF-8' );
 197                 // Clear previously left over PQresult
 198                 while ( $res = pg_get_result( $conn ) ) {
 199                         pg_free_result( $res );
 200                 }
 201                 if ( pg_send_query( $conn, $sql ) === false ) {
 202                         throw new DBUnexpectedError( $this, "Unable to post new query to PostgreSQL\n" );
 203                 }
 204                 $this->mLastResult = pg_get_result( $conn );
 205                 $this->mAffectedRows = null;
 206                 if ( pg_result_error( $this->mLastResult ) ) {
 207                         return false;
 208                 }
 209
 210                 return $this->mLastResult;
 211         }
 212
 213         protected function dumpError() {
 214                 $diags = [
 215                         PGSQL_DIAG_SEVERITY,
 216                         PGSQL_DIAG_SQLSTATE,
 217                         PGSQL_DIAG_MESSAGE_PRIMARY,
 218                         PGSQL_DIAG_MESSAGE_DETAIL,
 219                         PGSQL_DIAG_MESSAGE_HINT,
 220                         PGSQL_DIAG_STATEMENT_POSITION,
 221                         PGSQL_DIAG_INTERNAL_POSITION,
 222                         PGSQL_DIAG_INTERNAL_QUERY,
 223                         PGSQL_DIAG_CONTEXT,
 224                         PGSQL_DIAG_SOURCE_FILE,
 225                         PGSQL_DIAG_SOURCE_LINE,
 226                         PGSQL_DIAG_SOURCE_FUNCTION
 227                 ];
 228                 foreach ( $diags as $d ) {
 229                         $this->queryLogger->debug( sprintf( "PgSQL ERROR(%d): %s\n",
 230                                 $d, pg_result_error_field( $this->mLastResult, $d ) ) );
 231                 }
 232         }
 233
 234         function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
 235                 if ( $tempIgnore ) {
 236                         /* Check for constraint violation */
 237                         if ( $errno === '23505' ) {
 238                                 parent::reportQueryError( $error, $errno, $sql, $fname, $tempIgnore );
 239
 240                                 return;
 241                         }
 242                 }
 243                 /* Transaction stays in the ERROR state until rolled back */
 244                 if ( $this->mTrxLevel ) {
 245                         $ignore = $this->ignoreErrors( true );
 246                         $this->rollback( __METHOD__ );
 247                         $this->ignoreErrors( $ignore );
 248                 }
 249                 parent::reportQueryError( $error, $errno, $sql, $fname, false );
 250         }
 251
 252         function queryIgnore( $sql, $fname = __METHOD__ ) {
 253                 return $this->query( $sql, $fname, true );
 254         }
 255
 256         /**
 257          * @param stdClass|ResultWrapper $res
 258          * @throws DBUnexpectedError
 259          */
 260         function freeResult( $res ) {
 261                 if ( $res instanceof ResultWrapper ) {
 262                         $res = $res->result;
 263                 }
 264                 MediaWiki\suppressWarnings();
 265                 $ok = pg_free_result( $res );
 266                 MediaWiki\restoreWarnings();
 267                 if ( !$ok ) {
 268                         throw new DBUnexpectedError( $this, "Unable to free Postgres result\n" );
 269                 }
 270         }
 271
 272         /**
 273          * @param ResultWrapper|stdClass $res
 274          * @return stdClass
 275          * @throws DBUnexpectedError
 276          */
 277         function fetchObject( $res ) {
 278                 if ( $res instanceof ResultWrapper ) {
 279                         $res = $res->result;
 280                 }
 281                 MediaWiki\suppressWarnings();
 282                 $row = pg_fetch_object( $res );
 283                 MediaWiki\restoreWarnings();
 284                 # @todo FIXME: HACK HACK HACK HACK debug
 285
 286                 # @todo hashar: not sure if the following test really trigger if the object
 287                 #          fetching failed.
 288                 $conn = $this->getBindingHandle();
 289                 if ( pg_last_error( $conn ) ) {
 290                         throw new DBUnexpectedError(
 291                                 $this,
 292                                 'SQL error: ' . htmlspecialchars( pg_last_error( $conn ) )
 293                         );
 294                 }
 295
 296                 return $row;
 297         }
 298
 299         function fetchRow( $res ) {
 300                 if ( $res instanceof ResultWrapper ) {
 301                         $res = $res->result;
 302                 }
 303                 MediaWiki\suppressWarnings();
 304                 $row = pg_fetch_array( $res );
 305                 MediaWiki\restoreWarnings();
 306
 307                 $conn = $this->getBindingHandle();
 308                 if ( pg_last_error( $conn ) ) {
 309                         throw new DBUnexpectedError(
 310                                 $this,
 311                                 'SQL error: ' . htmlspecialchars( pg_last_error( $conn ) )
 312                         );
 313                 }
 314
 315                 return $row;
 316         }
 317
 318         function numRows( $res ) {
 319                 if ( $res instanceof ResultWrapper ) {
 320                         $res = $res->result;
 321                 }
 322                 MediaWiki\suppressWarnings();
 323                 $n = pg_num_rows( $res );
 324                 MediaWiki\restoreWarnings();
 325
 326                 $conn = $this->getBindingHandle();
 327                 if ( pg_last_error( $conn ) ) {
 328                         throw new DBUnexpectedError(
 329                                 $this,
 330                                 'SQL error: ' . htmlspecialchars( pg_last_error( $conn ) )
 331                         );
 332                 }
 333
 334                 return $n;
 335         }
 336
 337         function numFields( $res ) {
 338                 if ( $res instanceof ResultWrapper ) {
 339                         $res = $res->result;
 340                 }
 341
 342                 return pg_num_fields( $res );
 343         }
 344
 345         function fieldName( $res, $n ) {
 346                 if ( $res instanceof ResultWrapper ) {
 347                         $res = $res->result;
 348                 }
 349
 350                 return pg_field_name( $res, $n );
 351         }
 352
 353         /**
 354          * Return the result of the last call to nextSequenceValue();
 355          * This must be called after nextSequenceValue().
 356          *
 357          * @return int|null
 358          */
 359         function insertId() {
 360                 return $this->mInsertId;
 361         }
 362
 363         /**
 364          * @param mixed $res
 365          * @param int $row
 366          * @return bool
 367          */
 368         function dataSeek( $res, $row ) {
 369                 if ( $res instanceof ResultWrapper ) {
 370                         $res = $res->result;
 371                 }
 372
 373                 return pg_result_seek( $res, $row );
 374         }
 375
 376         function lastError() {
 377                 if ( $this->mConn ) {
 378                         if ( $this->mLastResult ) {
 379                                 return pg_result_error( $this->mLastResult );
 380                         } else {
 381                                 return pg_last_error();
 382                         }
 383                 }
 384
 385                 return $this->getLastPHPError() ?: 'No database connection';
 386         }
 387
 388         function lastErrno() {
 389                 if ( $this->mLastResult ) {
 390                         return pg_result_error_field( $this->mLastResult, PGSQL_DIAG_SQLSTATE );
 391                 } else {
 392                         return false;
 393                 }
 394         }
 395
 396         function affectedRows() {
 397                 if ( !is_null( $this->mAffectedRows ) ) {
 398                         // Forced result for simulated queries
 399                         return $this->mAffectedRows;
 400                 }
 401                 if ( empty( $this->mLastResult ) ) {
 402                         return 0;
 403                 }
 404
 405                 return pg_affected_rows( $this->mLastResult );
 406         }
 407
 408         /**
 409          * Estimate rows in dataset
 410          * Returns estimated count, based on EXPLAIN output
 411          * This is not necessarily an accurate estimate, so use sparingly
 412          * Returns -1 if count cannot be found
 413          * Takes same arguments as Database::select()
 414          *
 415          * @param string $table
 416          * @param string $vars
 417          * @param string $conds
 418          * @param string $fname
 419          * @param array $options
 420          * @return int
 421          */
 422         function estimateRowCount( $table, $vars = '*', $conds = '',
 423                 $fname = __METHOD__, $options = []
 424         ) {
 425                 $options['EXPLAIN'] = true;
 426                 $res = $this->select( $table, $vars, $conds, $fname, $options );
 427                 $rows = -1;
 428                 if ( $res ) {
 429                         $row = $this->fetchRow( $res );
 430                         $count = [];
 431                         if ( preg_match( '/rows=(\d+)/', $row[0], $count ) ) {
 432                                 $rows = (int)$count[1];
 433                         }
 434                 }
 435
 436                 return $rows;
 437         }
 438
 439         /**
 440          * Returns information about an index
 441          * If errors are explicitly ignored, returns NULL on failure
 442          *
 443          * @param string $table
 444          * @param string $index
 445          * @param string $fname
 446          * @return bool|null
 447          */
 448         function indexInfo( $table, $index, $fname = __METHOD__ ) {
 449                 $sql = "SELECT indexname FROM pg_indexes WHERE tablename='$table'";
 450                 $res = $this->query( $sql, $fname );
 451                 if ( !$res ) {
 452                         return null;
 453                 }
 454                 foreach ( $res as $row ) {
 455                         if ( $row->indexname == $this->indexName( $index ) ) {
 456                                 return $row;
 457                         }
 458                 }
 459
 460                 return false;
 461         }
 462
 463         /**
 464          * Returns is of attributes used in index
 465          *
 466          * @since 1.19
 467          * @param string $index
 468          * @param bool|string $schema
 469          * @return array
 470          */
 471         function indexAttributes( $index, $schema = false ) {
 472                 if ( $schema === false ) {
 473                         $schema = $this->getCoreSchema();
 474                 }
 475                 /*
 476                  * A subquery would be not needed if we didn't care about the order
 477                  * of attributes, but we do
 478                  */
 479                 $sql = <<<__INDEXATTR__
 480
 481                         SELECT opcname,
 482                                 attname,
 483                                 i.indoption[s.g] as option,
 484                                 pg_am.amname
 485                         FROM
 486                                 (SELECT generate_series(array_lower(isub.indkey,1), array_upper(isub.indkey,1)) AS g
 487                                         FROM
 488                                                 pg_index isub
 489                                         JOIN pg_class cis
 490                                                 ON cis.oid=isub.indexrelid
 491                                         JOIN pg_namespace ns
 492                                                 ON cis.relnamespace = ns.oid
 493                                         WHERE cis.relname='$index' AND ns.nspname='$schema') AS s,
 494                                 pg_attribute,
 495                                 pg_opclass opcls,
 496                                 pg_am,
 497                                 pg_class ci
 498                                 JOIN pg_index i
 499                                         ON ci.oid=i.indexrelid
 500                                 JOIN pg_class ct
 501                                         ON ct.oid = i.indrelid
 502                                 JOIN pg_namespace n
 503                                         ON ci.relnamespace = n.oid
 504                                 WHERE
 505                                         ci.relname='$index' AND n.nspname='$schema'
 506                                         AND     attrelid = ct.oid
 507                                         AND     i.indkey[s.g] = attnum
 508                                         AND     i.indclass[s.g] = opcls.oid
 509                                         AND     pg_am.oid = opcls.opcmethod
 510 __INDEXATTR__;
 511                 $res = $this->query( $sql, __METHOD__ );
 512                 $a = [];
 513                 if ( $res ) {
 514                         foreach ( $res as $row ) {
 515                                 $a[] = [
 516                                         $row->attname,
 517                                         $row->opcname,
 518                                         $row->amname,
 519                                         $row->option ];
 520                         }
 521                 } else {
 522                         return null;
 523                 }
 524
 525                 return $a;
 526         }
 527
 528         function indexUnique( $table, $index, $fname = __METHOD__ ) {
 529                 $sql = "SELECT indexname FROM pg_indexes WHERE tablename='{$table}'" .
 530                         " AND indexdef LIKE 'CREATE UNIQUE%(" .
 531                         $this->strencode( $this->indexName( $index ) ) .
 532                         ")'";
 533                 $res = $this->query( $sql, $fname );
 534                 if ( !$res ) {
 535                         return null;
 536                 }
 537
 538                 return $res->numRows() > 0;
 539         }
 540
 541         function selectSQLText(
 542                 $table, $vars, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
 543         ) {
 544                 // Change the FOR UPDATE option as necessary based on the join conditions. Then pass
 545                 // to the parent function to get the actual SQL text.
 546                 // In Postgres when using FOR UPDATE, only the main table and tables that are inner joined
 547                 // can be locked. That means tables in an outer join cannot be FOR UPDATE locked. Trying to
 548                 // do so causes a DB error. This wrapper checks which tables can be locked and adjusts it
 549                 // accordingly.
 550                 // MySQL uses "ORDER BY NULL" as an optimization hint, but that is illegal in PostgreSQL.
 551                 if ( is_array( $options ) ) {
 552                         $forUpdateKey = array_search( 'FOR UPDATE', $options, true );
 553                         if ( $forUpdateKey !== false && $join_conds ) {
 554                                 unset( $options[$forUpdateKey] );
 555
 556                                 foreach ( $join_conds as $table_cond => $join_cond ) {
 557                                         if ( 0 === preg_match( '/^(?:LEFT|RIGHT|FULL)(?: OUTER)? JOIN$/i', $join_cond[0] ) ) {
 558                                                 $options['FOR UPDATE'][] = $table_cond;
 559                                         }
 560                                 }
 561                         }
 562
 563                         if ( isset( $options['ORDER BY'] ) && $options['ORDER BY'] == 'NULL' ) {
 564                                 unset( $options['ORDER BY'] );
 565                         }
 566                 }
 567
 568                 return parent::selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
 569         }
 570
 571         /**
 572          * INSERT wrapper, inserts an array into a table
 573          *
 574          * $args may be a single associative array, or an array of these with numeric keys,
 575          * for multi-row insert (Postgres version 8.2 and above only).
 576          *
 577          * @param string $table Name of the table to insert to.
 578          * @param array $args Items to insert into the table.
 579          * @param string $fname Name of the function, for profiling
 580          * @param array|string $options String or array. Valid options: IGNORE
 581          * @return bool Success of insert operation. IGNORE always returns true.
 582          */
 583         function insert( $table, $args, $fname = __METHOD__, $options = [] ) {
 584                 if ( !count( $args ) ) {
 585                         return true;
 586                 }
 587
 588                 $table = $this->tableName( $table );
 589                 if ( !isset( $this->numericVersion ) ) {
 590                         $this->getServerVersion();
 591                 }
 592
 593                 if ( !is_array( $options ) ) {
 594                         $options = [ $options ];
 595                 }
 596
 597                 if ( isset( $args[0] ) && is_array( $args[0] ) ) {
 598                         $multi = true;
 599                         $keys = array_keys( $args[0] );
 600                 } else {
 601                         $multi = false;
 602                         $keys = array_keys( $args );
 603                 }
 604
 605                 // If IGNORE is set, we use savepoints to emulate mysql's behavior
 606                 $savepoint = $olde = null;
 607                 $numrowsinserted = 0;
 608                 if ( in_array( 'IGNORE', $options ) ) {
 609                         $savepoint = new SavepointPostgres( $this, 'mw', $this->queryLogger );
 610                         $olde = error_reporting( 0 );
 611                         // For future use, we may want to track the number of actual inserts
 612                         // Right now, insert (all writes) simply return true/false
 613                 }
 614
 615                 $sql = "INSERT INTO $table (" . implode( ',', $keys ) . ') VALUES ';
 616
 617                 if ( $multi ) {
 618                         if ( $this->numericVersion >= 8.2 && !$savepoint ) {
 619                                 $first = true;
 620                                 foreach ( $args as $row ) {
 621                                         if ( $first ) {
 622                                                 $first = false;
 623                                         } else {
 624                                                 $sql .= ',';
 625                                         }
 626                                         $sql .= '(' . $this->makeList( $row ) . ')';
 627                                 }
 628                                 $res = (bool)$this->query( $sql, $fname, $savepoint );
 629                         } else {
 630                                 $res = true;
 631                                 $origsql = $sql;
 632                                 foreach ( $args as $row ) {
 633                                         $tempsql = $origsql;
 634                                         $tempsql .= '(' . $this->makeList( $row ) . ')';
 635
 636                                         if ( $savepoint ) {
 637                                                 $savepoint->savepoint();
 638                                         }
 639
 640                                         $tempres = (bool)$this->query( $tempsql, $fname, $savepoint );
 641
 642                                         if ( $savepoint ) {
 643                                                 $bar = pg_result_error( $this->mLastResult );
 644                                                 if ( $bar != false ) {
 645                                                         $savepoint->rollback();
 646                                                 } else {
 647                                                         $savepoint->release();
 648                                                         $numrowsinserted++;
 649                                                 }
 650                                         }
 651
 652                                         // If any of them fail, we fail overall for this function call
 653                                         // Note that this will be ignored if IGNORE is set
 654                                         if ( !$tempres ) {
 655                                                 $res = false;
 656                                         }
 657                                 }
 658                         }
 659                 } else {
 660                         // Not multi, just a lone insert
 661                         if ( $savepoint ) {
 662                                 $savepoint->savepoint();
 663                         }
 664
 665                         $sql .= '(' . $this->makeList( $args ) . ')';
 666                         $res = (bool)$this->query( $sql, $fname, $savepoint );
 667                         if ( $savepoint ) {
 668                                 $bar = pg_result_error( $this->mLastResult );
 669                                 if ( $bar != false ) {
 670                                         $savepoint->rollback();
 671                                 } else {
 672                                         $savepoint->release();
 673                                         $numrowsinserted++;
 674                                 }
 675                         }
 676                 }
 677                 if ( $savepoint ) {
 678                         error_reporting( $olde );
 679                         $savepoint->commit();
 680
 681                         // Set the affected row count for the whole operation
 682                         $this->mAffectedRows = $numrowsinserted;
 683
 684                         // IGNORE always returns true
 685                         return true;
 686                 }
 687
 688                 return $res;
 689         }
 690
 691         /**
 692          * INSERT SELECT wrapper
 693          * $varMap must be an associative array of the form [ 'dest1' => 'source1', ... ]
 694          * Source items may be literals rather then field names, but strings should
 695          * be quoted with Database::addQuotes()
 696          * $conds may be "*" to copy the whole table
 697          * srcTable may be an array of tables.
 698          * @todo FIXME: Implement this a little better (seperate select/insert)?
 699          *
 700          * @param string $destTable
 701          * @param array|string $srcTable
 702          * @param array $varMap
 703          * @param array $conds
 704          * @param string $fname
 705          * @param array $insertOptions
 706          * @param array $selectOptions
 707          * @return bool
 708          */
 709         function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds, $fname = __METHOD__,
 710                 $insertOptions = [], $selectOptions = [] ) {
 711                 $destTable = $this->tableName( $destTable );
 712
 713                 if ( !is_array( $insertOptions ) ) {
 714                         $insertOptions = [ $insertOptions ];
 715                 }
 716
 717                 /*
 718                  * If IGNORE is set, we use savepoints to emulate mysql's behavior
 719                  * Ignore LOW PRIORITY option, since it is MySQL-specific
 720                  */
 721                 $savepoint = $olde = null;
 722                 $numrowsinserted = 0;
 723                 if ( in_array( 'IGNORE', $insertOptions ) ) {
 724                         $savepoint = new SavepointPostgres( $this, 'mw', $this->queryLogger );
 725                         $olde = error_reporting( 0 );
 726                         $savepoint->savepoint();
 727                 }
 728
 729                 if ( !is_array( $selectOptions ) ) {
 730                         $selectOptions = [ $selectOptions ];
 731                 }
 732                 list( $startOpts, $useIndex, $tailOpts, $ignoreIndex ) =
 733                         $this->makeSelectOptions( $selectOptions );
 734                 if ( is_array( $srcTable ) ) {
 735                         $srcTable = implode( ',', array_map( [ &$this, 'tableName' ], $srcTable ) );
 736                 } else {
 737                         $srcTable = $this->tableName( $srcTable );
 738                 }
 739
 740                 $sql = "INSERT INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
 741                         " SELECT $startOpts " . implode( ',', $varMap ) .
 742                         " FROM $srcTable $useIndex $ignoreIndex ";
 743
 744                 if ( $conds != '*' ) {
 745                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
 746                 }
 747
 748                 $sql .= " $tailOpts";
 749
 750                 $res = (bool)$this->query( $sql, $fname, $savepoint );
 751                 if ( $savepoint ) {
 752                         $bar = pg_result_error( $this->mLastResult );
 753                         if ( $bar != false ) {
 754                                 $savepoint->rollback();
 755                         } else {
 756                                 $savepoint->release();
 757                                 $numrowsinserted++;
 758                         }
 759                         error_reporting( $olde );
 760                         $savepoint->commit();
 761
 762                         // Set the affected row count for the whole operation
 763                         $this->mAffectedRows = $numrowsinserted;
 764
 765                         // IGNORE always returns true
 766                         return true;
 767                 }
 768
 769                 return $res;
 770         }
 771
 772         function tableName( $name, $format = 'quoted' ) {
 773                 // Replace reserved words with better ones
 774                 $name = $this->remappedTableName( $name );
 775
 776                 return parent::tableName( $name, $format );
 777         }
 778
 779         /**
 780          * @param string $name
 781          * @return string Value of $name or remapped name if $name is a reserved keyword
 782          * @TODO: dependency inject these...
 783          */
 784         public function remappedTableName( $name ) {
 785                 if ( $name === 'user' ) {
 786                         return 'mwuser';
 787                 } elseif ( $name === 'text' ) {
 788                         return 'pagecontent';
 789                 }
 790
 791                 return $name;
 792         }
 793
 794         /**
 795          * @param string $name
 796          * @param string $format
 797          * @return string Qualified and encoded (if requested) table name
 798          */
 799         public function realTableName( $name, $format = 'quoted' ) {
 800                 return parent::tableName( $name, $format );
 801         }
 802
 803         /**
 804          * Return the next in a sequence, save the value for retrieval via insertId()
 805          *
 806          * @param string $seqName
 807          * @return int|null
 808          */
 809         function nextSequenceValue( $seqName ) {
 810                 $safeseq = str_replace( "'", "''", $seqName );
 811                 $res = $this->query( "SELECT nextval('$safeseq')" );
 812                 $row = $this->fetchRow( $res );
 813                 $this->mInsertId = $row[0];
 814
 815                 return $this->mInsertId;
 816         }
 817
 818         /**
 819          * Return the current value of a sequence. Assumes it has been nextval'ed in this session.
 820          *
 821          * @param string $seqName
 822          * @return int
 823          */
 824         function currentSequenceValue( $seqName ) {
 825                 $safeseq = str_replace( "'", "''", $seqName );
 826                 $res = $this->query( "SELECT currval('$safeseq')" );
 827                 $row = $this->fetchRow( $res );
 828                 $currval = $row[0];
 829
 830                 return $currval;
 831         }
 832
 833         # Returns the size of a text field, or -1 for "unlimited"
 834         function textFieldSize( $table, $field ) {
 835                 $table = $this->tableName( $table );
 836                 $sql = "SELECT t.typname as ftype,a.atttypmod as size
 837                         FROM pg_class c, pg_attribute a, pg_type t
 838                         WHERE relname='$table' AND a.attrelid=c.oid AND
 839                                 a.atttypid=t.oid and a.attname='$field'";
 840                 $res = $this->query( $sql );
 841                 $row = $this->fetchObject( $res );
 842                 if ( $row->ftype == 'varchar' ) {
 843                         $size = $row->size - 4;
 844                 } else {
 845                         $size = $row->size;
 846                 }
 847
 848                 return $size;
 849         }
 850
 851         function limitResult( $sql, $limit, $offset = false ) {
 852                 return "$sql LIMIT $limit " . ( is_numeric( $offset ) ? " OFFSET {$offset} " : '' );
 853         }
 854
 855         function wasDeadlock() {
 856                 return $this->lastErrno() == '40P01';
 857         }
 858
 859         function duplicateTableStructure(
 860                 $oldName, $newName, $temporary = false, $fname = __METHOD__
 861         ) {
 862                 $newName = $this->addIdentifierQuotes( $newName );
 863                 $oldName = $this->addIdentifierQuotes( $oldName );
 864
 865                 return $this->query( 'CREATE ' . ( $temporary ? 'TEMPORARY ' : '' ) . " TABLE $newName " .
 866                         "(LIKE $oldName INCLUDING DEFAULTS)", $fname );
 867         }
 868
 869         function listTables( $prefix = null, $fname = __METHOD__ ) {
 870                 $eschema = $this->addQuotes( $this->getCoreSchema() );
 871                 $result = $this->query(
 872                         "SELECT tablename FROM pg_tables WHERE schemaname = $eschema", $fname );
 873                 $endArray = [];
 874
 875                 foreach ( $result as $table ) {
 876                         $vars = get_object_vars( $table );
 877                         $table = array_pop( $vars );
 878                         if ( !$prefix || strpos( $table, $prefix ) === 0 ) {
 879                                 $endArray[] = $table;
 880                         }
 881                 }
 882
 883                 return $endArray;
 884         }
 885
 886         function timestamp( $ts = 0 ) {
 887                 $ct = new ConvertibleTimestamp( $ts );
 888
 889                 return $ct->getTimestamp( TS_POSTGRES );
 890         }
 891
 892         /**
 893          * Posted by cc[plus]php[at]c2se[dot]com on 25-Mar-2009 09:12
 894          * to http://www.php.net/manual/en/ref.pgsql.php
 895          *
 896          * Parsing a postgres array can be a tricky problem, he's my
 897          * take on this, it handles multi-dimensional arrays plus
 898          * escaping using a nasty regexp to determine the limits of each
 899          * data-item.
 900          *
 901          * This should really be handled by PHP PostgreSQL module
 902          *
 903          * @since 1.19
 904          * @param string $text Postgreql array returned in a text form like {a,b}
 905          * @param string $output
 906          * @param int|bool $limit
 907          * @param int $offset
 908          * @return string
 909          */
 910         function pg_array_parse( $text, &$output, $limit = false, $offset = 1 ) {
 911                 if ( false === $limit ) {
 912                         $limit = strlen( $text ) - 1;
 913                         $output = [];
 914                 }
 915                 if ( '{}' == $text ) {
 916                         return $output;
 917                 }
 918                 do {
 919                         if ( '{' != $text[$offset] ) {
 920                                 preg_match( "/(\\{?\"([^\"\\\\]|\\\\.)*\"|[^,{}]+)+([,}]+)/",
 921                                         $text, $match, 0, $offset );
 922                                 $offset += strlen( $match[0] );
 923                                 $output[] = ( '"' != $match[1][0]
 924                                         ? $match[1]
 925                                         : stripcslashes( substr( $match[1], 1, -1 ) ) );
 926                                 if ( '},' == $match[3] ) {
 927                                         return $output;
 928                                 }
 929                         } else {
 930                                 $offset = $this->pg_array_parse( $text, $output, $limit, $offset + 1 );
 931                         }
 932                 } while ( $limit > $offset );
 933
 934                 return $output;
 935         }
 936
 937         /**
 938          * Return aggregated value function call
 939          * @param array $valuedata
 940          * @param string $valuename
 941          * @return array
 942          */
 943         public function aggregateValue( $valuedata, $valuename = 'value' ) {
 944                 return $valuedata;
 945         }
 946
 947         /**
 948          * @return string Wikitext of a link to the server software's web site
 949          */
 950         public function getSoftwareLink() {
 951                 return '[{{int:version-db-postgres-url}} PostgreSQL]';
 952         }
 953
 954         /**
 955          * Return current schema (executes SELECT current_schema())
 956          * Needs transaction
 957          *
 958          * @since 1.19
 959          * @return string Default schema for the current session
 960          */
 961         function getCurrentSchema() {
 962                 $res = $this->query( "SELECT current_schema()", __METHOD__ );
 963                 $row = $this->fetchRow( $res );
 964
 965                 return $row[0];
 966         }
 967
 968         /**
 969          * Return list of schemas which are accessible without schema name
 970          * This is list does not contain magic keywords like "$user"
 971          * Needs transaction
 972          *
 973          * @see getSearchPath()
 974          * @see setSearchPath()
 975          * @since 1.19
 976          * @return array List of actual schemas for the current sesson
 977          */
 978         function getSchemas() {
 979                 $res = $this->query( "SELECT current_schemas(false)", __METHOD__ );
 980                 $row = $this->fetchRow( $res );
 981                 $schemas = [];
 982
 983                 /* PHP pgsql support does not support array type, "{a,b}" string is returned */
 984
 985                 return $this->pg_array_parse( $row[0], $schemas );
 986         }
 987
 988         /**
 989          * Return search patch for schemas
 990          * This is different from getSchemas() since it contain magic keywords
 991          * (like "$user").
 992          * Needs transaction
 993          *
 994          * @since 1.19
 995          * @return array How to search for table names schemas for the current user
 996          */
 997         function getSearchPath() {
 998                 $res = $this->query( "SHOW search_path", __METHOD__ );
 999                 $row = $this->fetchRow( $res );
1000
1001                 /* PostgreSQL returns SHOW values as strings */
1002
1003                 return explode( ",", $row[0] );
1004         }
1005
1006         /**
1007          * Update search_path, values should already be sanitized
1008          * Values may contain magic keywords like "$user"
1009          * @since 1.19
1010          *
1011          * @param array $search_path List of schemas to be searched by default
1012          */
1013         function setSearchPath( $search_path ) {
1014                 $this->query( "SET search_path = " . implode( ", ", $search_path ) );
1015         }
1016
1017         /**
1018          * Determine default schema for the current application
1019          * Adjust this session schema search path if desired schema exists
1020          * and is not alread there.
1021          *
1022          * We need to have name of the core schema stored to be able
1023          * to query database metadata.
1024          *
1025          * This will be also called by the installer after the schema is created
1026          *
1027          * @since 1.19
1028          *
1029          * @param string $desiredSchema
1030          */
1031         function determineCoreSchema( $desiredSchema ) {
1032                 $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
1033                 if ( $this->schemaExists( $desiredSchema ) ) {
1034                         if ( in_array( $desiredSchema, $this->getSchemas() ) ) {
1035                                 $this->mCoreSchema = $desiredSchema;
1036                                 $this->queryLogger->debug(
1037                                         "Schema \"" . $desiredSchema . "\" already in the search path\n" );
1038                         } else {
1039                                 /**
1040                                  * Prepend our schema (e.g. 'mediawiki') in front
1041                                  * of the search path
1042                                  * Fixes bug 15816
1043                                  */
1044                                 $search_path = $this->getSearchPath();
1045                                 array_unshift( $search_path,
1046                                         $this->addIdentifierQuotes( $desiredSchema ) );
1047                                 $this->setSearchPath( $search_path );
1048                                 $this->mCoreSchema = $desiredSchema;
1049                                 $this->queryLogger->debug(
1050                                         "Schema \"" . $desiredSchema . "\" added to the search path\n" );
1051                         }
1052                 } else {
1053                         $this->mCoreSchema = $this->getCurrentSchema();
1054                         $this->queryLogger->debug(
1055                                 "Schema \"" . $desiredSchema . "\" not found, using current \"" .
1056                                 $this->mCoreSchema . "\"\n" );
1057                 }
1058                 /* Commit SET otherwise it will be rollbacked on error or IGNORE SELECT */
1059                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
1060         }
1061
1062         /**
1063          * Return schema name for core application tables
1064          *
1065          * @since 1.19
1066          * @return string Core schema name
1067          */
1068         function getCoreSchema() {
1069                 return $this->mCoreSchema;
1070         }
1071
1072         /**
1073          * @return string Version information from the database
1074          */
1075         function getServerVersion() {
1076                 if ( !isset( $this->numericVersion ) ) {
1077                         $conn = $this->getBindingHandle();
1078                         $versionInfo = pg_version( $conn );
1079                         if ( version_compare( $versionInfo['client'], '7.4.0', 'lt' ) ) {
1080                                 // Old client, abort install
1081                                 $this->numericVersion = '7.3 or earlier';
1082                         } elseif ( isset( $versionInfo['server'] ) ) {
1083                                 // Normal client
1084                                 $this->numericVersion = $versionInfo['server'];
1085                         } else {
1086                                 // Bug 16937: broken pgsql extension from PHP<5.3
1087                                 $this->numericVersion = pg_parameter_status( $conn, 'server_version' );
1088                         }
1089                 }
1090
1091                 return $this->numericVersion;
1092         }
1093
1094         /**
1095          * Query whether a given relation exists (in the given schema, or the
1096          * default mw one if not given)
1097          * @param string $table
1098          * @param array|string $types
1099          * @param bool|string $schema
1100          * @return bool
1101          */
1102         function relationExists( $table, $types, $schema = false ) {
1103                 if ( !is_array( $types ) ) {
1104                         $types = [ $types ];
1105                 }
1106                 if ( $schema === false ) {
1107                         $schema = $this->getCoreSchema();
1108                 }
1109                 $etable = $this->addQuotes( $table );
1110                 $eschema = $this->addQuotes( $schema );
1111                 $sql = "SELECT 1 FROM pg_catalog.pg_class c, pg_catalog.pg_namespace n "
1112                         . "WHERE c.relnamespace = n.oid AND c.relname = $etable AND n.nspname = $eschema "
1113                         . "AND c.relkind IN ('" . implode( "','", $types ) . "')";
1114                 $res = $this->query( $sql );
1115                 $count = $res ? $res->numRows() : 0;
1116
1117                 return (bool)$count;
1118         }
1119
1120         /**
1121          * For backward compatibility, this function checks both tables and
1122          * views.
1123          * @param string $table
1124          * @param string $fname
1125          * @param bool|string $schema
1126          * @return bool
1127          */
1128         function tableExists( $table, $fname = __METHOD__, $schema = false ) {
1129                 return $this->relationExists( $table, [ 'r', 'v' ], $schema );
1130         }
1131
1132         function sequenceExists( $sequence, $schema = false ) {
1133                 return $this->relationExists( $sequence, 'S', $schema );
1134         }
1135
1136         function triggerExists( $table, $trigger ) {
1137                 $q = <<<SQL
1138         SELECT 1 FROM pg_class, pg_namespace, pg_trigger
1139                 WHERE relnamespace=pg_namespace.oid AND relkind='r'
1140                           AND tgrelid=pg_class.oid
1141                           AND nspname=%s AND relname=%s AND tgname=%s
1142 SQL;
1143                 $res = $this->query(
1144                         sprintf(
1145                                 $q,
1146                                 $this->addQuotes( $this->getCoreSchema() ),
1147                                 $this->addQuotes( $table ),
1148                                 $this->addQuotes( $trigger )
1149                         )
1150                 );
1151                 if ( !$res ) {
1152                         return null;
1153                 }
1154                 $rows = $res->numRows();
1155
1156                 return $rows;
1157         }
1158
1159         function ruleExists( $table, $rule ) {
1160                 $exists = $this->selectField( 'pg_rules', 'rulename',
1161                         [
1162                                 'rulename' => $rule,
1163                                 'tablename' => $table,
1164                                 'schemaname' => $this->getCoreSchema()
1165                         ]
1166                 );
1167
1168                 return $exists === $rule;
1169         }
1170
1171         function constraintExists( $table, $constraint ) {
1172                 $sql = sprintf( "SELECT 1 FROM information_schema.table_constraints " .
1173                         "WHERE constraint_schema = %s AND table_name = %s AND constraint_name = %s",
1174                         $this->addQuotes( $this->getCoreSchema() ),
1175                         $this->addQuotes( $table ),
1176                         $this->addQuotes( $constraint )
1177                 );
1178                 $res = $this->query( $sql );
1179                 if ( !$res ) {
1180                         return null;
1181                 }
1182                 $rows = $res->numRows();
1183
1184                 return $rows;
1185         }
1186
1187         /**
1188          * Query whether a given schema exists. Returns true if it does, false if it doesn't.
1189          * @param string $schema
1190          * @return bool
1191          */
1192         function schemaExists( $schema ) {
1193                 if ( !strlen( $schema ) ) {
1194                         return false; // short-circuit
1195                 }
1196
1197                 $exists = $this->selectField(
1198                         '"pg_catalog"."pg_namespace"', 1, [ 'nspname' => $schema ], __METHOD__ );
1199
1200                 return (bool)$exists;
1201         }
1202
1203         /**
1204          * Returns true if a given role (i.e. user) exists, false otherwise.
1205          * @param string $roleName
1206          * @return bool
1207          */
1208         function roleExists( $roleName ) {
1209                 $exists = $this->selectField( '"pg_catalog"."pg_roles"', 1,
1210                         [ 'rolname' => $roleName ], __METHOD__ );
1211
1212                 return (bool)$exists;
1213         }
1214
1215         /**
1216          * @var string $table
1217          * @var string $field
1218          * @return PostgresField|null
1219          */
1220         function fieldInfo( $table, $field ) {
1221                 return PostgresField::fromText( $this, $table, $field );
1222         }
1223
1224         /**
1225          * pg_field_type() wrapper
1226          * @param ResultWrapper|resource $res ResultWrapper or PostgreSQL query result resource
1227          * @param int $index Field number, starting from 0
1228          * @return string
1229          */
1230         function fieldType( $res, $index ) {
1231                 if ( $res instanceof ResultWrapper ) {
1232                         $res = $res->result;
1233                 }
1234
1235                 return pg_field_type( $res, $index );
1236         }
1237
1238         /**
1239          * @param string $b
1240          * @return Blob
1241          */
1242         function encodeBlob( $b ) {
1243                 return new PostgresBlob( pg_escape_bytea( $b ) );
1244         }
1245
1246         function decodeBlob( $b ) {
1247                 if ( $b instanceof PostgresBlob ) {
1248                         $b = $b->fetch();
1249                 } elseif ( $b instanceof Blob ) {
1250                         return $b->fetch();
1251                 }
1252
1253                 return pg_unescape_bytea( $b );
1254         }
1255
1256         function strencode( $s ) {
1257                 // Should not be called by us
1258                 return pg_escape_string( $this->getBindingHandle(), $s );
1259         }
1260
1261         /**
1262          * @param string|int|null|bool|Blob $s
1263          * @return string|int
1264          */
1265         function addQuotes( $s ) {
1266                 $conn = $this->getBindingHandle();
1267
1268                 if ( is_null( $s ) ) {
1269                         return 'NULL';
1270                 } elseif ( is_bool( $s ) ) {
1271                         return intval( $s );
1272                 } elseif ( $s instanceof Blob ) {
1273                         if ( $s instanceof PostgresBlob ) {
1274                                 $s = $s->fetch();
1275                         } else {
1276                                 $s = pg_escape_bytea( $conn, $s->fetch() );
1277                         }
1278                         return "'$s'";
1279                 }
1280
1281                 return "'" . pg_escape_string( $conn, $s ) . "'";
1282         }
1283
1284         /**
1285          * Postgres specific version of replaceVars.
1286          * Calls the parent version in Database.php
1287          *
1288          * @param string $ins SQL string, read from a stream (usually tables.sql)
1289          * @return string SQL string
1290          */
1291         protected function replaceVars( $ins ) {
1292                 $ins = parent::replaceVars( $ins );
1293
1294                 if ( $this->numericVersion >= 8.3 ) {
1295                         // Thanks for not providing backwards-compatibility, 8.3
1296                         $ins = preg_replace( "/to_tsvector\s*\(\s*'default'\s*,/", 'to_tsvector(', $ins );
1297                 }
1298
1299                 if ( $this->numericVersion <= 8.1 ) { // Our minimum version
1300                         $ins = str_replace( 'USING gin', 'USING gist', $ins );
1301                 }
1302
1303                 return $ins;
1304         }
1305
1306         /**
1307          * Various select options
1308          *
1309          * @param array $options An associative array of options to be turned into
1310          *   an SQL query, valid keys are listed in the function.
1311          * @return array
1312          */
1313         function makeSelectOptions( $options ) {
1314                 $preLimitTail = $postLimitTail = '';
1315                 $startOpts = $useIndex = $ignoreIndex = '';
1316
1317                 $noKeyOptions = [];
1318                 foreach ( $options as $key => $option ) {
1319                         if ( is_numeric( $key ) ) {
1320                                 $noKeyOptions[$option] = true;
1321                         }
1322                 }
1323
1324                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1325
1326                 $preLimitTail .= $this->makeOrderBy( $options );
1327
1328                 // if ( isset( $options['LIMIT'] ) ) {
1329                 //      $tailOpts .= $this->limitResult( '', $options['LIMIT'],
1330                 //              isset( $options['OFFSET'] ) ? $options['OFFSET']
1331                 //              : false );
1332                 // }
1333
1334                 if ( isset( $options['FOR UPDATE'] ) ) {
1335                         $postLimitTail .= ' FOR UPDATE OF ' .
1336                                 implode( ', ', array_map( [ &$this, 'tableName' ], $options['FOR UPDATE'] ) );
1337                 } elseif ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1338                         $postLimitTail .= ' FOR UPDATE';
1339                 }
1340
1341                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1342                         $startOpts .= 'DISTINCT';
1343                 }
1344
1345                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1346         }
1347
1348         function getDBname() {
1349                 return $this->mDBname;
1350         }
1351
1352         function getServer() {
1353                 return $this->mServer;
1354         }
1355
1356         function buildConcat( $stringList ) {
1357                 return implode( ' || ', $stringList );
1358         }
1359
1360         public function buildGroupConcatField(
1361                 $delimiter, $table, $field, $conds = '', $options = [], $join_conds = []
1362         ) {
1363                 $fld = "array_to_string(array_agg($field)," . $this->addQuotes( $delimiter ) . ')';
1364
1365                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1366         }
1367
1368         /**
1369          * @param string $field Field or column to cast
1370          * @return string
1371          * @since 1.28
1372          */
1373         public function buildStringCast( $field ) {
1374                 return $field . '::text';
1375         }
1376
1377         public function streamStatementEnd( &$sql, &$newLine ) {
1378                 # Allow dollar quoting for function declarations
1379                 if ( substr( $newLine, 0, 4 ) == '$mw$' ) {
1380                         if ( $this->delimiter ) {
1381                                 $this->delimiter = false;
1382                         } else {
1383                                 $this->delimiter = ';';
1384                         }
1385                 }
1386
1387                 return parent::streamStatementEnd( $sql, $newLine );
1388         }
1389
1390         /**
1391          * Check to see if a named lock is available. This is non-blocking.
1392          * See http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1393          *
1394          * @param string $lockName Name of lock to poll
1395          * @param string $method Name of method calling us
1396          * @return bool
1397          * @since 1.20
1398          */
1399         public function lockIsFree( $lockName, $method ) {
1400                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1401                 $result = $this->query( "SELECT (CASE(pg_try_advisory_lock($key))
1402                         WHEN 'f' THEN 'f' ELSE pg_advisory_unlock($key) END) AS lockstatus", $method );
1403                 $row = $this->fetchObject( $result );
1404
1405                 return ( $row->lockstatus === 't' );
1406         }
1407
1408         /**
1409          * See http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1410          * @param string $lockName
1411          * @param string $method
1412          * @param int $timeout
1413          * @return bool
1414          */
1415         public function lock( $lockName, $method, $timeout = 5 ) {
1416                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1417                 $loop = new WaitConditionLoop(
1418                         function () use ( $lockName, $key, $timeout, $method ) {
1419                                 $res = $this->query( "SELECT pg_try_advisory_lock($key) AS lockstatus", $method );
1420                                 $row = $this->fetchObject( $res );
1421                                 if ( $row->lockstatus === 't' ) {
1422                                         parent::lock( $lockName, $method, $timeout ); // record
1423                                         return true;
1424                                 }
1425
1426                                 return WaitConditionLoop::CONDITION_CONTINUE;
1427                         },
1428                         $timeout
1429                 );
1430
1431                 return ( $loop->invoke() === $loop::CONDITION_REACHED );
1432         }
1433
1434         /**
1435          * See http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKSFROM
1436          * PG DOCS: http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1437          * @param string $lockName
1438          * @param string $method
1439          * @return bool
1440          */
1441         public function unlock( $lockName, $method ) {
1442                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1443                 $result = $this->query( "SELECT pg_advisory_unlock($key) as lockstatus", $method );
1444                 $row = $this->fetchObject( $result );
1445
1446                 if ( $row->lockstatus === 't' ) {
1447                         parent::unlock( $lockName, $method ); // record
1448                         return true;
1449                 }
1450
1451                 $this->queryLogger->debug( __METHOD__ . " failed to release lock\n" );
1452
1453                 return false;
1454         }
1455
1456         /**
1457          * @param string $lockName
1458          * @return string Integer
1459          */
1460         private function bigintFromLockName( $lockName ) {
1461                 return Wikimedia\base_convert( substr( sha1( $lockName ), 0, 15 ), 16, 10 );
1462         }
1463 }