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PostgresPlatform.php
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PostgresPlatform.php
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<?php
/**
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
* http://www.gnu.org/copyleft/gpl.html
*
* @file
*/
namespace Wikimedia\Rdbms\Platform;
use Wikimedia\Rdbms\DBLanguageError;
use Wikimedia\Rdbms\Query;
use Wikimedia\Timestamp\ConvertibleTimestamp;
/**
* @since 1.39
* @see ISQLPlatform
*/
class PostgresPlatform extends SQLPlatform {
/** @var string */
private $coreSchema;
public function limitResult( $sql, $limit, $offset = false ) {
return "$sql LIMIT $limit " . ( is_numeric( $offset ) ? " OFFSET {$offset} " : '' );
}
public function buildConcat( $stringList ) {
return implode( ' || ', $stringList );
}
public function timestamp( $ts = 0 ) {
$ct = new ConvertibleTimestamp( $ts );
return $ct->getTimestamp( TS_POSTGRES );
}
public function buildStringCast( $field ) {
return $field . '::text';
}
public function implicitOrderby() {
return false;
}
public function getCoreSchema(): string {
return $this->coreSchema;
}
public function setCoreSchema( string $coreSchema ): void {
$this->coreSchema = $coreSchema;
}
public function selectSQLText(
$tables, $vars, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
) {
if ( is_string( $options ) ) {
$options = [ $options ];
}
// Change the FOR UPDATE option as necessary based on the join conditions. Then pass
// to the parent function to get the actual SQL text.
// In Postgres when using FOR UPDATE, only the main table and tables that are inner joined
// can be locked. That means tables in an outer join cannot be FOR UPDATE locked. Trying to
// do so causes a DB error. This wrapper checks which tables can be locked and adjusts it
// accordingly.
// MySQL uses "ORDER BY NULL" as an optimization hint, but that is illegal in PostgreSQL.
if ( is_array( $options ) ) {
$forUpdateKey = array_search( 'FOR UPDATE', $options, true );
if ( $forUpdateKey !== false && $join_conds ) {
unset( $options[$forUpdateKey] );
$options['FOR UPDATE'] = [];
$toCheck = $tables;
reset( $toCheck );
while ( $toCheck ) {
$alias = key( $toCheck );
$table = $toCheck[$alias];
unset( $toCheck[$alias] );
if ( !is_string( $alias ) ) {
// No alias? Set it equal to the table name
$alias = $table;
}
if ( !isset( $join_conds[$alias] ) ||
!preg_match( '/^(?:LEFT|RIGHT|FULL)(?: OUTER)? JOIN$/i', $join_conds[$alias][0] )
) {
if ( is_array( $table ) ) {
// It's a parenthesized group, process all the tables inside the group.
$toCheck = array_merge( $toCheck, $table );
} else {
// If an alias is declared, then any FOR UPDATE FOR must use it
$options['FOR UPDATE'][] = $alias;
}
}
}
}
if (
isset( $options['ORDER BY'] ) &&
( $options['ORDER BY'] == 'NULL' || $options['ORDER BY'] == [ 'NULL' ] )
) {
unset( $options['ORDER BY'] );
}
}
return parent::selectSQLText( $tables, $vars, $conds, $fname, $options, $join_conds );
}
protected function makeSelectOptions( array $options ) {
$preLimitTail = $postLimitTail = '';
$startOpts = '';
$noKeyOptions = [];
foreach ( $options as $key => $option ) {
if ( is_numeric( $key ) ) {
$noKeyOptions[$option] = true;
}
}
$preLimitTail .= $this->makeGroupByWithHaving( $options );
$preLimitTail .= $this->makeOrderBy( $options );
if ( isset( $options['FOR UPDATE'] ) ) {
$postLimitTail .= ' FOR UPDATE OF ' . implode(
', ',
array_map( [ $this, 'addIdentifierQuotes' ], $options['FOR UPDATE'] )
);
} elseif ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
$postLimitTail .= ' FOR UPDATE';
}
if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
$startOpts .= 'DISTINCT';
}
return [ $startOpts, $preLimitTail, $postLimitTail ];
}
public function getDatabaseAndTableIdentifier( string $table ) {
$components = $this->qualifiedTableComponents( $table );
switch ( count( $components ) ) {
case 1:
return [ $this->currentDomain->getDatabase(), $components[0] ];
case 2:
return [ $this->currentDomain->getDatabase(), $components[1] ];
case 3:
return [ $components[0], $components[2] ];
default:
throw new DBLanguageError( 'Too many table components' );
}
}
protected function relationSchemaQualifier() {
if ( $this->coreSchema === $this->currentDomain->getSchema() ) {
// The schema to be used is now in the search path; no need for explicit qualification
return '';
}
return parent::relationSchemaQualifier();
}
public function buildGroupConcatField(
$delim, $tables, $field, $conds = '', $join_conds = []
) {
$fld = "array_to_string(array_agg($field)," . $this->quoter->addQuotes( $delim ) . ')';
return '(' . $this->selectSQLText( $tables, $fld, $conds, static::CALLER_SUBQUERY, [], $join_conds ) . ')';
}
public function makeInsertLists( array $rows, $aliasPrefix = '', array $typeByColumn = [] ) {
$firstRow = $rows[0];
if ( !is_array( $firstRow ) || !$firstRow ) {
throw new DBLanguageError( 'Got an empty row list or empty row' );
}
// List of columns that define the value tuple ordering
$tupleColumns = array_keys( $firstRow );
$valueTuples = [];
foreach ( $rows as $row ) {
$rowColumns = array_keys( $row );
// VALUES(...) requires a uniform correspondence of (column => value)
if ( $rowColumns !== $tupleColumns ) {
throw new DBLanguageError(
'Got row columns (' . implode( ', ', $rowColumns ) . ') ' .
'instead of expected (' . implode( ', ', $tupleColumns ) . ')'
);
}
// Make the value tuple that defines this row
$typedRowValues = [];
foreach ( $row as $column => $value ) {
$type = $typeByColumn[$column] ?? null;
if ( $value === null ) {
$typedRowValues[] = 'NULL';
} elseif ( $type !== null ) {
$typedRowValues[] = $this->quoter->addQuotes( $value ) . '::' . $type;
} else {
$typedRowValues[] = $this->quoter->addQuotes( $value );
}
}
$valueTuples[] = '(' . implode( ',', $typedRowValues ) . ')';
}
$magicAliasFields = [];
foreach ( $tupleColumns as $column ) {
$magicAliasFields[] = $aliasPrefix . $column;
}
return [
$this->makeList( $tupleColumns, self::LIST_NAMES ),
implode( ',', $valueTuples ),
$this->makeList( $magicAliasFields, self::LIST_NAMES )
];
}
protected function makeInsertNonConflictingVerbAndOptions() {
return [ 'INSERT INTO', 'ON CONFLICT DO NOTHING' ];
}
protected function makeUpdateOptionsArray( $options ) {
$options = $this->normalizeOptions( $options );
// PostgreSQL doesn't support anything like "ignore" for UPDATE.
$options = array_diff( $options, [ 'IGNORE' ] );
return parent::makeUpdateOptionsArray( $options );
}
public function isTransactableQuery( Query $sql ) {
return parent::isTransactableQuery( $sql ) &&
!preg_match( '/^SELECT\s+pg_(try_|)advisory_\w+\(/', $sql->getSQL() );
}
public function lockSQLText( $lockName, $timeout ) {
// http://www.postgresql.org/docs/9.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
$key = $this->quoter->addQuotes( $this->bigintFromLockName( $lockName ) );
return "SELECT (CASE WHEN pg_try_advisory_lock($key) " .
"THEN EXTRACT(epoch from clock_timestamp()) " .
"ELSE NULL " .
"END) AS acquired";
}
public function lockIsFreeSQLText( $lockName ) {
// http://www.postgresql.org/docs/9.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
$key = $this->quoter->addQuotes( $this->bigintFromLockName( $lockName ) );
return "SELECT (CASE(pg_try_advisory_lock($key))
WHEN FALSE THEN FALSE ELSE pg_advisory_unlock($key) END) AS unlocked";
}
public function unlockSQLText( $lockName ) {
// http://www.postgresql.org/docs/9.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
$key = $this->quoter->addQuotes( $this->bigintFromLockName( $lockName ) );
return "SELECT pg_advisory_unlock($key) AS released";
}
/**
* @param string $lockName
* @return string Integer
*/
private function bigintFromLockName( $lockName ) {
return \Wikimedia\base_convert( substr( sha1( $lockName ), 0, 15 ), 16, 10 );
}
}

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PostgresPlatform.php (8 KB)

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