1 files changed, 117 insertions, 0 deletions
diff --git a/www/wiki/extensions/SemanticMediaWiki/src/SQLStore/TableBuilder/TemporaryTableBuilder.php b/www/wiki/extensions/SemanticMediaWiki/src/SQLStore/TableBuilder/TemporaryTableBuilder.php
new file mode 100644
index 00000000..fac1bd90
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+++ b/www/wiki/extensions/SemanticMediaWiki/src/SQLStore/TableBuilder/TemporaryTableBuilder.php
@@ -0,0 +1,117 @@
+<?php
+
+namespace SMW\SQLStore\TableBuilder;
+
+use SMW\MediaWiki\Database;
+
+/**
+ * @license GNU GPL v2+
+ * @since 2.2
+ *
+ * @author Jeroen De Dauw < jeroendedauw@gmail.com >
+ * @author mwjames
+ */
+class TemporaryTableBuilder {
+
+	/**
+	 * @var Database
+	 */
+	private $connection;
+
+	/**
+	 * @var boolean
+	 */
+	private $autoCommitFlag = false;
+
+	/**
+	 * @since 2.3
+	 *
+	 * @param Database $connection
+	 */
+	public function __construct( Database $connection ) {
+		$this->connection = $connection;
+	}
+
+	/**
+	 * @see $smwgQTemporaryTablesWithAutoCommit
+	 * @since 2.5
+	 *
+	 * @param boolean $autoCommitFlag
+	 */
+	public function setAutoCommitFlag( $autoCommitFlag ) {
+		$this->autoCommitFlag = (bool)$autoCommitFlag;
+	}
+
+	/**
+	 * @since 2.5
+	 *
+	 * @param string $tableName
+	 */
+	public function create( $tableName ) {
+
+		if ( $this->autoCommitFlag ) {
+			$this->connection->setFlag( Database::AUTO_COMMIT );
+		}
+
+		$this->connection->query(
+			$this->getSQLCodeFor( $tableName ),
+			__METHOD__,
+			false
+		);
+	}
+
+	/**
+	 * @since 2.5
+	 *
+	 * @param string $tableName
+	 */
+	public function drop( $tableName ) {
+
+		if ( $this->autoCommitFlag ) {
+			$this->connection->setFlag( Database::AUTO_COMMIT );
+		}
+
+		$this->connection->query(
+			"DROP TEMPORARY TABLE " . $tableName,
+			__METHOD__,
+			false
+		);
+	}
+
+	/**
+	 * Get SQL code suitable to create a temporary table of the given name, used
+	 * to store ids.
+	 *
+	 * MySQL can do that simply by creating new temporary tables. PostgreSQL first
+	 * checks if such a table exists, so the code is ready to reuse existing tables
+	 * if the code was modified to keep them after query answering. Also, PostgreSQL
+	 * tables will use a RULE to achieve built-in duplicate elimination. The latter
+	 * is done using INSERT IGNORE in MySQL.
+	 *
+	 * @param string $tableName
+	 *
+	 * @return string
+	 */
+	private function getSQLCodeFor( $tableName ) {
+		// PostgreSQL: no memory tables, use RULE to emulate INSERT IGNORE
+		if ( $this->connection->isType( 'postgres' ) ) {
+
+			// Remove any double quotes from the name
+			$tableName = str_replace( '"', '', $tableName );
+
+			return "DO \$\$BEGIN "
+				. " IF EXISTS(SELECT NULL FROM pg_tables WHERE tablename='{$tableName}' AND schemaname = ANY (current_schemas(true))) "
+				. " THEN DELETE FROM {$tableName}; "
+				. " ELSE "
+				. "  CREATE TEMPORARY TABLE {$tableName} (id SERIAL); "
+				. "    CREATE RULE {$tableName}_ignore AS ON INSERT TO {$tableName} WHERE (EXISTS (SELECT 1 FROM {$tableName} "
+				. "	 WHERE ({$tableName}.id = new.id))) DO INSTEAD NOTHING; "
+				. " END IF; "
+				. "END\$\$";
+		}
+
+		// MySQL_ just a temporary table, use INSERT IGNORE later
+		return "CREATE TEMPORARY TABLE " . $tableName . "( id INT UNSIGNED KEY ) ENGINE=MEMORY";
+	}
+
+}