1 files changed, 87 insertions, 0 deletions
diff --git a/www/wiki/extensions/SemanticMediaWiki/src/MediaWiki/Connection/Sequence.php b/www/wiki/extensions/SemanticMediaWiki/src/MediaWiki/Connection/Sequence.php
new file mode 100644
index 00000000..e2b225ca
--- /dev/null
+++ b/www/wiki/extensions/SemanticMediaWiki/src/MediaWiki/Connection/Sequence.php
@@ -0,0 +1,87 @@
+<?php
+
+namespace SMW\MediaWiki\Connection;
+
+use SMW\SQLStore\SQLStore;
+use RuntimeException;
+
+/**
+ * @license GNU GPL v2+
+ * @since 3.0
+ *
+ * @author mwjames
+ */
+class Sequence {
+
+	/**
+	 * @var Database
+	 */
+	private $connection;
+
+	/**
+	 * @var string
+	 */
+	private $tablePrefix;
+
+	/**
+	 * @since 3.0
+	 */
+	public function __construct( $connection ) {
+
+		if ( !$connection instanceof Database && !$connection instanceof \DatabaseBase ) {
+			throw new RuntimeException( "Invalid connection instance!" );
+		}
+
+		$this->connection = $connection;
+	}
+
+	/**
+	 * @since 3.0
+	 */
+	public function tablePrefix( $tablePrefix = '' ) {
+		$this->tablePrefix = $tablePrefix;
+	}
+
+	/**
+	 * @since 3.0
+	 *
+	 * @param string $tableName
+	 * @param string $field
+	 *
+	 * @return string
+	 */
+	public static function makeSequence( $table, $field ) {
+		return "{$table}_{$field}_seq";
+	}
+
+	/**
+	 * @since 3.0
+	 *
+	 * @param string $tableName
+	 * @param string $field
+	 *
+	 * @return integer
+	 */
+	public function restart( $table, $field ) {
+
+		if ( $this->connection->getType() !== 'postgres' ) {
+			return;
+		}
+
+		if ( $this->tablePrefix !== null ) {
+			$this->connection->tablePrefix( $this->tablePrefix );
+		}
+
+		$seq_num = $this->connection->selectField( $table, "max({$field})", [], __METHOD__ );
+		$seq_num += 1;
+
+		$sequence = self::makeSequence( $table, $field );
+
+		$this->connection->onTransactionIdle( function() use( $sequence, $seq_num ) {
+			$this->connection->query( "ALTER SEQUENCE {$sequence} RESTART WITH {$seq_num}", __METHOD__ );
+		} );
+
+		return $seq_num;
+	}
+
+}