Move various DB helper classes to /libs/rdbms

Change-Id: I0724f1acce4f6c43b1f0983fa119e628e7c53ba5

22 files changed, 812 insertions, 846 deletions

diff --git a/autoload.php b/autoload.php
index 759c715f2a4d..1ebf728ca275 100644
--- a/autoload.php
+++ b/autoload.php
@@ -189,7 +189,7 @@ $wgAutoloadLocalClasses = [
 	'BitmapHandler' => __DIR__ . '/includes/media/Bitmap.php',
 	'BitmapHandler_ClientOnly' => __DIR__ . '/includes/media/Bitmap_ClientOnly.php',
 	'BitmapMetadataHandler' => __DIR__ . '/includes/media/BitmapMetadataHandler.php',
-	'Blob' => __DIR__ . '/includes/db/DatabaseUtility.php',
+	'Blob' => __DIR__ . '/includes/libs/rdbms/encasing/Blob.php',
 	'Block' => __DIR__ . '/includes/Block.php',
 	'BlockLevelPass' => __DIR__ . '/includes/parser/BlockLevelPass.php',
 	'BlockListPager' => __DIR__ . '/includes/specials/pagers/BlockListPager.php',
@@ -299,13 +299,13 @@ $wgAutoloadLocalClasses = [
 	'DBAccessBase' => __DIR__ . '/includes/dao/DBAccessBase.php',
 	'DBAccessError' => __DIR__ . '/includes/libs/rdbms/exception/DBError.php',
 	'DBAccessObjectUtils' => __DIR__ . '/includes/dao/DBAccessObjectUtils.php',
-	'DBConnRef' => __DIR__ . '/includes/libs/rdbms/database/RBConnRef.php',
+	'DBConnRef' => __DIR__ . '/includes/libs/rdbms/database/DBConnRef.php',
 	'DBConnectionError' => __DIR__ . '/includes/libs/rdbms/exception/DBError.php',
 	'DBError' => __DIR__ . '/includes/libs/rdbms/exception/DBError.php',
 	'DBExpectedError' => __DIR__ . '/includes/libs/rdbms/exception/DBError.php',
 	'DBFileJournal' => __DIR__ . '/includes/filebackend/filejournal/DBFileJournal.php',
 	'DBLockManager' => __DIR__ . '/includes/filebackend/lockmanager/DBLockManager.php',
-	'DBMasterPos' => __DIR__ . '/includes/db/DatabaseUtility.php',
+	'DBMasterPos' => __DIR__ . '/includes/libs/rdbms/database/position/DBMasterPos.php',
 	'DBQueryError' => __DIR__ . '/includes/libs/rdbms/exception/DBError.php',
 	'DBReadOnlyError' => __DIR__ . '/includes/libs/rdbms/exception/DBError.php',
 	'DBReplicationWaitError' => __DIR__ . '/includes/libs/rdbms/exception/DBError.php',
@@ -440,7 +440,7 @@ $wgAutoloadLocalClasses = [
 	'FakeAuthTemplate' => __DIR__ . '/includes/specialpage/LoginSignupSpecialPage.php',
 	'FakeConverter' => __DIR__ . '/languages/FakeConverter.php',
 	'FakeMaintenance' => __DIR__ . '/maintenance/Maintenance.php',
-	'FakeResultWrapper' => __DIR__ . '/includes/db/DatabaseUtility.php',
+	'FakeResultWrapper' => __DIR__ . '/includes/libs/rdbms/database/resultwrapper/FakeResultWrapper.php',
 	'FatalError' => __DIR__ . '/includes/exception/FatalError.php',
 	'FauxRequest' => __DIR__ . '/includes/FauxRequest.php',
 	'FauxResponse' => __DIR__ . '/includes/WebResponse.php',
@@ -448,7 +448,7 @@ $wgAutoloadLocalClasses = [
 	'FeedUtils' => __DIR__ . '/includes/FeedUtils.php',
 	'FetchText' => __DIR__ . '/maintenance/fetchText.php',
 	'FewestrevisionsPage' => __DIR__ . '/includes/specials/SpecialFewestrevisions.php',
-	'Field' => __DIR__ . '/includes/db/DatabaseUtility.php',
+	'Field' => __DIR__ . '/includes/libs/rdbms/field/Field.php',
 	'File' => __DIR__ . '/includes/filerepo/file/File.php',
 	'FileAwareNodeVisitor' => __DIR__ . '/maintenance/findDeprecated.php',
 	'FileBackend' => __DIR__ . '/includes/filebackend/FileBackend.php',
@@ -715,7 +715,7 @@ $wgAutoloadLocalClasses = [
 	'LegacyLogFormatter' => __DIR__ . '/includes/logging/LogFormatter.php',
 	'License' => __DIR__ . '/includes/Licenses.php',
 	'Licenses' => __DIR__ . '/includes/Licenses.php',
-	'LikeMatch' => __DIR__ . '/includes/db/DatabaseUtility.php',
+	'LikeMatch' => __DIR__ . '/includes/libs/rdbms/encasing/LikeMatch.php',
 	'LinkBatch' => __DIR__ . '/includes/cache/LinkBatch.php',
 	'LinkCache' => __DIR__ . '/includes/cache/LinkCache.php',
 	'LinkFilter' => __DIR__ . '/includes/LinkFilter.php',
@@ -943,10 +943,10 @@ $wgAutoloadLocalClasses = [
 	'MoveLogFormatter' => __DIR__ . '/includes/logging/MoveLogFormatter.php',
 	'MovePage' => __DIR__ . '/includes/MovePage.php',
 	'MovePageForm' => __DIR__ . '/includes/specials/SpecialMovepage.php',
-	'MssqlBlob' => __DIR__ . '/includes/db/DatabaseMssql.php',
-	'MssqlField' => __DIR__ . '/includes/db/DatabaseMssql.php',
+	'MssqlBlob' => __DIR__ . '/includes/libs/rdbms/encasing/MssqlBlob.php',
+	'MssqlField' => __DIR__ . '/includes/libs/rdbms/field/MssqlField.php',
 	'MssqlInstaller' => __DIR__ . '/includes/installer/MssqlInstaller.php',
-	'MssqlResultWrapper' => __DIR__ . '/includes/db/DatabaseMssql.php',
+	'MssqlResultWrapper' => __DIR__ . '/includes/libs/rdbms/database/resultwrapper/MssqlResultWrapper.php',
 	'MssqlUpdater' => __DIR__ . '/includes/installer/MssqlUpdater.php',
 	'MultiConfig' => __DIR__ . '/includes/config/MultiConfig.php',
 	'MultiHttpClient' => __DIR__ . '/includes/libs/MultiHttpClient.php',
@@ -954,8 +954,8 @@ $wgAutoloadLocalClasses = [
 	'MutableConfig' => __DIR__ . '/includes/config/MutableConfig.php',
 	'MutableContext' => __DIR__ . '/includes/context/MutableContext.php',
 	'MwSql' => __DIR__ . '/maintenance/sql.php',
-	'MySQLField' => __DIR__ . '/includes/db/DatabaseMysqlBase.php',
-	'MySQLMasterPos' => __DIR__ . '/includes/db/DatabaseMysqlBase.php',
+	'MySQLField' => __DIR__ . '/includes/libs/rdbms/field/MySQLField.php',
+	'MySQLMasterPos' => __DIR__ . '/includes/libs/rdbms/database/position/MySQLMasterPos.php',
 	'MySqlLockManager' => __DIR__ . '/includes/filebackend/lockmanager/MySqlLockManager.php',
 	'MysqlInstaller' => __DIR__ . '/includes/installer/MysqlInstaller.php',
 	'MysqlUpdater' => __DIR__ . '/includes/installer/MysqlUpdater.php',
@@ -980,7 +980,7 @@ $wgAutoloadLocalClasses = [
 	'NullStatsdDataFactory' => __DIR__ . '/includes/libs/stats/NullStatsdDataFactory.php',
 	'NumericUppercaseCollation' => __DIR__ . '/includes/collation/NumericUppercaseCollation.php',
 	'OOUIHTMLForm' => __DIR__ . '/includes/htmlform/OOUIHTMLForm.php',
-	'ORAField' => __DIR__ . '/includes/db/DatabaseOracle.php',
+	'ORAField' => __DIR__ . '/includes/libs/rdbms/field/ORAField.php',
 	'ORAResult' => __DIR__ . '/includes/db/DatabaseOracle.php',
 	'ObjectCache' => __DIR__ . '/includes/objectcache/ObjectCache.php',
 	'ObjectFactory' => __DIR__ . '/includes/libs/ObjectFactory.php',
@@ -1065,7 +1065,7 @@ $wgAutoloadLocalClasses = [
 	'PopulateRevisionLength' => __DIR__ . '/maintenance/populateRevisionLength.php',
 	'PopulateRevisionSha1' => __DIR__ . '/maintenance/populateRevisionSha1.php',
 	'PostgreSqlLockManager' => __DIR__ . '/includes/filebackend/lockmanager/PostgreSqlLockManager.php',
-	'PostgresBlob' => __DIR__ . '/includes/db/DatabasePostgres.php',
+	'PostgresBlob' => __DIR__ . '/includes/libs/rdbms/encasing/PostgresBlob.php',
 	'PostgresField' => __DIR__ . '/includes/db/DatabasePostgres.php',
 	'PostgresInstaller' => __DIR__ . '/includes/installer/PostgresInstaller.php',
 	'PostgresUpdater' => __DIR__ . '/includes/installer/PostgresUpdater.php',
@@ -1182,7 +1182,7 @@ $wgAutoloadLocalClasses = [
 	'ResourceLoaderUserTokensModule' => __DIR__ . '/includes/resourceloader/ResourceLoaderUserTokensModule.php',
 	'ResourceLoaderWikiModule' => __DIR__ . '/includes/resourceloader/ResourceLoaderWikiModule.php',
 	'RestbaseVirtualRESTService' => __DIR__ . '/includes/libs/virtualrest/RestbaseVirtualRESTService.php',
-	'ResultWrapper' => __DIR__ . '/includes/db/DatabaseUtility.php',
+	'ResultWrapper' => __DIR__ . '/includes/libs/rdbms/database/resultwrapper/ResultWrapper.php',
 	'RevDelArchiveItem' => __DIR__ . '/includes/revisiondelete/RevDelArchiveItem.php',
 	'RevDelArchiveList' => __DIR__ . '/includes/revisiondelete/RevDelArchiveList.php',
 	'RevDelArchivedFileItem' => __DIR__ . '/includes/revisiondelete/RevDelArchivedFileItem.php',
@@ -1214,7 +1214,7 @@ $wgAutoloadLocalClasses = [
 	'RowUpdateGenerator' => __DIR__ . '/includes/utils/RowUpdateGenerator.php',
 	'RunJobs' => __DIR__ . '/maintenance/runJobs.php',
 	'RunningStat' => __DIR__ . '/includes/compat/RunningStatCompat.php',
-	'SQLiteField' => __DIR__ . '/includes/db/DatabaseSqlite.php',
+	'SQLiteField' => __DIR__ . '/includes/libs/rdbms/field/SQLiteField.php',
 	'SVGMetadataExtractor' => __DIR__ . '/includes/media/SVGMetadataExtractor.php',
 	'SVGReader' => __DIR__ . '/includes/media/SVGMetadataExtractor.php',
 	'SamplingStatsdClient' => __DIR__ . '/includes/libs/SamplingStatsdClient.php',
diff --git a/includes/db/DatabaseMssql.php b/includes/db/DatabaseMssql.php
index 2439c600735a..1d7adc6856ee 100644
--- a/includes/db/DatabaseMssql.php
+++ b/includes/db/DatabaseMssql.php
@@ -1410,148 +1410,3 @@ class DatabaseMssql extends Database {
 		return wfSetVar( $this->mIgnoreErrors, $value );
 	}
 } // end DatabaseMssql class
-
-/**
- * Utility class.
- *
- * @ingroup Database
- */
-class MssqlField implements Field {
-	private $name, $tableName, $default, $max_length, $nullable, $type;
-
-	function __construct( $info ) {
-		$this->name = $info['COLUMN_NAME'];
-		$this->tableName = $info['TABLE_NAME'];
-		$this->default = $info['COLUMN_DEFAULT'];
-		$this->max_length = $info['CHARACTER_MAXIMUM_LENGTH'];
-		$this->nullable = !( strtolower( $info['IS_NULLABLE'] ) == 'no' );
-		$this->type = $info['DATA_TYPE'];
-	}
-
-	function name() {
-		return $this->name;
-	}
-
-	function tableName() {
-		return $this->tableName;
-	}
-
-	function defaultValue() {
-		return $this->default;
-	}
-
-	function maxLength() {
-		return $this->max_length;
-	}
-
-	function isNullable() {
-		return $this->nullable;
-	}
-
-	function type() {
-		return $this->type;
-	}
-}
-
-class MssqlBlob extends Blob {
-	public function __construct( $data ) {
-		if ( $data instanceof MssqlBlob ) {
-			return $data;
-		} elseif ( $data instanceof Blob ) {
-			$this->mData = $data->fetch();
-		} elseif ( is_array( $data ) && is_object( $data ) ) {
-			$this->mData = serialize( $data );
-		} else {
-			$this->mData = $data;
-		}
-	}
-
-	/**
-	 * Returns an unquoted hex representation of a binary string
-	 * for insertion into varbinary-type fields
-	 * @return string
-	 */
-	public function fetch() {
-		if ( $this->mData === null ) {
-			return 'null';
-		}
-
-		$ret = '0x';
-		$dataLength = strlen( $this->mData );
-		for ( $i = 0; $i < $dataLength; $i++ ) {
-			$ret .= bin2hex( pack( 'C', ord( $this->mData[$i] ) ) );
-		}
-
-		return $ret;
-	}
-}
-
-class MssqlResultWrapper extends ResultWrapper {
-	private $mSeekTo = null;
-
-	/**
-	 * @return stdClass|bool
-	 */
-	public function fetchObject() {
-		$res = $this->result;
-
-		if ( $this->mSeekTo !== null ) {
-			$result = sqlsrv_fetch_object( $res, 'stdClass', [],
-				SQLSRV_SCROLL_ABSOLUTE, $this->mSeekTo );
-			$this->mSeekTo = null;
-		} else {
-			$result = sqlsrv_fetch_object( $res );
-		}
-
-		// MediaWiki expects us to return boolean false when there are no more rows instead of null
-		if ( $result === null ) {
-			return false;
-		}
-
-		return $result;
-	}
-
-	/**
-	 * @return array|bool
-	 */
-	public function fetchRow() {
-		$res = $this->result;
-
-		if ( $this->mSeekTo !== null ) {
-			$result = sqlsrv_fetch_array( $res, SQLSRV_FETCH_BOTH,
-				SQLSRV_SCROLL_ABSOLUTE, $this->mSeekTo );
-			$this->mSeekTo = null;
-		} else {
-			$result = sqlsrv_fetch_array( $res );
-		}
-
-		// MediaWiki expects us to return boolean false when there are no more rows instead of null
-		if ( $result === null ) {
-			return false;
-		}
-
-		return $result;
-	}
-
-	/**
-	 * @param int $row
-	 * @return bool
-	 */
-	public function seek( $row ) {
-		$res = $this->result;
-
-		// check bounds
-		$numRows = $this->db->numRows( $res );
-		$row = intval( $row );
-
-		if ( $numRows === 0 ) {
-			return false;
-		} elseif ( $row < 0 || $row > $numRows - 1 ) {
-			return false;
-		}
-
-		// Unlike MySQL, the seek actually happens on the next access
-		$this->mSeekTo = $row;
-		return true;
-	}
-}
diff --git a/includes/db/DatabaseMysqlBase.php b/includes/db/DatabaseMysqlBase.php
index af80d24aef51..f8737a84dfe4 100644
--- a/includes/db/DatabaseMysqlBase.php
+++ b/includes/db/DatabaseMysqlBase.php
@@ -1351,243 +1351,3 @@ abstract class DatabaseMysqlBase extends Database {
 	}
 }
 
-/**
- * Utility class.
- * @ingroup Database
- */
-class MySQLField implements Field {
-	private $name, $tablename, $default, $max_length, $nullable,
-		$is_pk, $is_unique, $is_multiple, $is_key, $type, $binary,
-		$is_numeric, $is_blob, $is_unsigned, $is_zerofill;
-
-	function __construct( $info ) {
-		$this->name = $info->name;
-		$this->tablename = $info->table;
-		$this->default = $info->def;
-		$this->max_length = $info->max_length;
-		$this->nullable = !$info->not_null;
-		$this->is_pk = $info->primary_key;
-		$this->is_unique = $info->unique_key;
-		$this->is_multiple = $info->multiple_key;
-		$this->is_key = ( $this->is_pk || $this->is_unique || $this->is_multiple );
-		$this->type = $info->type;
-		$this->binary = isset( $info->binary ) ? $info->binary : false;
-		$this->is_numeric = isset( $info->numeric ) ? $info->numeric : false;
-		$this->is_blob = isset( $info->blob ) ? $info->blob : false;
-		$this->is_unsigned = isset( $info->unsigned ) ? $info->unsigned : false;
-		$this->is_zerofill = isset( $info->zerofill ) ? $info->zerofill : false;
-	}
-
-	/**
-	 * @return string
-	 */
-	function name() {
-		return $this->name;
-	}
-
-	/**
-	 * @return string
-	 */
-	function tableName() {
-		return $this->tablename;
-	}
-
-	/**
-	 * @return string
-	 */
-	function type() {
-		return $this->type;
-	}
-
-	/**
-	 * @return bool
-	 */
-	function isNullable() {
-		return $this->nullable;
-	}
-
-	function defaultValue() {
-		return $this->default;
-	}
-
-	/**
-	 * @return bool
-	 */
-	function isKey() {
-		return $this->is_key;
-	}
-
-	/**
-	 * @return bool
-	 */
-	function isMultipleKey() {
-		return $this->is_multiple;
-	}
-
-	/**
-	 * @return bool
-	 */
-	function isBinary() {
-		return $this->binary;
-	}
-
-	/**
-	 * @return bool
-	 */
-	function isNumeric() {
-		return $this->is_numeric;
-	}
-
-	/**
-	 * @return bool
-	 */
-	function isBlob() {
-		return $this->is_blob;
-	}
-
-	/**
-	 * @return bool
-	 */
-	function isUnsigned() {
-		return $this->is_unsigned;
-	}
-
-	/**
-	 * @return bool
-	 */
-	function isZerofill() {
-		return $this->is_zerofill;
-	}
-}
-
-/**
- * DBMasterPos class for MySQL/MariaDB
- *
- * Note that master positions and sync logic here make some assumptions:
- *  - Binlog-based usage assumes single-source replication and non-hierarchical replication.
- *  - GTID-based usage allows getting/syncing with multi-source replication. It is assumed
- *    that GTID sets are complete (e.g. include all domains on the server).
- */
-class MySQLMasterPos implements DBMasterPos {
-	/** @var string Binlog file */
-	public $file;
-	/** @var int Binglog file position */
-	public $pos;
-	/** @var string[] GTID list */
-	public $gtids = [];
-	/** @var float UNIX timestamp */
-	public $asOfTime = 0.0;
-
-	/**
-	 * @param string $file Binlog file name
-	 * @param integer $pos Binlog position
-	 * @param string $gtid Comma separated GTID set [optional]
-	 */
-	function __construct( $file, $pos, $gtid = '' ) {
-		$this->file = $file;
-		$this->pos = $pos;
-		$this->gtids = array_map( 'trim', explode( ',', $gtid ) );
-		$this->asOfTime = microtime( true );
-	}
-
-	/**
-	 * @return string <binlog file>/<position>, e.g db1034-bin.000976/843431247
-	 */
-	function __toString() {
-		return "{$this->file}/{$this->pos}";
-	}
-
-	function asOfTime() {
-		return $this->asOfTime;
-	}
-
-	function hasReached( DBMasterPos $pos ) {
-		if ( !( $pos instanceof self ) ) {
-			throw new InvalidArgumentException( "Position not an instance of " . __CLASS__ );
-		}
-
-		// Prefer GTID comparisons, which work with multi-tier replication
-		$thisPosByDomain = $this->getGtidCoordinates();
-		$thatPosByDomain = $pos->getGtidCoordinates();
-		if ( $thisPosByDomain && $thatPosByDomain ) {
-			$reached = true;
-			// Check that this has positions GTE all of those in $pos for all domains in $pos
-			foreach ( $thatPosByDomain as $domain => $thatPos ) {
-				$thisPos = isset( $thisPosByDomain[$domain] ) ? $thisPosByDomain[$domain] : -1;
-				$reached = $reached && ( $thatPos <= $thisPos );
-			}
-
-			return $reached;
-		}
-
-		// Fallback to the binlog file comparisons
-		$thisBinPos = $this->getBinlogCoordinates();
-		$thatBinPos = $pos->getBinlogCoordinates();
-		if ( $thisBinPos && $thatBinPos && $thisBinPos['binlog'] === $thatBinPos['binlog'] ) {
-			return ( $thisBinPos['pos'] >= $thatBinPos['pos'] );
-		}
-
-		// Comparing totally different binlogs does not make sense
-		return false;
-	}
-
-	function channelsMatch( DBMasterPos $pos ) {
-		if ( !( $pos instanceof self ) ) {
-			throw new InvalidArgumentException( "Position not an instance of " . __CLASS__ );
-		}
-
-		// Prefer GTID comparisons, which work with multi-tier replication
-		$thisPosDomains = array_keys( $this->getGtidCoordinates() );
-		$thatPosDomains = array_keys( $pos->getGtidCoordinates() );
-		if ( $thisPosDomains && $thatPosDomains ) {
-			// Check that this has GTIDs for all domains in $pos
-			return !array_diff( $thatPosDomains, $thisPosDomains );
-		}
-
-		// Fallback to the binlog file comparisons
-		$thisBinPos = $this->getBinlogCoordinates();
-		$thatBinPos = $pos->getBinlogCoordinates();
-
-		return ( $thisBinPos && $thatBinPos && $thisBinPos['binlog'] === $thatBinPos['binlog'] );
-	}
-
-	/**
-	 * @note: this returns false for multi-source replication GTID sets
-	 * @see https://mariadb.com/kb/en/mariadb/gtid
-	 * @see https://dev.mysql.com/doc/refman/5.6/en/replication-gtids-concepts.html
-	 * @return array Map of (domain => integer position) or false
-	 */
-	protected function getGtidCoordinates() {
-		$gtidInfos = [];
-		foreach ( $this->gtids as $gtid ) {
-			$m = [];
-			// MariaDB style: <domain>-<server id>-<sequence number>
-			if ( preg_match( '!^(\d+)-\d+-(\d+)$!', $gtid, $m ) ) {
-				$gtidInfos[(int)$m[1]] = (int)$m[2];
-			// MySQL style: <UUID domain>:<sequence number>
-			} elseif ( preg_match( '!^(\w{8}-\w{4}-\w{4}-\w{4}-\w{12}):(\d+)$!', $gtid, $m ) ) {
-				$gtidInfos[$m[1]] = (int)$m[2];
-			} else {
-				$gtidInfos = [];
-				break; // unrecognized GTID
-			}
-
-		}
-
-		return $gtidInfos;
-	}
-
-	/**
-	 * @see http://dev.mysql.com/doc/refman/5.7/en/show-master-status.html
-	 * @see http://dev.mysql.com/doc/refman/5.7/en/show-slave-status.html
-	 * @return array|bool (binlog, (integer file number, integer position)) or false
-	 */
-	protected function getBinlogCoordinates() {
-		$m = [];
-		if ( preg_match( '!^(.+)\.(\d+)/(\d+)$!', (string)$this, $m ) ) {
-			return [ 'binlog' => $m[1], 'pos' => [ (int)$m[2], (int)$m[3] ] ];
-		}
-
-		return false;
-	}
-}
diff --git a/includes/db/DatabaseOracle.php b/includes/db/DatabaseOracle.php
index 5d0ff447bae0..df311aafac2d 100644
--- a/includes/db/DatabaseOracle.php
+++ b/includes/db/DatabaseOracle.php
@@ -129,60 +129,6 @@ class ORAResult {
 }
 
 /**
- * Utility class.
- * @ingroup Database
- */
-class ORAField implements Field {
-	private $name, $tablename, $default, $max_length, $nullable,
-		$is_pk, $is_unique, $is_multiple, $is_key, $type;
-
-	function __construct( $info ) {
-		$this->name = $info['column_name'];
-		$this->tablename = $info['table_name'];
-		$this->default = $info['data_default'];
-		$this->max_length = $info['data_length'];
-		$this->nullable = $info['not_null'];
-		$this->is_pk = isset( $info['prim'] ) && $info['prim'] == 1 ? 1 : 0;
-		$this->is_unique = isset( $info['uniq'] ) && $info['uniq'] == 1 ? 1 : 0;
-		$this->is_multiple = isset( $info['nonuniq'] ) && $info['nonuniq'] == 1 ? 1 : 0;
-		$this->is_key = ( $this->is_pk || $this->is_unique || $this->is_multiple );
-		$this->type = $info['data_type'];
-	}
-
-	function name() {
-		return $this->name;
-	}
-
-	function tableName() {
-		return $this->tablename;
-	}
-
-	function defaultValue() {
-		return $this->default;
-	}
-
-	function maxLength() {
-		return $this->max_length;
-	}
-
-	function isNullable() {
-		return $this->nullable;
-	}
-
-	function isKey() {
-		return $this->is_key;
-	}
-
-	function isMultipleKey() {
-		return $this->is_multiple;
-	}
-
-	function type() {
-		return $this->type;
-	}
-}
-
-/**
  * @ingroup Database
  */
 class DatabaseOracle extends Database {
diff --git a/includes/db/DatabasePostgres.php b/includes/db/DatabasePostgres.php
index b1cc96bc7c67..590e1f4931db 100644
--- a/includes/db/DatabasePostgres.php
+++ b/includes/db/DatabasePostgres.php
@@ -1636,6 +1636,3 @@ SQL;
 		return Wikimedia\base_convert( substr( sha1( $lockName ), 0, 15 ), 16, 10 );
 	}
 } // end DatabasePostgres class
-
-class PostgresBlob extends Blob {
-}
diff --git a/includes/db/DatabaseSqlite.php b/includes/db/DatabaseSqlite.php
index 6bf48e23653f..fa4e453b6509 100644
--- a/includes/db/DatabaseSqlite.php
+++ b/includes/db/DatabaseSqlite.php
@@ -1044,45 +1044,3 @@ class DatabaseSqlite extends Database {
 	}
 
 } // end DatabaseSqlite class
-
-/**
- * @ingroup Database
- */
-class SQLiteField implements Field {
-	private $info, $tableName;
-
-	function __construct( $info, $tableName ) {
-		$this->info = $info;
-		$this->tableName = $tableName;
-	}
-
-	function name() {
-		return $this->info->name;
-	}
-
-	function tableName() {
-		return $this->tableName;
-	}
-
-	function defaultValue() {
-		if ( is_string( $this->info->dflt_value ) ) {
-			// Typically quoted
-			if ( preg_match( '/^\'(.*)\'$', $this->info->dflt_value ) ) {
-				return str_replace( "''", "'", $this->info->dflt_value );
-			}
-		}
-
-		return $this->info->dflt_value;
-	}
-
-	/**
-	 * @return bool
-	 */
-	function isNullable() {
-		return !$this->info->notnull;
-	}
-
-	function type() {
-		return $this->info->type;
-	}
-} // end SQLiteField
diff --git a/includes/db/DatabaseUtility.php b/includes/db/DatabaseUtility.php
deleted file mode 100644
index 2b8c8c6d4b7f..000000000000
--- a/includes/db/DatabaseUtility.php
+++ /dev/null
@@ -1,347 +0,0 @@
-<?php
-/**
- * This file contains database-related utility classes.
- *
- * 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
- * @ingroup Database
- */
-
-/**
- * Utility class
- * @ingroup Database
- *
- * This allows us to distinguish a blob from a normal string and an array of strings
- */
-class Blob {
-	/** @var string */
-	protected $mData;
-
-	function __construct( $data ) {
-		$this->mData = $data;
-	}
-
-	function fetch() {
-		return $this->mData;
-	}
-}
-
-/**
- * Base for all database-specific classes representing information about database fields
- * @ingroup Database
- */
-interface Field {
-	/**
-	 * Field name
-	 * @return string
-	 */
-	function name();
-
-	/**
-	 * Name of table this field belongs to
-	 * @return string
-	 */
-	function tableName();
-
-	/**
-	 * Database type
-	 * @return string
-	 */
-	function type();
-
-	/**
-	 * Whether this field can store NULL values
-	 * @return bool
-	 */
-	function isNullable();
-}
-
-/**
- * Result wrapper for grabbing data queried by someone else
- * @ingroup Database
- */
-class ResultWrapper implements Iterator {
-	/** @var resource */
-	public $result;
-
-	/** @var IDatabase */
-	protected $db;
-
-	/** @var int */
-	protected $pos = 0;
-
-	/** @var object|null */
-	protected $currentRow = null;
-
-	/**
-	 * Create a new result object from a result resource and a Database object
-	 *
-	 * @param IDatabase $database
-	 * @param resource|ResultWrapper $result
-	 */
-	function __construct( $database, $result ) {
-		$this->db = $database;
-
-		if ( $result instanceof ResultWrapper ) {
-			$this->result = $result->result;
-		} else {
-			$this->result = $result;
-		}
-	}
-
-	/**
-	 * Get the number of rows in a result object
-	 *
-	 * @return int
-	 */
-	function numRows() {
-		return $this->db->numRows( $this );
-	}
-
-	/**
-	 * Fetch the next row from the given result object, in object form. Fields can be retrieved with
-	 * $row->fieldname, with fields acting like member variables. If no more rows are available,
-	 * false is returned.
-	 *
-	 * @return stdClass|bool
-	 * @throws DBUnexpectedError Thrown if the database returns an error
-	 */
-	function fetchObject() {
-		return $this->db->fetchObject( $this );
-	}
-
-	/**
-	 * Fetch the next row from the given result object, in associative array form. Fields are
-	 * retrieved with $row['fieldname']. If no more rows are available, false is returned.
-	 *
-	 * @return array|bool
-	 * @throws DBUnexpectedError Thrown if the database returns an error
-	 */
-	function fetchRow() {
-		return $this->db->fetchRow( $this );
-	}
-
-	/**
-	 * Free a result object
-	 */
-	function free() {
-		$this->db->freeResult( $this );
-		unset( $this->result );
-		unset( $this->db );
-	}
-
-	/**
-	 * Change the position of the cursor in a result object.
-	 * See mysql_data_seek()
-	 *
-	 * @param int $row
-	 */
-	function seek( $row ) {
-		$this->db->dataSeek( $this, $row );
-	}
-
-	/*
-	 * ======= Iterator functions =======
-	 * Note that using these in combination with the non-iterator functions
-	 * above may cause rows to be skipped or repeated.
-	 */
-
-	function rewind() {
-		if ( $this->numRows() ) {
-			$this->db->dataSeek( $this, 0 );
-		}
-		$this->pos = 0;
-		$this->currentRow = null;
-	}
-
-	/**
-	 * @return stdClass|array|bool
-	 */
-	function current() {
-		if ( is_null( $this->currentRow ) ) {
-			$this->next();
-		}
-
-		return $this->currentRow;
-	}
-
-	/**
-	 * @return int
-	 */
-	function key() {
-		return $this->pos;
-	}
-
-	/**
-	 * @return stdClass
-	 */
-	function next() {
-		$this->pos++;
-		$this->currentRow = $this->fetchObject();
-
-		return $this->currentRow;
-	}
-
-	/**
-	 * @return bool
-	 */
-	function valid() {
-		return $this->current() !== false;
-	}
-}
-
-/**
- * Overloads the relevant methods of the real ResultsWrapper so it
- * doesn't go anywhere near an actual database.
- */
-class FakeResultWrapper extends ResultWrapper {
-	/** @var array */
-	public $result = [];
-
-	/** @var null And it's going to stay that way :D */
-	protected $db = null;
-
-	/** @var int */
-	protected $pos = 0;
-
-	/** @var array|stdClass|bool */
-	protected $currentRow = null;
-
-	/**
-	 * @param array $array
-	 */
-	function __construct( $array ) {
-		$this->result = $array;
-	}
-
-	/**
-	 * @return int
-	 */
-	function numRows() {
-		return count( $this->result );
-	}
-
-	/**
-	 * @return array|bool
-	 */
-	function fetchRow() {
-		if ( $this->pos < count( $this->result ) ) {
-			$this->currentRow = $this->result[$this->pos];
-		} else {
-			$this->currentRow = false;
-		}
-		$this->pos++;
-		if ( is_object( $this->currentRow ) ) {
-			return get_object_vars( $this->currentRow );
-		} else {
-			return $this->currentRow;
-		}
-	}
-
-	function seek( $row ) {
-		$this->pos = $row;
-	}
-
-	function free() {
-	}
-
-	/**
-	 * Callers want to be able to access fields with $this->fieldName
-	 * @return bool|stdClass
-	 */
-	function fetchObject() {
-		$this->fetchRow();
-		if ( $this->currentRow ) {
-			return (object)$this->currentRow;
-		} else {
-			return false;
-		}
-	}
-
-	function rewind() {
-		$this->pos = 0;
-		$this->currentRow = null;
-	}
-
-	/**
-	 * @return bool|stdClass
-	 */
-	function next() {
-		return $this->fetchObject();
-	}
-}
-
-/**
- * Used by DatabaseBase::buildLike() to represent characters that have special
- * meaning in SQL LIKE clauses and thus need no escaping. Don't instantiate it
- * manually, use DatabaseBase::anyChar() and anyString() instead.
- */
-class LikeMatch {
-	/** @var string */
-	private $str;
-
-	/**
-	 * Store a string into a LikeMatch marker object.
-	 *
-	 * @param string $s
-	 */
-	public function __construct( $s ) {
-		$this->str = $s;
-	}
-
-	/**
-	 * Return the original stored string.
-	 *
-	 * @return string
-	 */
-	public function toString() {
-		return $this->str;
-	}
-}
-
-/**
- * An object representing a master or replica DB position in a replicated setup.
- *
- * The implementation details of this opaque type are up to the database subclass.
- */
-interface DBMasterPos {
-	/**
-	 * @return float UNIX timestamp
-	 * @since 1.25
-	 */
-	public function asOfTime();
-
-	/**
-	 * @param DBMasterPos $pos
-	 * @return bool Whether this position is at or higher than $pos
-	 * @since 1.27
-	 */
-	public function hasReached( DBMasterPos $pos );
-
-	/**
-	 * @param DBMasterPos $pos
-	 * @return bool Whether this position appears to be for the same channel as another
-	 * @since 1.27
-	 */
-	public function channelsMatch( DBMasterPos $pos );
-
-	/**
-	 * @return string
-	 * @since 1.27
-	 */
-	public function __toString();
-}
diff --git a/includes/libs/rdbms/database/RBConnRef.php b/includes/libs/rdbms/database/DBConnRef.php
index 9035bbd5c94b..9035bbd5c94b 100644
--- a/includes/libs/rdbms/database/RBConnRef.php
+++ b/includes/libs/rdbms/database/DBConnRef.php
diff --git a/includes/libs/rdbms/database/position/DBMasterPos.php b/includes/libs/rdbms/database/position/DBMasterPos.php
new file mode 100644
index 000000000000..eda0ff32569c
--- /dev/null
+++ b/includes/libs/rdbms/database/position/DBMasterPos.php
@@ -0,0 +1,33 @@
+<?php
+/**
+ * An object representing a master or replica DB position in a replicated setup.
+ *
+ * The implementation details of this opaque type are up to the database subclass.
+ */
+interface DBMasterPos {
+	/**
+	 * @return float UNIX timestamp
+	 * @since 1.25
+	 */
+	public function asOfTime();
+
+	/**
+	 * @param DBMasterPos $pos
+	 * @return bool Whether this position is at or higher than $pos
+	 * @since 1.27
+	 */
+	public function hasReached( DBMasterPos $pos );
+
+	/**
+	 * @param DBMasterPos $pos
+	 * @return bool Whether this position appears to be for the same channel as another
+	 * @since 1.27
+	 */
+	public function channelsMatch( DBMasterPos $pos );
+
+	/**
+	 * @return string
+	 * @since 1.27
+	 */
+	public function __toString();
+}
diff --git a/includes/libs/rdbms/database/position/MySQLMasterPos.php b/includes/libs/rdbms/database/position/MySQLMasterPos.php
new file mode 100644
index 000000000000..71fbe7e5875e
--- /dev/null
+++ b/includes/libs/rdbms/database/position/MySQLMasterPos.php
@@ -0,0 +1,132 @@
+<?php
+/**
+ * DBMasterPos class for MySQL/MariaDB
+ *
+ * Note that master positions and sync logic here make some assumptions:
+ *  - Binlog-based usage assumes single-source replication and non-hierarchical replication.
+ *  - GTID-based usage allows getting/syncing with multi-source replication. It is assumed
+ *    that GTID sets are complete (e.g. include all domains on the server).
+ */
+class MySQLMasterPos implements DBMasterPos {
+	/** @var string Binlog file */
+	public $file;
+	/** @var int Binglog file position */
+	public $pos;
+	/** @var string[] GTID list */
+	public $gtids = [];
+	/** @var float UNIX timestamp */
+	public $asOfTime = 0.0;
+
+	/**
+	 * @param string $file Binlog file name
+	 * @param integer $pos Binlog position
+	 * @param string $gtid Comma separated GTID set [optional]
+	 */
+	function __construct( $file, $pos, $gtid = '' ) {
+		$this->file = $file;
+		$this->pos = $pos;
+		$this->gtids = array_map( 'trim', explode( ',', $gtid ) );
+		$this->asOfTime = microtime( true );
+	}
+
+	/**
+	 * @return string <binlog file>/<position>, e.g db1034-bin.000976/843431247
+	 */
+	function __toString() {
+		return "{$this->file}/{$this->pos}";
+	}
+
+	function asOfTime() {
+		return $this->asOfTime;
+	}
+
+	function hasReached( DBMasterPos $pos ) {
+		if ( !( $pos instanceof self ) ) {
+			throw new InvalidArgumentException( "Position not an instance of " . __CLASS__ );
+		}
+
+		// Prefer GTID comparisons, which work with multi-tier replication
+		$thisPosByDomain = $this->getGtidCoordinates();
+		$thatPosByDomain = $pos->getGtidCoordinates();
+		if ( $thisPosByDomain && $thatPosByDomain ) {
+			$reached = true;
+			// Check that this has positions GTE all of those in $pos for all domains in $pos
+			foreach ( $thatPosByDomain as $domain => $thatPos ) {
+				$thisPos = isset( $thisPosByDomain[$domain] ) ? $thisPosByDomain[$domain] : -1;
+				$reached = $reached && ( $thatPos <= $thisPos );
+			}
+
+			return $reached;
+		}
+
+		// Fallback to the binlog file comparisons
+		$thisBinPos = $this->getBinlogCoordinates();
+		$thatBinPos = $pos->getBinlogCoordinates();
+		if ( $thisBinPos && $thatBinPos && $thisBinPos['binlog'] === $thatBinPos['binlog'] ) {
+			return ( $thisBinPos['pos'] >= $thatBinPos['pos'] );
+		}
+
+		// Comparing totally different binlogs does not make sense
+		return false;
+	}
+
+	function channelsMatch( DBMasterPos $pos ) {
+		if ( !( $pos instanceof self ) ) {
+			throw new InvalidArgumentException( "Position not an instance of " . __CLASS__ );
+		}
+
+		// Prefer GTID comparisons, which work with multi-tier replication
+		$thisPosDomains = array_keys( $this->getGtidCoordinates() );
+		$thatPosDomains = array_keys( $pos->getGtidCoordinates() );
+		if ( $thisPosDomains && $thatPosDomains ) {
+			// Check that this has GTIDs for all domains in $pos
+			return !array_diff( $thatPosDomains, $thisPosDomains );
+		}
+
+		// Fallback to the binlog file comparisons
+		$thisBinPos = $this->getBinlogCoordinates();
+		$thatBinPos = $pos->getBinlogCoordinates();
+
+		return ( $thisBinPos && $thatBinPos && $thisBinPos['binlog'] === $thatBinPos['binlog'] );
+	}
+
+	/**
+	 * @note: this returns false for multi-source replication GTID sets
+	 * @see https://mariadb.com/kb/en/mariadb/gtid
+	 * @see https://dev.mysql.com/doc/refman/5.6/en/replication-gtids-concepts.html
+	 * @return array Map of (domain => integer position) or false
+	 */
+	protected function getGtidCoordinates() {
+		$gtidInfos = [];
+		foreach ( $this->gtids as $gtid ) {
+			$m = [];
+			// MariaDB style: <domain>-<server id>-<sequence number>
+			if ( preg_match( '!^(\d+)-\d+-(\d+)$!', $gtid, $m ) ) {
+				$gtidInfos[(int)$m[1]] = (int)$m[2];
+				// MySQL style: <UUID domain>:<sequence number>
+			} elseif ( preg_match( '!^(\w{8}-\w{4}-\w{4}-\w{4}-\w{12}):(\d+)$!', $gtid, $m ) ) {
+				$gtidInfos[$m[1]] = (int)$m[2];
+			} else {
+				$gtidInfos = [];
+				break; // unrecognized GTID
+			}
+
+		}
+
+		return $gtidInfos;
+	}
+
+	/**
+	 * @see http://dev.mysql.com/doc/refman/5.7/en/show-master-status.html
+	 * @see http://dev.mysql.com/doc/refman/5.7/en/show-slave-status.html
+	 * @return array|bool (binlog, (integer file number, integer position)) or false
+	 */
+	protected function getBinlogCoordinates() {
+		$m = [];
+		if ( preg_match( '!^(.+)\.(\d+)/(\d+)$!', (string)$this, $m ) ) {
+			return [ 'binlog' => $m[1], 'pos' => [ (int)$m[2], (int)$m[3] ] ];
+		}
+
+		return false;
+	}
+}
diff --git a/includes/libs/rdbms/database/resultwrapper/FakeResultWrapper.php b/includes/libs/rdbms/database/resultwrapper/FakeResultWrapper.php
new file mode 100644
index 000000000000..774def8086b8
--- /dev/null
+++ b/includes/libs/rdbms/database/resultwrapper/FakeResultWrapper.php
@@ -0,0 +1,81 @@
+<?php
+/**
+ * Overloads the relevant methods of the real ResultsWrapper so it
+ * doesn't go anywhere near an actual database.
+ */
+class FakeResultWrapper extends ResultWrapper {
+	/** @var array */
+	public $result = [];
+
+	/** @var null And it's going to stay that way :D */
+	protected $db = null;
+
+	/** @var int */
+	protected $pos = 0;
+
+	/** @var array|stdClass|bool */
+	protected $currentRow = null;
+
+	/**
+	 * @param array $array
+	 */
+	function __construct( $array ) {
+		$this->result = $array;
+	}
+
+	/**
+	 * @return int
+	 */
+	function numRows() {
+		return count( $this->result );
+	}
+
+	/**
+	 * @return array|bool
+	 */
+	function fetchRow() {
+		if ( $this->pos < count( $this->result ) ) {
+			$this->currentRow = $this->result[$this->pos];
+		} else {
+			$this->currentRow = false;
+		}
+		$this->pos++;
+		if ( is_object( $this->currentRow ) ) {
+			return get_object_vars( $this->currentRow );
+		} else {
+			return $this->currentRow;
+		}
+	}
+
+	function seek( $row ) {
+		$this->pos = $row;
+	}
+
+	function free() {
+	}
+
+	/**
+	 * Callers want to be able to access fields with $this->fieldName
+	 * @return bool|stdClass
+	 */
+	function fetchObject() {
+		$this->fetchRow();
+		if ( $this->currentRow ) {
+			return (object)$this->currentRow;
+		} else {
+			return false;
+		}
+	}
+
+	function rewind() {
+		$this->pos = 0;
+		$this->currentRow = null;
+	}
+
+	/**
+	 * @return bool|stdClass
+	 */
+	function next() {
+		return $this->fetchObject();
+	}
+}
diff --git a/includes/libs/rdbms/database/resultwrapper/MssqlResultWrapper.php b/includes/libs/rdbms/database/resultwrapper/MssqlResultWrapper.php
new file mode 100644
index 000000000000..cccb8f17d2ac
--- /dev/null
+++ b/includes/libs/rdbms/database/resultwrapper/MssqlResultWrapper.php
@@ -0,0 +1,70 @@
+<?php
+class MssqlResultWrapper extends ResultWrapper {
+	private $mSeekTo = null;
+
+	/**
+	 * @return stdClass|bool
+	 */
+	public function fetchObject() {
+		$res = $this->result;
+
+		if ( $this->mSeekTo !== null ) {
+			$result = sqlsrv_fetch_object( $res, 'stdClass', [],
+				SQLSRV_SCROLL_ABSOLUTE, $this->mSeekTo );
+			$this->mSeekTo = null;
+		} else {
+			$result = sqlsrv_fetch_object( $res );
+		}
+
+		// MediaWiki expects us to return boolean false when there are no more rows instead of null
+		if ( $result === null ) {
+			return false;
+		}
+
+		return $result;
+	}
+
+	/**
+	 * @return array|bool
+	 */
+	public function fetchRow() {
+		$res = $this->result;
+
+		if ( $this->mSeekTo !== null ) {
+			$result = sqlsrv_fetch_array( $res, SQLSRV_FETCH_BOTH,
+				SQLSRV_SCROLL_ABSOLUTE, $this->mSeekTo );
+			$this->mSeekTo = null;
+		} else {
+			$result = sqlsrv_fetch_array( $res );
+		}
+
+		// MediaWiki expects us to return boolean false when there are no more rows instead of null
+		if ( $result === null ) {
+			return false;
+		}
+
+		return $result;
+	}
+
+	/**
+	 * @param int $row
+	 * @return bool
+	 */
+	public function seek( $row ) {
+		$res = $this->result;
+
+		// check bounds
+		$numRows = $this->db->numRows( $res );
+		$row = intval( $row );
+
+		if ( $numRows === 0 ) {
+			return false;
+		} elseif ( $row < 0 || $row > $numRows - 1 ) {
+			return false;
+		}
+
+		// Unlike MySQL, the seek actually happens on the next access
+		$this->mSeekTo = $row;
+		return true;
+	}
+}
diff --git a/includes/libs/rdbms/database/resultwrapper/ResultWrapper.php b/includes/libs/rdbms/database/resultwrapper/ResultWrapper.php
new file mode 100644
index 000000000000..252f4f7e79ca
--- /dev/null
+++ b/includes/libs/rdbms/database/resultwrapper/ResultWrapper.php
@@ -0,0 +1,134 @@
+<?php
+/**
+ * Result wrapper for grabbing data queried by someone else
+ * @ingroup Database
+ */
+class ResultWrapper implements Iterator {
+	/** @var resource */
+	public $result;
+
+	/** @var DatabaseBase */
+	protected $db;
+
+	/** @var int */
+	protected $pos = 0;
+
+	/** @var object|null */
+	protected $currentRow = null;
+
+	/**
+	 * Create a new result object from a result resource and a Database object
+	 *
+	 * @param DatabaseBase $database
+	 * @param resource|ResultWrapper $result
+	 */
+	function __construct( $database, $result ) {
+		$this->db = $database;
+
+		if ( $result instanceof ResultWrapper ) {
+			$this->result = $result->result;
+		} else {
+			$this->result = $result;
+		}
+	}
+
+	/**
+	 * Get the number of rows in a result object
+	 *
+	 * @return int
+	 */
+	function numRows() {
+		return $this->db->numRows( $this );
+	}
+
+	/**
+	 * Fetch the next row from the given result object, in object form. Fields can be retrieved with
+	 * $row->fieldname, with fields acting like member variables. If no more rows are available,
+	 * false is returned.
+	 *
+	 * @return stdClass|bool
+	 * @throws DBUnexpectedError Thrown if the database returns an error
+	 */
+	function fetchObject() {
+		return $this->db->fetchObject( $this );
+	}
+
+	/**
+	 * Fetch the next row from the given result object, in associative array form. Fields are
+	 * retrieved with $row['fieldname']. If no more rows are available, false is returned.
+	 *
+	 * @return array|bool
+	 * @throws DBUnexpectedError Thrown if the database returns an error
+	 */
+	function fetchRow() {
+		return $this->db->fetchRow( $this );
+	}
+
+	/**
+	 * Free a result object
+	 */
+	function free() {
+		$this->db->freeResult( $this );
+		unset( $this->result );
+		unset( $this->db );
+	}
+
+	/**
+	 * Change the position of the cursor in a result object.
+	 * See mysql_data_seek()
+	 *
+	 * @param int $row
+	 */
+	function seek( $row ) {
+		$this->db->dataSeek( $this, $row );
+	}
+
+	/*
+	 * ======= Iterator functions =======
+	 * Note that using these in combination with the non-iterator functions
+	 * above may cause rows to be skipped or repeated.
+	 */
+
+	function rewind() {
+		if ( $this->numRows() ) {
+			$this->db->dataSeek( $this, 0 );
+		}
+		$this->pos = 0;
+		$this->currentRow = null;
+	}
+
+	/**
+	 * @return stdClass|array|bool
+	 */
+	function current() {
+		if ( is_null( $this->currentRow ) ) {
+			$this->next();
+		}
+
+		return $this->currentRow;
+	}
+
+	/**
+	 * @return int
+	 */
+	function key() {
+		return $this->pos;
+	}
+
+	/**
+	 * @return stdClass
+	 */
+	function next() {
+		$this->pos++;
+		$this->currentRow = $this->fetchObject();
+
+		return $this->currentRow;
+	}
+
+	/**
+	 * @return bool
+	 */
+	function valid() {
+		return $this->current() !== false;
+	}
+}
diff --git a/includes/libs/rdbms/encasing/Blob.php b/includes/libs/rdbms/encasing/Blob.php
new file mode 100644
index 000000000000..bd9033057789
--- /dev/null
+++ b/includes/libs/rdbms/encasing/Blob.php
@@ -0,0 +1,19 @@
+<?php
+/**
+ * Utility class
+ * @ingroup Database
+ *
+ * This allows us to distinguish a blob from a normal string and an array of strings
+ */
+class Blob {
+	/** @var string */
+	protected $mData;
+
+	function __construct( $data ) {
+		$this->mData = $data;
+	}
+
+	function fetch() {
+		return $this->mData;
+	}
+}
diff --git a/includes/libs/rdbms/encasing/LikeMatch.php b/includes/libs/rdbms/encasing/LikeMatch.php
new file mode 100644
index 000000000000..5dee884f2822
--- /dev/null
+++ b/includes/libs/rdbms/encasing/LikeMatch.php
@@ -0,0 +1,28 @@
+<?php
+/**
+ * Used by DatabaseBase::buildLike() to represent characters that have special
+ * meaning in SQL LIKE clauses and thus need no escaping. Don't instantiate it
+ * manually, use DatabaseBase::anyChar() and anyString() instead.
+ */
+class LikeMatch {
+	/** @var string */
+	private $str;
+
+	/**
+	 * Store a string into a LikeMatch marker object.
+	 *
+	 * @param string $s
+	 */
+	public function __construct( $s ) {
+		$this->str = $s;
+	}
+
+	/**
+	 * Return the original stored string.
+	 *
+	 * @return string
+	 */
+	public function toString() {
+		return $this->str;
+	}
+}
diff --git a/includes/libs/rdbms/encasing/MssqlBlob.php b/includes/libs/rdbms/encasing/MssqlBlob.php
new file mode 100644
index 000000000000..35be65c26e7c
--- /dev/null
+++ b/includes/libs/rdbms/encasing/MssqlBlob.php
@@ -0,0 +1,33 @@
+<?php
+class MssqlBlob extends Blob {
+	public function __construct( $data ) {
+		if ( $data instanceof MssqlBlob ) {
+			return $data;
+		} elseif ( $data instanceof Blob ) {
+			$this->mData = $data->fetch();
+		} elseif ( is_array( $data ) && is_object( $data ) ) {
+			$this->mData = serialize( $data );
+		} else {
+			$this->mData = $data;
+		}
+	}
+
+	/**
+	 * Returns an unquoted hex representation of a binary string
+	 * for insertion into varbinary-type fields
+	 * @return string
+	 */
+	public function fetch() {
+		if ( $this->mData === null ) {
+			return 'null';
+		}
+
+		$ret = '0x';
+		$dataLength = strlen( $this->mData );
+		for ( $i = 0; $i < $dataLength; $i++ ) {
+			$ret .= bin2hex( pack( 'C', ord( $this->mData[$i] ) ) );
+		}
+
+		return $ret;
+	}
+}
diff --git a/includes/libs/rdbms/encasing/PostgresBlob.php b/includes/libs/rdbms/encasing/PostgresBlob.php
new file mode 100644
index 000000000000..cc52336c299a
--- /dev/null
+++ b/includes/libs/rdbms/encasing/PostgresBlob.php
@@ -0,0 +1,4 @@
+<?php
+class PostgresBlob extends Blob {
+
+}
diff --git a/includes/libs/rdbms/field/Field.php b/includes/libs/rdbms/field/Field.php
new file mode 100644
index 000000000000..ed102f40c17c
--- /dev/null
+++ b/includes/libs/rdbms/field/Field.php
@@ -0,0 +1,30 @@
+<?php
+/**
+ * Base for all database-specific classes representing information about database fields
+ * @ingroup Database
+ */
+interface Field {
+	/**
+	 * Field name
+	 * @return string
+	 */
+	function name();
+
+	/**
+	 * Name of table this field belongs to
+	 * @return string
+	 */
+	function tableName();
+
+	/**
+	 * Database type
+	 * @return string
+	 */
+	function type();
+
+	/**
+	 * Whether this field can store NULL values
+	 * @return bool
+	 */
+	function isNullable();
+}
diff --git a/includes/libs/rdbms/field/MssqlField.php b/includes/libs/rdbms/field/MssqlField.php
new file mode 100644
index 000000000000..80e19245bf40
--- /dev/null
+++ b/includes/libs/rdbms/field/MssqlField.php
@@ -0,0 +1,38 @@
+<?php
+class MssqlField implements Field {
+	private $name, $tableName, $default, $max_length, $nullable, $type;
+
+	function __construct( $info ) {
+		$this->name = $info['COLUMN_NAME'];
+		$this->tableName = $info['TABLE_NAME'];
+		$this->default = $info['COLUMN_DEFAULT'];
+		$this->max_length = $info['CHARACTER_MAXIMUM_LENGTH'];
+		$this->nullable = !( strtolower( $info['IS_NULLABLE'] ) == 'no' );
+		$this->type = $info['DATA_TYPE'];
+	}
+
+	function name() {
+		return $this->name;
+	}
+
+	function tableName() {
+		return $this->tableName;
+	}
+
+	function defaultValue() {
+		return $this->default;
+	}
+
+	function maxLength() {
+		return $this->max_length;
+	}
+
+	function isNullable() {
+		return $this->nullable;
+	}
+
+	function type() {
+		return $this->type;
+	}
+}
+
diff --git a/includes/libs/rdbms/field/MySQLField.php b/includes/libs/rdbms/field/MySQLField.php
new file mode 100644
index 000000000000..8cf964cc3d9a
--- /dev/null
+++ b/includes/libs/rdbms/field/MySQLField.php
@@ -0,0 +1,106 @@
+<?php
+class MySQLField implements Field {
+	private $name, $tablename, $default, $max_length, $nullable,
+		$is_pk, $is_unique, $is_multiple, $is_key, $type, $binary,
+		$is_numeric, $is_blob, $is_unsigned, $is_zerofill;
+
+	function __construct( $info ) {
+		$this->name = $info->name;
+		$this->tablename = $info->table;
+		$this->default = $info->def;
+		$this->max_length = $info->max_length;
+		$this->nullable = !$info->not_null;
+		$this->is_pk = $info->primary_key;
+		$this->is_unique = $info->unique_key;
+		$this->is_multiple = $info->multiple_key;
+		$this->is_key = ( $this->is_pk || $this->is_unique || $this->is_multiple );
+		$this->type = $info->type;
+		$this->binary = isset( $info->binary ) ? $info->binary : false;
+		$this->is_numeric = isset( $info->numeric ) ? $info->numeric : false;
+		$this->is_blob = isset( $info->blob ) ? $info->blob : false;
+		$this->is_unsigned = isset( $info->unsigned ) ? $info->unsigned : false;
+		$this->is_zerofill = isset( $info->zerofill ) ? $info->zerofill : false;
+	}
+
+	/**
+	 * @return string
+	 */
+	function name() {
+		return $this->name;
+	}
+
+	/**
+	 * @return string
+	 */
+	function tableName() {
+		return $this->tablename;
+	}
+
+	/**
+	 * @return string
+	 */
+	function type() {
+		return $this->type;
+	}
+
+	/**
+	 * @return bool
+	 */
+	function isNullable() {
+		return $this->nullable;
+	}
+
+	function defaultValue() {
+		return $this->default;
+	}
+
+	/**
+	 * @return bool
+	 */
+	function isKey() {
+		return $this->is_key;
+	}
+
+	/**
+	 * @return bool
+	 */
+	function isMultipleKey() {
+		return $this->is_multiple;
+	}
+
+	/**
+	 * @return bool
+	 */
+	function isBinary() {
+		return $this->binary;
+	}
+
+	/**
+	 * @return bool
+	 */
+	function isNumeric() {
+		return $this->is_numeric;
+	}
+
+	/**
+	 * @return bool
+	 */
+	function isBlob() {
+		return $this->is_blob;
+	}
+
+	/**
+	 * @return bool
+	 */
+	function isUnsigned() {
+		return $this->is_unsigned;
+	}
+
+	/**
+	 * @return bool
+	 */
+	function isZerofill() {
+		return $this->is_zerofill;
+	}
+}
+
diff --git a/includes/libs/rdbms/field/ORAField.php b/includes/libs/rdbms/field/ORAField.php
new file mode 100644
index 000000000000..e48310ddc3e4
--- /dev/null
+++ b/includes/libs/rdbms/field/ORAField.php
@@ -0,0 +1,50 @@
+<?php
+class ORAField implements Field {
+	private $name, $tablename, $default, $max_length, $nullable,
+		$is_pk, $is_unique, $is_multiple, $is_key, $type;
+
+	function __construct( $info ) {
+		$this->name = $info['column_name'];
+		$this->tablename = $info['table_name'];
+		$this->default = $info['data_default'];
+		$this->max_length = $info['data_length'];
+		$this->nullable = $info['not_null'];
+		$this->is_pk = isset( $info['prim'] ) && $info['prim'] == 1 ? 1 : 0;
+		$this->is_unique = isset( $info['uniq'] ) && $info['uniq'] == 1 ? 1 : 0;
+		$this->is_multiple = isset( $info['nonuniq'] ) && $info['nonuniq'] == 1 ? 1 : 0;
+		$this->is_key = ( $this->is_pk || $this->is_unique || $this->is_multiple );
+		$this->type = $info['data_type'];
+	}
+
+	function name() {
+		return $this->name;
+	}
+
+	function tableName() {
+		return $this->tablename;
+	}
+
+	function defaultValue() {
+		return $this->default;
+	}
+
+	function maxLength() {
+		return $this->max_length;
+	}
+
+	function isNullable() {
+		return $this->nullable;
+	}
+
+	function isKey() {
+		return $this->is_key;
+	}
+
+	function isMultipleKey() {
+		return $this->is_multiple;
+	}
+
+	function type() {
+		return $this->type;
+	}
+}
diff --git a/includes/libs/rdbms/field/SQLiteField.php b/includes/libs/rdbms/field/SQLiteField.php
new file mode 100644
index 000000000000..0a2389bfb0a7
--- /dev/null
+++ b/includes/libs/rdbms/field/SQLiteField.php
@@ -0,0 +1,39 @@
+<?php
+class SQLiteField implements Field {
+	private $info, $tableName;
+
+	function __construct( $info, $tableName ) {
+		$this->info = $info;
+		$this->tableName = $tableName;
+	}
+
+	function name() {
+		return $this->info->name;
+	}
+
+	function tableName() {
+		return $this->tableName;
+	}
+
+	function defaultValue() {
+		if ( is_string( $this->info->dflt_value ) ) {
+			// Typically quoted
+			if ( preg_match( '/^\'(.*)\'$', $this->info->dflt_value ) ) {
+				return str_replace( "''", "'", $this->info->dflt_value );
+			}
+		}
+
+		return $this->info->dflt_value;
+	}
+
+	/**
+	 * @return bool
+	 */
+	function isNullable() {
+		return !$this->info->notnull;
+	}
+
+	function type() {
+		return $this->info->type;
+	}
+}