diff --git a/ddl/index.go b/ddl/index.go
index 7332121e76..66d1f537c5 100644
--- a/ddl/index.go
+++ b/ddl/index.go
@@ -394,7 +394,6 @@ func (d *ddl) getSnapshotRows(t table.Table, version uint64, seekHandle int64) (
 
 		handles = append(handles, handle)
 		if len(handles) == maxBatchSize {
-			seekHandle = handle + 1
 			break
 		}
 
@@ -476,54 +475,7 @@ func (d *ddl) backfillTableIndex(t table.Table, indexInfo *model.IndexInfo, hand
 
 func (d *ddl) dropTableIndex(t table.Table, indexInfo *model.IndexInfo) error {
 	prefix := kv.GenIndexPrefix(t.IndexPrefix(), indexInfo.ID)
-	for {
-		keys := make([]kv.Key, 0, maxBatchSize)
-		err := kv.RunInNewTxn(d.store, false, func(txn kv.Transaction) error {
-			iter, err := txn.Seek(prefix)
-			if err != nil {
-				return errors.Trace(err)
-			}
+	err := d.delKeysWithPrefix(prefix)
 
-			defer iter.Close()
-			for i := 0; i < maxBatchSize; i++ {
-				if iter.Valid() && iter.Key().HasPrefix(prefix) {
-					keys = append(keys, iter.Key().Clone())
-					err = iter.Next()
-					if err != nil {
-						return errors.Trace(err)
-					}
-				} else {
-					break
-				}
-			}
-
-			return nil
-		})
-
-		// if err or delete no keys, return.
-		if err != nil || len(keys) == 0 {
-			return errors.Trace(err)
-		}
-
-		// delete index key one by one
-		for _, key := range keys {
-			err = kv.RunInNewTxn(d.store, true, func(txn kv.Transaction) error {
-				if err1 := d.isReorgRunnable(txn); err1 != nil {
-					return errors.Trace(err1)
-				}
-
-				err1 := txn.Delete(key)
-				// if key doesn't exist, skip this error.
-				if err1 != nil && !terror.ErrorEqual(err1, kv.ErrNotExist) {
-					return errors.Trace(err1)
-				}
-
-				return nil
-			})
-
-			if err != nil {
-				return errors.Trace(err)
-			}
-		}
-	}
+	return errors.Trace(err)
 }
diff --git a/ddl/reorg.go b/ddl/reorg.go
index be27db8088..afaee3d2ef 100644
--- a/ddl/reorg.go
+++ b/ddl/reorg.go
@@ -182,6 +182,7 @@ func (d *ddl) delKeysWithPrefix(prefix kv.Key) error {
 			for _, key := range keys {
 				err := txn.Delete(key)
 				// must skip ErrNotExist
+				// if key doesn't exist, skip this error.
 				if err != nil && !terror.ErrorEqual(err, kv.ErrNotExist) {
 					return errors.Trace(err)
 				}
diff --git a/expression/builtin/builtin.go b/expression/builtin/builtin.go
index cb41f826a4..9c6f61fd68 100644
--- a/expression/builtin/builtin.go
+++ b/expression/builtin/builtin.go
@@ -114,6 +114,7 @@ var Funcs = map[string]Func{
 	"found_rows":    {builtinFoundRows, 0, 0, false, false},
 	"user":          {builtinUser, 0, 0, false, false},
 	"connection_id": {builtinConnectionID, 0, 0, true, false},
+	"version":       {builtinVersion, 0, 0, true, false},
 }
 
 func invArg(arg interface{}, s string) error {
diff --git a/expression/builtin/info.go b/expression/builtin/info.go
index 14687d6b42..34f255e2d9 100644
--- a/expression/builtin/info.go
+++ b/expression/builtin/info.go
@@ -20,6 +20,7 @@ package builtin
 import (
 	"github.com/juju/errors"
 	"github.com/pingcap/tidb/context"
+	"github.com/pingcap/tidb/mysql"
 	"github.com/pingcap/tidb/sessionctx/db"
 	"github.com/pingcap/tidb/sessionctx/variable"
 )
@@ -76,3 +77,7 @@ func builtinConnectionID(args []interface{}, data map[interface{}]interface{}) (
 	ctx := c.(context.Context)
 	return variable.GetSessionVars(ctx).ConnectionID, nil
 }
+
+func builtinVersion(args []interface{}, data map[interface{}]interface{}) (v interface{}, err error) {
+	return mysql.ServerVersion, nil
+}
diff --git a/expression/builtin/info_test.go b/expression/builtin/info_test.go
index 93eca4577b..987561a806 100644
--- a/expression/builtin/info_test.go
+++ b/expression/builtin/info_test.go
@@ -15,6 +15,7 @@ package builtin
 
 import (
 	. "github.com/pingcap/check"
+	"github.com/pingcap/tidb/mysql"
 	"github.com/pingcap/tidb/sessionctx/db"
 	"github.com/pingcap/tidb/sessionctx/variable"
 	"github.com/pingcap/tidb/util/mock"
@@ -94,3 +95,10 @@ func (s *testBuiltinSuite) TestConnectionID(c *C) {
 	c.Assert(err, IsNil)
 	c.Assert(v, Equals, uint64(1))
 }
+
+func (s *testBuiltinSuite) TestVersion(c *C) {
+	m := map[interface{}]interface{}{}
+	v, err := builtinVersion(nil, m)
+	c.Assert(err, IsNil)
+	c.Assert(v, Equals, mysql.ServerVersion)
+}
diff --git a/parser/parser.y b/parser/parser.y
index ccfd8ab8ff..b0ceb7baa8 100644
--- a/parser/parser.y
+++ b/parser/parser.y
@@ -280,6 +280,7 @@ import (
 	value		"VALUE"
 	values		"VALUES"
 	variables	"VARIABLES"
+	version		"VERSION"
 	warnings	"WARNINGS"
 	week		"WEEK"
 	weekday		"WEEKDAY"
@@ -1696,7 +1697,7 @@ NotKeywordToken:
 |	"DATE_ADD" | "DATE_SUB" | "DAYNAME" | "DAYOFMONTH" | "DAYOFWEEK" | "DAYOFYEAR" | "FOUND_ROWS" | "GROUP_CONCAT"| "HOUR"
 |	"IFNULL" | "LENGTH" | "LOCATE" | "MAX" | "MICROSECOND" | "MIN" | "MINUTE" | "NULLIF" | "MONTH" | "NOW" | "POW"
 |	"POWER" | "RAND" | "SECOND" | "SQL_CALC_FOUND_ROWS" | "SUBDATE" | "SUBSTRING" %prec lowerThanLeftParen
-|	"SUBSTRING_INDEX" | "SUM" | "TRIM" | "WEEKDAY" | "WEEKOFYEAR" |	"YEARWEEK"
+|	"SUBSTRING_INDEX" | "SUM" | "TRIM" | "VERSION" | "WEEKDAY" | "WEEKOFYEAR" |	"YEARWEEK"
 
 /************************************************************************************
  *
@@ -2043,7 +2044,7 @@ Function:
 |	FunctionCallAgg
 
 FunctionNameConflict:
-	"DATABASE" | "SCHEMA" | "IF" | "LEFT" | "REPEAT" | "CURRENT_USER" | "CURRENT_DATE"
+	"DATABASE" | "SCHEMA" | "IF" | "LEFT" | "REPEAT" | "CURRENT_USER" | "CURRENT_DATE" | "VERSION"
 
 FunctionCallConflict:
 	FunctionNameConflict '(' ExpressionListOpt ')' 
diff --git a/parser/parser_test.go b/parser/parser_test.go
index 7ce828d882..7f30e22712 100644
--- a/parser/parser_test.go
+++ b/parser/parser_test.go
@@ -41,7 +41,7 @@ func (s *testParserSuite) TestSimple(c *C) {
 		"collation", "comment", "avg_row_length", "checksum", "compression", "connection", "key_block_size",
 		"max_rows", "min_rows", "national", "row", "quarter", "escape", "grants", "status", "fields", "triggers",
 		"delay_key_write", "isolation", "repeatable", "committed", "uncommitted", "only", "serializable", "level",
-		"curtime", "variables", "dayname",
+		"curtime", "variables", "dayname", "version",
 	}
 	for _, kw := range unreservedKws {
 		src := fmt.Sprintf("SELECT %s FROM tbl;", kw)
@@ -355,6 +355,7 @@ func (s *testParserSuite) TestBuiltin(c *C) {
 		{"SELECT CURRENT_USER();", true},
 		{"SELECT CURRENT_USER;", true},
 		{"SELECT CONNECTION_ID();", true},
+		{"SELECT VERSION();", true},
 
 		{"SELECT SUBSTRING_INDEX('www.mysql.com', '.', 2);", true},
 		{"SELECT SUBSTRING_INDEX('www.mysql.com', '.', -2);", true},
diff --git a/parser/scanner.l b/parser/scanner.l
index 59cf21f7f0..808a2506b8 100644
--- a/parser/scanner.l
+++ b/parser/scanner.l
@@ -477,6 +477,7 @@ upper		{u}{p}{p}{e}{r}
 value		{v}{a}{l}{u}{e}
 values		{v}{a}{l}{u}{e}{s}
 variables	{v}{a}{r}{i}{a}{b}{l}{e}{s}
+version		{v}{e}{r}{s}{i}{o}{n}
 warnings	{w}{a}{r}{n}{i}{n}{g}{s}
 week		{w}{e}{e}{k}
 weekday		{w}{e}{e}{k}{d}{a}{y}
@@ -976,6 +977,8 @@ year_month		{y}{e}{a}{r}_{m}{o}{n}{t}{h}
 {values}		return values
 {variables}		lval.item = string(l.val)
 			return variables
+{version}		lval.item = string(l.val)
+			return version
 {warnings}		lval.item = string(l.val)
 			return warnings
 {week}			lval.item = string(l.val)