*: add a session variable for window function parser (#8511)

executor/prepared.go

@@ -112,7 +112,9 @@ func (e *PrepareExec) Next(ctx context.Context, chk *chunk.Chunk) error {
 	if sqlParser, ok := e.ctx.(sqlexec.SQLParser); ok {
 		stmts, err = sqlParser.ParseSQL(e.sqlText, charset, collation)
 	} else {
-		stmts, err = parser.New().Parse(e.sqlText, charset, collation)
+		p := parser.New()
+		p.EnableWindowFunc(vars.EnableWindowFunction)
+		stmts, err = p.Parse(e.sqlText, charset, collation)
 	}
 	if err != nil {
 		return errors.Trace(err)

go.mod

@@ -47,7 +47,7 @@ require (
 	github.com/pingcap/errors v0.11.0
 	github.com/pingcap/goleveldb v0.0.0-20171020122428-b9ff6c35079e
 	github.com/pingcap/kvproto v0.0.0-20181105061835-1b5d69cd1d26
-	github.com/pingcap/parser v0.0.0-20181126111651-a38036a60de7
+	github.com/pingcap/parser v0.0.0-20181204031237-721bcaad1aeb
 	github.com/pingcap/pd v2.1.0-rc.4+incompatible
 	github.com/pingcap/tidb-tools v0.0.0-20181112132202-4860a0d5de03
 	github.com/pingcap/tipb v0.0.0-20181012112600-11e33c750323

go.sum

@@ -107,8 +107,8 @@ github.com/pingcap/goleveldb v0.0.0-20171020122428-b9ff6c35079e h1:P73/4dPCL96rG
 github.com/pingcap/goleveldb v0.0.0-20171020122428-b9ff6c35079e/go.mod h1:O17XtbryoCJhkKGbT62+L2OlrniwqiGLSqrmdHCMzZw=
 github.com/pingcap/kvproto v0.0.0-20181105061835-1b5d69cd1d26 h1:JK4VLNYbSn36QSbCnqALi2ySXdH0DfcMssT/zmLf4Ls=
 github.com/pingcap/kvproto v0.0.0-20181105061835-1b5d69cd1d26/go.mod h1:0gwbe1F2iBIjuQ9AH0DbQhL+Dpr5GofU8fgYyXk+ykk=
-github.com/pingcap/parser v0.0.0-20181126111651-a38036a60de7 h1:E/T5kIrtzipWJhN/YREI+f3PiP6Uw5boE4KRcD+zVvo=
-github.com/pingcap/parser v0.0.0-20181126111651-a38036a60de7/go.mod h1:1FNvfp9+J0wvc4kl8eGNh7Rqrxveg15jJoWo/a0uHwA=
+github.com/pingcap/parser v0.0.0-20181204031237-721bcaad1aeb h1:GDXh3Y82QF1mRB1nQi2+4QJsIsPEk3BIbl6YSRJIVk0=
+github.com/pingcap/parser v0.0.0-20181204031237-721bcaad1aeb/go.mod h1:1FNvfp9+J0wvc4kl8eGNh7Rqrxveg15jJoWo/a0uHwA=
 github.com/pingcap/pd v2.1.0-rc.4+incompatible h1:/buwGk04aHO5odk/+O8ZOXGs4qkUjYTJ2UpCJXna8NE=
 github.com/pingcap/pd v2.1.0-rc.4+incompatible/go.mod h1:nD3+EoYes4+aNNODO99ES59V83MZSI+dFbhyr667a0E=
 github.com/pingcap/tidb-tools v0.0.0-20181112132202-4860a0d5de03 h1:xVuo5U+l6XAWHsb+xhkZ8zz3jerIwDfCHAO6kR2Kaog=

session/session.go

@@ -803,6 +803,7 @@ func (s *session) ParseSQL(ctx context.Context, sql, charset, collation string)
 		defer span1.Finish()
 	}
 	s.parser.SetSQLMode(s.sessionVars.SQLMode)
+	s.parser.EnableWindowFunc(s.sessionVars.EnableWindowFunction)
 	return s.parser.Parse(sql, charset, collation)
 }
 
@@ -1406,7 +1407,8 @@ const loadCommonGlobalVarsSQL = "select HIGH_PRIORITY * from mysql.global_variab
 	variable.TiDBMaxChunkSize + quoteCommaQuote +
 	variable.TiDBEnableCascadesPlanner + quoteCommaQuote +
 	variable.TiDBRetryLimit + quoteCommaQuote +
-	variable.TiDBDisableTxnAutoRetry + "')"
+	variable.TiDBDisableTxnAutoRetry + quoteCommaQuote +
+	variable.TiDBEnableWindowFunction + "')"
 
 // loadCommonGlobalVariablesIfNeeded loads and applies commonly used global variables for the session.
 func (s *session) loadCommonGlobalVariablesIfNeeded() error {

session/tidb.go

@@ -124,6 +124,7 @@ func Parse(ctx sessionctx.Context, src string) ([]ast.StmtNode, error) {
 	log.Debug("compiling", src)
 	charset, collation := ctx.GetSessionVars().GetCharsetInfo()
 	p := parser.New()
+	p.EnableWindowFunc(ctx.GetSessionVars().EnableWindowFunction)
 	p.SetSQLMode(ctx.GetSessionVars().SQLMode)
 	stmts, err := p.Parse(src, charset, collation)
 	if err != nil {

sessionctx/variable/session.go

@@ -311,6 +311,9 @@ type SessionVars struct {
 	// EnableCascadesPlanner enables the cascades planner.
 	EnableCascadesPlanner bool
 
+	// EnableWindowFunction enables the window function.
+	EnableWindowFunction bool
+
 	// DDLReorgPriority is the operation priority of adding indices.
 	DDLReorgPriority int
 
@@ -692,6 +695,8 @@ func (s *SessionVars) SetSystemVar(name string, val string) error {
 		atomic.StoreInt32(&ForcePriority, int32(mysql.Str2Priority(val)))
 	case TiDBEnableRadixJoin:
 		s.EnableRadixJoin = TiDBOptOn(val)
+	case TiDBEnableWindowFunction:
+		s.EnableWindowFunction = TiDBOptOn(val)
 	}
 	s.systems[name] = val
 	return nil

sessionctx/variable/sysvar.go

@@ -664,6 +664,7 @@ var defaultSysVars = []*SysVar{
 	{ScopeGlobal | ScopeSession, TiDBDisableTxnAutoRetry, boolToIntStr(DefTiDBDisableTxnAutoRetry)},
 	{ScopeGlobal | ScopeSession, TiDBConstraintCheckInPlace, boolToIntStr(DefTiDBConstraintCheckInPlace)},
 	{ScopeSession, TiDBOptimizerSelectivityLevel, strconv.Itoa(DefTiDBOptimizerSelectivityLevel)},
+	{ScopeGlobal | ScopeSession, TiDBEnableWindowFunction, boolToIntStr(DefEnableWindowFunction)},
 	/* The following variable is defined as session scope but is actually server scope. */
 	{ScopeSession, TiDBGeneralLog, strconv.Itoa(DefTiDBGeneralLog)},
 	{ScopeSession, TiDBSlowLogThreshold, strconv.Itoa(logutil.DefaultSlowThreshold)},

sessionctx/variable/tidb_vars.go

@@ -215,6 +215,9 @@ const (
 	// tidb_constraint_check_in_place indicates to check the constraint when the SQL executing.
 	// It could hurt the performance of bulking insert when it is ON.
 	TiDBConstraintCheckInPlace = "tidb_constraint_check_in_place"
+
+	// tidb_enable_window_function is used to control whether to enable the window function.
+	TiDBEnableWindowFunction = "tidb_enable_window_function"
 )
 
 // Default TiDB system variable values.
@@ -261,6 +264,7 @@ const (
 	DefTiDBHashAggFinalConcurrency   = 4
 	DefTiDBForcePriority             = mysql.NoPriority
 	DefTiDBUseRadixJoin              = false
+	DefEnableWindowFunction          = false
 )
 
 // Process global variables.

sessionctx/variable/varsutil.go

@@ -314,7 +314,7 @@ func ValidateSetSystemVar(vars *SessionVars, name string, value string) (string,
 	case AutocommitVar, TiDBSkipUTF8Check, TiDBOptAggPushDown,
 		TiDBOptInSubqToJoinAndAgg,
 		TiDBBatchInsert, TiDBDisableTxnAutoRetry, TiDBEnableStreaming,
-		TiDBBatchDelete, TiDBEnableCascadesPlanner:
+		TiDBBatchDelete, TiDBEnableCascadesPlanner, TiDBEnableWindowFunction:
 		if strings.EqualFold(value, "ON") || value == "1" || strings.EqualFold(value, "OFF") || value == "0" {
 			return value, nil
 		}