planner: disable LOCK IN SHARE MODE by default (#19506) (#21005)

Signed-off-by: ti-srebot <ti-srebot@pingcap.com>

Author: ti-srebot

expression/integration_test.go

@@ -6980,6 +6980,19 @@ func (s *testIntegrationSerialSuite) TestIssue19045(c *C) {
 	tk.MustQuery(`select  ( SELECT t1.a FROM  t1,  t2 WHERE t1.b = t2.a AND  t2.b = '03' AND t1.c = a.a) invode from t a ;`).Check(testkit.Rows("a011", "a011"))
 }
 
+func (s *testIntegrationSerialSuite) TestIssue19383(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+	tk.MustExec("use test")
+	tk.MustExec("DROP TABLE IF EXISTS t1")
+	tk.MustExec("CREATE TABLE t1 (a INT NOT NULL PRIMARY KEY)")
+	tk.MustExec("INSERT INTO t1 VALUES (1),(2),(3)")
+	_, err := tk.Exec("SELECT * FROM t1 LOCK IN SHARE MODE")
+	message := `function LOCK IN SHARE MODE has only noop implementation in tidb now, use tidb_enable_noop_functions to enable these functions`
+	c.Assert(strings.Contains(err.Error(), message), IsTrue)
+	tk.MustExec("SET tidb_enable_noop_functions=1")
+	tk.MustExec("SELECT * FROM t1 LOCK IN SHARE MODE")
+}
+
 func (s *testIntegrationSerialSuite) TestIssue19315(c *C) {
 	tk := testkit.NewTestKit(c, s.store)
 	tk.MustExec("use test")

planner/core/logical_plan_builder.go

@@ -2503,7 +2503,7 @@ func (b *PlanBuilder) buildSelect(ctx context.Context, sel *ast.SelectStmt) (p L
 		// table hints are only visible in the current SELECT statement.
 		b.popTableHints()
 	}()
-
+	enableNoopFuncs := b.ctx.GetSessionVars().EnableNoopFuncs
 	if sel.SelectStmtOpts != nil {
 		origin := b.inStraightJoin
 		b.inStraightJoin = sel.SelectStmtOpts.StraightJoin
@@ -2572,6 +2572,10 @@ func (b *PlanBuilder) buildSelect(ctx context.Context, sel *ast.SelectStmt) (p L
 	}
 
 	if sel.LockTp != ast.SelectLockNone {
+		if sel.LockTp == ast.SelectLockInShareMode && !enableNoopFuncs {
+			err = expression.ErrFunctionsNoopImpl.GenWithStackByArgs("LOCK IN SHARE MODE")
+			return nil, err
+		}
 		p = b.buildSelectLock(p, sel.LockTp)
 	}
 	b.handleHelper.popMap()