planner: introduce a new fix-control 43817 to control whether to allo…

…w the optimizer to evaluate non-correlated sub-queries in advance (#53782)

ref #43817

pkg/executor/executor.go

@@ -1446,6 +1446,10 @@ func init() {
 	// but the plan package cannot import the executor package because of the dependency cycle.
 	// So we assign a function implemented in the executor package to the plan package to avoid the dependency cycle.
 	plannercore.EvalSubqueryFirstRow = func(ctx context.Context, p base.PhysicalPlan, is infoschema.InfoSchema, pctx planctx.PlanContext) ([]types.Datum, error) {
+		if fixcontrol.GetBoolWithDefault(pctx.GetSessionVars().OptimizerFixControl, fixcontrol.Fix43817, false) {
+			return nil, errors.NewNoStackError("evaluate non-correlated sub-queries during optimization phase is not allowed by fix-control 43817")
+		}
+
 		defer func(begin time.Time) {
 			s := pctx.GetSessionVars()
 			s.StmtCtx.SetSkipPlanCache("query has uncorrelated sub-queries is un-cacheable")

pkg/planner/core/casetest/BUILD.bazel

@@ -12,7 +12,7 @@ go_test(
     ],
     data = glob(["testdata/**"]),
     flaky = True,
-    shard_count = 25,
+    shard_count = 26,
     deps = [
         "//pkg/domain",
         "//pkg/errno",

pkg/planner/core/casetest/integration_test.go

@@ -392,6 +392,19 @@ func TestIssue50926(t *testing.T) {
 	tk.MustQuery("select sum(json_extract(b, '$.path')) from v group by a").Check(testkit.Rows()) // no error
 }
 
+func TestFixControl43817(t *testing.T) {
+	store := testkit.CreateMockStore(t)
+	tk := testkit.NewTestKit(t, store)
+	tk.MustExec(`use test`)
+	tk.MustExec(`create table t1 (a int)`)
+	tk.MustExec(`create table t2 (a int)`)
+	tk.MustQuery(`select * from t1 where t1.a > (select max(a) from t2)`).Check(testkit.Rows()) // no error
+	tk.MustExec(`set tidb_opt_fix_control="43817:on"`)
+	tk.MustContainErrMsg(`select * from t1 where t1.a > (select max(a) from t2)`, "evaluate non-correlated sub-queries during optimization phase is not allowed by fix-control 43817")
+	tk.MustExec(`set tidb_opt_fix_control="43817:off"`)
+	tk.MustQuery(`select * from t1 where t1.a > (select max(a) from t2)`).Check(testkit.Rows()) // no error
+}
+
 func TestFixControl45132(t *testing.T) {
 	store := testkit.CreateMockStore(t)
 	tk := testkit.NewTestKit(t, store)

pkg/planner/util/fixcontrol/get.go

@@ -24,6 +24,10 @@ const (
 	// tables (both prepared statments and non-prepared statements)
 	// See #33031
 	Fix33031 uint64 = 33031
+	// Fix43817 controls whether to allow optimizer to evaluate non-correlated sub-queries in the optimization phase.
+	// If it is not allowed, the optimizer will return a particular error when encountering non-correlated sub-queries.
+	// This fix-control is mainly for Index Advisor.
+	Fix43817 uint64 = 43817
 	// Fix44262 controls whether to allow to use dynamic-mode to access partitioning tables without global-stats (#44262).
 	Fix44262 uint64 = 44262
 	// Fix44389 controls whether to consider non-point ranges of some CNF item when building ranges.