planner: allow the optimizer to cache query plans accessing generated…

… columns by default (#51654)

close #45798

pkg/executor/explainfor_test.go

@@ -707,8 +707,7 @@ func TestIndexMerge4PlanCache(t *testing.T) {
 	tk.MustExec("prepare stmt from 'SELECT /*+ USE_INDEX_MERGE(t0, i0, PRIMARY)*/ t0.c0 FROM t0 WHERE t0.c1 OR t0.c0;';")
 	tk.MustQuery("execute stmt;").Check(testkit.Rows("1"))
 	tk.MustQuery("execute stmt;").Check(testkit.Rows("1"))
-	// The plan contains the generated column, so it can not be cached.
-	tk.MustQuery("select @@last_plan_from_cache;").Check(testkit.Rows("0"))
+	tk.MustQuery("select @@last_plan_from_cache;").Check(testkit.Rows("1"))
 
 	tk.MustExec("drop table if exists t1, t2")
 	tk.MustExec("create table t1(id int primary key, a int, b int, c int, d int)")

pkg/planner/core/plan_cache_test.go

@@ -1005,6 +1005,8 @@ func TestNonPreparedPlanExplainWarning(t *testing.T) {
 		"select distinct a from t1 where a > 1 and b < 2",          // distinct
 		"select count(*) from t1 where a > 1 and b < 2 group by a", // group by
 		"select * from t1 order by a",                              // order by
+		"select * from t3 where full_name = 'a b'",                 // generated column
+		"select * from t3 where a > 1 and full_name = 'a b'",
 	}
 
 	unsupported := []string{
@@ -1022,8 +1024,6 @@ func TestNonPreparedPlanExplainWarning(t *testing.T) {
 		"select * from t where bt > 0", // bit
 		"select * from t where a > 1 and bt > 0",
 		"select data_type from INFORMATION_SCHEMA.columns where table_name = 'v'", // memTable
-		"select * from t3 where full_name = 'a b'",                                // generated column
-		"select * from t3 where a > 1 and full_name = 'a b'",
 		"select * from v",                // view
 		"select * from t where a = null", // null
 		"select * from t where false",    // table dual
@@ -1044,8 +1044,6 @@ func TestNonPreparedPlanExplainWarning(t *testing.T) {
 		"skip non-prepared plan-cache: query has some filters with JSON, Enum, Set or Bit columns",
 		"skip non-prepared plan-cache: query has some filters with JSON, Enum, Set or Bit columns",
 		"skip non-prepared plan-cache: access tables in system schema",
-		"skip non-prepared plan-cache: query accesses generated columns is un-cacheable",
-		"skip non-prepared plan-cache: query accesses generated columns is un-cacheable",
 		"skip non-prepared plan-cache: queries that access views are not supported",
 		"skip non-prepared plan-cache: query has null constants",
 		"skip non-prepared plan-cache: some parameters may be overwritten when constant propagation",

pkg/planner/core/plan_cacheable_checker.go

@@ -621,11 +621,11 @@ func getMaxParamLimit(sctx PlanContext) int {
 
 func enablePlanCacheForGeneratedCols(sctx PlanContext) bool {
 	// disable this by default since it's not well tested.
-	// TODO: complete its test and enable it by default.
+	defaultVal := true
 	if sctx == nil || sctx.GetSessionVars() == nil || sctx.GetSessionVars().GetOptimizerFixControlMap() == nil {
-		return false
+		return defaultVal
 	}
-	return fixcontrol.GetBoolWithDefault(sctx.GetSessionVars().GetOptimizerFixControlMap(), fixcontrol.Fix45798, false)
+	return fixcontrol.GetBoolWithDefault(sctx.GetSessionVars().GetOptimizerFixControlMap(), fixcontrol.Fix45798, defaultVal)
 }
 
 // checkTableCacheable checks whether a query accessing this table is cacheable.

tests/integrationtest/r/planner/core/indexmerge_path.result

@@ -470,15 +470,13 @@ Selection	23.98	root		json_overlaps(json_extract(planner__core__indexmerge_path.
 drop table if exists t;
 create table t(j json, index kj((cast(j as signed array))));
 prepare st from 'select /*+ use_index_merge(t, kj) */ * from t where (1 member of (j))';
-Level	Code	Message
-Warning	1105	skip prepared plan-cache: query accesses generated columns is un-cacheable
 execute st;
 j
 execute st;
 j
 select @@last_plan_from_cache;
 @@last_plan_from_cache
-0
+1
 drop table if exists t;
 create table t(j json, unique kj((cast(j as signed array))));
 explain select j from t where j=1;