cherry pick #37264 to release-6.1

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

cmd/explaintest/r/clustered_index.result

@@ -1,3 +1,4 @@
+set @@tidb_enable_outer_join_reorder=true;
 drop database if exists with_cluster_index;
 create database with_cluster_index;
 drop database if exists wout_cluster_index;
@@ -127,3 +128,4 @@ StreamAgg_17 1.00 root funcs:count(Column#9)->Column#7
 └─IndexReader_18 1.00 root index:StreamAgg_9
  └─StreamAgg_9 1.00 cop[tikv] funcs:count(1)->Column#9
  └─IndexRangeScan_16 109.70 cop[tikv] table:tbl_0, index:idx_3(col_0) range:[803163,+inf], keep order:false
+set @@tidb_enable_outer_join_reorder=false;

cmd/explaintest/r/select.result

@@ -1,3 +1,4 @@
+set @@tidb_enable_outer_join_reorder=true;
 DROP TABLE IF EXISTS t;
 CREATE TABLE t (
 c1 int,
@@ -654,3 +655,4 @@ create table t3(a char(10), primary key (a));
 insert into t3 values ('a');
 select * from t3 where a > 0x80;
 Error 1105: Cannot convert string '\x80' from binary to utf8mb4
+set @@tidb_enable_outer_join_reorder=false;

cmd/explaintest/t/clustered_index.test

@@ -1,3 +1,4 @@
+set @@tidb_enable_outer_join_reorder=true;
 drop database if exists with_cluster_index;
 create database with_cluster_index;
 drop database if exists wout_cluster_index;
@@ -53,3 +54,4 @@ explain select count(*) from wout_cluster_index.tbl_0 where col_0 <= 0 ;
 
 explain select count(*) from with_cluster_index.tbl_0 where col_0 >= 803163 ;
 explain select count(*) from wout_cluster_index.tbl_0 where col_0 >= 803163 ;
+set @@tidb_enable_outer_join_reorder=false;

cmd/explaintest/t/select.test

@@ -1,3 +1,4 @@
+set @@tidb_enable_outer_join_reorder=true;
 DROP TABLE IF EXISTS t;
 
 CREATE TABLE t (
@@ -279,3 +280,4 @@ create table t3(a char(10), primary key (a));
 insert into t3 values ('a');
 --error 1105
 select * from t3 where a > 0x80;
+set @@tidb_enable_outer_join_reorder=false;

planner/core/rule_join_reorder_test.go

@@ -239,6 +239,7 @@ func TestJoinOrderHint4StaticPartitionTable(t *testing.T) {
  tk.MustExec(`create table t3(a int, b int) partition by hash(b) partitions 3`)
 
  tk.MustExec(`set @@tidb_partition_prune_mode="static"`)
+ tk.MustExec("set @@tidb_enable_outer_join_reorder=true")
  runJoinReorderTestData(t, tk, "TestJoinOrderHint4StaticPartitionTable")
 }
 
@@ -255,6 +256,7 @@ func TestJoinOrderHint4DynamicPartitionTable(t *testing.T) {
  tk.MustExec(`create table t3(a int, b int) partition by hash(b) partitions 3`)
 
  tk.MustExec(`set @@tidb_partition_prune_mode="dynamic"`)
+ tk.MustExec("set @@tidb_enable_outer_join_reorder=true")
  runJoinReorderTestData(t, tk, "TestJoinOrderHint4DynamicPartitionTable")
 }
 
@@ -274,6 +276,7 @@ func TestJoinOrderHint4DifferentJoinType(t *testing.T) {
  tk.MustExec("create table t6(a int, b int, key(a));")
  tk.MustExec("create table t7(a int, b int, key(a));")
  tk.MustExec("create table t8(a int, b int, key(a));")
+ tk.MustExec("set @@tidb_enable_outer_join_reorder=true")
 
  runJoinReorderTestData(t, tk, "TestJoinOrderHint4DifferentJoinType")
 }
@@ -288,6 +291,13 @@ func TestJoinOrderHint4TiFlash(t *testing.T) {
  tk.MustExec("create table t1(a int, b int, key(a));")
  tk.MustExec("create table t2(a int, b int, key(a));")
  tk.MustExec("create table t3(a int, b int, key(a));")
+<<<<<<< HEAD
+=======
+ tk.MustExec("create table t4(a int, b int, key(a));")
+ tk.MustExec("create table t5(a int, b int, key(a));")
+ tk.MustExec("create table t6(a int, b int, key(a));")
+ tk.MustExec("set @@tidb_enable_outer_join_reorder=true")
+>>>>>>> 21847fe58... planner: set EnableOuterJoinReorder to false by default (#37264)
 
  // Create virtual tiflash replica info.
  dom := domain.GetDomain(tk.Session())
@@ -330,6 +340,28 @@ func TestJoinOrderHint4Subquery(t *testing.T) {
  runJoinReorderTestData(t, tk, "TestJoinOrderHint4Subquery")
 }
 
+<<<<<<< HEAD
+=======
+func TestLeadingJoinHint4OuterJoin(t *testing.T) {
+ store := testkit.CreateMockStore(t)
+
+ tk := testkit.NewTestKit(t, store)
+ tk.MustExec("use test")
+ tk.MustExec("drop table if exists t, t1, t2, t3, t4, t5, t6, t7, t8;")
+ tk.MustExec("create table t(a int, b int, key(a));")
+ tk.MustExec("create table t1(a int, b int, key(a));")
+ tk.MustExec("create table t2(a int, b int, key(a));")
+ tk.MustExec("create table t3(a int, b int, key(a));")
+ tk.MustExec("create table t4(a int, b int, key(a));")
+ tk.MustExec("create table t5(a int, b int, key(a));")
+ tk.MustExec("create table t6(a int, b int, key(a));")
+ tk.MustExec("create table t7(a int, b int, key(a));")
+ tk.MustExec("create table t8(a int, b int, key(a));")
+ tk.MustExec("set @@tidb_enable_outer_join_reorder=true")
+ runJoinReorderTestData(t, tk, "TestLeadingJoinHint4OuterJoin")
+}
+
+>>>>>>> 21847fe58... planner: set EnableOuterJoinReorder to false by default (#37264)
 func TestOuterJoinWIthEqCondCrossInnerJoin(t *testing.T) {
  store, clean := testkit.CreateMockStore(t)
  defer clean()

planner/core/rule_result_reorder_test.go

@@ -166,6 +166,7 @@ func TestOrderedResultModeOnJoin(t *testing.T) {
  tk.MustExec("drop table if exists t2")
  tk.MustExec("create table t1 (a int primary key, b int, c int, d int, key(b))")
  tk.MustExec("create table t2 (a int primary key, b int, c int, d int, key(b))")
+ tk.MustExec("set @@tidb_enable_outer_join_reorder=true")
  runTestData(t, tk, "TestOrderedResultModeOnJoin")
 }
 

sessionctx/variable/sysvar.go

@@ -196,7 +196,7 @@ var defaultSysVars = []*SysVar{
  s.OptimizerSelectivityLevel = tidbOptPositiveInt32(val, DefTiDBOptimizerSelectivityLevel)
  return nil
  }},
- {Scope: ScopeGlobal | ScopeSession, Name: TiDBOptimizerEnableOuterJoinReorder, Value: BoolToOnOff(DefTiDBEnableOuterJoinReorder), skipInit: true, Type: TypeBool, SetSession: func(s *SessionVars, val string) error {
+ {Scope: ScopeGlobal | ScopeSession, Name: TiDBOptimizerEnableOuterJoinReorder, Value: BoolToOnOff(DefTiDBEnableOuterJoinReorder), Type: TypeBool, SetSession: func(s *SessionVars, val string) error {
  s.EnableOuterJoinReorder = TiDBOptOn(val)
  return nil
  }},

sessionctx/variable/sysvar_test.go

@@ -677,6 +677,68 @@ func TestSettersandGetters(t *testing.T) {
  }
 }
 
+<<<<<<< HEAD
+=======
+// TestSkipInitIsUsed ensures that no new variables are added with skipInit: true.
+// This feature is deprecated, and if you need to run code to differentiate between init and "SET" (rare),
+// you can instead check if s.StmtCtx.StmtType == "Set".
+// The reason it is deprecated is that the behavior is typically wrong:
+// it means session settings won't inherit from global and don't apply until you first set
+// them in each session. This is a very weird behavior.
+// See: https://github.com/pingcap/tidb/issues/35051
+func TestSkipInitIsUsed(t *testing.T) {
+ for _, sv := range GetSysVars() {
+ if sv.skipInit {
+ // skipInit only ever applied to session scope, so if anyone is setting it on
+ // a variable without session, that doesn't make sense.
+ require.True(t, sv.HasSessionScope(), fmt.Sprintf("skipInit has no effect on a variable without session scope: %s", sv.Name))
+ // Since SetSession is the "init function" there is no init function to skip.
+ require.NotNil(t, sv.SetSession, fmt.Sprintf("skipInit has no effect on variables without an init (setsession) func: %s", sv.Name))
+ // Skipinit has no use on noop funcs, since noop funcs always skipinit.
+ require.False(t, sv.IsNoop, fmt.Sprintf("skipInit has no effect on noop variables: %s", sv.Name))
+
+ // Test for variables that have a default of "0" or "OFF"
+ // If it is session-only scoped there is likely no bug now.
+ // If it is also global-scoped, then there is a bug as soon as the global changes.
+ if !(sv.Name == RandSeed1 || sv.Name == RandSeed2) {
+ // The bug is because the tests might not realize the SetSession func was not called on init,
+ // because it would initialize some session field to the empty value anyway.
+ require.NotEqual(t, "0", sv.Value, fmt.Sprintf("default value is zero: %s", sv.Name))
+ require.NotEqual(t, "OFF", sv.Value, fmt.Sprintf("default value is OFF: %s", sv.Name))
+ }
+
+ // Many of these variables might allow skipInit to be removed,
+ // they need to be checked first. The purpose of this test is to make
+ // sure we don't introduce any new variables with skipInit, which seems
+ // to be a problem.
+ switch sv.Name {
+ case TiDBTxnScope,
+ TiDBSnapshot,
+ TiDBEnableChunkRPC,
+ TxnIsolationOneShot,
+ TiDBDDLReorgPriority,
+ TiDBSlowQueryFile,
+ TiDBWaitSplitRegionFinish,
+ TiDBWaitSplitRegionTimeout,
+ TiDBMetricSchemaStep,
+ TiDBMetricSchemaRangeDuration,
+ RandSeed1,
+ RandSeed2,
+ CollationDatabase,
+ CollationConnection,
+ CharsetDatabase,
+ CharacterSetConnection,
+ CharacterSetServer,
+ TiDBOptTiFlashConcurrencyFactor,
+ TiDBOptSeekFactor:
+ continue
+ }
+ require.Equal(t, false, sv.skipInit, fmt.Sprintf("skipInit should not be set on new system variables. variable %s is in violation", sv.Name))
+ }
+ }
+}
+
+>>>>>>> 21847fe58... planner: set EnableOuterJoinReorder to false by default (#37264)
 func TestSecureAuth(t *testing.T) {
  sv := GetSysVar(SecureAuth)
  vars := NewSessionVars()