txn: fix the lock behaviours when for update is used outside transactions | tidb-test=pr/2365

pkg/executor/adapter.go

@@ -581,8 +581,13 @@ func (a *ExecStmt) Exec(ctx context.Context) (_ sqlexec.RecordSet, err error) {
 	isPessimistic := sctx.GetSessionVars().TxnCtx.IsPessimistic
 
 	// Special handle for "select for update statement" in pessimistic transaction.
-	if isPessimistic && a.isSelectForUpdate {
-		return a.handlePessimisticSelectForUpdate(ctx, e)
+	if a.isSelectForUpdate {
+		if sctx.GetSessionVars().UseLowResolutionTSO() {
+			return nil, errors.New("can not execute select for update statement when 'tidb_low_resolution_tso' is set")
+		}
+		if isPessimistic {
+			return a.handlePessimisticSelectForUpdate(ctx, e)
+		}
 	}
 
 	a.prepareFKCascadeContext(e)
@@ -982,8 +987,7 @@ func (a *ExecStmt) handleNoDelayExecutor(ctx context.Context, e exec.Executor) (
 		if snapshotTS != 0 {
 			return nil, errors.New("can not execute write statement when 'tidb_snapshot' is set")
 		}
-		lowResolutionTSO := sctx.GetSessionVars().LowResolutionTSO
-		if lowResolutionTSO {
+		if sctx.GetSessionVars().UseLowResolutionTSO() {
 			return nil, errors.New("can not execute write statement when 'tidb_low_resolution_tso' is set")
 		}
 	}

pkg/executor/test/executor/executor_test.go

@@ -1886,21 +1886,60 @@ func TestLowResolutionTSORead(t *testing.T) {
 	tk := testkit.NewTestKit(t, store)
 	tk.MustExec("set @@autocommit=1")
 	tk.MustExec("use test")
-	tk.MustExec("create table low_resolution_tso(a int)")
+	tk.MustExec("create table low_resolution_tso(a int key)")
 	tk.MustExec("insert low_resolution_tso values (1)")
 
 	// enable low resolution tso
 	require.False(t, tk.Session().GetSessionVars().LowResolutionTSO)
 	tk.MustExec("set @@tidb_low_resolution_tso = 'on'")
 	require.True(t, tk.Session().GetSessionVars().LowResolutionTSO)
 
-	time.Sleep(3 * time.Second)
-	tk.MustQuery("select * from low_resolution_tso").Check(testkit.Rows("1"))
+	tk.MustQuery("select * from low_resolution_tso")
 	err := tk.ExecToErr("update low_resolution_tso set a = 2")
 	require.Error(t, err)
 	tk.MustExec("set @@tidb_low_resolution_tso = 'off'")
 	tk.MustExec("update low_resolution_tso set a = 2")
 	tk.MustQuery("select * from low_resolution_tso").Check(testkit.Rows("2"))
+
+	// Test select for update could not be executed when `tidb_low_resolution_tso` is enabled.
+	type testCase struct {
+		optimistic bool
+		pointGet   bool
+	}
+	cases := []testCase{
+		{true, true},
+		{true, false},
+		{false, true},
+		{false, false},
+	}
+	tk.MustExec("set @@tidb_low_resolution_tso = 'on'")
+	for _, test := range cases {
+		if test.optimistic {
+			tk.MustExec("begin optimistic")
+		} else {
+			tk.MustExec("begin")
+		}
+		var err error
+		if test.pointGet {
+			err = tk.ExecToErr("select * from low_resolution_tso where a = 1 for update")
+		} else {
+			err = tk.ExecToErr("select * from low_resolution_tso for update")
+		}
+		require.Error(t, err)
+		tk.MustExec("rollback")
+	}
+	tk.MustQuery("select * from low_resolution_tso for update")
+	tk.MustQuery("select * from low_resolution_tso where a = 1 for update")
+
+	origPessimisticAutoCommit := config.GetGlobalConfig().PessimisticTxn.PessimisticAutoCommit.Load()
+	config.GetGlobalConfig().PessimisticTxn.PessimisticAutoCommit.Store(true)
+	defer func() {
+		config.GetGlobalConfig().PessimisticTxn.PessimisticAutoCommit.Store(origPessimisticAutoCommit)
+	}()
+	err = tk.ExecToErr("select * from low_resolution_tso where a = 1 for update")
+	require.Error(t, err)
+	err = tk.ExecToErr("select * from low_resolution_tso for update")
+	require.Error(t, err)
 }
 
 func TestAdapterStatement(t *testing.T) {

pkg/planner/core/casetest/dag/testdata/plan_suite_out.json

@@ -416,7 +416,7 @@
     "Cases": [
       {
         "SQL": "select * from t order by b limit 1 for update",
-        "Best": "TableReader(Table(t)->TopN([test.t.b],0,1))->TopN([test.t.b],0,1)->Lock",
+        "Best": "TableReader(Table(t)->TopN([test.t.b],0,1))->TopN([test.t.b],0,1)",
         "Hints": "use_index(@`sel_1` `test`.`t` ), no_order_index(@`sel_1` `test`.`t` `primary`), limit_to_cop(@`sel_1`)"
       },
       {

pkg/planner/core/logical_plan_builder.go

@@ -3903,9 +3903,12 @@ func (b *PlanBuilder) buildSelect(ctx context.Context, sel *ast.SelectStmt) (p b
 			}
 			b.ctx.GetSessionVars().StmtCtx.LockTableIDs[tName.TableInfo.ID] = struct{}{}
 		}
-		p, err = b.buildSelectLock(p, l)
-		if err != nil {
-			return nil, err
+		lock, _ := getLockWaitTime(b.ctx, l)
+		if lock {
+			p, err = b.buildSelectLock(p, l)
+			if err != nil {
+				return nil, err
+			}
 		}
 	}
 	b.handleHelper.popMap()

pkg/planner/core/testdata/plan_suite_unexported_out.json

@@ -39,7 +39,7 @@
   {
     "Name": "TestPlanBuilder",
     "Cases": [
-      "DataScan(t)->Lock->Projection",
+      "DataScan(t)->Projection",
       "TableReader(Table(t)->Limit)->Limit->Update",
       "TableReader(Table(t)->Limit)->Limit->Delete",
       "*core.Explain",

pkg/sessionctx/variable/session.go

@@ -1091,6 +1091,7 @@ type SessionVars struct {
 	TxnMode string
 
 	// LowResolutionTSO is used for reading data with low resolution TSO which is updated once every two seconds.
+	// Do not use it directly, use the `UseLowResolutionTSO` method below.
 	LowResolutionTSO bool
 
 	// MaxExecutionTime is the timeout for select statement, in milliseconds.
@@ -3875,3 +3876,8 @@ const (
 func (s *SessionVars) GetOptObjective() string {
 	return s.OptObjective
 }
+
+// UseLowResolutionTSO indicates whether low resolution tso could be used for execution.
+func (s *SessionVars) UseLowResolutionTSO() bool {
+	return !s.InRestrictedSQL && s.LowResolutionTSO
+}

pkg/sessiontxn/isolation/base.go

@@ -650,7 +650,7 @@ func newOracleFuture(ctx context.Context, sctx sessionctx.Context, scope string)
 	oracleStore := sctx.GetStore().GetOracle()
 	option := &oracle.Option{TxnScope: scope}
 
-	if sctx.GetSessionVars().LowResolutionTSO {
+	if sctx.GetSessionVars().UseLowResolutionTSO() {
 		return oracleStore.GetLowResolutionTimestampAsync(ctx, option)
 	}
 	return oracleStore.GetTimestampAsync(ctx, option)

tests/integrationtest/r/executor/distsql.result

@@ -153,14 +153,15 @@ a	b	c
 15	15	15
 drop table if exists t;
 create table t(a int, b int, index k(b)) PARTITION BY HASH(a) partitions 4;
+begin;
 insert into t(a, b) values (1,1),(2,2),(3,3),(4,4),(5,5),(6,6),(7,7),(8,8);
 explain format='brief' select b from t use index(k) where b > 2 order by b limit 1 for update;
 id	estRows	task	access object	operator info
 Projection	1.00	root		executor__distsql.t.b
 └─SelectLock	1.00	root		for update 0
   └─Limit	1.00	root		offset:0, count:1
-    └─IndexReader	1.00	root	partition:all	index:Limit
-      └─Limit	1.00	cop[tikv]		offset:0, count:1
+    └─UnionScan	1.00	root		gt(executor__distsql.t.b, 2)
+      └─IndexReader	1.00	root	partition:all	index:IndexRangeScan
         └─IndexRangeScan	1.00	cop[tikv]	table:t, index:k(b)	range:(2,+inf], keep order:true, stats:pseudo
 select b from t use index(k) where b > 2 order by b limit 1 for update;
 b
@@ -171,9 +172,30 @@ id	estRows	task	access object	operator info
 Projection	1.00	root		executor__distsql.t.b
 └─SelectLock	1.00	root		for update 0
   └─Limit	1.00	root		offset:0, count:1
-    └─IndexReader	1.00	root	partition:all	index:Limit
-      └─Limit	1.00	cop[tikv]		offset:0, count:1
-        └─IndexRangeScan	1.00	cop[tikv]	table:t, index:k(b)	range:(2,+inf], keep order:true
+    └─UnionScan	1.00	root		gt(executor__distsql.t.b, 2)
+      └─IndexReader	1.00	root	partition:all	index:IndexRangeScan
+        └─IndexRangeScan	1.00	cop[tikv]	table:t, index:k(b)	range:(2,+inf], keep order:true, stats:pseudo
+select b from t use index(k) where b > 2 order by b limit 1 for update;
+b
+3
+rollback;
+insert into t(a, b) values (1,1),(2,2),(3,3),(4,4),(5,5),(6,6),(7,7),(8,8);
+explain format='brief' select b from t use index(k) where b > 2 order by b limit 1 for update;
+id	estRows	task	access object	operator info
+Limit	1.00	root		offset:0, count:1
+└─IndexReader	1.00	root	partition:all	index:Limit
+  └─Limit	1.00	cop[tikv]		offset:0, count:1
+    └─IndexRangeScan	1.00	cop[tikv]	table:t, index:k(b)	range:(2,+inf], keep order:true, stats:pseudo
+select b from t use index(k) where b > 2 order by b limit 1 for update;
+b
+3
+analyze table t;
+explain format='brief' select b from t use index(k) where b > 2 order by b limit 1 for update;
+id	estRows	task	access object	operator info
+Limit	1.00	root		offset:0, count:1
+└─IndexReader	1.00	root	partition:all	index:Limit
+  └─Limit	1.00	cop[tikv]		offset:0, count:1
+    └─IndexRangeScan	1.00	cop[tikv]	table:t, index:k(b)	range:(2,+inf], keep order:true
 select b from t use index(k) where b > 2 order by b limit 1 for update;
 b
 3

tests/integrationtest/r/index_merge.result

@@ -419,6 +419,7 @@ update t1 set c1 = 100, c2 = 100, c3 = 100 where c1 in (select /*+ use_index_mer
 select * from t1;
 c1	c2	c3
 ///// FOR UPDATE
+begin;
 explain select /*+ use_index_merge(t1) */ * from t1 where c1 < 10 or c2 < 10 and c3 < 10 order by 1 for update;
 id	estRows	task	access object	operator info
 Sort_6	4060.74	root		index_merge.t1.c1
@@ -431,6 +432,17 @@ Sort_6	4060.74	root		index_merge.t1.c1
         └─TableRowIDScan_12	5542.21	cop[tikv]	table:t1	keep order:false, stats:pseudo
 select /*+ use_index_merge(t1) */ * from t1 where c1 < 10 or c2 < 10 and c3 < 10 order by 1 for update;
 c1	c2	c3
+rollback;
+explain select /*+ use_index_merge(t1) */ * from t1 where c1 < 10 or c2 < 10 and c3 < 10 order by 1 for update;
+id	estRows	task	access object	operator info
+Sort_5	4060.74	root		index_merge.t1.c1
+└─IndexMerge_12	2250.55	root		type: union
+  ├─IndexRangeScan_8(Build)	3323.33	cop[tikv]	table:t1, index:c1(c1)	range:[-inf,10), keep order:false, stats:pseudo
+  ├─IndexRangeScan_9(Build)	3323.33	cop[tikv]	table:t1, index:c2(c2)	range:[-inf,10), keep order:false, stats:pseudo
+  └─Selection_11(Probe)	2250.55	cop[tikv]		or(lt(index_merge.t1.c1, 10), and(lt(index_merge.t1.c2, 10), lt(index_merge.t1.c3, 10)))
+    └─TableRowIDScan_10	5542.21	cop[tikv]	table:t1	keep order:false, stats:pseudo
+select /*+ use_index_merge(t1) */ * from t1 where c1 < 10 or c2 < 10 and c3 < 10 order by 1 for update;
+c1	c2	c3
 ///// TEMPORARY Table. Not support for now.
 drop table if exists t1;
 create temporary table t1(c1 int, c2 int, c3 int, key(c1), key(c2));

tests/integrationtest/r/planner/core/casetest/physicalplantest/physical_plan.result

@@ -694,13 +694,20 @@ CTE_0	2.00	root		Recursive CTE
 ├─Projection(Seed Part)	1.00	root		1->Column#2
 │ └─TableDual	1.00	root		rows:1
 └─CTETable(Recursive Part)	1.00	root		Scan on CTE_0
+begin;
 explain format='brief' with x as (select * from (select a from t for update) s) select * from x where a = 1;
 id	estRows	task	access object	operator info
 Projection	10.00	root		planner__core__casetest__physicalplantest__physical_plan.t.a
 └─SelectLock	10.00	root		for update 0
   └─TableReader	10.00	root		data:Selection
     └─Selection	10.00	cop[tikv]		eq(planner__core__casetest__physicalplantest__physical_plan.t.a, 1)
       └─TableFullScan	10000.00	cop[tikv]	table:t	keep order:false, stats:pseudo
+rollback;
+explain format='brief' with x as (select * from (select a from t for update) s) select * from x where a = 1;
+id	estRows	task	access object	operator info
+TableReader	10.00	root		data:Selection
+└─Selection	10.00	cop[tikv]		eq(planner__core__casetest__physicalplantest__physical_plan.t.a, 1)
+  └─TableFullScan	10000.00	cop[tikv]	table:t	keep order:false, stats:pseudo
 set tidb_opt_force_inline_cte=1; -- enable force inline CTE;
 explain format='brief' with cte as (select 1) select * from cte union select * from cte; -- force inline cte while multi-consumer;
 id	estRows	task	access object	operator info

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

@@ -21,11 +21,16 @@ explain format='brief' select count(_tidb_rowid) from t where a=1;
 id	estRows	task	access object	operator info
 StreamAgg	1.00	root		funcs:count(planner__core__point_get_plan.t._tidb_rowid)->Column#4
 └─Point_Get	1.00	root	table:t, index:idx(a)	
+begin;
+explain format='brief' select *, date_format(b, "") from t where a =1 for update;
+id	estRows	task	access object	operator info
+Projection	1.00	root		planner__core__point_get_plan.t.a, planner__core__point_get_plan.t.b, date_format(cast(planner__core__point_get_plan.t.b, datetime BINARY), )->Column#4
+└─Point_Get	1.00	root	table:t, index:idx(a)	lock
+rollback;
 explain format='brief' select *, date_format(b, "") from t where a =1 for update;
 id	estRows	task	access object	operator info
 Projection	1.00	root		planner__core__point_get_plan.t.a, planner__core__point_get_plan.t.b, date_format(cast(planner__core__point_get_plan.t.b, datetime BINARY), )->Column#4
-└─SelectLock	1.00	root		for update 0
-  └─Point_Get	1.00	root	table:t, index:idx(a)	
+└─Point_Get	1.00	root	table:t, index:idx(a)	
 create table t1 (pk int, a int, b int, primary key(pk), unique key(a));
 explain format='brief' select t1.*, _tidb_rowid from t1 where a = 1;
 Error 1054 (42S22): Unknown column '_tidb_rowid' in 'field list'

tests/integrationtest/t/executor/distsql.test

@@ -80,10 +80,17 @@ select * from tbl use index(idx_a) where a > 10 order by a asc limit 4,1;
 # TestIndexLookUpWithSelectForUpdateOnPartitionTable
 drop table if exists t;
 create table t(a int, b int, index k(b)) PARTITION BY HASH(a) partitions 4;
+begin;
+insert into t(a, b) values (1,1),(2,2),(3,3),(4,4),(5,5),(6,6),(7,7),(8,8);
+explain format='brief' select b from t use index(k) where b > 2 order by b limit 1 for update;
+select b from t use index(k) where b > 2 order by b limit 1 for update;
+analyze table t;
+explain format='brief' select b from t use index(k) where b > 2 order by b limit 1 for update;
+select b from t use index(k) where b > 2 order by b limit 1 for update;
+rollback;
 insert into t(a, b) values (1,1),(2,2),(3,3),(4,4),(5,5),(6,6),(7,7),(8,8);
 explain format='brief' select b from t use index(k) where b > 2 order by b limit 1 for update;
 select b from t use index(k) where b > 2 order by b limit 1 for update;
 analyze table t;
 explain format='brief' select b from t use index(k) where b > 2 order by b limit 1 for update;
 select b from t use index(k) where b > 2 order by b limit 1 for update;
-

tests/integrationtest/t/index_merge.test

@@ -118,8 +118,12 @@ update t1 set c1 = 100, c2 = 100, c3 = 100 where c1 in (select /*+ use_index_mer
 select * from t1;
 
 --echo ///// FOR UPDATE
+begin;
 explain select /*+ use_index_merge(t1) */ * from t1 where c1 < 10 or c2 < 10 and c3 < 10 order by 1 for update;
-select /*+ use_index_merge(t1) */ * from t1 where c1 < 10 or c2 < 10 and c3 < 10 order by 1 for update; 
+select /*+ use_index_merge(t1) */ * from t1 where c1 < 10 or c2 < 10 and c3 < 10 order by 1 for update;
+rollback;
+explain select /*+ use_index_merge(t1) */ * from t1 where c1 < 10 or c2 < 10 and c3 < 10 order by 1 for update;
+select /*+ use_index_merge(t1) */ * from t1 where c1 < 10 or c2 < 10 and c3 < 10 order by 1 for update;
 
 --echo ///// TEMPORARY Table. Not support for now.
 drop table if exists t1;

tests/integrationtest/t/planner/core/casetest/physicalplantest/physical_plan.test

@@ -202,6 +202,9 @@ explain format='brief' with cte1 as (select 1), cte2 as (with cte3 as (select *
 explain format='brief' with cte1 as (select 1), cte2 as (with cte3 as (select * from cte1) select * from cte3) select * from cte2; -- inline cte1, cte2, cte3;
 explain format='brief' with cte1 as (select 1), cte2 as (select * from cte1) select * from cte2 a, cte2 b; -- inline cte1, cannot be inlined cte2;
 explain format='brief' with recursive cte(a) as (select 1 union select a from cte) select * from cte; -- recursive cte cannot be inlined;
+begin;
+explain format='brief' with x as (select * from (select a from t for update) s) select * from x where a = 1;
+rollback;
 explain format='brief' with x as (select * from (select a from t for update) s) select * from x where a = 1;
 set tidb_opt_force_inline_cte=1; -- enable force inline CTE;
 explain format='brief' with cte as (select 1) select * from cte union select * from cte; -- force inline cte while multi-consumer;
@@ -1005,4 +1008,4 @@ insert into tbl_43 values("BCmuENPHzSOIMJLPB"),("LDOdXZYpOR"),("R"),("TloTqcHhdg
 explain format = 'brief' select min(col_304) from (select /*+ use_index_merge( tbl_43 ) */ * from tbl_43 where not( tbl_43.col_304 between 'YEpfYfPVvhMlHGHSMKm' and 'PE' ) or tbl_43.col_304 in ( 'LUBGzGMA' ) and tbl_43.col_304 between 'HpsjfuSReCwBoh' and 'fta' or not( tbl_43.col_304 between 'MFWmuOsoyDv' and 'TSeMYpDXnFIyp' ) order by col_304) x;
 select min(col_304) from (select /*+ use_index_merge( tbl_43 ) */ * from tbl_43 where not( tbl_43.col_304 between 'YEpfYfPVvhMlHGHSMKm' and 'PE' ) or tbl_43.col_304 in ( 'LUBGzGMA' ) and tbl_43.col_304 between 'HpsjfuSReCwBoh' and 'fta' or not( tbl_43.col_304 between 'MFWmuOsoyDv' and 'TSeMYpDXnFIyp' ) order by col_304) x;
 explain format = 'brief' select max(col_304) from (select /*+ use_index_merge( tbl_43 ) */ * from tbl_43 where not( tbl_43.col_304 between 'YEpfYfPVvhMlHGHSMKm' and 'PE' ) or tbl_43.col_304 in ( 'LUBGzGMA' ) and tbl_43.col_304 between 'HpsjfuSReCwBoh' and 'fta' or not( tbl_43.col_304 between 'MFWmuOsoyDv' and 'TSeMYpDXnFIyp' ) order by col_304) x;
-select max(col_304) from (select /*+ use_index_merge( tbl_43 ) */ * from tbl_43 where not( tbl_43.col_304 between 'YEpfYfPVvhMlHGHSMKm' and 'PE' ) or tbl_43.col_304 in ( 'LUBGzGMA' ) and tbl_43.col_304 between 'HpsjfuSReCwBoh' and 'fta' or not( tbl_43.col_304 between 'MFWmuOsoyDv' and 'TSeMYpDXnFIyp' ) order by col_304) x;
+select max(col_304) from (select /*+ use_index_merge( tbl_43 ) */ * from tbl_43 where not( tbl_43.col_304 between 'YEpfYfPVvhMlHGHSMKm' and 'PE' ) or tbl_43.col_304 in ( 'LUBGzGMA' ) and tbl_43.col_304 between 'HpsjfuSReCwBoh' and 'fta' or not( tbl_43.col_304 between 'MFWmuOsoyDv' and 'TSeMYpDXnFIyp' ) order by col_304) x;

tests/integrationtest/t/planner/core/point_get_plan.test

@@ -12,6 +12,9 @@ insert into t values (1, 1);
 explain format='brief' select t.*, _tidb_rowid from t where a = 1;
 commit;
 explain format='brief' select count(_tidb_rowid) from t where a=1;
+begin;
+explain format='brief' select *, date_format(b, "") from t where a =1 for update;
+rollback;
 explain format='brief' select *, date_format(b, "") from t where a =1 for update;
 create table t1 (pk int, a int, b int, primary key(pk), unique key(a));
 -- error 1054