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planner: fix can't find proper physical plan caused by virtual column (#41132) #41243

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Aug 14, 2023
Merged

planner: fix can't find proper physical plan caused by virtual column (#41132) #41243

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0c6c3e5
fix can't find proper physical plan caused by virtual column
AilinKid Feb 7, 2023
fc06334
Update planner/core/exhaust_physical_plans.go
AilinKid Feb 8, 2023
cdf574a
address comment
AilinKid Feb 8, 2023
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27 changes: 27 additions & 0 deletions executor/tiflashtest/tiflash_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -1236,6 +1236,33 @@ func TestGroupStreamAggOnTiFlash(t *testing.T) {
}
}

// TestIssue41014 test issue that can't find proper physical plan
func TestIssue41014(t *testing.T) {
store := testkit.CreateMockStore(t, withMockTiFlash(2))
tk := testkit.NewTestKit(t, store)
tk.MustExec("use test;")
tk.MustExec("CREATE TABLE `tai1` (\n `aid` int(11) DEFAULT NULL,\n `rid` int(11) DEFAULT NULL\n) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin")
tk.MustExec("CREATE TABLE `tai2` (\n `rid` int(11) DEFAULT NULL,\n `prilan` varchar(20) DEFAULT NULL\n) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin")
tk.MustExec("alter table tai1 set tiflash replica 1")
tk.MustExec("alter table tai2 set tiflash replica 1")
tk.MustExec("alter table tai2 add index idx((lower(prilan)));")
tk.MustExec("set @@tidb_opt_distinct_agg_push_down = 1;")

tk.MustQuery("explain select count(distinct tai1.aid) as cb from tai1 inner join tai2 on tai1.rid = tai2.rid where lower(prilan) LIKE LOWER('%python%');").Check(
testkit.Rows("HashAgg_11 1.00 root funcs:count(distinct test.tai1.aid)->Column#8",
"└─HashJoin_15 9990.00 root inner join, equal:[eq(test.tai2.rid, test.tai1.rid)]",
" ├─Selection_20(Build) 8000.00 root like(lower(test.tai2.prilan), \"%python%\", 92)",
" │ └─Projection_19 10000.00 root test.tai2.rid, lower(test.tai2.prilan)",
" │ └─TableReader_18 9990.00 root data:Selection_17",
" │ └─Selection_17 9990.00 cop[tikv] not(isnull(test.tai2.rid))",
" │ └─TableFullScan_16 10000.00 cop[tikv] table:tai2 keep order:false, stats:pseudo",
" └─TableReader_23(Probe) 9990.00 root data:Selection_22",
" └─Selection_22 9990.00 cop[tikv] not(isnull(test.tai1.rid))",
" └─TableFullScan_21 10000.00 cop[tikv] table:tai1 keep order:false, stats:pseudo"))
tk.MustQuery("select count(distinct tai1.aid) as cb from tai1 inner join tai2 on tai1.rid = tai2.rid where lower(prilan) LIKE LOWER('%python%');").Check(
testkit.Rows("0"))
}

func TestTiflashEmptyDynamicPruneResult(t *testing.T) {
store := testkit.CreateMockStore(t, withMockTiFlash(2))
tk := testkit.NewTestKit(t, store)
Expand Down
17 changes: 15 additions & 2 deletions planner/core/exhaust_physical_plans.go
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Original file line number Diff line number Diff line change
Expand Up @@ -2682,7 +2682,9 @@ func (la *LogicalAggregation) getStreamAggs(prop *property.PhysicalProperty) []P
if la.HasDistinct() {
// TODO: remove AllowDistinctAggPushDown after the cost estimation of distinct pushdown is implemented.
// If AllowDistinctAggPushDown is set to true, we should not consider RootTask.
if !la.ctx.GetSessionVars().AllowDistinctAggPushDown {
if !la.ctx.GetSessionVars().AllowDistinctAggPushDown || !la.canPushToCop(kv.TiKV) {
// if variable doesn't allow DistinctAggPushDown, just produce root task type.
// if variable does allow DistinctAggPushDown, but OP itself can't be pushed down to tikv, just produce root task type.
taskTypes = []property.TaskType{property.RootTaskType}
} else if !la.distinctArgsMeetsProperty() {
continue
Expand Down Expand Up @@ -2831,6 +2833,15 @@ func (la *LogicalAggregation) tryToGetMppHashAggs(prop *property.PhysicalPropert
return
}

// getHashAggs will generate some kinds of taskType here, which finally converted to different task plan.
// when deciding whether to add a kind of taskType, there is a rule here. [Not is Not, Yes is not Sure]
// eg: which means
//
// 1: when you find something here that block hashAgg to be pushed down to XXX, just skip adding the XXXTaskType.
// 2: when you find nothing here to block hashAgg to be pushed down to XXX, just add the XXXTaskType here.
// for 2, the final result for this physical operator enumeration is chosen or rejected is according to more factors later (hint/variable/partition/virtual-col/cost)
//
// That is to say, the non-complete positive judgement of canPushDownToMPP/canPushDownToTiFlash/canPushDownToTiKV is not that for sure here.
func (la *LogicalAggregation) getHashAggs(prop *property.PhysicalProperty) []PhysicalPlan {
if !prop.IsSortItemEmpty() {
return nil
Expand All @@ -2844,7 +2855,9 @@ func (la *LogicalAggregation) getHashAggs(prop *property.PhysicalProperty) []Phy
canPushDownToMPP := canPushDownToTiFlash && la.ctx.GetSessionVars().IsMPPAllowed() && la.checkCanPushDownToMPP()
if la.HasDistinct() {
// TODO: remove after the cost estimation of distinct pushdown is implemented.
if !la.ctx.GetSessionVars().AllowDistinctAggPushDown {
if !la.ctx.GetSessionVars().AllowDistinctAggPushDown || !la.canPushToCop(kv.TiKV) {
// if variable doesn't allow DistinctAggPushDown, just produce root task type.
// if variable does allow DistinctAggPushDown, but OP itself can't be pushed down to tikv, just produce root task type.
taskTypes = []property.TaskType{property.RootTaskType}
}
} else if !la.aggHints.preferAggToCop {
Expand Down