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planner: reserve the OFFSET when outer join's inner side is unique (#56483) #57361

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merged 4 commits into from
Nov 14, 2024
Merged

planner: reserve the OFFSET when outer join's inner side is unique (#56483) #57361

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02f7f6f
planner: reverse the OFFSET when outer join's inner side is unique
winoros Oct 8, 2024
c321ead
add tests and fix the logic
winoros Nov 5, 2024
299a1e6
address comment
winoros Nov 13, 2024
7e6477d
address comments
winoros Nov 13, 2024
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38 changes: 25 additions & 13 deletions pkg/expression/schema.go
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Original file line number Diff line number Diff line change
Expand Up @@ -128,22 +128,34 @@ func (s *Schema) RetrieveColumn(col *Column) *Column {
return nil
}

// IsUniqueKey checks if this column is a unique key.
func (s *Schema) IsUniqueKey(col *Column) bool {
for _, key := range s.Keys {
if len(key) == 1 && key[0].EqualColumn(col) {
return true
}
// IsUnique checks if the column is unique key.
// Pass strong=true to check strong contraint: unique && notnull.
// Pass strong=false to check weak contraint: unique && nullable.
func (s *Schema) IsUnique(strong bool, cols ...*Column) bool {
slicesToBeIterated := s.UniqueKeys
if strong {
slicesToBeIterated = s.Keys
}
return false
}
for _, key := range slicesToBeIterated {
if len(key) > len(cols) {
continue
}
allFound := true
nextKeyCol:

// IsUnique checks if this column is a unique key which may contain duplicate nulls .
func (s *Schema) IsUnique(col *Column) bool {
for _, key := range s.UniqueKeys {
if len(key) == 1 && key[0].EqualColumn(col) {
return true
for _, keyCols := range key {
for _, col := range cols {
if keyCols.EqualColumn(col) {
continue nextKeyCol
}
}
allFound = false
break
}
if !allFound {
continue
}
return true
}
return false
}
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6 changes: 3 additions & 3 deletions pkg/expression/schema_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -77,12 +77,12 @@ func TestSchemaIsUniqueKey(t *testing.T) {
}
for i, col := range schema.Columns {
if i < len(schema.Columns)-1 {
require.Equal(t, true, schema.IsUniqueKey(col))
require.Equal(t, true, schema.IsUnique(true, col))
} else {
require.Equal(t, false, schema.IsUniqueKey(col))
require.Equal(t, false, schema.IsUnique(true, col))
}
}
require.Equal(t, false, schema.IsUniqueKey(colOutSchema))
require.Equal(t, false, schema.IsUnique(true, colOutSchema))
}

func TestSchemaContains(t *testing.T) {
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36 changes: 35 additions & 1 deletion pkg/planner/core/operator/logicalop/logical_join.go
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Expand Up @@ -1091,9 +1091,43 @@ func (p *LogicalJoin) pushDownTopNToChild(topN *LogicalTopN, idx int, opt *optim
}
}
}
count, offset := topN.Count+topN.Offset, uint64(0)
if p.JoinType == LeftOuterJoin {
innerChild := p.Children()[1]
innerJoinKey := make([]*expression.Column, 0, len(p.EqualConditions))
isNullEQ := false
for _, eqCond := range p.EqualConditions {
innerJoinKey = append(innerJoinKey, eqCond.GetArgs()[1].(*expression.Column))
if eqCond.FuncName.L == ast.NullEQ {
isNullEQ = true
}
}
// If it's unique key(unique with not null), we can push the offset down safely whatever the join key is normal eq or nulleq.
// If the join key is nulleq, then we can only push the offset down when the inner side is unique key.
// Only when the join key is normal eq, we can push the offset down when the inner side is unique(could be null).
if innerChild.Schema().IsUnique(true, innerJoinKey...) ||
(!isNullEQ && innerChild.Schema().IsUnique(false, innerJoinKey...)) {
count, offset = topN.Count, topN.Offset
}
} else if p.JoinType == RightOuterJoin {
innerChild := p.Children()[0]
innerJoinKey := make([]*expression.Column, 0, len(p.EqualConditions))
isNullEQ := false
for _, eqCond := range p.EqualConditions {
innerJoinKey = append(innerJoinKey, eqCond.GetArgs()[0].(*expression.Column))
if eqCond.FuncName.L == ast.NullEQ {
isNullEQ = true
}
}
if innerChild.Schema().IsUnique(true, innerJoinKey...) ||
(!isNullEQ && innerChild.Schema().IsUnique(false, innerJoinKey...)) {
count, offset = topN.Count, topN.Offset
}
}

newTopN := LogicalTopN{
Count: topN.Count + topN.Offset,
Count: count,
Offset: offset,
ByItems: make([]*util.ByItems, len(topN.ByItems)),
PreferLimitToCop: topN.PreferLimitToCop,
}.Init(topN.SCtx(), topN.QueryBlockOffset())
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16 changes: 15 additions & 1 deletion pkg/planner/core/testdata/plan_suite_unexported_in.json
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Expand Up @@ -173,8 +173,22 @@
"select a, b from (select @i as a, @i := @i+1 as b from t) t order by a desc limit 1",
// Test TopN + Left Join + Proj.
"select * from t left outer join t s on t.a = s.a order by t.a limit 5",
// Test TopN + Left Join + Proj.
// Test TopN(with offset) + Left Join + Proj, outer side join key is unique key and not null.
"select * from t left outer join t s on t.a = s.a order by t.a limit 5, 5",
// Test TopN(with offset) + Left Join + Proj, outer side join key is unique key and not null.
"select * from t left outer join t s on t.f = s.f and t.g = s.g order by t.f, t.g limit 5, 5",
// Test TopN(with offset) + Left Join + Proj, outer side join key is unique key and not null.
"select * from t left outer join t s on t.f = s.f and t.g = s.g order by t.g, t.f limit 5, 5",
// Test TopN(with offset) + Left Join + Proj, outer side join key is part of unique key and not null.
"select * from t left outer join t s on t.g = s.g order by t.g limit 5, 5",
// Test TopN(with offset) + Left Join + Proj, outer side join key is part of unique key and not null.
"select * from t left outer join t s on t.g = s.g order by t.f, t.g limit 5, 5",
// Test TopN(with offset) + Left Join + Proj, outer side join key is unique key(c, d, e) but nullable.
"select * from t left outer join t s on t.c = s.c and t.d=s.d and t.e=s.e order by t.c, t.d, t.e limit 5, 5",
// Test TopN(with offset) + Left Join + Proj, outer side join key is part of unique key(c, d, e) but nullable.
"select * from t left outer join t s on t.c = s.c and t.d=s.d order by t.c, t.d limit 5, 5",
// Test TopN(with offset) + Left Join + Proj, outer side join key is not unique.
"select * from t left outer join t s on t.b = s.b order by t.b limit 5, 5",
// Test Limit + Left Join + Proj.
"select * from t left outer join t s on t.a = s.a limit 5",
// Test Limit + Left Join Apply + Proj.
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9 changes: 8 additions & 1 deletion pkg/planner/core/testdata/plan_suite_unexported_out.json
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Original file line number Diff line number Diff line change
Expand Up @@ -151,7 +151,14 @@
"Join{DataScan(t)->DataScan(s)}->Limit->Projection",
"DataScan(t)->Projection->TopN([Column#13 true],0,1)->Projection",
"Join{DataScan(t)->TopN([test.t.a],0,5)->DataScan(s)}(test.t.a,test.t.a)->TopN([test.t.a],0,5)->Projection",
"Join{DataScan(t)->TopN([test.t.a],0,10)->DataScan(s)}(test.t.a,test.t.a)->TopN([test.t.a],5,5)->Projection",
"Join{DataScan(t)->TopN([test.t.a],5,5)->DataScan(s)}(test.t.a,test.t.a)->TopN([test.t.a],5,5)->Projection",
"Join{DataScan(t)->TopN([test.t.f test.t.g],5,5)->DataScan(s)}(test.t.f,test.t.f)(test.t.g,test.t.g)->TopN([test.t.f test.t.g],5,5)->Projection",
"Join{DataScan(t)->TopN([test.t.g test.t.f],5,5)->DataScan(s)}(test.t.f,test.t.f)(test.t.g,test.t.g)->TopN([test.t.g test.t.f],5,5)->Projection",
"Join{DataScan(t)->TopN([test.t.g],0,10)->DataScan(s)}(test.t.g,test.t.g)->TopN([test.t.g],5,5)->Projection",
"Join{DataScan(t)->TopN([test.t.f test.t.g],0,10)->DataScan(s)}(test.t.g,test.t.g)->TopN([test.t.f test.t.g],5,5)->Projection",
"Join{DataScan(t)->TopN([test.t.c test.t.d test.t.e],5,5)->DataScan(s)}(test.t.c,test.t.c)(test.t.d,test.t.d)(test.t.e,test.t.e)->TopN([test.t.c test.t.d test.t.e],5,5)->Projection",
"Join{DataScan(t)->TopN([test.t.c test.t.d],0,10)->DataScan(s)}(test.t.c,test.t.c)(test.t.d,test.t.d)->TopN([test.t.c test.t.d],5,5)->Projection",
"Join{DataScan(t)->TopN([test.t.b],0,10)->DataScan(s)}(test.t.b,test.t.b)->TopN([test.t.b],5,5)->Projection",
"Join{DataScan(t)->Limit->DataScan(s)}(test.t.a,test.t.a)->Limit->Projection",
"Join{DataScan(t)->Limit->DataScan(s)}(test.t.a,test.t.a)->Limit->Projection",
"Join{DataScan(t)->TopN([test.t.a],0,5)->DataScan(s)}(test.t.a,test.t.a)->TopN([test.t.a],0,5)->Projection",
Expand Down