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plan, expression: support is null in hash partition pruning (#17281) (
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#17308)

* cherry pick #17281 to release-3.0

Signed-off-by: sre-bot <sre-bot@pingcap.com>

* fix conflict

* fix ci

Co-authored-by: Lingyu Song <songlingyu@pingcap.com>
Co-authored-by: tiancaiamao <tiancaiamao@gmail.com>
Co-authored-by: ti-srebot <66930949+ti-srebot@users.noreply.github.com>
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@sre-bot @tiancaiamao @ti-srebot
4 people authored Jun 28, 2020
1 parent 82846dd commit 6609b1f
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Showing 4 changed files with 80 additions and 23 deletions.
58 changes: 36 additions & 22 deletions expression/partition_pruner.go
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Original file line number Diff line number Diff line change
Expand Up @@ -79,7 +79,18 @@ func (p *hashPartitionPruner) reduceColumnEQ() bool {

func (p *hashPartitionPruner) reduceConstantEQ() bool {
for _, con := range p.conditions {
col, cond := validEqualCond(con)
var col *Column
var cond *Constant
if fn, ok := con.(*ScalarFunction); ok {
if fn.FuncName.L == ast.IsNull {
col, ok = fn.GetArgs()[0].(*Column)
if ok {
cond = Null.Clone().(*Constant)
}
} else {
col, cond = validEqualCond(con)
}
}
if col != nil {
id := p.getColID(col)
if p.constantMap[id] != nil {
Expand All @@ -94,18 +105,18 @@ func (p *hashPartitionPruner) reduceConstantEQ() bool {
return false
}

func (p *hashPartitionPruner) tryEvalPartitionExpr(piExpr Expression) (val int64, success bool, isNil bool) {
func (p *hashPartitionPruner) tryEvalPartitionExpr(piExpr Expression) (val int64, success bool, isNull bool) {
switch pi := piExpr.(type) {
case *ScalarFunction:
if pi.FuncName.L == ast.Plus || pi.FuncName.L == ast.Minus || pi.FuncName.L == ast.Mul || pi.FuncName.L == ast.Div {
left, right := pi.GetArgs()[0], pi.GetArgs()[1]
leftVal, ok, isNil := p.tryEvalPartitionExpr(left)
if !ok {
return 0, ok, isNil
leftVal, ok, isNull := p.tryEvalPartitionExpr(left)
if !ok || isNull {
return 0, ok, isNull
}
rightVal, ok, isNil := p.tryEvalPartitionExpr(right)
if !ok {
return 0, ok, isNil
rightVal, ok, isNull := p.tryEvalPartitionExpr(right)
if !ok || isNull {
return 0, ok, isNull
}
switch pi.FuncName.L {
case ast.Plus:
Expand All @@ -123,11 +134,11 @@ func (p *hashPartitionPruner) tryEvalPartitionExpr(piExpr Expression) (val int64
val := p.constantMap[idx]
if val != nil {
pi.GetArgs()[0] = val
ret, _, err := pi.EvalInt(p.ctx, chunk.Row{})
ret, isNull, err := pi.EvalInt(p.ctx, chunk.Row{})
if err != nil {
return 0, false, false
}
return ret, true, false
return ret, true, isNull
}
return 0, false, false
}
Expand All @@ -137,7 +148,7 @@ func (p *hashPartitionPruner) tryEvalPartitionExpr(piExpr Expression) (val int64
return 0, false, false
}
if val.IsNull() {
return 0, false, true
return 0, true, true
}
if val.Kind() == types.KindInt64 {
return val.GetInt64(), true, false
Expand All @@ -164,8 +175,8 @@ func newHashPartitionPruner() *hashPartitionPruner {
}

// solve eval the hash partition expression, the first return value represent the result of partition expression. The second
// return value is whether eval success. The third return value represent whether the eval result of partition value is null.
func (p *hashPartitionPruner) solve(ctx sessionctx.Context, conds []Expression, piExpr Expression) (val int64, ok bool, isNil bool) {
// return value is whether eval success. The third return value represent whether the query conditions is always false.
func (p *hashPartitionPruner) solve(ctx sessionctx.Context, conds []Expression, piExpr Expression) (val int64, ok bool, isAlwaysFalse bool) {
p.ctx = ctx
for _, cond := range conds {
p.conditions = append(p.conditions, SplitCNFItems(cond)...)
Expand All @@ -176,17 +187,20 @@ func (p *hashPartitionPruner) solve(ctx sessionctx.Context, conds []Expression,
for _, col := range ExtractColumns(piExpr) {
p.insertCol(col)
}
p.constantMap = make([]*Constant, p.numColumn, p.numColumn)
conflict := p.reduceConstantEQ()
if conflict {
return 0, false, conflict
p.constantMap = make([]*Constant, p.numColumn)
isAlwaysFalse = p.reduceConstantEQ()
if isAlwaysFalse {
return 0, false, isAlwaysFalse
}
isAlwaysFalse = p.reduceColumnEQ()
if isAlwaysFalse {
return 0, false, isAlwaysFalse
}
conflict = p.reduceColumnEQ()
if conflict {
return 0, false, conflict
res, ok, isNull := p.tryEvalPartitionExpr(piExpr)
if isNull && ok {
return 0, ok, false
}
res, ok, isNil := p.tryEvalPartitionExpr(piExpr)
return res, ok, isNil
return res, ok, false
}

// FastLocateHashPartition is used to get hash partition quickly.
Expand Down
2 changes: 2 additions & 0 deletions expression/partition_pruner_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -69,6 +69,8 @@ func (s *testSuite2) TestHashPartitionPruner(c *C) {
tk.MustExec("create table t3(id int, a int, b int, primary key(id, a)) partition by hash(id) partitions 10;")
tk.MustExec("create table t4(d datetime, a int, b int, primary key(d, a)) partition by hash(year(d)) partitions 10;")
tk.MustExec("create table t5(d date, a int, b int, primary key(d, a)) partition by hash(month(d)) partitions 10;")
tk.MustExec("create table t6(a int, b int) partition by hash(a) partitions 3;")
tk.MustExec("create table t7(a int, b int) partition by hash(a + b) partitions 10;")

var input []string
var output []struct {
Expand Down
6 changes: 5 additions & 1 deletion expression/testdata/partition_pruner_in.json
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Original file line number Diff line number Diff line change
Expand Up @@ -14,7 +14,11 @@
"explain select * from t1 left join t2 on true where t1.a = 1 and null",
"explain select * from t1 left join t2 on true where t1.a = null",
"explain select * from t4 where d = '2019-10-07 10:40:00' and a = 1",
"explain select * from t5 where d = '2019-10-07'"
"explain select * from t5 where d = '2019-10-07'",
"explain select * from t6 where a is null",
"explain select * from t6 where b is null",
"explain select * from t5 where d is null",
"explain select * from t7 where b = -3 and a is null"
]
}
]
37 changes: 37 additions & 0 deletions expression/testdata/partition_pruner_out.json
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Original file line number Diff line number Diff line change
Expand Up @@ -107,6 +107,43 @@
"├─IndexScan_9 10.00 cop table:t5, partition:p0, index:d, a, range:[2019-10-07,2019-10-07], keep order:false, stats:pseudo",
"└─TableScan_10 10.00 cop table:t5, partition:p0, keep order:false, stats:pseudo"
]
},
{
"SQL": "explain select * from t6 where a is null",
"Result": [
"TableReader_8 10.00 root data:Selection_7",
"└─Selection_7 10.00 cop isnull(test_partition.t6.a)",
" └─TableScan_6 10000.00 cop table:t6, partition:p0, range:[-inf,+inf], keep order:false, stats:pseudo"
]
},
{
"SQL": "explain select * from t6 where b is null",
"Result": [
"Union_9 30.00 root ",
"├─TableReader_12 10.00 root data:Selection_11",
"│ └─Selection_11 10.00 cop isnull(test_partition.t6.b)",
"│ └─TableScan_10 10000.00 cop table:t6, partition:p0, range:[-inf,+inf], keep order:false, stats:pseudo",
"├─TableReader_15 10.00 root data:Selection_14",
"│ └─Selection_14 10.00 cop isnull(test_partition.t6.b)",
"│ └─TableScan_13 10000.00 cop table:t6, partition:p1, range:[-inf,+inf], keep order:false, stats:pseudo",
"└─TableReader_18 10.00 root data:Selection_17",
" └─Selection_17 10.00 cop isnull(test_partition.t6.b)",
" └─TableScan_16 10000.00 cop table:t6, partition:p2, range:[-inf,+inf], keep order:false, stats:pseudo"
]
},
{
"SQL": "explain select * from t5 where d is null",
"Result": [
"TableDual_6 0.00 root rows:0"
]
},
{
"SQL": "explain select * from t7 where b = -3 and a is null",
"Result": [
"TableReader_8 0.01 root data:Selection_7",
"└─Selection_7 0.01 cop eq(test_partition.t7.b, -3), isnull(test_partition.t7.a)",
" └─TableScan_6 10000.00 cop table:t7, partition:p0, range:[-inf,+inf], keep order:false, stats:pseudo"
]
}
]
}
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