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planner,expression: use constraint propagation in partition pruning #8885

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6cbf528
expression: constraint propagate for '>' and monotonous function
tiancaiamao Dec 10, 2018
f966b75
Merge branch 'master' into propagate-pruning
tiancaiamao Dec 11, 2018
e11f0ed
Merge master
tiancaiamao Dec 11, 2018
12d9212
gofmt
tiancaiamao Dec 11, 2018
3376571
fix CI
tiancaiamao Dec 11, 2018
9a3659b
fix CI
tiancaiamao Dec 11, 2018
b3287fc
address comment
tiancaiamao Dec 29, 2018
0f08c3e
Merge branch 'master' into propagate-pruning
tiancaiamao Dec 29, 2018
934bddd
planner,expression: use constraint propagation in partition pruning
tiancaiamao Dec 29, 2018
bdcf799
make the code more general and remove useless part
tiancaiamao Jan 2, 2019
c661aa7
Merge branch 'propagate-pruning' into re-partition-prune
tiancaiamao Jan 2, 2019
c3bddb8
update test
tiancaiamao Jan 2, 2019
1939df5
Merge branch 'master' into re-partition-prune
tiancaiamao Jan 4, 2019
32dae16
handle filter conditions that do not push down in partition pruning
tiancaiamao Jan 4, 2019
4a5735e
update partition pruning test in explain
tiancaiamao Jan 4, 2019
bf90c2a
address comment
tiancaiamao Jan 7, 2019
10fb9b1
fix ci
tiancaiamao Jan 7, 2019
084ce7a
address comment
tiancaiamao Jan 7, 2019
8518cc0
address comment
tiancaiamao Jan 7, 2019
03aff65
address comment
tiancaiamao Jan 8, 2019
5bec8fc
address comment
tiancaiamao Jan 15, 2019
7d57f56
Merge branch 'master' into re-partition-prune
tiancaiamao Jan 15, 2019
0a52d72
fix typo
tiancaiamao Jan 15, 2019
5f5acb1
Merge branch 'master' into re-partition-prune
tiancaiamao Jan 15, 2019
1b0825b
address comment
tiancaiamao Jan 16, 2019
89e597f
Merge branch 'master' into re-partition-prune
tiancaiamao Jan 17, 2019
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3,924 changes: 1,446 additions & 2,478 deletions cmd/explaintest/r/partition_pruning.result

Large diffs are not rendered by default.

7 changes: 6 additions & 1 deletion expression/constraint_propagation.go
Original file line number Diff line number Diff line change
Expand Up @@ -250,7 +250,7 @@ func ruleColumnOPConst(ctx sessionctx.Context, i, j int, exprs *exprSet) {
return
}
}
if !col1.Equal(ctx, col2) {
if col1.ColName.L != col2.ColName.L {
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return
}
v, isNull, err := compareConstant(ctx, negOP(OP2), fc1, con2)
Expand Down Expand Up @@ -302,3 +302,8 @@ func compareConstant(ctx sessionctx.Context, fn string, c1, c2 Expression) (int6
}
return cmp.EvalInt(ctx, chunk.Row{})
}

// NewPartitionPruneSolver returns a constraintSolver for partition pruning.
func NewPartitionPruneSolver() constraintSolver {
return newConstraintSolver(ruleColumnOPConst)
}
2 changes: 2 additions & 0 deletions planner/core/logical_plans.go
Original file line number Diff line number Diff line change
Expand Up @@ -300,6 +300,8 @@ type DataSource struct {

// pushedDownConds are the conditions that will be pushed down to coprocessor.
pushedDownConds []expression.Expression
// allConds include those conditions that can be pushed down and can't be.
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allConds []expression.Expression

// relevantIndices means the indices match the push down conditions
relevantIndices []bool
Expand Down
59 changes: 59 additions & 0 deletions planner/core/partition_pruning_test.go
Original file line number Diff line number Diff line change
@@ -0,0 +1,59 @@
// Copyright 2018 PingCAP, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
// // Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.

package core_test

import (
. "github.com/pingcap/check"
"github.com/pingcap/parser"
"github.com/pingcap/parser/ast"
"github.com/pingcap/tidb/ddl"
"github.com/pingcap/tidb/expression"
"github.com/pingcap/tidb/planner/core"
"github.com/pingcap/tidb/util/mock"
)

var _ = Suite(&testPartitionPruningSuite{})

type testPartitionPruningSuite struct{}

func (s *testPartitionPruningSuite) TestCanBePrune(c *C) {
p := parser.New()
stmt, err := p.ParseOneStmt("create table t (d datetime not null)", "", "")
c.Assert(err, IsNil)
tblInfo, err := ddl.BuildTableInfoFromAST(stmt.(*ast.CreateTableStmt))
c.Assert(err, IsNil)

// For the following case:
// CREATE TABLE t1 ( recdate DATETIME NOT NULL )
// PARTITION BY RANGE( TO_DAYS(recdate) ) (
// PARTITION p0 VALUES LESS THAN ( TO_DAYS('2007-03-08') ),
// PARTITION p1 VALUES LESS THAN ( TO_DAYS('2007-04-01') )
// );
// SELECT * FROM t1 WHERE recdate < '2007-03-08 00:00:00';
// SELECT * FROM t1 WHERE recdate > '2018-03-08 00:00:00';

ctx := mock.NewContext()
partitionExpr, err := expression.ParseSimpleExprWithTableInfo(ctx, "to_days(d) < to_days('2007-03-08') and to_days(d) >= to_days('2007-03-07')", tblInfo)
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c.Assert(err, IsNil)
queryExpr, err := expression.ParseSimpleExprWithTableInfo(ctx, "d < '2000-03-08 00:00:00'", tblInfo)
c.Assert(err, IsNil)
succ, err := core.CanBePruned(ctx, partitionExpr, []expression.Expression{queryExpr})
c.Assert(err, IsNil)
c.Assert(succ, IsTrue)

queryExpr, err = expression.ParseSimpleExprWithTableInfo(ctx, "d > '2018-03-08 00:00:00'", tblInfo)
c.Assert(err, IsNil)
succ, err = core.CanBePruned(ctx, partitionExpr, []expression.Expression{queryExpr})
c.Assert(err, IsNil)
c.Assert(succ, IsTrue)
}
8 changes: 8 additions & 0 deletions planner/core/planbuilder_test.go
Original file line number Diff line number Diff line change
Expand Up @@ -17,8 +17,16 @@ import (
. "github.com/pingcap/check"
"github.com/pingcap/parser/ast"
"github.com/pingcap/parser/model"
"github.com/pingcap/tidb/expression"
"github.com/pingcap/tidb/sessionctx"
)

// CanBePruned is provided for testing.
func CanBePruned(sctx sessionctx.Context, partitionExpr expression.Expression, filterExprs []expression.Expression) (bool, error) {
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var s partitionProcessor
return s.canBePruned(sctx, nil, partitionExpr, filterExprs)
}

var _ = Suite(&testPlanBuilderSuite{})

func (s *testPlanBuilderSuite) SetUpSuite(c *C) {
Expand Down
56 changes: 36 additions & 20 deletions planner/core/rule_partition_processor.go
Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,7 @@ import (
"github.com/pingcap/tidb/expression"
"github.com/pingcap/tidb/sessionctx"
"github.com/pingcap/tidb/table/tables"
"github.com/pingcap/tidb/util/chunk"
"github.com/pingcap/tidb/util/ranger"
)

Expand All @@ -37,9 +38,6 @@ import (
type partitionProcessor struct{}

func (s *partitionProcessor) optimize(lp LogicalPlan) (LogicalPlan, error) {
// NOTE: partitionProcessor will assume all filter conditions are pushed down to
// DataSource, there will not be a Selection->DataSource case, so the rewrite just
// handle the DataSource node.
return s.rewriteDataSource(lp)
}

Expand Down Expand Up @@ -87,15 +85,13 @@ func (s *partitionProcessor) prune(ds *DataSource) (LogicalPlan, error) {
// partitions according to the filter conditions pushed to the DataSource.
children := make([]LogicalPlan, 0, len(pi.Definitions))
for i, expr := range partitionExprs {
if col != nil {
// If the selection condition would never be satisified, prune that partition.
prune, err := s.canBePrune(ds.context(), col, expr, ds.pushedDownConds)
if err != nil {
return nil, errors.Trace(err)
}
if prune {
continue
}
// If the selection condition would never be satisified, prune that partition.
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prune, err := s.canBePruned(ds.context(), col, expr, ds.allConds)
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if err != nil {
return nil, errors.Trace(err)
}
if prune {
continue
}

// Not a deep copy.
Expand Down Expand Up @@ -126,17 +122,37 @@ func (s *partitionProcessor) prune(ds *DataSource) (LogicalPlan, error) {
return unionAll, nil
}

// canBePrune checks if partition expression will never meets the selection condition.
var solver = expression.NewPartitionPruneSolver()

// canBePruned checks if partition expression will never meets the selection condition.
// For example, partition by column a > 3, and select condition is a < 3, then canBePrune returns true.
func (s *partitionProcessor) canBePrune(ctx sessionctx.Context, col *expression.Column, partitionCond expression.Expression, copConds []expression.Expression) (bool, error) {
conds := make([]expression.Expression, 0, 1+len(copConds))
conds = append(conds, partitionCond)
conds = append(conds, copConds...)
conds = expression.PropagateConstant(ctx, conds)
func (s *partitionProcessor) canBePruned(sctx sessionctx.Context, partCol *expression.Column, partitionExpr expression.Expression, filterExprs []expression.Expression) (bool, error) {
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conds := make([]expression.Expression, 0, 1+len(filterExprs))
conds = append(conds, partitionExpr)
conds = append(conds, filterExprs...)
conds = expression.PropagateConstant(sctx, conds)
conds = solver.Solve(sctx, conds)

if len(conds) == 1 {
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// Constant false.
if con, ok := conds[0].(*expression.Constant); ok && con.DeferredExpr == nil {
ret, err := expression.EvalBool(sctx, expression.CNFExprs{con}, chunk.Row{})
if err == nil && ret == false {
return true, nil
}
}
}

if partCol == nil {
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can we check partCol == nil first when entering this function?

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Do you mean check partCol == nil at the beginning of this function and return false? No we can't do that.

In to_days(c) > xx and c < yy, partCol is nil, but I want to handle it.
If this branch moved to the beginning, the canBePruned will return immediately.

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Got it. Could you add a comment about this to let others know why we intentionally put this check after solver.Solve()?

return false, nil
}

// Calculate the column range to prune.
accessConds := ranger.ExtractAccessConditionsForColumn(conds, col.UniqueID)
r, err := ranger.BuildColumnRange(accessConds, ctx.GetSessionVars().StmtCtx, col.RetType)
// TODO: Remove prune by calculating range. Current constraint propagate doesn't
// handle the null condition, while calculate range can prune something like:
// "select * from t where t is null"
accessConds := ranger.ExtractAccessConditionsForColumn(conds, partCol.UniqueID)
r, err := ranger.BuildColumnRange(accessConds, sctx.GetSessionVars().StmtCtx, partCol.RetType)
if err != nil {
return false, errors.Trace(err)
}
Expand Down
1 change: 1 addition & 0 deletions planner/core/rule_predicate_push_down.go
Original file line number Diff line number Diff line change
Expand Up @@ -99,6 +99,7 @@ func (p *LogicalUnionScan) PredicatePushDown(predicates []expression.Expression)

// PredicatePushDown implements LogicalPlan PredicatePushDown interface.
func (ds *DataSource) PredicatePushDown(predicates []expression.Expression) ([]expression.Expression, LogicalPlan) {
ds.allConds = predicates
_, ds.pushedDownConds, predicates = expression.ExpressionsToPB(ds.ctx.GetSessionVars().StmtCtx, predicates, ds.ctx.GetClient())
return predicates, ds
}
Expand Down