55 lines
1.6 KiB
Go
55 lines
1.6 KiB
Go
// Copyright 2018 PingCAP, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package memo
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import (
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"fmt"
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plannercore "github.com/pingcap/tidb/planner/core"
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)
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// GroupExpr is used to store all the logically equivalent expressions which
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// have the same root operator. Different from a normal expression, the
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// Children of a Group expression are expression Groups, not expressions.
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// Another property of Group expression is that the child Group references will
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// never be changed once the Group expression is created.
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type GroupExpr struct {
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ExprNode plannercore.LogicalPlan
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Children []*Group
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Explored bool
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Group *Group
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selfFingerprint string
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}
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// NewGroupExpr creates a GroupExpr based on a logical plan node.
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func NewGroupExpr(node plannercore.LogicalPlan) *GroupExpr {
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return &GroupExpr{
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ExprNode: node,
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Children: nil,
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Explored: false,
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}
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}
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// FingerPrint gets the unique fingerprint of the Group expression.
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func (e *GroupExpr) FingerPrint() string {
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if e.selfFingerprint == "" {
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e.selfFingerprint = fmt.Sprintf("%v", e.ExprNode.ID())
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for i := range e.Children {
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e.selfFingerprint += e.Children[i].FingerPrint()
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}
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}
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return e.selfFingerprint
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}
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