tidb implementation 代码
文件路径：/planner/memo/implementation.go
// 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,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package memo
import (
plannercore "github.com/pingcap/tidb/planner/core"
)
// Implementation defines the interface for cost of physical plan.
type Implementation interface {
CalcCost(outCount float64, children ...Implementation) float64
SetCost(cost float64)
GetCost() float64
GetPlan() plannercore.PhysicalPlan
// AttachChildren is used to attach children implementations and returns it self.
AttachChildren(children ...Implementation) Implementation
// GetCostLimit gets the costLimit for implementing the next childGroup.
GetCostLimit(costLimit float64, children ...Implementation) float64
}