/
physical_sort.go
71 lines (61 loc) · 2.07 KB
/
physical_sort.go
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//
// This source code is a modified form of original source from the TiDB project, which has the following copyright header(s):
//
// Copyright 2016 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 planner
import (
"github.com/squareup/pranadb/tidb/expression"
"github.com/squareup/pranadb/tidb/planner/property"
"github.com/squareup/pranadb/tidb/planner/util"
"github.com/squareup/pranadb/tidb/sessionctx"
"math"
)
var _ PhysicalPlan = &PhysicalSort{}
// PhysicalSort is the physical operator of sort, which implements a memory sort.
type PhysicalSort struct {
basePhysicalPlan
ByItems []*util.ByItems
}
// Init initializes PhysicalSort.
func (p PhysicalSort) Init(ctx sessionctx.Context, stats *property.StatsInfo, offset int, props ...*property.PhysicalProperty) *PhysicalSort {
p.basePhysicalPlan = newBasePhysicalPlan(ctx, TypeSort, &p, offset)
p.childrenReqProps = props
p.stats = stats
return &p
}
// ResolveIndices implements Plan interface.
func (p *PhysicalSort) ResolveIndices() (err error) {
err = p.basePhysicalPlan.ResolveIndices()
if err != nil {
return err
}
for _, item := range p.ByItems {
item.Expr, err = item.Expr.ResolveIndices(p.children[0].Schema())
if err != nil {
return err
}
}
return err
}
// GetCost computes the cost of in memory sort.
func (p *PhysicalSort) GetCost(count float64, schema *expression.Schema) float64 {
if count < 2.0 {
count = 2.0
}
sessVars := p.ctx.GetSessionVars()
cpuCost := count * math.Log2(count) * sessVars.CPUFactor
memoryCost := count * sessVars.MemoryFactor
return cpuCost + memoryCost
}