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169 lines
4.4 KiB
169 lines
4.4 KiB
// Copyright 2019 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 aggfuncs
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import (
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"github.com/pingcap/errors"
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"github.com/pingcap/tidb/sessionctx"
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"github.com/pingcap/tidb/util/chunk"
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"github.com/pingcap/tidb/util/set"
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)
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type baseVarPopAggFunc struct {
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baseAggFunc
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}
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type varPop4Float64 struct {
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baseVarPopAggFunc
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}
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type partialResult4VarPopFloat64 struct {
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count int64
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sum float64
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variance float64
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}
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func (e *varPop4Float64) AllocPartialResult() PartialResult {
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return PartialResult(&partialResult4VarPopFloat64{})
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}
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func (e *varPop4Float64) ResetPartialResult(pr PartialResult) {
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p := (*partialResult4VarPopFloat64)(pr)
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p.count = 0
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p.sum = 0
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p.variance = 0
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}
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func (e *varPop4Float64) AppendFinalResult2Chunk(sctx sessionctx.Context, pr PartialResult, chk *chunk.Chunk) error {
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p := (*partialResult4VarPopFloat64)(pr)
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if p.count == 0 {
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chk.AppendNull(e.ordinal)
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return nil
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}
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variance := p.variance / float64(p.count)
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chk.AppendFloat64(e.ordinal, variance)
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return nil
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}
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func calculateIntermediate(count int64, sum float64, input float64, variance float64) float64 {
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t := float64(count)*input - sum
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variance += (t * t) / (float64(count * (count - 1)))
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return variance
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}
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func (e *varPop4Float64) UpdatePartialResult(sctx sessionctx.Context, rowsInGroup []chunk.Row, pr PartialResult) error {
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p := (*partialResult4VarPopFloat64)(pr)
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for _, row := range rowsInGroup {
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input, isNull, err := e.args[0].EvalReal(sctx, row)
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if err != nil {
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return errors.Trace(err)
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}
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if isNull {
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continue
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}
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p.count++
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p.sum += input
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if p.count > 1 {
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p.variance = calculateIntermediate(p.count, p.sum, input, p.variance)
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}
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}
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return nil
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}
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func calculateMerge(srcCount, dstCount int64, srcSum, dstSum, srcVariance, dstVariance float64) float64 {
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srcCountFloat64 := float64(srcCount)
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dstCountFloat64 := float64(dstCount)
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t := (srcCountFloat64/dstCountFloat64)*dstSum - srcSum
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dstVariance += srcVariance + ((dstCountFloat64/srcCountFloat64)/(dstCountFloat64+srcCountFloat64))*t*t
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return dstVariance
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}
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func (e *varPop4Float64) MergePartialResult(sctx sessionctx.Context, src PartialResult, dst PartialResult) error {
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p1, p2 := (*partialResult4VarPopFloat64)(src), (*partialResult4VarPopFloat64)(dst)
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if p1.count == 0 {
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return nil
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}
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if p2.count == 0 {
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p2.count = p1.count
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p2.sum = p1.sum
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p2.variance = p1.variance
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return nil
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}
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if p2.count != 0 && p1.count != 0 {
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p2.variance = calculateMerge(p1.count, p2.count, p1.sum, p2.sum, p1.variance, p2.variance)
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p2.count += p1.count
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p2.sum += p1.sum
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}
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return nil
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}
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type varPop4DistinctFloat64 struct {
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baseVarPopAggFunc
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}
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type partialResult4VarPopDistinctFloat64 struct {
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count int64
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sum float64
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variance float64
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valSet set.Float64Set
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}
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func (e *varPop4DistinctFloat64) AllocPartialResult() PartialResult {
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p := new(partialResult4VarPopDistinctFloat64)
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p.count = 0
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p.sum = 0
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p.variance = 0
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p.valSet = set.NewFloat64Set()
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return PartialResult(p)
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}
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func (e *varPop4DistinctFloat64) ResetPartialResult(pr PartialResult) {
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p := (*partialResult4VarPopDistinctFloat64)(pr)
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p.count = 0
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p.sum = 0
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p.variance = 0
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p.valSet = set.NewFloat64Set()
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}
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func (e *varPop4DistinctFloat64) AppendFinalResult2Chunk(sctx sessionctx.Context, pr PartialResult, chk *chunk.Chunk) error {
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p := (*partialResult4VarPopDistinctFloat64)(pr)
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if p.count == 0 {
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chk.AppendNull(e.ordinal)
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return nil
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}
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variance := p.variance / float64(p.count)
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chk.AppendFloat64(e.ordinal, variance)
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return nil
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}
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func (e *varPop4DistinctFloat64) UpdatePartialResult(sctx sessionctx.Context, rowsInGroup []chunk.Row, pr PartialResult) error {
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p := (*partialResult4VarPopDistinctFloat64)(pr)
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for _, row := range rowsInGroup {
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input, isNull, err := e.args[0].EvalReal(sctx, row)
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if err != nil {
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return errors.Trace(err)
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}
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if isNull || p.valSet.Exist(input) {
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continue
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}
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p.valSet.Insert(input)
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p.count++
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p.sum += input
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if p.count > 1 {
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p.variance = calculateIntermediate(p.count, p.sum, input, p.variance)
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}
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}
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return nil
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}
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