52 lines
1.4 KiB
Go
52 lines
1.4 KiB
Go
// 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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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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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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"math"
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"github.com/pingcap/tidb/pkg/util/chunk"
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)
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type stdDevPop4Float64 struct {
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varPop4Float64
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}
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func (e *stdDevPop4Float64) AppendFinalResult2Chunk(_ AggFuncUpdateContext, 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, math.Sqrt(variance))
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return nil
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}
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type stdDevPop4DistinctFloat64 struct {
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varPop4DistinctFloat64
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}
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func (e *stdDevPop4DistinctFloat64) AppendFinalResult2Chunk(_ AggFuncUpdateContext, 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, math.Sqrt(variance))
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return nil
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}
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