54 lines
1.7 KiB
Go
54 lines
1.7 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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// 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/tidb/sessionctx"
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"github.com/pingcap/tidb/util/chunk"
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)
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// percentRank calculates the percentage of partition values less than the value in the current row, excluding the highest value.
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// It can be calculated as `(rank - 1) / (total_rows_in_set - 1).
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type percentRank struct {
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baseAggFunc
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rowComparer
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}
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func (pr *percentRank) AllocPartialResult() PartialResult {
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return PartialResult(&partialResult4Rank{})
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}
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func (pr *percentRank) ResetPartialResult(partial PartialResult) {
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p := (*partialResult4Rank)(partial)
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p.reset()
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}
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func (pr *percentRank) UpdatePartialResult(sctx sessionctx.Context, rowsInGroup []chunk.Row, partial PartialResult) error {
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p := (*partialResult4Rank)(partial)
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p.updatePartialResult(rowsInGroup, false, pr.compareRows)
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return nil
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}
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func (pr *percentRank) AppendFinalResult2Chunk(sctx sessionctx.Context, partial PartialResult, chk *chunk.Chunk) error {
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p := (*partialResult4Rank)(partial)
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numRows := len(p.results)
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if numRows == 1 {
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chk.AppendFloat64(pr.ordinal, 0)
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} else {
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chk.AppendFloat64(pr.ordinal, float64(p.results[p.curIdx]-1)/float64(numRows-1))
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}
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p.curIdx++
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return nil
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}
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