122 lines
2.8 KiB
Go
122 lines
2.8 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/expression"
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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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type rank struct {
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baseAggFunc
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isDense bool
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rowComparer
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}
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type partialResult4Rank struct {
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curIdx int64
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seenRows int64
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results []int64
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lastRow chunk.Row
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}
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func (p *partialResult4Rank) reset() {
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p.curIdx = 0
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p.seenRows = 0
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p.results = p.results[:0]
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}
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func (p *partialResult4Rank) updatePartialResult(
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rowsInGroup []chunk.Row,
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isDense bool,
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compareRows func(prev, curr chunk.Row) int,
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) {
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if len(rowsInGroup) == 0 {
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return
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}
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lastRow := p.lastRow
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for _, row := range rowsInGroup {
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p.seenRows++
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if p.seenRows == 1 {
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p.results = append(p.results, 1)
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lastRow = row
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continue
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}
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var rank int64
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if compareRows(lastRow, row) == 0 {
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rank = p.results[len(p.results)-1]
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} else if isDense {
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rank = p.results[len(p.results)-1] + 1
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} else {
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rank = p.seenRows
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}
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p.results = append(p.results, rank)
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lastRow = row
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}
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p.lastRow = rowsInGroup[len(rowsInGroup)-1].CopyConstruct()
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}
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func (r *rank) AllocPartialResult() PartialResult {
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return PartialResult(&partialResult4Rank{})
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}
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func (r *rank) ResetPartialResult(pr PartialResult) {
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p := (*partialResult4Rank)(pr)
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p.reset()
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}
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func (r *rank) UpdatePartialResult(sctx sessionctx.Context, rowsInGroup []chunk.Row, pr PartialResult) error {
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p := (*partialResult4Rank)(pr)
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p.updatePartialResult(rowsInGroup, r.isDense, r.compareRows)
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return nil
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}
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func (r *rank) AppendFinalResult2Chunk(sctx sessionctx.Context, pr PartialResult, chk *chunk.Chunk) error {
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p := (*partialResult4Rank)(pr)
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chk.AppendInt64(r.ordinal, p.results[p.curIdx])
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p.curIdx++
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return nil
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}
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type rowComparer struct {
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cmpFuncs []chunk.CompareFunc
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colIdx []int
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}
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func buildRowComparer(cols []*expression.Column) rowComparer {
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rc := rowComparer{}
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rc.colIdx = make([]int, 0, len(cols))
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rc.cmpFuncs = make([]chunk.CompareFunc, 0, len(cols))
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for _, col := range cols {
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cmpFunc := chunk.GetCompareFunc(col.RetType)
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if cmpFunc == nil {
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continue
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}
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rc.cmpFuncs = append(rc.cmpFuncs, chunk.GetCompareFunc(col.RetType))
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rc.colIdx = append(rc.colIdx, col.Index)
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}
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return rc
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}
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func (rc *rowComparer) compareRows(prev, curr chunk.Row) int {
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for i, idx := range rc.colIdx {
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res := rc.cmpFuncs[i](prev, idx, curr, idx)
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if res != 0 {
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return res
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}
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}
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return 0
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}
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