// Copyright 2019 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, // See the License for the specific language governing permissions and // limitations under the License. package aggfuncs import ( "github.com/pingcap/tidb/sessionctx" "github.com/pingcap/tidb/util/chunk" ) // percentRank calculates the percentage of partition values less than the value in the current row, excluding the highest value. // It can be calculated as `(rank - 1) / (total_rows_in_set - 1). type percentRank struct { baseAggFunc rowComparer } func (pr *percentRank) AllocPartialResult() PartialResult { return PartialResult(&partialResult4Rank{}) } func (pr *percentRank) ResetPartialResult(partial PartialResult) { p := (*partialResult4Rank)(partial) p.curIdx = 0 p.lastRank = 0 p.rows = p.rows[:0] } func (pr *percentRank) UpdatePartialResult(sctx sessionctx.Context, rowsInGroup []chunk.Row, partial PartialResult) error { p := (*partialResult4Rank)(partial) p.rows = append(p.rows, rowsInGroup...) return nil } func (pr *percentRank) AppendFinalResult2Chunk(sctx sessionctx.Context, partial PartialResult, chk *chunk.Chunk) error { p := (*partialResult4Rank)(partial) numRows := int64(len(p.rows)) p.curIdx++ if p.curIdx == 1 { p.lastRank = 1 chk.AppendFloat64(pr.ordinal, 0) return nil } if pr.compareRows(p.rows[p.curIdx-2], p.rows[p.curIdx-1]) == 0 { chk.AppendFloat64(pr.ordinal, float64(p.lastRank-1)/float64(numRows-1)) return nil } p.lastRank = p.curIdx chk.AppendFloat64(pr.ordinal, float64(p.lastRank-1)/float64(numRows-1)) return nil }