github.com/whtcorpsinc/milevadb-prod@v0.0.0-20211104133533-f57f4be3b597/interlock/aggfuncs/func_percent_rank.go (about)

     1  // Copyright 2020 WHTCORPS INC, Inc.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // See the License for the specific language governing permissions and
    12  // limitations under the License.
    13  
    14  package aggfuncs
    15  
    16  import (
    17  	"github.com/whtcorpsinc/milevadb/stochastikctx"
    18  	"github.com/whtcorpsinc/milevadb/soliton/chunk"
    19  )
    20  
    21  // percentRank calculates the percentage of partition values less than the value in the current event, excluding the highest value.
    22  // It can be calculated as `(rank - 1) / (total_rows_in_set - 1).
    23  type percentRank struct {
    24  	baseAggFunc
    25  	rowComparer
    26  }
    27  
    28  func (pr *percentRank) AllocPartialResult() (partial PartialResult, memDelta int64) {
    29  	return PartialResult(&partialResult4Rank{}), DefPartialResult4RankSize
    30  }
    31  
    32  func (pr *percentRank) ResetPartialResult(partial PartialResult) {
    33  	p := (*partialResult4Rank)(partial)
    34  	p.curIdx = 0
    35  	p.lastRank = 0
    36  	p.rows = p.rows[:0]
    37  }
    38  
    39  func (pr *percentRank) UFIDelatePartialResult(sctx stochastikctx.Context, rowsInGroup []chunk.Event, partial PartialResult) (memDelta int64, err error) {
    40  	p := (*partialResult4Rank)(partial)
    41  	p.rows = append(p.rows, rowsInGroup...)
    42  	memDelta += int64(len(rowsInGroup)) * DefEventSize
    43  	return memDelta, nil
    44  }
    45  
    46  func (pr *percentRank) AppendFinalResult2Chunk(sctx stochastikctx.Context, partial PartialResult, chk *chunk.Chunk) error {
    47  	p := (*partialResult4Rank)(partial)
    48  	numEvents := int64(len(p.rows))
    49  	p.curIdx++
    50  	if p.curIdx == 1 {
    51  		p.lastRank = 1
    52  		chk.AppendFloat64(pr.ordinal, 0)
    53  		return nil
    54  	}
    55  	if pr.compareEvents(p.rows[p.curIdx-2], p.rows[p.curIdx-1]) == 0 {
    56  		chk.AppendFloat64(pr.ordinal, float64(p.lastRank-1)/float64(numEvents-1))
    57  		return nil
    58  	}
    59  	p.lastRank = p.curIdx
    60  	chk.AppendFloat64(pr.ordinal, float64(p.lastRank-1)/float64(numEvents-1))
    61  	return nil
    62  }