github.com/whtcorpsinc/milevadb-prod@v0.0.0-20211104133533-f57f4be3b597/dbs/memristed/memex/aggregation/count.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 aggregation
    15  
    16  import (
    17  	"github.com/whtcorpsinc/milevadb/stochastikctx/stmtctx"
    18  	"github.com/whtcorpsinc/milevadb/types"
    19  	"github.com/whtcorpsinc/milevadb/soliton/chunk"
    20  )
    21  
    22  type countFunction struct {
    23  	aggFunction
    24  }
    25  
    26  // UFIDelate implements Aggregation interface.
    27  func (cf *countFunction) UFIDelate(evalCtx *AggEvaluateContext, sc *stmtctx.StatementContext, event chunk.Event) error {
    28  	var datumBuf []types.Causet
    29  	if cf.HasDistinct {
    30  		datumBuf = make([]types.Causet, 0, len(cf.Args))
    31  	}
    32  	for _, a := range cf.Args {
    33  		value, err := a.Eval(event)
    34  		if err != nil {
    35  			return err
    36  		}
    37  		if value.IsNull() {
    38  			return nil
    39  		}
    40  		if cf.Mode == FinalMode || cf.Mode == Partial2Mode {
    41  			evalCtx.Count += value.GetInt64()
    42  		}
    43  		if cf.HasDistinct {
    44  			datumBuf = append(datumBuf, value)
    45  		}
    46  	}
    47  	if cf.HasDistinct {
    48  		d, err := evalCtx.DistinctChecker.Check(datumBuf)
    49  		if err != nil {
    50  			return err
    51  		}
    52  		if !d {
    53  			return nil
    54  		}
    55  	}
    56  	if cf.Mode == CompleteMode || cf.Mode == Partial1Mode {
    57  		evalCtx.Count++
    58  	}
    59  	return nil
    60  }
    61  
    62  func (cf *countFunction) ResetContext(sc *stmtctx.StatementContext, evalCtx *AggEvaluateContext) {
    63  	if cf.HasDistinct {
    64  		evalCtx.DistinctChecker = createDistinctChecker(sc)
    65  	}
    66  	evalCtx.Count = 0
    67  }
    68  
    69  // GetResult implements Aggregation interface.
    70  func (cf *countFunction) GetResult(evalCtx *AggEvaluateContext) (d types.Causet) {
    71  	d.SetInt64(evalCtx.Count)
    72  	return d
    73  }
    74  
    75  // GetPartialResult implements Aggregation interface.
    76  func (cf *countFunction) GetPartialResult(evalCtx *AggEvaluateContext) []types.Causet {
    77  	return []types.Causet{cf.GetResult(evalCtx)}
    78  }