/
count.go
111 lines (102 loc) · 2.85 KB
/
count.go
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// Copyright 2017 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 aggregation
import (
log "github.com/Sirupsen/logrus"
"github.com/juju/errors"
"github.com/pingcap/tidb/context"
"github.com/pingcap/tidb/expression"
"github.com/pingcap/tidb/mysql"
"github.com/pingcap/tidb/sessionctx/variable"
"github.com/pingcap/tidb/util/types"
)
type countFunction struct {
aggFunction
}
// Clone implements Aggregation interface.
func (cf *countFunction) Clone() Aggregation {
nf := *cf
for i, arg := range cf.Args {
nf.Args[i] = arg.Clone()
}
return &nf
}
// CalculateDefaultValue implements Aggregation interface.
func (cf *countFunction) CalculateDefaultValue(schema *expression.Schema, ctx context.Context) (d types.Datum, valid bool) {
for _, arg := range cf.Args {
result, err := expression.EvaluateExprWithNull(ctx, schema, arg)
if err != nil {
log.Warnf("Evaluate expr with null failed in function %s, err msg is %s", cf, err.Error())
return d, false
}
if con, ok := result.(*expression.Constant); ok {
if con.Value.IsNull() {
return types.NewDatum(0), true
}
} else {
return d, false
}
}
return types.NewDatum(1), true
}
// GetType implements Aggregation interface.
func (cf *countFunction) GetType() *types.FieldType {
ft := types.NewFieldType(mysql.TypeLonglong)
ft.Flen = 21
types.SetBinChsClnFlag(ft)
return ft
}
// Update implements Aggregation interface.
func (cf *countFunction) Update(ctx *AggEvaluateContext, sc *variable.StatementContext, row []types.Datum) error {
var datumBuf []types.Datum
if cf.Distinct {
datumBuf = make([]types.Datum, 0, len(cf.Args))
}
for _, a := range cf.Args {
value, err := a.Eval(row)
if err != nil {
return errors.Trace(err)
}
if value.GetValue() == nil {
return nil
}
if cf.mode == FinalMode {
ctx.Count += value.GetInt64()
}
if cf.Distinct {
datumBuf = append(datumBuf, value)
}
}
if cf.Distinct {
d, err := ctx.DistinctChecker.Check(datumBuf)
if err != nil {
return errors.Trace(err)
}
if !d {
return nil
}
}
if cf.mode == CompleteMode {
ctx.Count++
}
return nil
}
// GetResult implements Aggregation interface.
func (cf *countFunction) GetResult(ctx *AggEvaluateContext) (d types.Datum) {
d.SetInt64(ctx.Count)
return d
}
// GetPartialResult implements Aggregation interface.
func (cf *countFunction) GetPartialResult(ctx *AggEvaluateContext) []types.Datum {
return []types.Datum{cf.GetResult(ctx)}
}