25b5a2ce18
Aggregation results were stored in aggregation functions, so one map is created for each function to store different groups’ results, which requires much memory. The aggregation functions are refactored and are now stateless, and the maps are kept in executor (executor.HashAggExec and mocktikv.aggregateExec) so that only one map is needed to store all the functions’ results, which reduced the memory usage.
101 lines
2.5 KiB
Go
101 lines
2.5 KiB
Go
// Copyright 2017 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 aggregation
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import (
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"bytes"
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"fmt"
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"github.com/juju/errors"
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"github.com/pingcap/tidb/mysql"
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"github.com/pingcap/tidb/sessionctx/variable"
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"github.com/pingcap/tidb/util/types"
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)
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type concatFunction struct {
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aggFunction
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}
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// Clone implements Aggregation interface.
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func (cf *concatFunction) Clone() Aggregation {
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nf := *cf
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for i, arg := range cf.Args {
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nf.Args[i] = arg.Clone()
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}
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return &nf
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}
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// GetType implements Aggregation interface.
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func (cf *concatFunction) GetType() *types.FieldType {
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return types.NewFieldType(mysql.TypeVarString)
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}
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func (cf *concatFunction) writeValue(ctx *AggEvaluateContext, val types.Datum) {
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if val.Kind() == types.KindBytes {
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ctx.Buffer.Write(val.GetBytes())
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} else {
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ctx.Buffer.WriteString(fmt.Sprintf("%v", val.GetValue()))
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}
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}
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// Update implements Aggregation interface.
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func (cf *concatFunction) Update(ctx *AggEvaluateContext, sc *variable.StatementContext, row []types.Datum) error {
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datumBuf := make([]types.Datum, 0, len(cf.Args))
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for _, a := range cf.Args {
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value, err := a.Eval(row)
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if err != nil {
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return errors.Trace(err)
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}
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if value.GetValue() == nil {
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return nil
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}
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datumBuf = append(datumBuf, value)
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}
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if cf.Distinct {
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d, err := ctx.DistinctChecker.Check(datumBuf)
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if err != nil {
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return errors.Trace(err)
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}
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if !d {
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return nil
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}
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}
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if ctx.Buffer == nil {
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ctx.Buffer = &bytes.Buffer{}
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} else {
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// now use comma separator
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ctx.Buffer.WriteString(",")
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}
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for _, val := range datumBuf {
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cf.writeValue(ctx, val)
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}
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// TODO: if total length is greater than global var group_concat_max_len, truncate it.
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return nil
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}
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// GetResult implements Aggregation interface.
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func (cf *concatFunction) GetResult(ctx *AggEvaluateContext) (d types.Datum) {
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if ctx.Buffer != nil {
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d.SetString(ctx.Buffer.String())
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} else {
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d.SetNull()
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}
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return d
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}
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// GetPartialResult implements Aggregation interface.
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func (cf *concatFunction) GetPartialResult(ctx *AggEvaluateContext) []types.Datum {
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return []types.Datum{cf.GetResult(ctx)}
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}
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