tidb sum 代码
文件路径：/expression/aggregation/sum.go
/ 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,
/ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
/ See the License for the specific language governing permissions and
/ limitations under the License.
package aggregation
import (
"github.com/pingcap/tidb/sessionctx/stmtctx"
"github.com/pingcap/tidb/types"
"github.com/pingcap/tidb/util/chunk"
)
type sumFunction struct {
aggFunction
}
/ Update implements Aggregation interface.
func (sf *sumFunction) Update(evalCtx *AggEvaluateContext, sc *stmtctx.StatementContext, row chunk.Row) error {
return sf.updateSum(sc, evalCtx, row)
}
/ GetResult implements Aggregation interface.
func (sf *sumFunction) GetResult(evalCtx *AggEvaluateContext) (d types.Datum) {
return evalCtx.Value
}
/ GetPartialResult implements Aggregation interface.
func (sf *sumFunction) GetPartialResult(evalCtx *AggEvaluateContext) []types.Datum {
return []types.Datum{sf.GetResult(evalCtx)}
}