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group_plan.go
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/
group_plan.go
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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 dml
import (
"context"
)
import (
"github.com/pkg/errors"
)
import (
"github.com/arana-db/arana/pkg/dataset"
"github.com/arana-db/arana/pkg/merge"
"github.com/arana-db/arana/pkg/proto"
"github.com/arana-db/arana/pkg/resultx"
)
// GroupPlan TODO now only support stmt which group by items equal with order by items, such as
// `select uid, max(score) from student group by uid order by uid`
type GroupPlan struct {
Plan proto.Plan
AggItems map[int]func() merge.Aggregator
GroupItems []dataset.OrderByItem
OriginColumnCount int
}
func (g *GroupPlan) Type() proto.PlanType {
return proto.PlanTypeQuery
}
func (g *GroupPlan) ExecIn(ctx context.Context, conn proto.VConn) (proto.Result, error) {
res, err := g.Plan.ExecIn(ctx, conn)
if err != nil {
return nil, errors.WithStack(err)
}
ds, err := res.Dataset()
if err != nil {
return nil, errors.WithStack(err)
}
fields, err := ds.Fields()
if err != nil {
return nil, errors.WithStack(err)
}
return resultx.New(resultx.WithDataset(dataset.Pipe(ds, dataset.GroupReduce(
g.GroupItems,
func(fields []proto.Field) []proto.Field {
return fields[0:g.OriginColumnCount]
},
func() dataset.Reducer {
return dataset.NewGroupReducer(g.AggItems, fields, g.OriginColumnCount)
},
)))), nil
}