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