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133 lines
3.6 KiB
133 lines
3.6 KiB
// 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/cznic/mathutil"
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"github.com/pingcap/errors"
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"github.com/pingcap/tidb/expression"
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"github.com/pingcap/tidb/sessionctx/stmtctx"
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"github.com/pingcap/tidb/types"
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"github.com/pingcap/tidb/util/chunk"
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)
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type concatFunction struct {
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aggFunction
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separator string
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maxLen uint64
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sepInited bool
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// truncated according to MySQL, a 'group_concat' function generates exactly one 'truncated' warning during its life time, no matter
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// how many group actually truncated. 'truncated' acts as a sentinel to indicate whether this warning has already been
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// generated.
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truncated bool
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}
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func (cf *concatFunction) writeValue(evalCtx *AggEvaluateContext, val types.Datum) {
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if val.Kind() == types.KindBytes {
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evalCtx.Buffer.Write(val.GetBytes())
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} else {
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evalCtx.Buffer.WriteString(fmt.Sprintf("%v", val.GetValue()))
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}
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}
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func (cf *concatFunction) initSeparator(sc *stmtctx.StatementContext, row chunk.Row) error {
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sepArg := cf.Args[len(cf.Args)-1]
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sepDatum, err := sepArg.Eval(row)
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if err != nil {
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return err
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}
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if sepDatum.IsNull() {
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return errors.Errorf("Invalid separator argument.")
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}
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cf.separator, err = sepDatum.ToString()
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return err
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}
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// Update implements Aggregation interface.
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func (cf *concatFunction) Update(evalCtx *AggEvaluateContext, sc *stmtctx.StatementContext, row chunk.Row) error {
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datumBuf := make([]types.Datum, 0, len(cf.Args))
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if !cf.sepInited {
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err := cf.initSeparator(sc, row)
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if err != nil {
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return err
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}
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cf.sepInited = true
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}
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// The last parameter is the concat separator, we only concat the first "len(cf.Args)-1" parameters.
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for i, length := 0, len(cf.Args)-1; i < length; i++ {
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value, err := cf.Args[i].Eval(row)
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if err != nil {
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return err
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}
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if value.IsNull() {
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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.HasDistinct {
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d, err := evalCtx.DistinctChecker.Check(datumBuf)
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if err != nil {
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return 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 evalCtx.Buffer == nil {
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evalCtx.Buffer = &bytes.Buffer{}
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} else {
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evalCtx.Buffer.WriteString(cf.separator)
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}
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for _, val := range datumBuf {
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cf.writeValue(evalCtx, val)
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}
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if cf.maxLen > 0 && uint64(evalCtx.Buffer.Len()) > cf.maxLen {
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i := mathutil.MaxInt
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if uint64(i) > cf.maxLen {
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i = int(cf.maxLen)
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}
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evalCtx.Buffer.Truncate(i)
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if !cf.truncated {
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sc.AppendWarning(expression.ErrCutValueGroupConcat.GenWithStackByArgs(cf.Args[0].String()))
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}
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cf.truncated = true
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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 *concatFunction) GetResult(evalCtx *AggEvaluateContext) (d types.Datum) {
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if evalCtx.Buffer != nil {
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d.SetString(evalCtx.Buffer.String(), cf.RetTp.Collate)
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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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func (cf *concatFunction) ResetContext(sc *stmtctx.StatementContext, evalCtx *AggEvaluateContext) {
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if cf.HasDistinct {
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evalCtx.DistinctChecker = createDistinctChecker(sc)
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}
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evalCtx.Buffer = nil
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}
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// GetPartialResult implements Aggregation interface.
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func (cf *concatFunction) GetPartialResult(evalCtx *AggEvaluateContext) []types.Datum {
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return []types.Datum{cf.GetResult(evalCtx)}
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}
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