78 lines
2.3 KiB
Go
78 lines
2.3 KiB
Go
// Copyright 2021 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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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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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 executor
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import (
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"context"
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"github.com/pingcap/errors"
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"github.com/pingcap/tidb/executor/internal/exec"
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"github.com/pingcap/tidb/util/chunk"
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"github.com/pingcap/tidb/util/cteutil"
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)
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// CTETableReaderExec scans data in iterInTbl, which is filled by corresponding CTEExec.
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type CTETableReaderExec struct {
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exec.BaseExecutor
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iterInTbl cteutil.Storage
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chkIdx int
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curIter int
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}
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// Open implements the Executor interface.
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func (e *CTETableReaderExec) Open(ctx context.Context) error {
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e.reset()
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return e.BaseExecutor.Open(ctx)
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}
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// Next implements the Executor interface.
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func (e *CTETableReaderExec) Next(_ context.Context, req *chunk.Chunk) (err error) {
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req.Reset()
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// We should read `iterInTbl` from the beginning when the next iteration starts.
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// Can not directly judge whether to start the next iteration based on e.chkIdx,
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// because some operators(Selection) may use for loop to read all data in `iterInTbl`.
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if e.curIter != e.iterInTbl.GetIter() {
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if e.curIter > e.iterInTbl.GetIter() {
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return errors.Errorf("invalid iteration for CTETableReaderExec (e.curIter: %d, e.iterInTbl.GetIter(): %d)",
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e.curIter, e.iterInTbl.GetIter())
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}
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e.chkIdx = 0
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e.curIter = e.iterInTbl.GetIter()
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}
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if e.chkIdx < e.iterInTbl.NumChunks() {
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res, err := e.iterInTbl.GetChunk(e.chkIdx)
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if err != nil {
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return err
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}
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// Need to copy chunk to make sure upper operators will not change chunk in iterInTbl.
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req.SwapColumns(res.CopyConstructSel())
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e.chkIdx++
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}
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return nil
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}
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// Close implements the Executor interface.
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func (e *CTETableReaderExec) Close() (err error) {
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e.reset()
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return e.BaseExecutor.Close()
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}
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func (e *CTETableReaderExec) reset() {
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e.chkIdx = 0
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e.curIter = 0
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}
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