// Copyright 2016 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, // See the License for the specific language governing permissions and // limitations under the License. package executor import ( "context" "github.com/cznic/mathutil" "github.com/pingcap/errors" "github.com/pingcap/tidb/planner/core" "github.com/pingcap/tidb/util/chunk" ) // ExplainExec represents an explain executor. type ExplainExec struct { baseExecutor explain *core.Explain analyzeExec Executor executed bool rows [][]string cursor int } // Open implements the Executor Open interface. func (e *ExplainExec) Open(ctx context.Context) error { if e.analyzeExec != nil { return e.analyzeExec.Open(ctx) } return nil } // Close implements the Executor Close interface. func (e *ExplainExec) Close() error { e.rows = nil return nil } // Next implements the Executor Next interface. func (e *ExplainExec) Next(ctx context.Context, req *chunk.Chunk) error { if e.rows == nil { var err error e.rows, err = e.generateExplainInfo(ctx) if err != nil { return err } } req.GrowAndReset(e.maxChunkSize) if e.cursor >= len(e.rows) { return nil } numCurRows := mathutil.Min(req.Capacity(), len(e.rows)-e.cursor) for i := e.cursor; i < e.cursor+numCurRows; i++ { for j := range e.rows[i] { req.AppendString(j, e.rows[i][j]) } } e.cursor += numCurRows return nil } func (e *ExplainExec) executeAnalyzeExec(ctx context.Context) (err error) { if e.analyzeExec != nil && !e.executed { defer func() { err1 := e.analyzeExec.Close() if err1 != nil { if err != nil { err = errors.New(err.Error() + ", " + err1.Error()) } else { err = err1 } } }() e.executed = true chk := newFirstChunk(e.analyzeExec) for { err = Next(ctx, e.analyzeExec, chk) if err != nil || chk.NumRows() == 0 { break } } } return err } func (e *ExplainExec) generateExplainInfo(ctx context.Context) (rows [][]string, err error) { if err = e.executeAnalyzeExec(ctx); err != nil { return nil, err } if err = e.explain.RenderResult(); err != nil { return nil, err } return e.explain.Rows, nil } // getAnalyzeExecToExecutedNoDelay gets the analyze DML executor to execute in handleNoDelay function. // For explain analyze insert/update/delete statement, the analyze executor should be executed in handleNoDelay // function and then commit transaction if needed. // Otherwise, in autocommit transaction, the table record change of analyze executor(insert/update/delete...) // will not be committed. func (e *ExplainExec) getAnalyzeExecToExecutedNoDelay() Executor { if e.analyzeExec != nil && !e.executed && e.analyzeExec.Schema().Len() == 0 { e.executed = true return e.analyzeExec } return nil }