tidb delete 源码
tidb delete 代码
文件路径：/executor/delete.go
// Copyright 2018 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,
// 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 executor
import (
"context"
"github.com/pingcap/errors"
"github.com/pingcap/tidb/kv"
"github.com/pingcap/tidb/parser/model"
plannercore "github.com/pingcap/tidb/planner/core"
"github.com/pingcap/tidb/sessionctx"
"github.com/pingcap/tidb/sessionctx/variable"
"github.com/pingcap/tidb/sessiontxn"
"github.com/pingcap/tidb/table"
"github.com/pingcap/tidb/types"
"github.com/pingcap/tidb/util/chunk"
"github.com/pingcap/tidb/util/logutil"
"github.com/pingcap/tidb/util/memory"
"go.uber.org/zap"
)
// DeleteExec represents a delete executor.
// See https://dev.mysql.com/doc/refman/5.7/en/delete.html
type DeleteExec struct {
baseExecutor
IsMultiTable bool
tblID2Table map[int64]table.Table
// tblColPosInfos stores relationship between column ordinal to its table handle.
// the columns ordinals is present in ordinal range format, @see plannercore.TblColPosInfos
tblColPosInfos plannercore.TblColPosInfoSlice
memTracker *memory.Tracker
}
// Next implements the Executor Next interface.
func (e *DeleteExec) Next(ctx context.Context, req *chunk.Chunk) error {
req.Reset()
if e.IsMultiTable {
return e.deleteMultiTablesByChunk(ctx)
}
return e.deleteSingleTableByChunk(ctx)
}
func (e *DeleteExec) deleteOneRow(tbl table.Table, handleCols plannercore.HandleCols, isExtraHandle bool, row []types.Datum) error {
end := len(row)
if isExtraHandle {
end--
}
handle, err := handleCols.BuildHandleByDatums(row)
if err != nil {
return err
}
err = e.removeRow(e.ctx, tbl, handle, row[:end])
if err != nil {
return err
}
return nil
}
func (e *DeleteExec) deleteSingleTableByChunk(ctx context.Context) error {
var (
tbl table.Table
isExtrahandle bool
handleCols plannercore.HandleCols
rowCount int
)
for _, info := range e.tblColPosInfos {
tbl = e.tblID2Table[info.TblID]
handleCols = info.HandleCols
if !tbl.Meta().IsCommonHandle {
isExtrahandle = handleCols.IsInt() && handleCols.GetCol(0).ID == model.ExtraHandleID
}
}
batchDMLSize := e.ctx.GetSessionVars().DMLBatchSize
// If tidb_batch_delete is ON and not in a transaction, we could use BatchDelete mode.
batchDelete := e.ctx.GetSessionVars().BatchDelete && !e.ctx.GetSessionVars().InTxn() &&
variable.EnableBatchDML.Load() && batchDMLSize > 0
fields := retTypes(e.children[0])
chk := newFirstChunk(e.children[0])
columns := e.children[0].Schema().Columns
if len(columns) != len(fields) {
logutil.BgLogger().Error("schema columns and fields mismatch",
zap.Int("len(columns)", len(columns)),
zap.Int("len(fields)", len(fields)))
// Should never run here, so the error code is not defined.
return errors.New("schema columns and fields mismatch")
}
memUsageOfChk := int64(0)
for {
e.memTracker.Consume(-memUsageOfChk)
iter := chunk.NewIterator4Chunk(chk)
err := Next(ctx, e.children[0], chk)
if err != nil {
return err
}
if chk.NumRows() == 0 {
break
}
memUsageOfChk = chk.MemoryUsage()
e.memTracker.Consume(memUsageOfChk)
for chunkRow := iter.Begin(); chunkRow != iter.End(); chunkRow = iter.Next() {
if batchDelete && rowCount >= batchDMLSize {
if err := e.doBatchDelete(ctx); err != nil {
return err
}
rowCount = 0
}
datumRow := make([]types.Datum, 0, len(fields))
for i, field := range fields {
if columns[i].ID == model.ExtraPidColID || columns[i].ID == model.ExtraPhysTblID {
continue
}
datum := chunkRow.GetDatum(i, field)
datumRow = append(datumRow, datum)
}
err = e.deleteOneRow(tbl, handleCols, isExtrahandle, datumRow)
if err != nil {
return err
}
rowCount++
}
chk = chunk.Renew(chk, e.maxChunkSize)
}
return nil
}
func (e *DeleteExec) doBatchDelete(ctx context.Context) error {
txn, err := e.ctx.Txn(false)
if err != nil {
return ErrBatchInsertFail.GenWithStack("BatchDelete failed with error: %v", err)
}
e.memTracker.Consume(-int64(txn.Size()))
e.ctx.StmtCommit()
if err := sessiontxn.NewTxnInStmt(ctx, e.ctx); err != nil {
// We should return a special error for batch insert.
return ErrBatchInsertFail.GenWithStack("BatchDelete failed with error: %v", err)
}
return nil
}
func (e *DeleteExec) composeTblRowMap(tblRowMap tableRowMapType, colPosInfos []plannercore.TblColPosInfo, joinedRow []types.Datum) error {
// iterate all the joined tables, and got the corresponding rows in joinedRow.
for _, info := range colPosInfos {
if unmatchedOuterRow(info, joinedRow) {
continue
}
if tblRowMap[info.TblID] == nil {
tblRowMap[info.TblID] = kv.NewMemAwareHandleMap[[]types.Datum]()
}
handle, err := info.HandleCols.BuildHandleByDatums(joinedRow)
if err != nil {
return err
}
// tblRowMap[info.TblID][handle] hold the row datas binding to this table and this handle.
_, exist := tblRowMap[info.TblID].Get(handle)
memDelta := tblRowMap[info.TblID].Set(handle, joinedRow[info.Start:info.End])
if !exist {
memDelta += types.EstimatedMemUsage(joinedRow, 1)
memDelta += int64(handle.ExtraMemSize())
}
e.memTracker.Consume(memDelta)
}
return nil
}
func (e *DeleteExec) deleteMultiTablesByChunk(ctx context.Context) error {
colPosInfos := e.tblColPosInfos
tblRowMap := make(tableRowMapType)
fields := retTypes(e.children[0])
chk := newFirstChunk(e.children[0])
memUsageOfChk := int64(0)
for {
e.memTracker.Consume(-memUsageOfChk)
iter := chunk.NewIterator4Chunk(chk)
err := Next(ctx, e.children[0], chk)
if err != nil {
return err
}
if chk.NumRows() == 0 {
break
}
memUsageOfChk = chk.MemoryUsage()
e.memTracker.Consume(memUsageOfChk)
for joinedChunkRow := iter.Begin(); joinedChunkRow != iter.End(); joinedChunkRow = iter.Next() {
joinedDatumRow := joinedChunkRow.GetDatumRow(fields)
err := e.composeTblRowMap(tblRowMap, colPosInfos, joinedDatumRow)
if err != nil {
return err
}
}
chk = chunk.Renew(chk, e.maxChunkSize)
}
return e.removeRowsInTblRowMap(tblRowMap)
}
func (e *DeleteExec) removeRowsInTblRowMap(tblRowMap tableRowMapType) error {
for id, rowMap := range tblRowMap {
var err error
rowMap.Range(func(h kv.Handle, val interface{}) bool {
err = e.removeRow(e.ctx, e.tblID2Table[id], h, val.([]types.Datum))
return err == nil
})
if err != nil {
return err
}
}
return nil
}
func (e *DeleteExec) removeRow(ctx sessionctx.Context, t table.Table, h kv.Handle, data []types.Datum) error {
txnState, err := e.ctx.Txn(false)
if err != nil {
return err
}
memUsageOfTxnState := txnState.Size()
err = t.RemoveRecord(ctx, h, data)
if err != nil {
return err
}
e.memTracker.Consume(int64(txnState.Size() - memUsageOfTxnState))
ctx.GetSessionVars().StmtCtx.AddAffectedRows(1)
return nil
}
// Close implements the Executor Close interface.
func (e *DeleteExec) Close() error {
defer e.memTracker.ReplaceBytesUsed(0)
return e.children[0].Close()
}
// Open implements the Executor Open interface.
func (e *DeleteExec) Open(ctx context.Context) error {
e.memTracker = memory.NewTracker(e.id, -1)
e.memTracker.AttachTo(e.ctx.GetSessionVars().StmtCtx.MemTracker)
return e.children[0].Open(ctx)
}
// tableRowMapType is a map for unique (Table, Row) pair. key is the tableID.
// the key in map[int64]Row is the joined table handle, which represent a unique reference row.
// the value in map[int64]Row is the deleting row.
type tableRowMapType map[int64]*kv.MemAwareHandleMap[[]types.Datum]
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