forked from pingcap/tidb
/
delete.go
323 lines (298 loc) · 7.31 KB
/
delete.go
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// Copyright 2015 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 stmts
import (
"strings"
"github.com/juju/errors"
"github.com/ngaut/log"
"github.com/pingcap/tidb/column"
"github.com/pingcap/tidb/context"
"github.com/pingcap/tidb/expression"
"github.com/pingcap/tidb/expression/expressions"
"github.com/pingcap/tidb/plan"
"github.com/pingcap/tidb/plan/plans"
"github.com/pingcap/tidb/rset"
"github.com/pingcap/tidb/rset/rsets"
"github.com/pingcap/tidb/sessionctx/variable"
"github.com/pingcap/tidb/stmt"
"github.com/pingcap/tidb/table"
"github.com/pingcap/tidb/util"
"github.com/pingcap/tidb/util/format"
)
var _ stmt.Statement = (*DeleteStmt)(nil) // TODO optimizer plan
// DeleteStmt is a statement to delete rows from table.
// See: https://dev.mysql.com/doc/refman/5.7/en/delete.html
type DeleteStmt struct {
TableIdent table.Ident
Where expression.Expression
Order *rsets.OrderByRset
Limit *rsets.LimitRset
LowPriority bool
Ignore bool
Quick bool
MultiTable bool
BeforeFrom bool
TableIdents []table.Ident
Refs *rsets.JoinRset
Text string
}
// Explain implements the stmt.Statement Explain interface.
func (s *DeleteStmt) Explain(ctx context.Context, w format.Formatter) {
p, err := s.indexPlan(ctx)
if err != nil {
log.Error(err)
return
}
if p != nil {
p.Explain(w)
} else {
w.Format("┌Iterate all rows of table: %s\n", s.TableIdent)
}
w.Format("└Delete row\n")
}
// IsDDL implements the stmt.Statement IsDDL interface.
func (s *DeleteStmt) IsDDL() bool {
return false
}
// OriginText implements the stmt.Statement OriginText interface.
func (s *DeleteStmt) OriginText() string {
return s.Text
}
// SetText implements the stmt.Statement SetText interface.
func (s *DeleteStmt) SetText(text string) {
s.Text = text
}
func (s *DeleteStmt) indexPlan(ctx context.Context) (plan.Plan, error) {
if s.MultiTable {
return s.planMultiTable(ctx)
}
t, err := getTable(ctx, s.TableIdent)
if err != nil {
return nil, err
}
p, filtered, err := (&plans.TableDefaultPlan{T: t}).FilterForUpdateAndDelete(ctx, s.Where)
if err != nil {
return nil, err
}
if !filtered {
return nil, nil
}
return p, nil
}
func (s *DeleteStmt) planMultiTable(ctx context.Context) (plan.Plan, error) {
var (
r plan.Plan
err error
)
if s.Refs != nil {
r, err = s.Refs.Plan(ctx)
if err != nil {
return nil, err
}
}
if s.Where != nil {
r, err = (&rsets.WhereRset{Expr: s.Where, Src: r}).Plan(ctx)
if err != nil {
return nil, err
}
}
return r, nil
}
func (s *DeleteStmt) hitWhere(ctx context.Context, t table.Table, data []interface{}) (bool, error) {
if s.Where == nil {
return true, nil
}
m := map[interface{}]interface{}{}
// Set parameter for evaluating expression.
for _, col := range t.Cols() {
m[col.Name.L] = data[col.Offset]
}
ok, err := expressions.EvalBoolExpr(ctx, s.Where, m)
if err != nil {
return false, errors.Trace(err)
}
return ok, nil
}
func (s *DeleteStmt) removeRow(ctx context.Context, t table.Table, h int64, data []interface{}) error {
// remove row's all indexies
if err := t.RemoveRowAllIndex(ctx, h, data); err != nil {
return err
}
// remove row
if err := t.RemoveRow(ctx, h); err != nil {
return err
}
variable.GetSessionVars(ctx).AddAffectedRows(1)
return nil
}
func (s *DeleteStmt) tryDeleteUsingIndex(ctx context.Context, t table.Table) (bool, error) {
log.Info("try delete with index", ctx)
p, err := s.indexPlan(ctx)
if err != nil {
return false, err
}
if p != nil {
var ids []int64
err := p.Do(ctx, func(id interface{}, _ []interface{}) (bool, error) {
// Generate ids for coming deletion.
ids = append(ids, id.(int64))
return true, nil
})
if err != nil {
return false, err
}
var cnt uint64
for _, id := range ids {
if s.Limit != nil && cnt >= s.Limit.Count {
break
}
data, err := t.Row(ctx, id)
if err != nil {
return false, err
}
log.Infof("try delete with index id:%d, ctx:%s", id, ctx)
ok, err := s.hitWhere(ctx, t, data)
if err != nil {
return false, errors.Trace(err)
}
if !ok {
return true, nil
}
err = s.removeRow(ctx, t, id, data)
if err != nil {
return false, err
}
cnt++
}
return true, nil
}
return false, nil
}
// Exec implements the stmt.Statement Exec interface.
func (s *DeleteStmt) Exec(ctx context.Context) (_ rset.Recordset, err error) {
if s.MultiTable {
return s.execMultiTable(ctx)
}
t, err := getTable(ctx, s.TableIdent)
if err != nil {
return nil, err
}
ok, err := s.tryDeleteUsingIndex(ctx, t)
if err != nil {
return nil, err
}
if ok {
// Delete using index OK.
log.Info("try delete with index OK")
return nil, nil
}
var cnt uint64
err = t.IterRecords(ctx, t.FirstKey(), t.Cols(), func(h int64, data []interface{}, cols []*column.Col) (bool, error) {
if s.Limit != nil && cnt >= s.Limit.Count {
return false, nil
}
ok, err = s.hitWhere(ctx, t, data)
if err != nil {
return false, errors.Trace(err)
}
if !ok {
return true, nil
}
err = s.removeRow(ctx, t, h, data)
if err != nil {
return false, err
}
cnt++
return true, nil
})
if err != nil {
return nil, err
}
return nil, nil
}
func (s *DeleteStmt) execMultiTable(ctx context.Context) (_ rset.Recordset, err error) {
log.Info("Delete from multi-table")
if len(s.TableIdents) == 0 {
return nil, nil
}
p, err := s.indexPlan(ctx)
if err != nil {
return nil, errors.Trace(err)
}
if p == nil {
return nil, nil
}
tblIDMap := make(map[int64]bool, len(s.TableIdents))
// Get table alias map.
fs := p.GetFields()
tblAliasMap := make(map[string]string)
for _, f := range fs {
if f.TableName != f.OrgTableName {
tblAliasMap[f.TableName] = f.OrgTableName
}
}
for _, t := range s.TableIdents {
// Consider DBName.
oname, ok := tblAliasMap[t.Name.O]
if ok {
t.Name.O = oname
t.Name.L = strings.ToLower(oname)
}
var tbl table.Table
tbl, err = getTable(ctx, t)
if err != nil {
return nil, errors.Trace(err)
}
tblIDMap[tbl.TableID()] = true
}
rowKeyMap := make(map[string]table.Table)
err = p.Do(ctx, func(_ interface{}, in []interface{}) (bool, error) {
// Generate ids for coming deletion.
var rowKeys *plans.RowKeyList
if in != nil && len(in) > 0 {
t := in[len(in)-1]
switch vt := t.(type) {
case *plans.RowKeyList:
rowKeys = vt
}
}
if rowKeys != nil {
for _, entry := range rowKeys.Keys {
tid := entry.Tbl.TableID()
if _, ok := tblIDMap[tid]; !ok {
continue
}
rowKeyMap[entry.Key] = entry.Tbl
}
}
return true, nil
})
if err != nil {
return nil, errors.Trace(err)
}
for k, t := range rowKeyMap {
id, err := util.DecodeHandleFromRowKey(k)
if err != nil {
return nil, errors.Trace(err)
}
data, err := t.Row(ctx, id)
if err != nil {
return nil, errors.Trace(err)
}
err = s.removeRow(ctx, t, id, data)
if err != nil {
return nil, errors.Trace(err)
}
}
return nil, nil
}