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// 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"
"fmt"
"strings"
"github.com/pingcap/errors"
"github.com/pingcap/parser/ast"
"github.com/pingcap/parser/model"
"github.com/pingcap/parser/mysql"
"github.com/pingcap/parser/terror"
"github.com/pingcap/tidb/config"
"github.com/pingcap/tidb/ddl"
"github.com/pingcap/tidb/domain"
"github.com/pingcap/tidb/infoschema"
"github.com/pingcap/tidb/meta"
"github.com/pingcap/tidb/planner/core"
"github.com/pingcap/tidb/sessionctx/variable"
"github.com/pingcap/tidb/types"
"github.com/pingcap/tidb/util/admin"
"github.com/pingcap/tidb/util/chunk"
"github.com/pingcap/tidb/util/gcutil"
"github.com/pingcap/tidb/util/logutil"
"github.com/pingcap/tidb/util/sqlexec"
"go.uber.org/zap"
)
// DDLExec represents a DDL executor.
// It grabs a DDL instance from Domain, calling the DDL methods to do the work.
type DDLExec struct {
baseExecutor
stmt ast.StmtNode
is infoschema.InfoSchema
done bool
}
// toErr converts the error to the ErrInfoSchemaChanged when the schema is outdated.
func (e *DDLExec) toErr(err error) error {
// The err may be cause by schema changed, here we distinguish the ErrInfoSchemaChanged error from other errors.
dom := domain.GetDomain(e.ctx)
checker := domain.NewSchemaChecker(dom, e.is.SchemaMetaVersion(), nil)
txn, err1 := e.ctx.Txn(true)
if err1 != nil {
logutil.BgLogger().Error("active txn failed", zap.Error(err))
return err1
}
_, schemaInfoErr := checker.Check(txn.StartTS())
if schemaInfoErr != nil {
return errors.Trace(schemaInfoErr)
}
return err
}
// Next implements the Executor Next interface.
func (e *DDLExec) Next(ctx context.Context, req *chunk.Chunk) (err error) {
if e.done {
return nil
}
e.done = true
// For each DDL, we should commit the previous transaction and create a new transaction.
if err = e.ctx.NewTxn(ctx); err != nil {
return err
}
defer func() { e.ctx.GetSessionVars().StmtCtx.IsDDLJobInQueue = false }()
switch x := e.stmt.(type) {
case *ast.AlterDatabaseStmt:
err = e.executeAlterDatabase(x)
case *ast.AlterTableStmt:
err = e.executeAlterTable(x)
case *ast.CreateIndexStmt:
err = e.executeCreateIndex(x)
case *ast.CreateDatabaseStmt:
err = e.executeCreateDatabase(x)
case *ast.CreateTableStmt:
err = e.executeCreateTable(x)
case *ast.CreateViewStmt:
err = e.executeCreateView(x)
case *ast.DropIndexStmt:
err = e.executeDropIndex(x)
case *ast.DropDatabaseStmt:
err = e.executeDropDatabase(x)
case *ast.DropTableStmt:
if x.IsView {
err = e.executeDropView(x)
} else {
err = e.executeDropTable(x)
}
case *ast.RecoverTableStmt:
err = e.executeRecoverTable(x)
case *ast.FlashBackTableStmt:
err = e.executeFlashbackTable(x)
case *ast.RenameTableStmt:
err = e.executeRenameTable(x)
case *ast.TruncateTableStmt:
err = e.executeTruncateTable(x)
case *ast.LockTablesStmt:
err = e.executeLockTables(x)
case *ast.UnlockTablesStmt:
err = e.executeUnlockTables(x)
case *ast.CleanupTableLockStmt:
err = e.executeCleanupTableLock(x)
case *ast.RepairTableStmt:
err = e.executeRepairTable(x)
case *ast.CreateSequenceStmt:
err = e.executeCreateSequence(x)
case *ast.DropSequenceStmt:
err = e.executeDropSequence(x)
}
if err != nil {
// If the owner return ErrTableNotExists error when running this DDL, it may be caused by schema changed,
// otherwise, ErrTableNotExists can be returned before putting this DDL job to the job queue.
if (e.ctx.GetSessionVars().StmtCtx.IsDDLJobInQueue && infoschema.ErrTableNotExists.Equal(err)) ||
!e.ctx.GetSessionVars().StmtCtx.IsDDLJobInQueue {
return e.toErr(err)
}
return err
}
dom := domain.GetDomain(e.ctx)
// Update InfoSchema in TxnCtx, so it will pass schema check.
is := dom.InfoSchema()
txnCtx := e.ctx.GetSessionVars().TxnCtx
txnCtx.InfoSchema = is
txnCtx.SchemaVersion = is.SchemaMetaVersion()
// DDL will force commit old transaction, after DDL, in transaction status should be false.
e.ctx.GetSessionVars().SetStatusFlag(mysql.ServerStatusInTrans, false)
return nil
}
func (e *DDLExec) executeTruncateTable(s *ast.TruncateTableStmt) error {
ident := ast.Ident{Schema: s.Table.Schema, Name: s.Table.Name}
err := domain.GetDomain(e.ctx).DDL().TruncateTable(e.ctx, ident)
return err
}
func (e *DDLExec) executeRenameTable(s *ast.RenameTableStmt) error {
if len(s.TableToTables) != 1 {
// Now we only allow one schema changing at the same time.
return errors.Errorf("can't run multi schema change")
}
oldIdent := ast.Ident{Schema: s.OldTable.Schema, Name: s.OldTable.Name}
newIdent := ast.Ident{Schema: s.NewTable.Schema, Name: s.NewTable.Name}
isAlterTable := false
err := domain.GetDomain(e.ctx).DDL().RenameTable(e.ctx, oldIdent, newIdent, isAlterTable)
return err
}
func (e *DDLExec) executeCreateDatabase(s *ast.CreateDatabaseStmt) error {
var opt *ast.CharsetOpt
if len(s.Options) != 0 {
opt = &ast.CharsetOpt{}
for _, val := range s.Options {
switch val.Tp {
case ast.DatabaseOptionCharset:
opt.Chs = val.Value
case ast.DatabaseOptionCollate:
opt.Col = val.Value
}
}
}
err := domain.GetDomain(e.ctx).DDL().CreateSchema(e.ctx, model.NewCIStr(s.Name), opt)
if err != nil {
if infoschema.ErrDatabaseExists.Equal(err) && s.IfNotExists {
err = nil
}
}
return err
}
func (e *DDLExec) executeAlterDatabase(s *ast.AlterDatabaseStmt) error {
err := domain.GetDomain(e.ctx).DDL().AlterSchema(e.ctx, s)
return err
}
func (e *DDLExec) executeCreateTable(s *ast.CreateTableStmt) error {
err := domain.GetDomain(e.ctx).DDL().CreateTable(e.ctx, s)
return err
}
func (e *DDLExec) executeCreateView(s *ast.CreateViewStmt) error {
err := domain.GetDomain(e.ctx).DDL().CreateView(e.ctx, s)
return err
}
func (e *DDLExec) executeCreateIndex(s *ast.CreateIndexStmt) error {
ident := ast.Ident{Schema: s.Table.Schema, Name: s.Table.Name}
err := domain.GetDomain(e.ctx).DDL().CreateIndex(e.ctx, ident, s.KeyType, model.NewCIStr(s.IndexName),
s.IndexPartSpecifications, s.IndexOption, s.IfNotExists)
return err
}
func (e *DDLExec) executeDropDatabase(s *ast.DropDatabaseStmt) error {
dbName := model.NewCIStr(s.Name)
// Protect important system table from been dropped by a mistake.
// I can hardly find a case that a user really need to do this.
if dbName.L == "mysql" {
return errors.New("Drop 'mysql' database is forbidden")
}
err := domain.GetDomain(e.ctx).DDL().DropSchema(e.ctx, dbName)
if infoschema.ErrDatabaseNotExists.Equal(err) {
if s.IfExists {
err = nil
} else {
err = infoschema.ErrDatabaseDropExists.GenWithStackByArgs(s.Name)
}
}
sessionVars := e.ctx.GetSessionVars()
if err == nil && strings.ToLower(sessionVars.CurrentDB) == dbName.L {
sessionVars.CurrentDB = ""
err = variable.SetSessionSystemVar(sessionVars, variable.CharsetDatabase, types.NewStringDatum(mysql.DefaultCharset))
if err != nil {
return err
}
err = variable.SetSessionSystemVar(sessionVars, variable.CollationDatabase, types.NewStringDatum(mysql.DefaultCollationName))
if err != nil {
return err
}
}
return err
}
// If one drop those tables by mistake, it's difficult to recover.
// In the worst case, the whole TiDB cluster fails to bootstrap, so we prevent user from dropping them.
var systemTables = map[string]struct{}{
"tidb": {},
"gc_delete_range": {},
"gc_delete_range_done": {},
}
func isSystemTable(schema, table string) bool {
if schema != "mysql" {
return false
}
if _, ok := systemTables[table]; ok {
return true
}
return false
}
type objectType int
const (
tableObject objectType = iota
viewObject
sequenceObject
)
func (e *DDLExec) executeDropTable(s *ast.DropTableStmt) error {
return e.dropTableObject(s.Tables, tableObject, s.IfExists)
}
func (e *DDLExec) executeDropView(s *ast.DropTableStmt) error {
return e.dropTableObject(s.Tables, viewObject, s.IfExists)
}
func (e *DDLExec) executeDropSequence(s *ast.DropSequenceStmt) error {
return e.dropTableObject(s.Sequences, sequenceObject, s.IfExists)
}
// dropTableObject actually applies to `tableObject`, `viewObject` and `sequenceObject`.
func (e *DDLExec) dropTableObject(objects []*ast.TableName, obt objectType, ifExists bool) error {
var notExistTables []string
for _, tn := range objects {
fullti := ast.Ident{Schema: tn.Schema, Name: tn.Name}
_, ok := e.is.SchemaByName(tn.Schema)
if !ok {
// TODO: we should return special error for table not exist, checking "not exist" is not enough,
// because some other errors may contain this error string too.
notExistTables = append(notExistTables, fullti.String())
continue
}
_, err := e.is.TableByName(tn.Schema, tn.Name)
if err != nil && infoschema.ErrTableNotExists.Equal(err) {
notExistTables = append(notExistTables, fullti.String())
continue
} else if err != nil {
return err
}
// Protect important system table from been dropped by a mistake.
// I can hardly find a case that a user really need to do this.
if isSystemTable(tn.Schema.L, tn.Name.L) {
return errors.Errorf("Drop tidb system table '%s.%s' is forbidden", tn.Schema.L, tn.Name.L)
}
if obt == tableObject && config.CheckTableBeforeDrop {
logutil.BgLogger().Warn("admin check table before drop",
zap.String("database", fullti.Schema.O),
zap.String("table", fullti.Name.O),
)
sql := fmt.Sprintf("admin check table `%s`.`%s`", fullti.Schema.O, fullti.Name.O)
_, _, err = e.ctx.(sqlexec.RestrictedSQLExecutor).ExecRestrictedSQL(sql)
if err != nil {
return err
}
}
switch obt {
case tableObject:
err = domain.GetDomain(e.ctx).DDL().DropTable(e.ctx, fullti)
case viewObject:
err = domain.GetDomain(e.ctx).DDL().DropView(e.ctx, fullti)
case sequenceObject:
err = domain.GetDomain(e.ctx).DDL().DropSequence(e.ctx, fullti, ifExists)
}
if infoschema.ErrDatabaseNotExists.Equal(err) || infoschema.ErrTableNotExists.Equal(err) {
notExistTables = append(notExistTables, fullti.String())
} else if err != nil {
return err
}
}
if len(notExistTables) > 0 && !ifExists {
if obt == sequenceObject {
return infoschema.ErrSequenceDropExists.GenWithStackByArgs(strings.Join(notExistTables, ","))
}
return infoschema.ErrTableDropExists.GenWithStackByArgs(strings.Join(notExistTables, ","))
}
// We need add warning when use if exists.
if len(notExistTables) > 0 && ifExists {
for _, table := range notExistTables {
if obt == sequenceObject {
e.ctx.GetSessionVars().StmtCtx.AppendNote(infoschema.ErrSequenceDropExists.GenWithStackByArgs(table))
} else {
e.ctx.GetSessionVars().StmtCtx.AppendNote(infoschema.ErrTableDropExists.GenWithStackByArgs(table))
}
}
}
return nil
}
func (e *DDLExec) executeDropIndex(s *ast.DropIndexStmt) error {
ti := ast.Ident{Schema: s.Table.Schema, Name: s.Table.Name}
err := domain.GetDomain(e.ctx).DDL().DropIndex(e.ctx, ti, model.NewCIStr(s.IndexName), s.IfExists)
if (infoschema.ErrDatabaseNotExists.Equal(err) || infoschema.ErrTableNotExists.Equal(err)) && s.IfExists {
err = nil
}
return err
}
func (e *DDLExec) executeAlterTable(s *ast.AlterTableStmt) error {
ti := ast.Ident{Schema: s.Table.Schema, Name: s.Table.Name}
err := domain.GetDomain(e.ctx).DDL().AlterTable(e.ctx, ti, s.Specs)
return err
}
// executeRecoverTable represents a recover table executor.
// It is built from "recover table" statement,
// is used to recover the table that deleted by mistake.
func (e *DDLExec) executeRecoverTable(s *ast.RecoverTableStmt) error {
txn, err := e.ctx.Txn(true)
if err != nil {
return err
}
t := meta.NewMeta(txn)
dom := domain.GetDomain(e.ctx)
var job *model.Job
var tblInfo *model.TableInfo
if s.JobID != 0 {
job, tblInfo, err = e.getRecoverTableByJobID(s, t, dom)
} else {
job, tblInfo, err = e.getRecoverTableByTableName(s.Table)
}
if err != nil {
return err
}
// Check the table ID was not exists.
tbl, ok := dom.InfoSchema().TableByID(tblInfo.ID)
if ok {
return infoschema.ErrTableExists.GenWithStack("Table '%-.192s' already been recover to '%-.192s', can't be recover repeatedly", s.Table.Name.O, tbl.Meta().Name.O)
}
autoIncID, autoRandID, err := e.getTableAutoIDsFromSnapshot(job)
if err != nil {
return err
}
recoverInfo := &ddl.RecoverInfo{
SchemaID: job.SchemaID,
TableInfo: tblInfo,
DropJobID: job.ID,
SnapshotTS: job.StartTS,
CurAutoIncID: autoIncID,
CurAutoRandID: autoRandID,
}
// Call DDL RecoverTable.
err = domain.GetDomain(e.ctx).DDL().RecoverTable(e.ctx, recoverInfo)
return err
}
func (e *DDLExec) getTableAutoIDsFromSnapshot(job *model.Job) (autoIncID, autoRandID int64, err error) {
// Get table original autoIDs before table drop.
dom := domain.GetDomain(e.ctx)
m, err := dom.GetSnapshotMeta(job.StartTS)
if err != nil {
return 0, 0, err
}
autoIncID, err = m.GetAutoTableID(job.SchemaID, job.TableID)
if err != nil {
return 0, 0, errors.Errorf("recover table_id: %d, get original autoIncID from snapshot meta err: %s", job.TableID, err.Error())
}
autoRandID, err = m.GetAutoRandomID(job.SchemaID, job.TableID)
if err != nil {
return 0, 0, errors.Errorf("recover table_id: %d, get original autoRandID from snapshot meta err: %s", job.TableID, err.Error())
}
return autoIncID, autoRandID, nil
}
func (e *DDLExec) getRecoverTableByJobID(s *ast.RecoverTableStmt, t *meta.Meta, dom *domain.Domain) (*model.Job, *model.TableInfo, error) {
job, err := t.GetHistoryDDLJob(s.JobID)
if err != nil {
return nil, nil, err
}
if job == nil {
return nil, nil, admin.ErrDDLJobNotFound.GenWithStackByArgs(s.JobID)
}
if job.Type != model.ActionDropTable && job.Type != model.ActionTruncateTable {
return nil, nil, errors.Errorf("Job %v type is %v, not dropped/truncated table", job.ID, job.Type)
}
// Check GC safe point for getting snapshot infoSchema.
err = gcutil.ValidateSnapshot(e.ctx, job.StartTS)
if err != nil {
return nil, nil, err
}
// Get the snapshot infoSchema before drop table.
snapInfo, err := dom.GetSnapshotInfoSchema(job.StartTS)
if err != nil {
return nil, nil, err
}
// Get table meta from snapshot infoSchema.
table, ok := snapInfo.TableByID(job.TableID)
if !ok {
return nil, nil, infoschema.ErrTableNotExists.GenWithStackByArgs(
fmt.Sprintf("(Schema ID %d)", job.SchemaID),
fmt.Sprintf("(Table ID %d)", job.TableID),
)
}
return job, table.Meta(), nil
}
// GetDropOrTruncateTableInfoFromJobs gets the dropped/truncated table information from DDL jobs,
// it will use the `start_ts` of DDL job as snapshot to get the dropped/truncated table information.
func GetDropOrTruncateTableInfoFromJobs(jobs []*model.Job, gcSafePoint uint64, dom *domain.Domain, fn func(*model.Job, *model.TableInfo) (bool, error)) (bool, error) {
for _, job := range jobs {
// Check GC safe point for getting snapshot infoSchema.
err := gcutil.ValidateSnapshotWithGCSafePoint(job.StartTS, gcSafePoint)
if err != nil {
return false, err
}
if job.Type != model.ActionDropTable && job.Type != model.ActionTruncateTable {
continue
}
snapMeta, err := dom.GetSnapshotMeta(job.StartTS)
if err != nil {
return false, err
}
tbl, err := snapMeta.GetTable(job.SchemaID, job.TableID)
if err != nil {
if meta.ErrDBNotExists.Equal(err) {
// The dropped/truncated DDL maybe execute failed that caused by the parallel DDL execution,
// then can't find the table from the snapshot info-schema. Should just ignore error here,
// see more in TestParallelDropSchemaAndDropTable.
continue
}
return false, err
}
if tbl == nil {
// The dropped/truncated DDL maybe execute failed that caused by the parallel DDL execution,
// then can't find the table from the snapshot info-schema. Should just ignore error here,
// see more in TestParallelDropSchemaAndDropTable.
continue
}
finish, err := fn(job, tbl)
if err != nil || finish {
return finish, err
}
}
return false, nil
}
func (e *DDLExec) getRecoverTableByTableName(tableName *ast.TableName) (*model.Job, *model.TableInfo, error) {
txn, err := e.ctx.Txn(true)
if err != nil {
return nil, nil, err
}
schemaName := tableName.Schema.L
if schemaName == "" {
schemaName = strings.ToLower(e.ctx.GetSessionVars().CurrentDB)
}
if schemaName == "" {
return nil, nil, errors.Trace(core.ErrNoDB)
}
gcSafePoint, err := gcutil.GetGCSafePoint(e.ctx)
if err != nil {
return nil, nil, err
}
var jobInfo *model.Job
var tableInfo *model.TableInfo
dom := domain.GetDomain(e.ctx)
handleJobAndTableInfo := func(job *model.Job, tblInfo *model.TableInfo) (bool, error) {
if tblInfo.Name.L != tableName.Name.L {
return false, nil
}
schema, ok := dom.InfoSchema().SchemaByID(job.SchemaID)
if !ok {
return false, nil
}
if schema.Name.L == schemaName {
tableInfo = tblInfo
jobInfo = job
return true, nil
}
return false, nil
}
fn := func(jobs []*model.Job) (bool, error) {
return GetDropOrTruncateTableInfoFromJobs(jobs, gcSafePoint, dom, handleJobAndTableInfo)
}
err = admin.IterHistoryDDLJobs(txn, fn)
if err != nil {
if terror.ErrorEqual(variable.ErrSnapshotTooOld, err) {
return nil, nil, errors.Errorf("Can't find dropped/truncated table '%s' in GC safe point %s", tableName.Name.O, model.TSConvert2Time(gcSafePoint).String())
}
return nil, nil, err
}
if tableInfo == nil || jobInfo == nil {
return nil, nil, errors.Errorf("Can't find dropped/truncated table: %v in DDL history jobs", tableName.Name)
}
return jobInfo, tableInfo, nil
}
func (e *DDLExec) executeFlashbackTable(s *ast.FlashBackTableStmt) error {
job, tblInfo, err := e.getRecoverTableByTableName(s.Table)
if err != nil {
return err
}
if len(s.NewName) != 0 {
tblInfo.Name = model.NewCIStr(s.NewName)
}
// Check the table ID was not exists.
is := domain.GetDomain(e.ctx).InfoSchema()
tbl, ok := is.TableByID(tblInfo.ID)
if ok {
return infoschema.ErrTableExists.GenWithStack("Table '%-.192s' already been flashback to '%-.192s', can't be flashback repeatedly", s.Table.Name.O, tbl.Meta().Name.O)
}
autoIncID, autoRandID, err := e.getTableAutoIDsFromSnapshot(job)
if err != nil {
return err
}
recoverInfo := &ddl.RecoverInfo{
SchemaID: job.SchemaID,
TableInfo: tblInfo,
DropJobID: job.ID,
SnapshotTS: job.StartTS,
CurAutoIncID: autoIncID,
CurAutoRandID: autoRandID,
}
// Call DDL RecoverTable.
err = domain.GetDomain(e.ctx).DDL().RecoverTable(e.ctx, recoverInfo)
return err
}
func (e *DDLExec) executeLockTables(s *ast.LockTablesStmt) error {
if !config.TableLockEnabled() {
return nil
}
return domain.GetDomain(e.ctx).DDL().LockTables(e.ctx, s)
}
func (e *DDLExec) executeUnlockTables(s *ast.UnlockTablesStmt) error {
if !config.TableLockEnabled() {
return nil
}
lockedTables := e.ctx.GetAllTableLocks()
return domain.GetDomain(e.ctx).DDL().UnlockTables(e.ctx, lockedTables)
}
func (e *DDLExec) executeCleanupTableLock(s *ast.CleanupTableLockStmt) error {
return domain.GetDomain(e.ctx).DDL().CleanupTableLock(e.ctx, s.Tables)
}
func (e *DDLExec) executeRepairTable(s *ast.RepairTableStmt) error {
return domain.GetDomain(e.ctx).DDL().RepairTable(e.ctx, s.Table, s.CreateStmt)
}
func (e *DDLExec) executeCreateSequence(s *ast.CreateSequenceStmt) error {
return domain.GetDomain(e.ctx).DDL().CreateSequence(e.ctx, s)
}