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ddl.go
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ddl.go
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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 (
"fmt"
"strings"
"github.com/pingcap/tidb/ast"
"github.com/pingcap/tidb/config"
"github.com/pingcap/tidb/domain"
"github.com/pingcap/tidb/infoschema"
"github.com/pingcap/tidb/model"
"github.com/pingcap/tidb/mysql"
"github.com/pingcap/tidb/sessionctx/variable"
"github.com/pingcap/tidb/types"
"github.com/pingcap/tidb/util/chunk"
"github.com/pingcap/tidb/util/sqlexec"
"github.com/pkg/errors"
log "github.com/sirupsen/logrus"
"golang.org/x/net/context"
)
// 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// toErr converts the error to the ErrInfoSchemaChanged when the schema is outdated.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 {
if e.ctx.GetSessionVars().StmtCtx.IsDDLJobInQueue {
return errors.Trace(err)
}
// Before the DDL job is ready, it encouters an error that may be due to the outdated schema information.
// After the DDL job is ready, the ErrInfoSchemaChanged error won't happen because we are getting the schema directly from storage.
// So we needn't to consider this condition.
// Here we distinguish the ErrInfoSchemaChanged error from other errors.
dom := domain.GetDomain(e.ctx)
checker := domain.NewSchemaChecker(dom, e.is.SchemaMetaVersion(), nil)
schemaInfoErr := checker.Check(e.ctx.Txn().StartTS())
if schemaInfoErr != nil {
return errors.Trace(schemaInfoErr)
}
return errors.Trace(err)
}
// Next implements the Executor Next interface.
func (e *DDLExec) Next(ctx context.Context, chk *chunk.Chunk) (err error) {
if e.done {
return nil
}
e.done = true
defer func() { e.ctx.GetSessionVars().StmtCtx.IsDDLJobInQueue = false }()
switch x := e.stmt.(type) {
case *ast.TruncateTableStmt:
err = e.executeTruncateTable(x)
case *ast.CreateDatabaseStmt:
err = e.executeCreateDatabase(x)
case *ast.CreateTableStmt:
err = e.executeCreateTable(x)
case *ast.CreateIndexStmt:
err = e.executeCreateIndex(x)
case *ast.DropDatabaseStmt:
err = e.executeDropDatabase(x)
case *ast.DropTableStmt:
err = e.executeDropTable(x)
case *ast.DropIndexStmt:
err = e.executeDropIndex(x)
case *ast.AlterTableStmt:
err = e.executeAlterTable(x)
case *ast.RenameTableStmt:
err = e.executeRenameTable(x)
}
if err != nil {
return errors.Trace(e.toErr(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 errors.Trace(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}
err := domain.GetDomain(e.ctx).DDL().RenameTable(e.ctx, oldIdent, newIdent)
return errors.Trace(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 errors.Trace(err)
}
func (e *DDLExec) executeCreateTable(s *ast.CreateTableStmt) error {
err := domain.GetDomain(e.ctx).DDL().CreateTable(e.ctx, s)
return errors.Trace(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.Unique, model.NewCIStr(s.IndexName), s.IndexColNames, s.IndexOption)
return errors.Trace(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("utf8"))
if err != nil {
return errors.Trace(err)
}
err = variable.SetSessionSystemVar(sessionVars, variable.CollationDatabase, types.NewStringDatum("utf8_unicode_ci"))
if err != nil {
return errors.Trace(err)
}
}
return errors.Trace(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
}
func (e *DDLExec) executeDropTable(s *ast.DropTableStmt) error {
var notExistTables []string
for _, tn := range s.Tables {
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 errors.Trace(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 config.CheckTableBeforeDrop {
log.Warnf("admin check table `%s`.`%s` before drop.", fullti.Schema.O, fullti.Name.O)
sql := fmt.Sprintf("admin check table `%s`.`%s`", fullti.Schema.O, fullti.Name.O)
_, _, err = e.ctx.(sqlexec.RestrictedSQLExecutor).ExecRestrictedSQL(e.ctx, sql)
if err != nil {
return errors.Trace(err)
}
}
err = domain.GetDomain(e.ctx).DDL().DropTable(e.ctx, fullti)
if infoschema.ErrDatabaseNotExists.Equal(err) || infoschema.ErrTableNotExists.Equal(err) {
notExistTables = append(notExistTables, fullti.String())
} else if err != nil {
return errors.Trace(err)
}
}
if len(notExistTables) > 0 && !s.IfExists {
return infoschema.ErrTableDropExists.GenWithStackByArgs(strings.Join(notExistTables, ","))
}
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))
if (infoschema.ErrDatabaseNotExists.Equal(err) || infoschema.ErrTableNotExists.Equal(err)) && s.IfExists {
err = nil
}
return errors.Trace(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 errors.Trace(err)
}