meta,executor: support show auto id

executor/show.go

@@ -412,6 +412,7 @@ func (e *ShowExec) fetchShowCreateTable() error {
 	var buf bytes.Buffer
 	buf.WriteString(fmt.Sprintf("CREATE TABLE `%s` (\n", tb.Meta().Name.O))
 	var pkCol *table.Column
+	var hasAutoIncID bool
 	for i, col := range tb.Cols() {
 		buf.WriteString(fmt.Sprintf("  `%s` %s", col.Name.O, col.GetTypeDesc()))
 		if col.IsGenerated() {
@@ -424,6 +425,7 @@ func (e *ShowExec) fetchShowCreateTable() error {
 			}
 		}
 		if mysql.HasAutoIncrementFlag(col.Flag) {
+			hasAutoIncID = true
 			buf.WriteString(" NOT NULL AUTO_INCREMENT")
 		} else {
 			if mysql.HasNotNullFlag(col.Flag) {
@@ -544,8 +546,15 @@ func (e *ShowExec) fetchShowCreateTable() error {
 	// to make it work on MySQL server which has default collate utf8_general_ci.
 	buf.WriteString(fmt.Sprintf(" DEFAULT CHARSET=%s COLLATE=%s", charsetName, collate))
 
-	if tb.Meta().AutoIncID > 0 {
-		buf.WriteString(fmt.Sprintf(" AUTO_INCREMENT=%d", tb.Meta().AutoIncID))
+	if hasAutoIncID {
+		autoIncID, err := tb.Allocator().NextGlobalAutoID(tb.Meta().ID)
+		if err != nil {
+			return errors.Trace(err)
+		}
+		// It's campatible with MySQL.
+		if autoIncID > 1 {
+			buf.WriteString(fmt.Sprintf(" AUTO_INCREMENT=%d", autoIncID))
+		}
 	}
 
 	if len(tb.Meta().Comment) > 0 {

executor/show_test.go

@@ -14,10 +14,12 @@
 package executor_test
 
 import (
+	"strconv"
 	"strings"
 
 	. "github.com/pingcap/check"
 	"github.com/pingcap/tidb"
+	"github.com/pingcap/tidb/meta/autoid"
 	"github.com/pingcap/tidb/mysql"
 	"github.com/pingcap/tidb/plan"
 	"github.com/pingcap/tidb/privilege/privileges"
@@ -164,13 +166,43 @@ func (s *testSuite) TestShow(c *C) {
 	// Test show create table with AUTO_INCREMENT option
 	// for issue https://github.com/pingcap/tidb/issues/3747
 	tk.MustExec(`drop table if exists show_auto_increment`)
-	tk.MustExec(`create table show_auto_increment (id int) auto_increment=4`)
+	tk.MustExec(`create table show_auto_increment (id int key auto_increment) auto_increment=4`)
 	tk.MustQuery(`show create table show_auto_increment`).Check(testutil.RowsWithSep("|",
 		""+
 			"show_auto_increment CREATE TABLE `show_auto_increment` (\n"+
-			"  `id` int(11) DEFAULT NULL\n"+
+			"  `id` int(11) NOT NULL AUTO_INCREMENT,\n"+
+			"  PRIMARY KEY (`id`)\n"+
 			") ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_bin AUTO_INCREMENT=4",
 	))
+	// for issue https://github.com/pingcap/tidb/issues/4678
+	autoIDStep := autoid.GetStep()
+	tk.MustExec("insert into show_auto_increment values(20)")
+	autoID := autoIDStep + 21
+	tk.MustQuery(`show create table show_auto_increment`).Check(testutil.RowsWithSep("|",
+		""+
+			"show_auto_increment CREATE TABLE `show_auto_increment` (\n"+
+			"  `id` int(11) NOT NULL AUTO_INCREMENT,\n"+
+			"  PRIMARY KEY (`id`)\n"+
+			") ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_bin AUTO_INCREMENT="+strconv.Itoa(int(autoID)),
+	))
+	tk.MustExec(`drop table show_auto_increment`)
+	tk.MustExec(`create table show_auto_increment (id int primary key auto_increment)`)
+	tk.MustQuery(`show create table show_auto_increment`).Check(testutil.RowsWithSep("|",
+		""+
+			"show_auto_increment CREATE TABLE `show_auto_increment` (\n"+
+			"  `id` int(11) NOT NULL AUTO_INCREMENT,\n"+
+			"  PRIMARY KEY (`id`)\n"+
+			") ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_bin",
+	))
+	tk.MustExec("insert into show_auto_increment values(10)")
+	autoID = autoIDStep + 11
+	tk.MustQuery(`show create table show_auto_increment`).Check(testutil.RowsWithSep("|",
+		""+
+			"show_auto_increment CREATE TABLE `show_auto_increment` (\n"+
+			"  `id` int(11) NOT NULL AUTO_INCREMENT,\n"+
+			"  PRIMARY KEY (`id`)\n"+
+			") ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_bin AUTO_INCREMENT="+strconv.Itoa(int(autoID)),
+	))
 
 	// Test show table with column's comment contain escape character
 	// for issue https://github.com/pingcap/tidb/issues/4411

meta/autoid/autoid.go

@@ -41,6 +41,8 @@ type Allocator interface {
 	// If allocIDs is true, it will allocate some IDs and save to the cache.
 	// If allocIDs is false, it will not allocate IDs.
 	Rebase(tableID, newBase int64, allocIDs bool) error
+	// NextGlobalAutoID returns the next global autoID.
+	NextGlobalAutoID(tableID int64) (int64, error)
 }
 
 type allocator struct {
@@ -56,6 +58,18 @@ func GetStep() int64 {
 	return step
 }
 
+// NextGlobalAutoID implements autoid.Allocator NextGlobalAutoID interface.
+func (alloc *allocator) NextGlobalAutoID(tableID int64) (int64, error) {
+	var autoID int64
+	err := kv.RunInNewTxn(alloc.store, true, func(txn kv.Transaction) error {
+		var err1 error
+		m := meta.NewMeta(txn)
+		autoID, err1 = m.GetAutoTableID(alloc.dbID, tableID)
+		return errors.Trace(err1)
+	})
+	return autoID + 1, errors.Trace(err)
+}
+
 // Rebase implements autoid.Allocator Rebase interface.
 // The requiredBase is the minimum base value after Rebase.
 // The real base may be greater than the required base.
@@ -154,6 +168,13 @@ type memoryAllocator struct {
 	dbID int64
 }
 
+// NextGlobalAutoID implements autoid.Allocator NextGlobalAutoID interface.
+func (alloc *memoryAllocator) NextGlobalAutoID(tableID int64) (int64, error) {
+	memIDLock.Lock()
+	defer memIDLock.Unlock()
+	return memID + 1, nil
+}
+
 // Rebase implements autoid.Allocator Rebase interface.
 func (alloc *memoryAllocator) Rebase(tableID, newBase int64, allocIDs bool) error {
 	// TODO: implement it.

meta/autoid/autoid_test.go

@@ -61,6 +61,9 @@ func (*testSuite) TestT(c *C) {
 	alloc := NewAllocator(store, 1)
 	c.Assert(alloc, NotNil)
 
+	globalAutoID, err := alloc.NextGlobalAutoID(1)
+	c.Assert(err, IsNil)
+	c.Assert(globalAutoID, Equals, int64(1))
 	id, err := alloc.Alloc(1)
 	c.Assert(err, IsNil)
 	c.Assert(id, Equals, int64(1))
@@ -69,6 +72,9 @@ func (*testSuite) TestT(c *C) {
 	c.Assert(id, Equals, int64(2))
 	id, err = alloc.Alloc(0)
 	c.Assert(err, NotNil)
+	globalAutoID, err = alloc.NextGlobalAutoID(1)
+	c.Assert(err, IsNil)
+	c.Assert(globalAutoID, Equals, int64(step+1))
 
 	// rebase
 	err = alloc.Rebase(1, int64(1), true)