ddl: allow altering auto_increment to a large number (#19241)

* ddl: allow altering auto_increment to a large number

* fix the edge case problem of auto_inc option

* revert last commit

Co-authored-by: Arenatlx <ailinsilence4@gmail.com>
Co-authored-by: ti-srebot <66930949+ti-srebot@users.noreply.github.com>

ddl/db_integration_test.go

@@ -2401,16 +2401,26 @@ func (s *testIntegrationSuite5) TestDropColumnsWithMultiIndex(c *C) {
 	tk.MustQuery(query).Check(testkit.Rows())
 }
 
-func (s *testIntegrationSuite7) TestAutoIncrementAllocator(c *C) {
+func (s *testIntegrationSuite7) TestAutoIncrementTableOption(c *C) {
 	tk := testkit.NewTestKit(c, s.store)
 	defer config.RestoreFunc()()
 	config.UpdateGlobal(func(conf *config.Config) {
+		// Make sure the integer primary key is the handle(PkIsHandle).
 		conf.AlterPrimaryKey = false
 	})
-	tk.MustExec("drop database if exists test_create_table_option_auto_inc;")
-	tk.MustExec("create database test_create_table_option_auto_inc;")
-	tk.MustExec("use test_create_table_option_auto_inc;")
+	tk.MustExec("drop database if exists test_auto_inc_table_opt;")
+	tk.MustExec("create database test_auto_inc_table_opt;")
+	tk.MustExec("use test_auto_inc_table_opt;")
 
+	// Empty auto_inc allocator should not cause error.
 	tk.MustExec("create table t (a bigint primary key) auto_increment = 10;")
 	tk.MustExec("alter table t auto_increment = 10;")
+	tk.MustExec("alter table t auto_increment = 12345678901234567890;")
+
+	// Rebase the auto_inc allocator to a large integer should work.
+	tk.MustExec("drop table t;")
+	tk.MustExec("create table t (a bigint unsigned auto_increment, unique key idx(a));")
+	tk.MustExec("alter table t auto_increment = 12345678901234567890;")
+	tk.MustExec("insert into t values ();")
+	tk.MustQuery("select * from t;").Check(testkit.Rows("12345678901234567890"))
 }

ddl/ddl_api.go

@@ -2392,7 +2392,7 @@ func (d *ddl) RebaseAutoID(ctx sessionctx.Context, ident ast.Ident, newBase int6
 		// If the user sends SQL `alter table t1 auto_increment = 100` to TiDB-B,
 		// and TiDB-B finds 100 < 30001 but returns without any handling,
 		// then TiDB-A may still allocate 99 for auto_increment column. This doesn't make sense for the user.
-		newBase = mathutil.MaxInt64(newBase, autoID)
+		newBase = int64(mathutil.MaxUint64(uint64(newBase), uint64(autoID)))
 	}
 	job := &model.Job{
 		SchemaID:   schema.ID,