ddl: Add warning for resetting specified AUTO_INCREMENT value (#32078)

ref #32043
pingcap · Mar 31, 2022 · a262981 · a262981
1 parent 0f47064
commit a262981
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diff --git a/ddl/db_integration_test.go b/ddl/db_integration_test.go
@@ -2793,6 +2793,23 @@ func TestAutoIncrementForce(t *testing.T) {
 	tk.MustQuery("select * from t;").Check(testkit.Rows("101", "112", "500"))
 	tk.MustQuery("select * from t order by a;").Check(testkit.Rows("101", "112", "500"))
 	tk.MustExec("drop table if exists t;")
+
+	// Check for warning in case we can't set the auto_increment to the desired value
+	tk.MustExec("create table t(a int primary key auto_increment)")
+	tk.MustExec("insert into t values (200)")
+	tk.MustQuery("show create table t").Check(testkit.Rows(
+		"t CREATE TABLE `t` (\n" +
+			"  `a` int(11) NOT NULL AUTO_INCREMENT,\n" +
+			"  PRIMARY KEY (`a`) /*T![clustered_index] CLUSTERED */\n" +
+			") ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin AUTO_INCREMENT=5201"))
+	tk.MustExec("alter table t auto_increment=100;")
+	tk.MustQuery("show warnings").Check(testkit.Rows("Warning 1105 Can't reset AUTO_INCREMENT to 100 without FORCE option, using 5201 instead"))
+	tk.MustQuery("show create table t").Check(testkit.Rows(
+		"t CREATE TABLE `t` (\n" +
+			"  `a` int(11) NOT NULL AUTO_INCREMENT,\n" +
+			"  PRIMARY KEY (`a`) /*T![clustered_index] CLUSTERED */\n" +
+			") ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin AUTO_INCREMENT=5201"))
+	tk.MustExec("drop table t")
 }
 
 func TestIssue20490(t *testing.T) {

diff --git a/ddl/ddl_api.go b/ddl/ddl_api.go
@@ -3247,10 +3247,17 @@ func (d *ddl) RebaseAutoID(ctx sessionctx.Context, ident ast.Ident, newBase int6
 	}
 
 	if !force {
-		newBase, err = adjustNewBaseToNextGlobalID(ctx, t, tp, newBase)
+		newBaseTemp, err := adjustNewBaseToNextGlobalID(ctx, t, tp, newBase)
 		if err != nil {
 			return err
 		}
+		if newBase != newBaseTemp {
+			ctx.GetSessionVars().StmtCtx.AppendWarning(
+				fmt.Errorf("Can't reset AUTO_INCREMENT to %d without FORCE option, using %d instead",
+					newBase, newBaseTemp,
+				))
+		}
+		newBase = newBaseTemp
 	}
 	job := &model.Job{
 		SchemaID:   schema.ID,