ddl: forbid disabling concurrent DDL if MDL is enabled (#39301)

close #39131
pingcap · Nov 22, 2022 · 75efe68 · 75efe68
1 parent d5e9ef0
commit 75efe68
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Showing 4 changed files with 19 additions and 0 deletions.
diff --git a/ddl/concurrentddltest/BUILD.bazel b/ddl/concurrentddltest/BUILD.bazel
@@ -14,6 +14,7 @@ go_test(
         "//ddl",
         "//kv",
         "//meta",
+        "//sessionctx/variable",
         "//testkit",
         "//testkit/testsetup",
         "//util",

diff --git a/ddl/concurrentddltest/switch_test.go b/ddl/concurrentddltest/switch_test.go
@@ -23,6 +23,7 @@ import (
 
 	"github.com/pingcap/tidb/kv"
 	"github.com/pingcap/tidb/meta"
+	"github.com/pingcap/tidb/sessionctx/variable"
 	"github.com/pingcap/tidb/testkit"
 	"github.com/pingcap/tidb/util"
 	"github.com/stretchr/testify/require"
@@ -134,3 +135,15 @@ func TestConcurrentDDLSwitch(t *testing.T) {
 		}
 	}
 }
+
+func TestConcurrentDDLSwitchWithMDL(t *testing.T) {
+	if !variable.EnableConcurrentDDL.Load() {
+		t.Skip("skip test if concurrent DDL is disabled")
+	}
+	store := testkit.CreateMockStore(t)
+	tk := testkit.NewTestKit(t, store)
+	tk.MustGetErrMsg("set global tidb_enable_concurrent_ddl=off", "can not disable concurrent ddl when metadata lock is enabled")
+	tk.MustExec("set global tidb_enable_metadata_lock=0")
+	tk.MustExec("set global tidb_enable_concurrent_ddl=off")
+	tk.MustExec("create table test.t(a int)")
+}
diff --git a/ddl/ddl.go b/ddl/ddl.go
@@ -1198,6 +1198,10 @@ func (d *ddl) SwitchConcurrentDDL(toConcurrentDDL bool) error {
 		})
 	}
 
+	if variable.EnableMDL.Load() && !toConcurrentDDL {
+		return errors.New("can not disable concurrent ddl when metadata lock is enabled")
+	}
+
 	ctx, cancel := context.WithTimeout(context.Background(), time.Second*30)
 	defer cancel()
 	d.waiting.Store(true)

diff --git a/expression/integration_serial_test.go b/expression/integration_serial_test.go
@@ -3766,6 +3766,7 @@ func TestSetVariables(t *testing.T) {
 	tk.MustExec("set @@global.tidb_enable_concurrent_ddl=1")
 	tk.MustQuery("select @@global.tidb_enable_concurrent_ddl").Check(testkit.Rows("1"))
 	require.True(t, variable.EnableConcurrentDDL.Load())
+	tk.MustExec("set @@global.tidb_enable_metadata_lock=0")
 	tk.MustExec("set @@global.tidb_enable_concurrent_ddl=0")
 	tk.MustQuery("select @@global.tidb_enable_concurrent_ddl").Check(testkit.Rows("0"))
 	require.False(t, variable.EnableConcurrentDDL.Load())