session: display mDDLTableVersion in mysql.tidb table

close pingcap#39778

pkg/session/bootstrap.go

@@ -751,6 +751,8 @@ const (
 	// The variable name in mysql.tidb table and it records the default value of
 	// oom-action when upgrade from v3.0.x to v4.0.11+.
 	tidbDefOOMAction = "default_oom_action"
+	// The variable name in mysql.tidb table and it records the current DDLTableVersion
+	tidbDDLTableVersion = "ddl_table_version"
 	// Const for TiDB server version 2.
 	version2  = 2
 	version3  = 3
@@ -1014,11 +1016,15 @@ const (
 	// version 177
 	//   add `mysql.dist_framework_meta`
 	version177 = 177
+
+	// version 178
+	//   write mDDLTableVersion into `mysql.tidb` table
+	version178 = 178
 )
 
 // currentBootstrapVersion is defined as a variable, so we can modify its value for testing.
 // please make sure this is the largest version
-var currentBootstrapVersion int64 = version177
+var currentBootstrapVersion int64 = version178
 
 // DDL owner key's expired time is ManagerSessionTTL seconds, we should wait the time and give more time to have a chance to finish it.
 var internalSQLTimeout = owner.ManagerSessionTTL + 15
@@ -1171,6 +1177,7 @@ var (
 		upgradeToVer175,
 		upgradeToVer176,
 		upgradeToVer177,
+		upgradeToVer178,
 	}
 )
 
@@ -2846,6 +2853,32 @@ func upgradeToVer177(s Session, ver int64) {
 	}
 }
 
+// writeDDLTableVersion writes mDDLTableVersion into mysql.tidb
+func writeDDLTableVersion(s Session) {
+	var err error
+	var ddlTableVersion meta.DDLTableVersion
+	err = kv.RunInNewTxn(kv.WithInternalSourceType(context.Background(), kv.InternalTxnBootstrap), s.GetStore(), true, func(ctx context.Context, txn kv.Transaction) error {
+		t := meta.NewMeta(txn)
+		ddlTableVersion, err = t.CheckDDLTableVersion()
+		return err
+	})
+	terror.MustNil(err)
+	mustExecute(s, `INSERT HIGH_PRIORITY INTO %n.%n VALUES (%?, %?, "DDL Table Version. Do not delete.") ON DUPLICATE KEY UPDATE VARIABLE_VALUE= %?`,
+		mysql.SystemDB,
+		mysql.TiDBTable,
+		tidbDDLTableVersion,
+		ddlTableVersion,
+		ddlTableVersion,
+	)
+}
+
+func upgradeToVer178(s Session, ver int64) {
+	if ver >= version178 {
+		return
+	}
+	writeDDLTableVersion(s)
+}
+
 func writeOOMAction(s Session) {
 	comment := "oom-action is `log` by default in v3.0.x, `cancel` by default in v4.0.11+"
 	mustExecute(s, `INSERT HIGH_PRIORITY INTO %n.%n VALUES (%?, %?, %?) ON DUPLICATE KEY UPDATE VARIABLE_VALUE= %?`,
@@ -3102,6 +3135,8 @@ func doDMLWorks(s Session) {
 
 	writeStmtSummaryVars(s)
 
+	writeDDLTableVersion(s)
+
 	ctx := kv.WithInternalSourceType(context.Background(), kv.InternalTxnBootstrap)
 	_, err := s.ExecuteInternal(ctx, "COMMIT")
 	if err != nil {

pkg/session/bootstrap_test.go

@@ -2118,3 +2118,71 @@ func TestTiDBUpgradeToVer177(t *testing.T) {
 	MustExec(t, seV176, "SELECT * from mysql.dist_framework_meta")
 	dom.Close()
 }
+
+func TestWriteDDLTableVersionToMySQLTiDB(t *testing.T) {
+	ctx := context.Background()
+	store, dom := CreateStoreAndBootstrap(t)
+	defer func() { require.NoError(t, store.Close()) }()
+
+	txn, err := store.Begin()
+	require.NoError(t, err)
+	m := meta.NewMeta(txn)
+	ddlTableVer, err := m.CheckDDLTableVersion()
+	require.NoError(t, err)
+
+	// Verify that 'ddl_table_version' has been set to the correct value
+	se := CreateSessionAndSetID(t, store)
+	r := MustExecToRecodeSet(t, se, fmt.Sprintf(`SELECT VARIABLE_VALUE from mysql.TiDB where VARIABLE_NAME='%s'`, tidbDDLTableVersion))
+	req := r.NewChunk(nil)
+	err = r.Next(ctx, req)
+	require.NoError(t, err)
+	require.Equal(t, 1, req.NumRows())
+	require.Equal(t, []byte(fmt.Sprintf("%d", ddlTableVer)), req.GetRow(0).GetBytes(0))
+	require.NoError(t, r.Close())
+	dom.Close()
+}
+
+func TestWriteDDLTableVersionToMySQLTiDBWhenUpgradingTo178(t *testing.T) {
+	ctx := context.Background()
+	store, _ := CreateStoreAndBootstrap(t)
+	defer func() { require.NoError(t, store.Close()) }()
+
+	txn, err := store.Begin()
+	require.NoError(t, err)
+	m := meta.NewMeta(txn)
+	ddlTableVer, err := m.CheckDDLTableVersion()
+	require.NoError(t, err)
+
+	// bootstrap as version177
+	ver177 := version177
+	seV177 := CreateSessionAndSetID(t, store)
+	err = m.FinishBootstrap(int64(ver177))
+	require.NoError(t, err)
+	MustExec(t, seV177, fmt.Sprintf("update mysql.tidb set variable_value=%d where variable_name='tidb_server_version'", ver177))
+	// remove the ddl_table_version entry from mysql.tidb table
+	MustExec(t, seV177, fmt.Sprintf("delete from mysql.tidb where VARIABLE_NAME='%s'", tidbDDLTableVersion))
+	err = txn.Commit(ctx)
+	require.NoError(t, err)
+	unsetStoreBootstrapped(store.UUID())
+	ver, err := getBootstrapVersion(seV177)
+	require.NoError(t, err)
+	require.Equal(t, int64(ver177), ver)
+
+	// upgrade to current version
+	domCurVer, err := BootstrapSession(store)
+	require.NoError(t, err)
+	defer domCurVer.Close()
+	seCurVer := CreateSessionAndSetID(t, store)
+	ver, err = getBootstrapVersion(seCurVer)
+	require.NoError(t, err)
+	require.Equal(t, currentBootstrapVersion, ver)
+
+	// check if the DDLTableVersion has been set in the `mysql.tidb` table during upgrade
+	r := MustExecToRecodeSet(t, seCurVer, fmt.Sprintf(`SELECT VARIABLE_VALUE from mysql.TiDB where VARIABLE_NAME='%s'`, tidbDDLTableVersion))
+	req := r.NewChunk(nil)
+	err = r.Next(ctx, req)
+	require.NoError(t, err)
+	require.Equal(t, 1, req.NumRows())
+	require.Equal(t, []byte(fmt.Sprintf("%d", ddlTableVer)), req.GetRow(0).GetBytes(0))
+	require.NoError(t, r.Close())
+}