[release-22.0] vtorc: detect errant GTIDs for replicas not connected to primary (#19224) (#19233)

Co-authored-by: vitess-bot[bot] <108069721+vitess-bot[bot]@users.noreply.github.com>

Author: vitess-bot[bot]

go/vt/vtorc/inst/instance_dao.go

@@ -405,27 +405,37 @@ Cleanup:
 func detectErrantGTIDs(instance *Instance, tablet *topodatapb.Tablet) (err error) {
 	// If the tablet is not replicating from anyone, then it could be the previous primary.
 	// We should check for errant GTIDs by finding the difference with the shard's current primary.
-	if instance.primaryExecutedGtidSet == "" && instance.SourceHost == "" {
-		var primaryInstance *Instance
-		primaryAlias, _, _ := ReadShardPrimaryInformation(tablet.Keyspace, tablet.Shard)
-		if primaryAlias != "" {
-			// Check if the current tablet is the primary.
-			// If it is, then we don't need to run errant gtid detection on it.
-			if primaryAlias == instance.InstanceAlias {
-				return nil
-			}
-			primaryInstance, _, _ = ReadInstance(primaryAlias)
+	primaryAlias, _, err := ReadShardPrimaryInformation(tablet.Keyspace, tablet.Shard)
+	if err != nil {
+		return fmt.Errorf("failed to read shard primary for %s/%s: %w", tablet.Keyspace, tablet.Shard, err)
+	}
+
+	// Check if the current tablet is the primary. If it is, then we don't need to
+	// run errant GTID detection on it.
+	if primaryAlias == instance.InstanceAlias {
+		return nil
+	}
+
+	var primaryInstance *Instance
+	if primaryAlias != "" {
+		primaryInstance, _, err = ReadInstance(primaryAlias)
+		if err != nil {
+			return fmt.Errorf("failed to read primary instance %q: %w", primaryAlias, err)
 		}
-		// Only run errant GTID detection, if we are sure that the data read of the current primary
-		// is up-to-date enough to reflect that it has been promoted. This is needed to prevent
-		// flagging incorrect errant GTIDs. If we were to use old data, we could have some GTIDs
-		// accepted by the old primary (this tablet) that don't show in the new primary's set.
-		if primaryInstance != nil {
-			if primaryInstance.SourceHost == "" {
-				instance.primaryExecutedGtidSet = primaryInstance.ExecutedGtidSet
-			}
+	}
+
+	// Only run errant GTID detection if we are sure that the data read of the current primary
+	// is up-to-date enough to reflect that it has been promoted. This is needed to prevent
+	// flagging incorrect errant GTIDs. If we were to use old data, we could have some GTIDs
+	// accepted by the old primary (this tablet) that don't show in the new primary's set.
+	if primaryInstance != nil && primaryInstance.SourceHost == "" {
+		// If the instance has no replication source and no primary GTID set yet, or if the instance's replication
+		// source is not the primary, use the shard primary's executed GTID set for comparison.
+		if (instance.SourceHost == "" && instance.primaryExecutedGtidSet == "") || !sourceIsPrimary(instance, primaryInstance) {
+			instance.primaryExecutedGtidSet = primaryInstance.ExecutedGtidSet
 		}
 	}
+
 	if instance.ExecutedGtidSet != "" && instance.primaryExecutedGtidSet != "" {
 		// Compare primary & replica GTID sets, but ignore the sets that present the primary's UUID.
 		// This is because vtorc may pool primary and replica at an inconvenient timing,
@@ -458,6 +468,19 @@ func detectErrantGTIDs(instance *Instance, tablet *topodatapb.Tablet) (err error
 	return err
 }
 
+// sourceIsPrimary returns true if the instance's replication source is the given primary.
+func sourceIsPrimary(instance *Instance, primaryInstance *Instance) bool {
+	if instance.SourceHost == "" {
+		return false
+	}
+
+	if instance.SourceUUID != "" && primaryInstance.ServerUUID != "" {
+		return instance.SourceUUID == primaryInstance.ServerUUID
+	}
+
+	return instance.SourceHost == primaryInstance.Hostname && instance.SourcePort == primaryInstance.Port
+}
+
 // getKeyspaceShardName returns a single string having both the keyspace and shard
 func getKeyspaceShardName(keyspace, shard string) string {
 	return fmt.Sprintf("%v:%v", keyspace, shard)

go/vt/vtorc/inst/instance_dao_test.go

@@ -898,6 +898,29 @@ func TestExpireTableData(t *testing.T) {
 }
 
 func TestDetectErrantGTIDs(t *testing.T) {
+	keyspaceName := "ks"
+	shardName := "0"
+	tablet := &topodatapb.Tablet{
+		Alias: &topodatapb.TabletAlias{
+			Cell: "zone-1",
+			Uid:  100,
+		},
+		Keyspace: keyspaceName,
+		Shard:    shardName,
+	}
+	primaryTablet := &topodatapb.Tablet{
+		Alias: &topodatapb.TabletAlias{
+			Cell: "zone-1",
+			Uid:  101,
+		},
+		Keyspace: keyspaceName,
+		Shard:    shardName,
+		Type:     topodatapb.TabletType_PRIMARY,
+
+		MysqlHostname: "primary-host",
+		MysqlPort:     6714,
+	}
+
 	tests := []struct {
 		name            string
 		instance        *Instance
@@ -947,6 +970,8 @@ func TestDetectErrantGTIDs(t *testing.T) {
 			primaryInstance: &Instance{
 				SourceHost:      "",
 				ExecutedGtidSet: "230ea8ea-81e3-11e4-972a-e25ec4bd140a:1-10589,8bc65c84-3fe4-11ed-a912-257f0fcdd6c9:1-34,316d193c-70e5-11e5-adb2-ecf4bb2262ff:1-341",
+				Hostname:        primaryTablet.MysqlHostname,
+				Port:            int(primaryTablet.MysqlPort),
 			},
 			wantErrantGTID: "316d193c-70e5-11e5-adb2-ecf4bb2262ff:342",
 		}, {
@@ -963,24 +988,6 @@ func TestDetectErrantGTIDs(t *testing.T) {
 		},
 	}
 
-	keyspaceName := "ks"
-	shardName := "0"
-	tablet := &topodatapb.Tablet{
-		Alias: &topodatapb.TabletAlias{
-			Cell: "zone-1",
-			Uid:  100,
-		},
-		Keyspace: keyspaceName,
-		Shard:    shardName,
-	}
-	primaryTablet := &topodatapb.Tablet{
-		Alias: &topodatapb.TabletAlias{
-			Cell: "zone-1",
-			Uid:  101,
-		},
-		Keyspace: keyspaceName,
-		Shard:    shardName,
-	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			// Clear the database after the test. The easiest way to do that is to run all the initialization commands again.
@@ -997,6 +1004,7 @@ func TestDetectErrantGTIDs(t *testing.T) {
 
 			if tt.primaryInstance != nil {
 				tt.primaryInstance.InstanceAlias = topoproto.TabletAliasString(primaryTablet.Alias)
+
 				err = SaveTablet(primaryTablet)
 				require.NoError(t, err)
 				err = WriteInstance(tt.primaryInstance, true, nil)
@@ -1015,6 +1023,109 @@ func TestDetectErrantGTIDs(t *testing.T) {
 	}
 }
 
+// TestDetectErrantGTIDsWithWrongPrimarySource ensures that errant GTIDs are
+// detected by comparing against the shard primary when a replica is pointed at
+// a different source.
+func TestDetectErrantGTIDsWithWrongPrimarySource(t *testing.T) {
+	defer func() {
+		db.ClearVTOrcDatabase()
+	}()
+	db.ClearVTOrcDatabase()
+
+	keyspaceName := "ks"
+	shardName := "0"
+
+	primaryUUID := "a5ce8e8a-4e56-11ef-9f7d-92339a7d9f6c"
+	wrongPrimaryUUID := "bb1db5f6-4e56-11ef-8bda-3ae65c7f7f5e"
+	replicaUUID := "cc946b58-4e56-11ef-9e6f-3e527c1a9e9d"
+
+	primaryTablet := &topodatapb.Tablet{
+		Alias: &topodatapb.TabletAlias{
+			Cell: "zone-1",
+			Uid:  101,
+		},
+		Keyspace: keyspaceName,
+		Shard:    shardName,
+		Type:     topodatapb.TabletType_PRIMARY,
+
+		MysqlHostname: "primary-host",
+		MysqlPort:     6714,
+	}
+
+	replicaTablet := &topodatapb.Tablet{
+		Alias: &topodatapb.TabletAlias{
+			Cell: "zone-1",
+			Uid:  100,
+		},
+		Keyspace: keyspaceName,
+		Shard:    shardName,
+	}
+
+	err := SaveShard(topo.NewShardInfo(keyspaceName, shardName, &topodatapb.Shard{
+		PrimaryAlias: primaryTablet.Alias,
+	}, nil))
+	require.NoError(t, err)
+
+	err = SaveTablet(primaryTablet)
+	require.NoError(t, err)
+
+	// Create the real shard primary instance and give it a GTID set that does
+	// not include the replica UUID. This represents the authoritative primary.
+	primaryInstance := &Instance{
+		InstanceAlias:   topoproto.TabletAliasString(primaryTablet.Alias),
+		Hostname:        "primary-host",
+		Port:            6714,
+		SourceHost:      "",
+		ExecutedGtidSet: primaryUUID + ":1-10",
+		ServerUUID:      primaryUUID,
+	}
+
+	err = WriteInstance(primaryInstance, true, nil)
+	require.NoError(t, err)
+
+	// Create a wrong primary instance that contains the replica UUID in its
+	// executed GTID set. This masks errant GTIDs if the replica uses it for
+	// comparison
+	wrongPrimaryInstance := &Instance{
+		InstanceAlias:   "zone-1-0000000102",
+		Hostname:        "wrong-primary",
+		Port:            6720,
+		SourceHost:      "",
+		ExecutedGtidSet: fmt.Sprintf("%s:1-10,%s:1-5", wrongPrimaryUUID, replicaUUID),
+		ServerUUID:      wrongPrimaryUUID,
+		AncestryUUID:    wrongPrimaryUUID,
+	}
+
+	err = WriteInstance(wrongPrimaryInstance, true, nil)
+	require.NoError(t, err)
+
+	// Create a replica instance that is pointed at the wrong primary. The replica
+	// contains errant GTIDs that should be caught.
+	replicaInstance := &Instance{
+		InstanceAlias:   topoproto.TabletAliasString(replicaTablet.Alias),
+		Hostname:        "replica-host",
+		Port:            6711,
+		SourceHost:      wrongPrimaryInstance.Hostname,
+		SourcePort:      wrongPrimaryInstance.Port,
+		SourceUUID:      wrongPrimaryInstance.ServerUUID,
+		ExecutedGtidSet: fmt.Sprintf("%s:1-10,%s:1-5", wrongPrimaryUUID, replicaUUID),
+		ServerUUID:      replicaUUID,
+	}
+
+	err = ReadInstanceClusterAttributes(replicaInstance)
+	require.NoError(t, err)
+	require.Equal(t, wrongPrimaryInstance.ExecutedGtidSet, replicaInstance.primaryExecutedGtidSet)
+	require.Equal(t, wrongPrimaryInstance.AncestryUUID, replicaInstance.AncestryUUID)
+
+	// Run errant GTID detection. We should find some.
+	err = detectErrantGTIDs(replicaInstance, replicaTablet)
+	require.NoError(t, err)
+
+	// The replica's own UUID entries should be reported as errant because the
+	// real shard primary does not include them.
+	require.Equal(t, replicaUUID+":1-5", replicaInstance.GtidErrant)
+}
+
 // TestPrimaryErrantGTIDs tests that we don't run Errant GTID detection on the primary tablet itself!
 func TestPrimaryErrantGTIDs(t *testing.T) {
 	// Clear the database after the test. The easiest way to do that is to run all the initialization commands again.