Add missing tables to globally routed list in schema tracker only if …

…they are not already present in a VSchema

Signed-off-by: Rohit Nayak <rohit@planetscale.com>

go/test/endtoend/vtgate/gen4/gen4_test.go

@@ -520,3 +520,40 @@ func TestDualJoinQueries(t *testing.T) {
 	mcmp.Exec("select t.title, t2.id from t2 left join (select 'ABC' as title) as t on t.title = t2.tcol1")
 
 }
+
+// TestSchemaTrackingGlobalTables tests that schema tracking works as intended with global table routing.
+// This test creates a new table in a schema and verifies we can query it without needing to add it to the vschema as long
+// as the name of the table is unique. It also creates a table which is already in the vschema to ensure that we
+// don't mark it as ambiguous when schema tracking also finds it.
+func TestSchemaTrackingGlobalTables(t *testing.T) {
+	// Create a new vtgate connection.
+	tables := []string{"uniqueTableName", "t1"}
+	for _, table := range tables {
+		t.Run(table, func(t *testing.T) {
+			vtConn, err := mysql.Connect(context.Background(), &vtParams)
+			require.NoError(t, err)
+			defer vtConn.Close()
+
+			// Create a new table in the unsharded keyspace such that it has a unique name that allows for global routing.
+			utils.Exec(t, vtConn, `use `+unshardedKs)
+			// Use the same schema as t1 from sharded_schema.sql
+			utils.Exec(t, vtConn, fmt.Sprintf(`create table if not exists %s(id bigint, col bigint, primary key(id))`, table))
+			defer utils.Exec(t, vtConn, fmt.Sprintf(`drop table %s`, table))
+
+			// Wait for schema tracking to see this column.
+			err = utils.WaitForAuthoritative(t, unshardedKs, table, clusterInstance.VtgateProcess.ReadVSchema)
+			require.NoError(t, err)
+
+			// Create a new vtgate connection.
+			vtConn2, err := mysql.Connect(context.Background(), &vtParams)
+			require.NoError(t, err)
+			defer vtConn2.Close()
+
+			// Insert rows into the table and select them to verify we can use them.
+			utils.Exec(t, vtConn2, fmt.Sprintf(`insert into %s(id, col) values (10, 100),(20, 200)`, table))
+			require.NoError(t, err)
+			utils.AssertMatches(t, vtConn2, fmt.Sprintf(`select * from %s order by id`, table),
+				`[[INT64(10) INT64(100)] [INT64(20) INT64(200)]]`)
+		})
+	}
+}

go/vt/vtgate/vindexes/vschema.go

@@ -356,7 +356,7 @@ func BuildVSchema(source *vschemapb.SrvVSchema, parser *sqlparser.Parser) (vsche
 	buildKeyspaces(source, vschema, parser)
 	// buildGlobalTables before buildReferences so that buildReferences can
 	// resolve sources which reference global tables.
-	buildGlobalTables(source, vschema)
+	BuildGlobalTables(source, vschema, true)
 	buildReferences(source, vschema)
 	buildRoutingRule(source, vschema, parser)
 	buildShardRoutingRule(source, vschema)
@@ -461,23 +461,27 @@ func (vschema *VSchema) AddUDF(ksname, udfName string) error {
 	return nil
 }
 
-func buildGlobalTables(source *vschemapb.SrvVSchema, vschema *VSchema) {
+func BuildGlobalTables(source *vschemapb.SrvVSchema, vschema *VSchema, skipIfAlreadyGlobal bool) {
 	for ksname, ks := range source.Keyspaces {
 		ksvschema := vschema.Keyspaces[ksname]
 		// If the keyspace requires explicit routing, don't include any of
 		// its tables in global tables.
 		if ks.RequireExplicitRouting {
 			continue
 		}
-		buildKeyspaceGlobalTables(vschema, ksvschema)
+		buildKeyspaceGlobalTables(vschema, ksvschema, skipIfAlreadyGlobal)
 	}
 }
 
-func buildKeyspaceGlobalTables(vschema *VSchema, ksvschema *KeyspaceSchema) {
+func buildKeyspaceGlobalTables(vschema *VSchema, ksvschema *KeyspaceSchema, skipIfAlreadyGlobal bool) {
 	for tname, t := range ksvschema.Tables {
 		if gt, ok := vschema.globalTables[tname]; ok {
 			// There is already an entry table stored in global tables
 			// with this name.
+			if !skipIfAlreadyGlobal {
+				// Called when updating from schema tracking
+				continue
+			}
 			if gt == nil {
 				// Table name is already marked ambiguous, nothing to do.
 				continue

go/vt/vtgate/vschema_manager.go

@@ -194,6 +194,10 @@ func (vm *VSchemaManager) buildAndEnhanceVSchema(v *vschemapb.SrvVSchema) *vinde
 		// We mark the keyspaces that have foreign key management in Vitess and have cyclic foreign keys
 		// to have an error. This makes all queries against them to fail.
 		markErrorIfCyclesInFk(vschema)
+		// Add tables from schema tracking into globally routable tables, if they are not already present.
+		// We need to skip if already present, to handle the case where MoveTables has switched traffic
+		// and removed the source vschema but not from the source database because user asked to --keep-data
+		vindexes.BuildGlobalTables(v, vschema, false)
 	}
 	return vschema
 }