Schema RPC to fetch table/view definition

go/vt/vtcombo/tablet_map.go

@@ -661,6 +661,12 @@ func (itc *internalTabletConn) Release(ctx context.Context, target *querypb.Targ
 	return tabletconn.ErrorFromGRPC(vterrors.ToGRPC(err))
 }
 
+// GetSchema is part of the QueryService interface.
+func (itc *internalTabletConn) GetSchema(ctx context.Context, target *querypb.Target, tableType querypb.TableType, tableNames []string) (map[string]string, error) {
+	response, err := itc.tablet.qsc.QueryService().GetSchema(ctx, target, tableType, tableNames)
+	return response, tabletconn.ErrorFromGRPC(vterrors.ToGRPC(err))
+}
+
 // Close is part of queryservice.QueryService
 func (itc *internalTabletConn) Close(ctx context.Context) error {
 	return nil

go/vt/vttablet/grpctabletconn/conn.go

@@ -1018,6 +1018,29 @@ func (conn *gRPCQueryClient) Release(ctx context.Context, target *querypb.Target
 	return nil
 }
 
+// GetSchema implements the queryservice interface
+func (conn *gRPCQueryClient) GetSchema(ctx context.Context, target *querypb.Target, tableType querypb.TableType, tableNames []string) (map[string]string, error) {
+	conn.mu.RLock()
+	defer conn.mu.RUnlock()
+	if conn.cc == nil {
+		return nil, tabletconn.ConnClosed
+	}
+
+	req := &querypb.GetSchemaRequest{
+		Target:     target,
+		Type:       tableType,
+		TableNames: tableNames,
+	}
+	reply, err := conn.c.GetSchema(ctx, req)
+	if err != nil {
+		return nil, tabletconn.ErrorFromGRPC(err)
+	}
+	if reply.Error != nil {
+		return nil, tabletconn.ErrorFromVTRPC(reply.Error)
+	}
+	return reply.GetTableDefinition(), nil
+}
+
 // Close closes underlying gRPC channel.
 func (conn *gRPCQueryClient) Close(ctx context.Context) error {
 	conn.mu.Lock()

go/vt/vttablet/queryservice/queryservice.go

@@ -117,6 +117,9 @@ type QueryService interface {
 
 	Release(ctx context.Context, target *querypb.Target, transactionID, reservedID int64) error
 
+	// GetSchema returns the table definition for the specified tables.
+	GetSchema(ctx context.Context, target *querypb.Target, tableType querypb.TableType, tableNames []string) (map[string]string, error)
+
 	// Close must be called for releasing resources.
 	Close(ctx context.Context) error
 }

go/vt/vttablet/queryservice/wrapped.go

@@ -324,6 +324,15 @@ func (ws *wrappedService) Release(ctx context.Context, target *querypb.Target, t
 	})
 }
 
+func (ws *wrappedService) GetSchema(ctx context.Context, target *querypb.Target, tableType querypb.TableType, tableNames []string) (schemaDef map[string]string, err error) {
+	err = ws.wrapper(ctx, target, ws.impl, "GetSchema", false, func(ctx context.Context, target *querypb.Target, conn QueryService) (bool, error) {
+		var innerErr error
+		schemaDef, innerErr = conn.GetSchema(ctx, target, tableType, tableNames)
+		return canRetry(ctx, innerErr), innerErr
+	})
+	return schemaDef, err
+}
+
 func (ws *wrappedService) Close(ctx context.Context) error {
 	return ws.wrapper(ctx, nil, ws.impl, "Close", false, func(ctx context.Context, target *querypb.Target, conn QueryService) (bool, error) {
 		// No point retrying Close.

go/vt/vttablet/sandboxconn/sandboxconn.go

@@ -576,6 +576,11 @@ func (sbc *SandboxConn) Release(ctx context.Context, target *querypb.Target, tra
 	return sbc.getError()
 }
 
+// GetSchema implements the QueryService interface
+func (sbc *SandboxConn) GetSchema(ctx context.Context, target *querypb.Target, tableType querypb.TableType, tableNames []string) (map[string]string, error) {
+	panic("not implemented")
+}
+
 // Close does not change ExecCount
 func (sbc *SandboxConn) Close(ctx context.Context) error {
 	return nil

go/vt/vttablet/tabletconntest/fakequeryservice.go

@@ -749,6 +749,11 @@ func (f *FakeQueryService) Release(ctx context.Context, target *querypb.Target,
 	panic("implement me")
 }
 
+// GetSchema implements the QueryService interface
+func (f *FakeQueryService) GetSchema(ctx context.Context, target *querypb.Target, tableType querypb.TableType, tableNames []string) (map[string]string, error) {
+	panic("implement me")
+}
+
 // CreateFakeServer returns the fake server for the tests
 func CreateFakeServer(t testing.TB) *FakeQueryService {
 	return &FakeQueryService{