Add EXPERIMENTAL tablet type to vtgate serving path

Allow vtgate to route queries to EXPERIMENTAL tablets by adding the type
to the serving graph, SrvKeyspace partition rebuild, update stream, and
SHOW TABLETS output.

Co-Authored-By: Claude <svc-devxp-claude@slack-corp.com>
Signed-off-by: Eduardo Ortega <5791035+ejortegau@users.noreply.github.com>

Author: ejortegau

go/vt/topo/tablet.go

@@ -59,7 +59,7 @@ func IsTrivialTypeChange(oldTabletType, newTabletType topodatapb.TabletType) boo
 // IsInServingGraph returns if a tablet appears in the serving graph
 func IsInServingGraph(tt topodatapb.TabletType) bool {
 	switch tt {
-	case topodatapb.TabletType_PRIMARY, topodatapb.TabletType_REPLICA, topodatapb.TabletType_RDONLY:
+	case topodatapb.TabletType_PRIMARY, topodatapb.TabletType_REPLICA, topodatapb.TabletType_RDONLY, topodatapb.TabletType_EXPERIMENTAL:
 		return true
 	}
 	return false
@@ -78,7 +78,7 @@ func IsRunningQueryService(tt topodatapb.TabletType) bool {
 // RPC service.
 func IsRunningUpdateStream(tt topodatapb.TabletType) bool {
 	switch tt {
-	case topodatapb.TabletType_PRIMARY, topodatapb.TabletType_REPLICA, topodatapb.TabletType_RDONLY:
+	case topodatapb.TabletType_PRIMARY, topodatapb.TabletType_REPLICA, topodatapb.TabletType_RDONLY, topodatapb.TabletType_EXPERIMENTAL:
 		return true
 	}
 	return false

go/vt/topotools/rebuild_keyspace.go

@@ -126,7 +126,7 @@ func RebuildKeyspaceLocked(ctx context.Context, log logutil.Logger, ts *topo.Ser
 		}
 	}
 
-	servedTypes := []topodatapb.TabletType{topodatapb.TabletType_PRIMARY, topodatapb.TabletType_REPLICA, topodatapb.TabletType_RDONLY}
+	servedTypes := []topodatapb.TabletType{topodatapb.TabletType_PRIMARY, topodatapb.TabletType_REPLICA, topodatapb.TabletType_RDONLY, topodatapb.TabletType_EXPERIMENTAL}
 
 	// for each entry in the srvKeyspaceMap map, we do the following:
 	// - get the Shard structures for each shard / cell

go/vt/vtgate/executor.go

@@ -990,8 +990,8 @@ func (e *Executor) ShowVitessReplicationStatus(ctx context.Context, filter *sqlp
 
 	for _, s := range status {
 		for _, ts := range s.TabletsStats {
-			// We only want to show REPLICA and RDONLY tablets
-			if ts.Target.TabletType != topodatapb.TabletType_REPLICA && ts.Target.TabletType != topodatapb.TabletType_RDONLY {
+			// We only want to show REPLICA, RDONLY, and EXPERIMENTAL tablets
+			if ts.Target.TabletType != topodatapb.TabletType_REPLICA && ts.Target.TabletType != topodatapb.TabletType_RDONLY && ts.Target.TabletType != topodatapb.TabletType_EXPERIMENTAL {
 				continue
 			}