Add possible implementation for CT-1498

core/dbt/adapters/base/impl.py

@@ -718,6 +718,24 @@ def list_relations(self, database: Optional[str], schema: str) -> List[BaseRelat
         # we can't build the relations cache because we don't have a
         # manifest so we can't run any operations.
         relations = self.list_relations_without_caching(schema_relation)
+
+        # if the cache is already populated, add this schema in
+        # otherwise, skip updating the cache and just ignore
+        if self.cache:
+            for relation in relations:
+                self.cache.add(relation)
+            if not relations:
+                # it's possible that there were no relations in some schemas. We want
+                # to insert the schemas we query into the cache's `.schemas` attribute
+                # so we can check it later
+
+                # Jeremy: what was the intent behind this inner loop?
+                # cache_update: Set[Tuple[Optional[str], Optional[str]]] = set()
+                # for relation in cache_schemas:
+                #     cache_update.add((database, schema))
+
+                self.cache.update_schemas(set((database, schema)))
+
         fire_event(
             ListRelations(
                 database=cast_to_str(database),