make the number of connections configurable

.config/example.yml

@@ -77,18 +77,23 @@ db:
 #   # appear in their home timeline.
 #   #
 #   # (default 14)
-#   sparseTimelineDays: 14
+#   #sparseTimelineDays: 14
 #
 #   # <queryLimit> determines the number of maximum rows read within one pagination.
 #   # You may need to make [max_clustering_key_restrictions_per_query] larger for ScyllaDB
 #   # if you want to set this value larger than 100.
 #   # (default 100, max 5000, min 1)
-#   queryLimit: 100
+#   #queryLimit: 100
 #
 #   # Credentials for authentication (leave blank if not needed)
 #   #credentials:
 #   #  username: username
 #   #  password: password
+#
+#   # Number of pooled connections per host
+#   #connections:
+#   #  local: 2
+#   #  remote: 1
 
 
 #   ┌─────────────────────┐

packages/backend/src/config/types.ts

@@ -27,7 +27,11 @@ export type Source = {
 		credentials?: {
 			username: string;
 			password: string;
-		}
+		};
+		connections?: {
+			local: number;
+			remote: number;
+		};
 	};
 	redis: {
 		host: string;

packages/backend/src/db/scylla.ts

@@ -29,8 +29,8 @@ function newClient(): Client | null {
 		keyspace: config.scylla.keyspace,
 		pooling: {
 			coreConnectionsPerHost: {
-				[types.distance.local]: 2,
+				[types.distance.local]: config.scylla.connections?.local || 2,
-				[types.distance.remote]: 1,
+				[types.distance.remote]: config.scylla.connections?.remote || 1,
 			},
 		},
 		requestTracker,