diff --git a/DysonNetwork.Sphere/Account/NotificationService.cs b/DysonNetwork.Sphere/Account/NotificationService.cs
index 3b43cc0..8b0d90d 100644
--- a/DysonNetwork.Sphere/Account/NotificationService.cs
+++ b/DysonNetwork.Sphere/Account/NotificationService.cs
@@ -215,7 +215,7 @@ public class NotificationService(
 
         var notifications = subDict.Select(value =>
         {
-            int platformCode = value.Key switch
+            var platformCode = value.Key switch
             {
                 NotificationPushProvider.Apple => 1,
                 NotificationPushProvider.Google => 2,
diff --git a/DysonNetwork.Sphere/Chat/ChatRoomController.cs b/DysonNetwork.Sphere/Chat/ChatRoomController.cs
index 1d5be21..6961590 100644
--- a/DysonNetwork.Sphere/Chat/ChatRoomController.cs
+++ b/DysonNetwork.Sphere/Chat/ChatRoomController.cs
@@ -262,26 +262,19 @@ public class ChatRoomController(
             chatRoom.RealmId = member.RealmId;
         }
 
-        var chatRoomResourceId = $"chatroom:{chatRoom.Id}";
-
         if (request.PictureId is not null)
         {
             var picture = await db.Files.FindAsync(request.PictureId);
             if (picture is null) return BadRequest("Invalid picture id, unable to find the file on cloud.");
 
             // Remove old references for pictures
-            var oldPictureRefs =
-                await fileRefService.GetResourceReferencesAsync(chatRoomResourceId, "chat.room.picture");
-            foreach (var oldRef in oldPictureRefs)
-            {
-                await fileRefService.DeleteReferenceAsync(oldRef.Id);
-            }
+            await fileRefService.DeleteResourceReferencesAsync(chatRoom.ResourceIdentifier, "chat.room.picture");
 
             // Add a new reference
             await fileRefService.CreateReferenceAsync(
                 picture.Id,
                 "chat.room.picture",
-                chatRoomResourceId
+                chatRoom.ResourceIdentifier
             );
 
             chatRoom.Picture = picture.ToReferenceObject();
@@ -293,18 +286,13 @@ public class ChatRoomController(
             if (background is null) return BadRequest("Invalid background id, unable to find the file on cloud.");
 
             // Remove old references for backgrounds
-            var oldBackgroundRefs =
-                await fileRefService.GetResourceReferencesAsync(chatRoomResourceId, "chat.room.background");
-            foreach (var oldRef in oldBackgroundRefs)
-            {
-                await fileRefService.DeleteReferenceAsync(oldRef.Id);
-            }
+            await fileRefService.DeleteResourceReferencesAsync(chatRoom.ResourceIdentifier, "chat.room.background");
 
             // Add a new reference
             await fileRefService.CreateReferenceAsync(
                 background.Id,
                 "chat.room.background",
-                chatRoomResourceId
+                chatRoom.ResourceIdentifier
             );
 
             chatRoom.Background = background.ToReferenceObject();
diff --git a/DysonNetwork.Sphere/Publisher/PublisherController.cs b/DysonNetwork.Sphere/Publisher/PublisherController.cs
index 76c49a9..e35f151 100644
--- a/DysonNetwork.Sphere/Publisher/PublisherController.cs
+++ b/DysonNetwork.Sphere/Publisher/PublisherController.cs
@@ -355,12 +355,7 @@ public class PublisherController(
             // Remove old references for the publisher picture
             if (publisher.Picture is not null)
             {
-                var oldPictureRefs = await fileRefService.GetResourceReferencesAsync(
-                    publisher.ResourceIdentifier,
-                    "publisher.picture"
-                );
-                foreach (var oldRef in oldPictureRefs)
-                    await fileRefService.DeleteReferenceAsync(oldRef.Id);
+                await fileRefService.DeleteResourceReferencesAsync(publisher.ResourceIdentifier, "publisher.picture");
             }
 
             publisher.Picture = picture.ToReferenceObject();
@@ -378,17 +373,10 @@ public class PublisherController(
             var background = await db.Files.Where(f => f.Id == request.BackgroundId).FirstOrDefaultAsync();
             if (background is null) return BadRequest("Invalid background id.");
 
-            var publisherResourceId = $"publisher:{publisher.Id}";
-
             // Remove old references for the publisher background
             if (publisher.Background is not null)
             {
-                var oldBackgroundRefs =
-                    await fileRefService.GetResourceReferencesAsync(publisherResourceId, "publisher.background");
-                foreach (var oldRef in oldBackgroundRefs)
-                {
-                    await fileRefService.DeleteReferenceAsync(oldRef.Id);
-                }
+                await fileRefService.DeleteResourceReferencesAsync(publisher.ResourceIdentifier, "publisher.background");
             }
 
             publisher.Background = background.ToReferenceObject();
@@ -397,7 +385,7 @@ public class PublisherController(
             await fileRefService.CreateReferenceAsync(
                 background.Id,
                 "publisher.background",
-                publisherResourceId
+                publisher.ResourceIdentifier
             );
         }
 
diff --git a/DysonNetwork.Sphere/Publisher/PublisherSubscriptionService.cs b/DysonNetwork.Sphere/Publisher/PublisherSubscriptionService.cs
index 9475d16..c48dfbb 100644
--- a/DysonNetwork.Sphere/Publisher/PublisherSubscriptionService.cs
+++ b/DysonNetwork.Sphere/Publisher/PublisherSubscriptionService.cs
@@ -69,7 +69,7 @@ public class PublisherSubscriptionService(
 
         // Notify each subscriber
         var notifiedCount = 0;
-        foreach (var subscription in subscribers)
+        foreach (var subscription in subscribers.GroupBy(s => s.AccountId).Select(g => g.First()))
         {
             try
             {
diff --git a/DysonNetwork.Sphere/Realm/RealmController.cs b/DysonNetwork.Sphere/Realm/RealmController.cs
index ebbc2bf..2b12311 100644
--- a/DysonNetwork.Sphere/Realm/RealmController.cs
+++ b/DysonNetwork.Sphere/Realm/RealmController.cs
@@ -409,8 +409,6 @@ public class RealmController(
         if (request.IsPublic is not null)
             realm.IsPublic = request.IsPublic.Value;
 
-        var realmResourceId = $"realm:{realm.Id}";
-
         if (request.PictureId is not null)
         {
             var picture = await db.Files.FindAsync(request.PictureId);
@@ -419,11 +417,7 @@ public class RealmController(
             // Remove old references for the realm picture
             if (realm.Picture is not null)
             {
-                var oldPictureRefs = await fileRefService.GetResourceReferencesAsync(realmResourceId, "realm.picture");
-                foreach (var oldRef in oldPictureRefs)
-                {
-                    await fileRefService.DeleteReferenceAsync(oldRef.Id);
-                }
+                await fileRefService.DeleteResourceReferencesAsync(realm.ResourceIdentifier, "realm.picture");
             }
 
             realm.Picture = picture.ToReferenceObject();
@@ -432,7 +426,7 @@ public class RealmController(
             await fileRefService.CreateReferenceAsync(
                 picture.Id,
                 "realm.picture",
-                realmResourceId
+                realm.ResourceIdentifier
             );
         }
 
@@ -444,12 +438,7 @@ public class RealmController(
             // Remove old references for the realm background
             if (realm.Background is not null)
             {
-                var oldBackgroundRefs =
-                    await fileRefService.GetResourceReferencesAsync(realmResourceId, "realm.background");
-                foreach (var oldRef in oldBackgroundRefs)
-                {
-                    await fileRefService.DeleteReferenceAsync(oldRef.Id);
-                }
+                await fileRefService.DeleteResourceReferencesAsync(realm.ResourceIdentifier, "realm.background");
             }
 
             realm.Background = background.ToReferenceObject();
@@ -458,7 +447,7 @@ public class RealmController(
             await fileRefService.CreateReferenceAsync(
                 background.Id,
                 "realm.background",
-                realmResourceId
+                realm.ResourceIdentifier
             );
         }
 
diff --git a/DysonNetwork.Sphere/Storage/FileReferenceService.cs b/DysonNetwork.Sphere/Storage/FileReferenceService.cs
index 4353ecc..6c92682 100644
--- a/DysonNetwork.Sphere/Storage/FileReferenceService.cs
+++ b/DysonNetwork.Sphere/Storage/FileReferenceService.cs
@@ -156,6 +156,36 @@ public class FileReferenceService(AppDatabase db, FileService fileService, ICach
         return deletedCount;
     }
 
+    /// <summary>
+    /// Deletes references for a specific resource and usage
+    /// </summary>
+    /// <param name="resourceId">The ID of the resource</param>
+    /// <param name="usage">The usage context</param>
+    /// <returns>The number of deleted references</returns>
+    public async Task<int> DeleteResourceReferencesAsync(string resourceId, string usage)
+    {
+        var references = await db.FileReferences
+            .Where(r => r.ResourceId == resourceId && r.Usage == usage)
+            .ToListAsync();
+
+        if (!references.Any())
+        {
+            return 0;
+        }
+
+        var fileIds = references.Select(r => r.FileId).Distinct().ToList();
+
+        db.FileReferences.RemoveRange(references);
+        var deletedCount = await db.SaveChangesAsync();
+
+        // Purge caches
+        var tasks = fileIds.Select(fileService._PurgeCacheAsync).ToList();
+        tasks.Add(PurgeCacheForResourceAsync(resourceId));
+        await Task.WhenAll(tasks);
+
+        return deletedCount;
+    }
+
     /// <summary>
     /// Deletes a specific file reference
     /// </summary>