diff --git a/crates/core/database/src/models/admin_migrations/ops/mongodb/init.rs b/crates/core/database/src/models/admin_migrations/ops/mongodb/init.rs
index 82ff3ee9..ab25819b 100644
--- a/crates/core/database/src/models/admin_migrations/ops/mongodb/init.rs
+++ b/crates/core/database/src/models/admin_migrations/ops/mongodb/init.rs
@@ -222,6 +222,12 @@ pub async fn create_database(db: &MongoDb) {
                         "hash": 1_i32
                     },
                     "name": "hash"
+                },
+                {
+                    "key": {
+                        "used_for.id": 1_i32
+                    },
+                    "name": "used_for_id"
                 }
             ]
         },
diff --git a/crates/core/database/src/models/admin_migrations/ops/mongodb/scripts.rs b/crates/core/database/src/models/admin_migrations/ops/mongodb/scripts.rs
index 525b1551..5a22cd6d 100644
--- a/crates/core/database/src/models/admin_migrations/ops/mongodb/scripts.rs
+++ b/crates/core/database/src/models/admin_migrations/ops/mongodb/scripts.rs
@@ -1187,6 +1187,28 @@ pub async fn run_migrations(db: &MongoDb, revision: i32) -> i32 {
         }
     }
 
+    if revision <= 30 {
+        info!("Running migration [revision 30 / 29-09-2024]: Add index for used_for.id to attachments.");
+
+        db.db()
+            .run_command(
+                doc! {
+                    "createIndexes": "attachments",
+                    "indexes": [
+                        {
+                            "key": {
+                                "used_for.id": 1_i32
+                            },
+                            "name": "used_for_id"
+                        }
+                    ]
+                },
+                None,
+            )
+            .await
+            .expect("Failed to create attachments index.");
+    }
+
     // Need to migrate fields on attachments, change `user_id`, `object_id`, etc to `parent`.
 
     // Reminder to update LATEST_REVISION when adding new migrations.
diff --git a/crates/core/database/src/models/channels/ops/mongodb.rs b/crates/core/database/src/models/channels/ops/mongodb.rs
index 5f847dd7..51c6b66e 100644
--- a/crates/core/database/src/models/channels/ops/mongodb.rs
+++ b/crates/core/database/src/models/channels/ops/mongodb.rs
@@ -261,7 +261,7 @@ impl AbstractChannels for MongoDb {
 
         // Delete associated attachments
         self.delete_many_attachments(doc! {
-            "object_id": &id
+            "used_for.id": &id
         })
         .await?;
 
diff --git a/crates/core/database/src/models/servers/ops/mongodb.rs b/crates/core/database/src/models/servers/ops/mongodb.rs
index 639cd76b..e6bee03f 100644
--- a/crates/core/database/src/models/servers/ops/mongodb.rs
+++ b/crates/core/database/src/models/servers/ops/mongodb.rs
@@ -260,7 +260,7 @@ impl MongoDb {
 
         // Update many attachments with parent id.
         self.delete_many_attachments(doc! {
-            "object_id": &server_id
+            "used_for.id": &server_id
         })
         .await?;