diff --git a/crates/db_schema/src/impls/activity.rs b/crates/db_schema/src/impls/activity.rs
index 5ec5d49db..d946d628f 100644
--- a/crates/db_schema/src/impls/activity.rs
+++ b/crates/db_schema/src/impls/activity.rs
@@ -127,7 +127,7 @@ mod tests {
     let inserted_activity = Activity::create(&conn, &activity_form).unwrap();
 
     let expected_activity = Activity {
-      ap_id: Some(ap_id.clone()),
+      ap_id: ap_id.clone(),
       id: inserted_activity.id,
       data: test_json,
       local: true,
diff --git a/crates/db_schema/src/schema.rs b/crates/db_schema/src/schema.rs
index 6cd2e2af0..034edbe9d 100644
--- a/crates/db_schema/src/schema.rs
+++ b/crates/db_schema/src/schema.rs
@@ -5,7 +5,7 @@ table! {
         local -> Bool,
         published -> Timestamp,
         updated -> Nullable<Timestamp>,
-        ap_id -> Nullable<Text>,
+        ap_id -> Text,
         sensitive -> Nullable<Bool>,
     }
 }
diff --git a/crates/db_schema/src/source/activity.rs b/crates/db_schema/src/source/activity.rs
index c5ac833ed..5bdeb1db2 100644
--- a/crates/db_schema/src/source/activity.rs
+++ b/crates/db_schema/src/source/activity.rs
@@ -10,7 +10,7 @@ pub struct Activity {
   pub local: bool,
   pub published: chrono::NaiveDateTime,
   pub updated: Option<chrono::NaiveDateTime>,
-  pub ap_id: Option<DbUrl>,
+  pub ap_id: DbUrl,
   pub sensitive: Option<bool>,
 }
 
diff --git a/migrations/2021-11-22-135324_add_activity_ap_id_index/down.sql b/migrations/2021-11-22-135324_add_activity_ap_id_index/down.sql
new file mode 100644
index 000000000..d2d3ad9dc
--- /dev/null
+++ b/migrations/2021-11-22-135324_add_activity_ap_id_index/down.sql
@@ -0,0 +1,5 @@
+alter table activity alter column ap_id drop not null;
+
+create unique index idx_activity_unique_apid on activity ((data ->> 'id'::text));
+
+drop index idx_activity_ap_id;
diff --git a/migrations/2021-11-22-135324_add_activity_ap_id_index/up.sql b/migrations/2021-11-22-135324_add_activity_ap_id_index/up.sql
new file mode 100644
index 000000000..fedd94f5e
--- /dev/null
+++ b/migrations/2021-11-22-135324_add_activity_ap_id_index/up.sql
@@ -0,0 +1,22 @@
+
+-- Delete the empty ap_ids
+delete from activity where ap_id is null;
+
+-- Make it required
+alter table activity alter column ap_id set not null;
+
+-- Delete dupes, keeping the first one
+delete
+from activity
+where id not in (
+  select min(id)
+  from activity
+  group by ap_id
+);
+
+-- The index
+create unique index idx_activity_ap_id on activity(ap_id);
+
+-- Drop the old index
+drop index idx_activity_unique_apid;
+