diff --git a/README.md b/README.md
index 2e045c1..f44724d 100644
--- a/README.md
+++ b/README.md
@@ -23,7 +23,7 @@ Matrix chat: [#mitra:halogen.city](https://matrix.to/#/#mitra:halogen.city)
 ## Requirements
 
 - Rust 1.54+
-- PostgreSQL 10.2+
+- PostgreSQL 12+
 - IPFS node (optional, see [guide](./docs/ipfs.md))
 - Ethereum node (optional)
 
diff --git a/migrations/V0022__actor_profile__add_actor_id.sql b/migrations/V0022__actor_profile__add_actor_id.sql
new file mode 100644
index 0000000..03a2f4c
--- /dev/null
+++ b/migrations/V0022__actor_profile__add_actor_id.sql
@@ -0,0 +1 @@
+ALTER TABLE actor_profile ADD COLUMN actor_id VARCHAR(200) UNIQUE GENERATED ALWAYS AS (actor_json ->> 'id') STORED;
diff --git a/migrations/schema.sql b/migrations/schema.sql
index c58f93a..d082be3 100644
--- a/migrations/schema.sql
+++ b/migrations/schema.sql
@@ -12,6 +12,7 @@ CREATE TABLE actor_profile (
     following_count INTEGER NOT NULL CHECK (following_count >= 0) DEFAULT 0,
     post_count INTEGER NOT NULL CHECK (post_count >= 0) DEFAULT 0,
     actor_json JSONB,
+    actor_id VARCHAR(200) UNIQUE GENERATED ALWAYS AS (actor_json ->> 'id') STORED,
     created_at TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT now()
 );
 
diff --git a/src/activitypub/activity.rs b/src/activitypub/activity.rs
index 99bf94f..ddb21e6 100644
--- a/src/activitypub/activity.rs
+++ b/src/activitypub/activity.rs
@@ -572,6 +572,7 @@ mod tests {
                 url: Some(parent_author_actor_url.to_string()),
                 ..Default::default()
             }),
+            actor_id: Some(parent_author_actor_id.to_string()),
             ..Default::default()
         };
         let parent = Post {
diff --git a/src/models/profiles/queries.rs b/src/models/profiles/queries.rs
index 2cf3155..7dad2e2 100644
--- a/src/models/profiles/queries.rs
+++ b/src/models/profiles/queries.rs
@@ -116,7 +116,7 @@ pub async fn get_profile_by_actor_id(
         "
         SELECT actor_profile
         FROM actor_profile
-        WHERE actor_profile.actor_json ->> 'id' = $1
+        WHERE actor_id = $1
         ",
         &[&actor_id],
     ).await?;
@@ -471,6 +471,7 @@ pub async fn update_post_count(
 
 #[cfg(test)]
 mod tests {
+    use serde_json::json;
     use serial_test::serial;
     use crate::database::test_utils::create_test_database;
     use crate::models::profiles::queries::create_profile;
@@ -491,6 +492,38 @@ mod tests {
         assert_eq!(profile.username, "test");
     }
 
+    #[tokio::test]
+    #[serial]
+    async fn test_actor_id_unique() {
+        let db_client = create_test_database().await;
+        let actor_id = "https://example.com/users/test";
+        let create_actor_value = |actor_id| {
+            json!({
+                "id": actor_id,
+                "type": "Person",
+                "preferredUsername": "test",
+                "inbox": "https://test",
+                "outbox": "https://test",
+                "publicKey": {"id": "test", "owner": "test", "publicKeyPem": "test"},
+            })
+        };
+        let profile_data_1 = ProfileCreateData {
+            username: "test-1".to_string(),
+            acct: "test-1@example.com".to_string(),
+            actor_json: Some(create_actor_value(actor_id)),
+            ..Default::default()
+        };
+        create_profile(&db_client, profile_data_1).await.unwrap();
+        let profile_data_2 = ProfileCreateData {
+            username: "test-2".to_string(),
+            acct: "test-2@example.com".to_string(),
+            actor_json: Some(create_actor_value(actor_id)),
+            ..Default::default()
+        };
+        let error = create_profile(&db_client, profile_data_2).await.err().unwrap();
+        assert_eq!(error.to_string(), "profile");
+    }
+
     #[tokio::test]
     #[serial]
     async fn test_delete_profile() {
diff --git a/src/models/profiles/types.rs b/src/models/profiles/types.rs
index ceea604..3e8a3f8 100644
--- a/src/models/profiles/types.rs
+++ b/src/models/profiles/types.rs
@@ -86,6 +86,9 @@ pub struct DbActorProfile {
     pub post_count: i32,
     pub created_at: DateTime<Utc>,
     pub actor_json: Option<Actor>,
+
+    // auto-generated database fields
+    pub actor_id: Option<String>,
 }
 
 impl DbActorProfile {
@@ -94,6 +97,7 @@ impl DbActorProfile {
     }
 
     pub fn actor_id(&self, instance_url: &str) -> String {
+        // TODO: use actor_id field
         match self.actor_json {
             Some(ref actor) => actor.id.clone(),
             None => get_actor_url(instance_url, &self.username),
@@ -137,6 +141,7 @@ impl Default for DbActorProfile {
             post_count: 0,
             created_at: Utc::now(),
             actor_json: None,
+            actor_id: None,
         }
     }
 }