Activity feed / timeline database schema

Table activity {
  id          uuid pk
  actor_id    uuid [ref: > user_account.id, not null]
  verb        text not null   // followed, liked, commented
  object_type text not null
  object_id   uuid not null
  target_type text
  target_id   uuid
  created_at  timestamptz default `now()`
}

Table timeline_entry {
  user_id     uuid [ref: > user_account.id]
  activity_id uuid [ref: > activity.id]
  created_at  timestamptz not null
  pk (user_id, created_at, activity_id)
}

Table follow {
  follower_id uuid [ref: > user_account.id]
  followee_id uuid [ref: > user_account.id]
  pk (follower_id, followee_id)
}