There were a couple of issues on how we handle pinned messages:
1) Clock of the message was only checked when saving, meaning that the
client would receive potentially updates that were not to be
processed.
2) We relied on the client to generate a notification for a pinned
message by sending a normal message through the wire. This PR changes
the behavior so that the notification is generated locally, either on
response to a network event or client event.
3) When deleting a message, we pull all the replies/pinned notifications
and send them over to the client so they know that those messages
needs updating.
We only write up migrations, down migrations are not always possible in sqlite or
too complex/too expensive. For example to remove a column you would have to duplicate
the table, copy over the data, delete and recreated.
This can be very expensive for some tables (user_messages for example), so should not be attempted.
Notes
One issue we faced multiple times is that updates to user_messages can be very
expensive, leading to slow upgrade times and interrupted migrations. So avoid
writes if not necessary.
7650f3003e