Andrea Maria Piana f75f7bb738 Expand confirmations to private group chat messages
This commit expands the confirmation mechanism to allow private group
chat messages to be confirmed:

Changes:

- Added a separate table for message confirmations as group chat
messages have same messageID but multiple datasyncID
- Removed DataSyncID from raw message (I haven't removed the column name
as it can't be done in sqlite without copying over the table)
2021-03-16 13:41:14 +01:00
..
2020-01-10 19:59:01 +01:00
2020-01-10 19:59:01 +01:00
2020-04-16 15:51:28 +02:00
2021-01-08 08:43:16 +01:00

How to write migrations?

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.