This task is manly for me to track progress for the migration to notedb. Currently this is low priority until we update to 2.15. I am filling this early as bugs have begun appearing due to upstream reading the index for things like external id. This was done as a preparation change to migrate to notedb. Setting autoMograte under [notedb “changes”] will migrate things without needing us to do an offline migration. There is a trial option which will not migrate everything but be able to try notedb before migrating fully.

"* Migrate data to to NoteDb, read from NoteDb, but ReviewDb is still the source of truth ("trial mode")."

See docs https://gerrit-review.googlesource.com/Documentation/note-db.html#online-migration

I think we should go with the full migration instead of trial mode because we can do it online and once it is migrated to notedb we can switch the config to read from notedb.

This will mean increased in storage as the repo's will be increased. This will also make the db redundant.

Though trial mode will write to notedb but still write to both reviewdb and notedb but reads from notedb once migrated. But looking at docs i think this is only supported offline which requires downtime.

Also actually we should do it in 2.15 so we have the chance to decide weather to do it online or offline, 3.x removes online migrations

Also this will require a an init to migrate accounts over to notedb which has to be done offline. Changes can be done online.

Migrating accounts should be quicker offline then doing changes which will require lots of downtime but luckily we can do that online so no downtime required for changes.

Once we have migrated to notedb we need to set

[noteDb "changes"]
    autoMigrate = false
    trial = false
    write = true
    read = true
    sequence = true
    primaryStorage = note db
    disableReviewDb = true

immediately otherwise there is a risk of data loss.

Note that this is for changes only, accounts are migrated to notedb automatically when you upgrade to 2.15.