Order 'most recently closed' on 'Bugtask.id DESC' instead of 'BugTask.id'

Major oopser.

Bjorn, I discussed this with you briefly, and it seemed as though the root problem had been lost in the mists of time.
Reminder to self: get an explain plan of the relevant query for before/after this change to try and discover the root problem.

Stuart, do you remember what needs to be done to fix this bug?

As far as I know, this bug isn't causing any timeouts. Is this something that we have to fix, or can we drop this bug? I'm unassigning the bug from any milestone until we know more about the problem.

At the moment, when bugs are ordered by 'most recently closed' the ORDER BY clause is ORDER BY date_closed DESC, id. The id is there to make the results deterministic in the test suite (in real life, it is unnecessary). This ORDER BY clause is unable to use the index created to make this query run quickly. The ORDER BY should be ORDER BY date_closed DESC, id DESC.

The fix may just be a case of finding the relevant order_by parameter and inserting a '-' sign.

High as per oops policy; our test needs should never impact production speed: we can write things to cater for production's needs in a more sophisticated way; still : remaining action here is to find an example oops and fix. If its still happening.

https://bugs.edge.launchpad.net/malone/+bug/606914 seems to be related - Stuart makes the same comment in both bugs.

sorting by id is also a nice UI thing, on reflection. Perhaps we should make the index:
CREATE INDEX bugtask__date_closed__id__idx ON BugTask (date_closed, id desc nulls first);

which will support ORDER BY date_closed desc, id

Fixed and deployed \o/

Fixed in db-stable r9802 (http://bazaar.launchpad.net/~launchpad-pqm/launchpad/db-stable/revision/9802) by a commit, but not testable.