Feature/issue59

[msolomon]

Should fix #59

I don't think this actually changes the logic, since we never check any of the locked rows bar the latest. @hoddez should verify

[RyanBalfanz]

Good catch.

[hoddez]

oh cool that's much cleaner. I'm guessing it does the same thing under the hood tho right?
(fyi the [0] causes a LIMIT 1 on the query so it doesnt get all pks)

[hoddez]

also not sure if it's causing any trouble but I think the select_for_update can be removed. I originally put it in to try and fix the race condition but that never really worked out as you know..

[hoddez]

just checked, its the same thing. wont make anything faster but is nicer looking:
In [9]: User.objects.all().values('id').order_by('-pk')[0]
DEBUG util (0.000) SELECT auth_user.id FROM auth_user ORDER BY auth_user.id DESC LIMIT 1; args=()

In [10]: User.objects.values('id').latest('pk')
DEBUG util (0.000) SELECT auth_user.id FROM auth_user ORDER BY auth_user.id DESC LIMIT 1; args=()

[RyanBalfanz]

Noted.

SELECT `sendgrid_­emailmessage`.­`id`,­ `sendgrid_­emailmessage`.­`message_­id`,­ `sendgrid_­emailmessage`.­`from_­email`,­ `sendgrid_­emailmessage`.­`to_­email`,­ `sendgrid_­emailmessage`.­`category`,­ `sendgrid_­emailmessage`.­`response`,­ `sendgrid_­emailmessage`.­`creation_­time`,­ `sendgrid_­emailmessage`.­`last_­modified_­time` FROM `sendgrid_­emailmessage` ORDER BY `sendgrid_­emailmessage`.­`id` DESC LIMIT ? FOR UPDATE

I think the solution is something like

self.select_for_update().values('pk').latest(field_name='pk')[0]["pk"] + 1

[hoddez]

Huh? latest returns an instance of the model, not a list or queryset so that would raise an exception. Also are we sure that query you posted is coming from this line?

[RyanBalfanz]

If latest doesn't just slice then maybe that's not quite right. The point it that it only selects values which are indexed.