Moving udd away from sqlite

[Vincent Ladeuil]

>>>>> James Westby <james.westby at canonical.com> writes:

    > Hi,

    > We're interested in moving our deployment of udd away from sqlite
    > to postgres, and we're interested in doing the same thing for the
    > package importer deployment.

There is a work in progress regarding the jubany package importer
deployment, let's try to no step on each other feet ;)

<snip/>

    > That didn't go so well, as after a few hours/days of usage it
    > would deadlock due to sqlite locking. That's one of the reasons
    > why sqlite isn't a great choice, as it shows we are currently
    > operating close to the threshold that sqlite allows.

Hopefully we won't run into the same issues right ?

    > After lots of head-scratching I believe I've worked out why
    > changing to storm made this happen when the underlying db was the
    > same. Storm forces sqlite to operate at a higher isolation level,
    > so udd was taking locks more frequently or holding them for
    > longer, leading to more contention and eventually the deadlock.

But we already know we can have deadlocks with sqlite
(https://bugs.launchpad.net/udd/+bug/724893) so I'm not convinced
changing the db will magically fix the issues.

<snip/>

    >   4) Leave the package importer on sqlite and do something else for our
    >      instance (fork basically)

As I mentioned before, I favor a friendly fork that can be merged back
after thorough tests.

    > Are there any others?

Setup a test environment with a launchpad test instance where you can
demonstrate that the importer won't break when this change is deployed ?

            Vincent