limit=0 in sqlalchemy means 0 instead of unlimit

[Feilong Wang]

We're using limit=0 to query unlimited records. Unfornuately, it doesn't work when a sql based database is used as pool management database. In sqlalchemy, it means 0. See:

https://github.com/openstack/marconi/blob/master/marconi/queues/storage/pooling.py#L76
https://github.com/openstack/marconi/blob/master/marconi/queues/storage/pooling.py#L397
https://github.com/openstack/marconi/blob/master/marconi/queues/storage/pooling.py#L142

https://github.com/openstack/marconi/blob/master/marconi/queues/storage/sqlalchemy/pools.py#L52

[peng fei wang (wpf)]

Is it the conversion that limit=0 means unlimited records?

from the current storage controller for mongodb and sqlalchemy , limit=0 is meaningful though it does not make sence, the code will only check whether it's None or not , if None ,then unlimited , or not event it's 0.

[peng fei wang (wpf)]

I mean that even in the Non-Pool context, it means 0 either.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/105353

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/105353
Committed: https://git.openstack.org/cgit/openstack/marconi/commit/?id=b02e9c1089503dee99e303229d40d4917505243e
Submitter: Jenkins
Branch: master

commit b02e9c1089503dee99e303229d40d4917505243e
Author: Fei Long Wang <email address hidden>
Date: Tue Jul 8 16:50:58 2014 +1200

    limit=0 in sqlalchemy means 0 instead of unlimited

    We're using limit=0 to query unlimited records. Unfornuately,
    it doesn't work when a sql based database is used as pool
    management database. In sqlalchemy, it means 0. This patch
    will check if the limit is 0 to decide if applying the
    limit() query for sqlalchemy.

    Closes-Bug: 1337191

    Change-Id: Iefc07ac41b17f52f7aa6607b0eb83dbc4cdef088