SAWarning: The IN-predicate on [...] was invoked with an empty sequence

[Johannes Erdfelt]

When the list of retrieved servers is empty, warnings are printed in the nova-api logs:

SAWarning: The IN-predicate on "instance_faults.instance_uuid" was invoked with an empty sequence. This results in a contradiction, which nonetheless can be expensive to evaluate. Consider alternative strategies for improved performance.

This is the result of querying the database with an empty list of UUIDs. The fix is to not query the DB in that case.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/4082

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/4082
Committed: http://github.com/openstack/nova/commit/7347a14213919aa78ad156b50deee846ec333b6a
Submitter: Jenkins
Branch: master

commit 7347a14213919aa78ad156b50deee846ec333b6a
Author: Johannes Erdfelt <email address hidden>
Date: Mon Feb 13 20:51:29 2012 +0000

    Don't query database with an empty list for IN clause

    Fixes bug 931687

    Change-Id: Ieec2c43c1d56c8d54d5bce606db9909b2ef5d6d4