Merge lp:~stevenk/launchpad/buildfarmjob-index-redux into lp:launchpad

[Steve Kowalik]

Add a partial index on BuildFarmJob(builder, status, date_finished, id).

The index that was created in https://code.launchpad.net/~stevenk/launchpad/buildfarmjob-index/+merge/123675 does solve the main case of Builder:+history, and makes the page performant. The page also allows the user to filter by status, and the query to filter by BuildFarmJob.status results in a table scan. Let's add another index that looks like the existing one but adds status into the mix.

[Stuart Bishop (stub)]

review: Approve (db)

[Stuart Bishop (stub)]

applied to both qastaging and production

=== added file 'database/schema/patch-2209-27-4.sql'
--- database/schema/patch-2209-27-4.sql	1970-01-01 00:00:00 +0000
+++ database/schema/patch-2209-27-4.sql	2012-09-11 22:47:21 +0000
@@ -0,0 +1,8 @@
+-- Copyright 2012 Canonical Ltd.  This software is licensed under the
+-- GNU Affero General Public License version 3 (see the file LICENSE).
+
+SET client_min_messages=ERROR;
+
+CREATE INDEX buildfarmjob__builder__status__date_finished__id__idx ON BuildFarmJob(builder, status, date_finished DESC, id) WHERE builder IS NOT NULL;
+
+INSERT INTO LaunchpadDatabaseRevision VALUES (2209, 27, 4);