Merge lp:~cjwatson/launchpad/db-snap-preferred-series into lp:launchpad/db-devel

[Colin Watson]

Add SnappyDistroSeries.preferred column.

See https://code.launchpad.net/~cjwatson/launchpad/snap-preferred-series/+merge/310216 for rationale.

[William Grant (wgrant)]

Is this just snappydistroseries.preferred, with UNIQUE snappydistroseries (snappy_series) WHERE preferred?

review: Needs Fixing (db)

[Colin Watson (cjwatson)]

That makes the code rather more complicated, but on the other hand it does a better job of encoding the constraint that the preferred distroseries must be usable, so I guess that's a win. I've rearranged this and the corresponding code branch accordingly.

[William Grant (wgrant)]

review: Approve (db)

=== added file 'database/schema/patch-2209-69-6.sql'
--- database/schema/patch-2209-69-6.sql	1970-01-01 00:00:00 +0000
+++ database/schema/patch-2209-69-6.sql	2016-11-08 16:47:32 +0000
@@ -0,0 +1,12 @@
+-- Copyright 2016 Canonical Ltd.  This software is licensed under the
+-- GNU Affero General Public License version 3 (see the file LICENSE).
+
+SET client_min_messages=ERROR;
+
+ALTER TABLE SnappyDistroSeries ADD COLUMN preferred boolean DEFAULT false NOT NULL;
+
+CREATE UNIQUE INDEX snappydistroseries__snappy_series__preferred__idx ON SnappyDistroSeries (snappy_series) WHERE preferred;
+
+COMMENT ON COLUMN SnappyDistroSeries.preferred IS 'True if this record identifies the default distribution series for builds for this snappy series.';
+
+INSERT INTO LaunchpadDatabaseRevision VALUES (2209, 69, 6);