Merge lp:~stevenk/launchpad/index-previewdiff-merge_proposal into lp:launchpad

[Steve Kowalik]

Add an index across PreviewDiff.{branch_merge_proposal,date_created}.

Add an index onto PreviewDiff.merge_propsosal and set it to not null now that it is populated.

[William Grant (wgrant)]

This should be a compound index so it can also be used for the sort in https://code.launchpad.net/~stevenk/launchpad/switch-bmp-to-previewdiff-merge_proposal/+merge/162916.

review: Needs Fixing (db)

[William Grant (wgrant)]

review: Approve (code)

[William Grant (wgrant)]

The index needs to be applied live, while the NOT NULL cannot be. I'd move the NOT NULLs to the cold patch, lp:~stevenk/launchpad/drop-branchmergeproposal-merge_diff.

(Ignore the previous code vote; wrong MP.)

review: Needs Fixing (db)

[William Grant (wgrant)]

review: Approve (code)

[William Grant (wgrant)]

review: Approve (db)

=== added file 'database/schema/patch-2209-44-1.sql'
--- database/schema/patch-2209-44-1.sql	1970-01-01 00:00:00 +0000
+++ database/schema/patch-2209-44-1.sql	2013-05-13 06:57:29 +0000
@@ -0,0 +1,9 @@
+-- Copyright 2013 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 UNIQUE INDEX previewdiff__branch_merge_proposal__date_created__key
+    ON previewdiff (branch_merge_proposal, date_created);
+
+INSERT INTO LaunchpadDatabaseRevision VALUES (2209, 44, 1);