Ian Booth has proposed merging
lp:~wallyworld/launchpad/person-bugs-timeout-897923 into lp:launchpad.
Commit message:
Remove an unnecessary and costly distinct from a subquery used to search
commented bugs.
Requested reviews:
Ian Booth (wallyworld)
Related bugs:
Bug #897923 in Launchpad itself: "Person:+bugs timeout"
https://bugs.launchpad.net/launchpad/+bug/897923
For more details, see:
https://code.launchpad.net/~wallyworld/launchpad/person-bugs-timeout-897923/+merge/130280
The core issue was that the subselect used to get the bug ids of the relevant
bug messages was using distinct.
eg
SELECT BugTaskFlat.bugtask FROM BugTaskFlat LEFT JOIN Product ON
BugTaskFlat.product = Product.id AND Product.active WHERE BugTaskFlat.status IN
(25, 10, 20, 21, 22, 13, 14) AND BugTaskFlat.duplicateof IS NULL AND
(BugTaskFlat.product IS NULL OR Product.active = True) AND BugTaskFlat.bug IN
(SELECT DISTINCT BugMessage.bug FROM BugMessage WHERE BugMessage.index > 0 AND
BugMessage.owner = 1) AND True ORDER BY BugTaskFlat.importance DESC,
BugTaskFlat.bugtask LIMIT 8 OFFSET 0
The DISTINCT messed up Postgres, causing it to sort the potentially large list
of bugs and then filter, rather than the other way around.
I use a feature flag to (by default) remove the DISTINCT.
--
https://code.launchpad.net/~wallyworld/launchpad/person-bugs-timeout-897923/+merge/130280
Your team Launchpad code reviewers is subscribed to branch lp:launchpad.
=== modified file 'lib/lp/bugs/model/bugtasksearch.py'
--- lib/lp/bugs/model/bugtasksearch.py 2012-10-01 03:40:51 +0000
+++ lib/lp/bugs/model/bugtasksearch.py 2012-10-18 04:30:40 +0000
@@ -92,6 +92,7 @@
get_where_for_reference,
Unnest,
)
+from lp.services.features import getFeatureFlag
from lp.services.propertycache import get_property_cache
from lp.services.searchbuilder import (
all,
@@ -623,13 +624,15 @@
extra_clauses.append(BugTaskFlat.bug_owner == params.bug_reporter)
if params.bug_commenter:
+ use_distinct = bool(getFeatureFlag(
+ 'bug_comment_search.use_distinct.enabled'))
extra_clauses.append(
BugTaskFlat.bug_id.is_in(Select(
BugMessage.bugID, tables=[BugMessage],
where=And(
BugMessage.index > 0,
BugMessage.owner == params.bug_commenter),
- distinct=True)))
+ distinct=use_distinct)))
if params.affects_me:
params.affected_user = params.user
=== modified file 'lib/lp/services/features/flags.py'
--- lib/lp/services/features/flags.py 2012-10-12 03:11:38 +0000
+++ lib/lp/services/features/flags.py 2012-10-18 04:30:40 +0000
@@ -214,6 +214,13 @@
'',
'',
''),
+ ('bug_comment_search.use_distinct.enabled',
+ 'boolean',
+ ('If true, the bug message sub query for finding commented bugs '
+ 'uses DISTINCT.'),
+ '',
+ '',
+ ''),
('registry.upcoming_work_view.enabled',
'boolean',
('If true, the new upcoming work view of teams is available.'),
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