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Viewing changes to src/oopstools/oops/views.py
- Committer: Tarmac
- Date: 2012-12-06 02:10:46 UTC
- mfrom: (50.1.3 recent-oopses)
- Revision ID: launchpad@pqm.canonical.com-20121206021046-q5tjvtab4ksawk3z
Improve the query performance of the recent oopses view.
Firstly the planner was picking a difficult plan because of the join, but
we expect few prefixes per-report, so getting the prefix ids first, then
using a simple IN rather than a join leads to an easier plan.
Once the easier plan is in use the indexes still aren't that helpful, as
it chooses the index on 'date', but it still has to filter based on the
prefix, so we add an index on (prefix_id, date) so that it can select the
right rows as quickly as possible.
Lastly lazy evaluation was causing 50 queries for the 'oopsinfestation'
info, so we use select_related() to include that in the main query.
There's a test that we do 1 query for the last point, but no test for
the speed of the query.
Firstly the planner was picking a difficult plan because of the join, but
we expect few prefixes per-report, so getting the prefix ids first, then
using a simple IN rather than a join leads to an easier plan.
Once the easier plan is in use the indexes still aren't that helpful, as
it chooses the index on 'date', but it still has to filter based on the
prefix, so we add an index on (prefix_id, date) so that it can select the
right rows as quickly as possible.
Lastly lazy evaluation was causing 50 queries for the 'oopsinfestation'
info, so we use select_related() to include that in the main query.
There's a test that we do 1 query for the last point, but no test for
the speed of the query.
- files modified:
- src/oopstools/oops/test/test_report.py
added
removed
src/oopstools/oops/views.py
