> > > > EXPLAIN ANALYZE SELECT * FROM measurement_events WHERE > > measurement_source_id='df86917e-8df0-11e1-8f8f-525400e76ceb' ORDER BY > > measurement_time DESC LIMIT 1; > > > > This seems to fail, scanning all tables. Do you think this can be > improved > > at all ? The query plan of the above query is as follows: > > The combination of sorting by measurement_source_id and limit > hinders constraint exclusion because the order of the column > across whole the inheritance is not known to planner. And the > below plan also dosn't show whether constraint exclusion worked > or not, by the same reason. But I suppose it worked. >
It is ORDER BY measurement_time, not measurement_id, and measurement_time is used to create the partition. So the planner should know the correct order, but instead it seems to query tables in the wrong order.
