> > default_statistics_target = 100 (tried with 500, no change). Vacuum
> > analyzed
> > before initial query, and after each change to default_statistics_target.
> Modifying the statistics target is useful only if the estimates are
> seriously off, which is not your case - so it won't help, at least not
> > The same query, with a different "ofid", will occasionally get the more
> > optimal plan -- I assume that the distribution of data is the
> > differentiator
> > there.
> Yes, the difference between costs of the two plans is quite small (11796
> vs. 13153) so it's very sensible to data distribution.
> > Is there any other data I can provide to shed some light on this?
> You may try to play with the 'cost' constants - see this:
> You just need to modify them so that the bitmap index scan / bitmap heap
> scan is prefered to plain index scan.
> Just be careful - if set in the postgresql.conf, it affects all the
> queries and may cause serious problems with other queries. So it deserves
> proper testing ...
Playing around with seq_page_cost (1) and random_page_cost (1), I can get
the correct index selected. Applying those same settings to our production
server does not produce the optimal plan, though.
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