Re: Performance problem with semi-large tables

PFC <lists(at)boutiquenumerique(dot)com> writes:
>> For example, let's add another filter to get all the shipments with
>> release code '5' that are 7 days old or newer.
>>
>> ss.date >= current_date - 7

> It's the order by + limit which makes the query behaves badly, and which
> forces use of kludges to use the index. If you add another condition like
> that, it should be a breeze.

Actually, that date condition has its own problem, namely that the
compared-to value isn't a constant. The 8.0 planner is able to realize
that this is a pretty selective condition, but prior releases fall back
on a very pessimistic default estimate. I'm sure that has something to
do with Ken not being able to get it to use an index on date.

regards, tom lane