Re: Query much slower when run from postgres function

Mario Splivalo <mario(dot)splivalo(at)megafon(dot)hr> writes:
> So, it is the same. When I do EXPLAIN ANALYZE EXECUTE I get completely
> different execution plan:
> ...
> -> Bitmap Heap Scan on messages
> (cost=287.98..21192.42 rows=12848 width=4) (actual time=0.049..0.169
> rows=62 loops=1)
> Recheck Cond: (service_id = $1)
> -> Bitmap Index Scan on
> messages_uq__service_id__tan (cost=0.00..284.77 rows=12848 width=0)
> (actual time=0.038..0.038 rows=62 loops=1)
> Index Cond: (service_id = $1)

Well, there's the problem: without knowing what the specific service_id
is, the planner is estimating 12848 matching rows, which is evidently
off by a couple of orders of magnitude. And that's pushing it to adopt
a hash join instead of a nestloop. Are you sure the stats on this
table are up to date? Maybe you need to increase the stats target?

regards, tom lane