Unfortunately I had double-posted this - originally in General.
Tom Lane pointed out (in PG-GENERAL) that the planner will take any IN
(SELECT...) statement and do a JOIN, which is what is causing the planner
problem - even though the SELECT was just returning a constant. Obviously,
the real query this was testing was something more real-world.
SO, I took my original query and turned it to this:
SELECT *
FROM mdx_core.vw_provider AS p
WHERE provider_id = ANY array(
SELECT provider_id
FROM mdx_core.provider_alias
)
BLISTERINGLY fast!
PG version is 8.3 - as for configuration, I didn't want to throw too much
info as my concern was actually whether views were as klunky as other DB
platforms.
Carlo
-----Original Message-----
From: Kevin Grittner [mailto:Kevin.Grittner@wicourts.gov]
Sent: August 13, 2010 9:29 AM
To: pgsql-performance@postgresql.org; Carlo Stonebanks
Subject: Re: [PERFORM] Very bad plan when using VIEW and IN (SELECT...*)
"Carlo Stonebanks" <stonec.register@sympatico.ca> wrote:
> SELECT *
> FROM mdx_core.vw_provider AS p
> WHERE provider_id IN (SELECT 13083101)
>
> I am using the simple IN (SELECT n) in QUERY 2 to simplify the
> problem. I noticed the oddity of the behaviour when I used a
> proper "IN (SELECT myId FROM myTable)"
Did you try?:
SELECT *
FROM mdx_core.vw_provider AS p
WHERE EXISTS (SELECT * FROM myTable WHERE myId = provider_id)
For any follow-up you should probably mention what version of
PostgreSQL this is and how it's configured.
http://wiki.postgresql.org/wiki/SlowQueryQuestions
-Kevin