Re: Slow query-plan generation (fast query) PG 9.2

On 03/09/13 09:47, Craig Ringer wrote:
> On 09/03/2013 03:46 PM, jesper(at)krogh(dot)cc wrote:
>> Hi.
>>
>> I have a strange situation where generating the query plan takes 6s+ and
>> executing it takes very little time.
> How do you determine that it's planning time at fault here?
Not that I'm sure, but the timing I send were only for "explain" not
"explain analyze". The database is constantly updating and at the moment
i cannot reproduce it any more. But at the time I picked the numbers it
were very reproducible.. (tried 10+ times over 15 minutes).

Please take separate timing for: PREPARE testq AS select table.id
from db.table left join db.tablepro on db.id = tablepro.table_id
where table.fts @@ to_tsquery('english','q12345') ; and then:
EXPLAIN ANALYZE EXECUTE testq;

I'll try to do that if i see the problem re-occour. I'm just very
interested in what explain then does if it is not only the time for the
query plan. When I did try the "PREPARE / EXECUTE" dance as you
described .. i didnt see the prepare state take time, which seems to be
consistent with that the planning time is in the EXECUTE step according
to the documentation.

--
Jesper