Re: BUG #6426: Complex query runs 10 times longer with "LIMIT 20"

Andrew Schetinin wrote:
> Hi Alex,
>
> Thank you. I played with subqueries, but in this case I did not see a
> good enough improvement.
>
> In my specific case, what I've seen from the query execution plans, is
> that without LIMIT the query uses Hash Joins, but once I add LIMIT, it
> starts using Nested Loop Joins almost everywhere.
>
> Regards,
>
> Andrew
>
> On Wed, Feb 1, 2012 at 9:42 PM, Alex Lai <alai@sesda2.com
> <mailto:alai@sesda2.com>> wrote:
>
>     Hi Andrew,
>     I posted for another post, its may give you a workaround.
>     I still not fully understand how PG choose execute plan that slow
>     down so much.
>
>     I had the same situation in one of my query.
>     Use the subquery can speed up almost by 100 times faster.
>
>     ..........
>
>
>
>     Hope this help.
>
>
>     Best Regards,
>     Alex Lai
>
>     --
>     Best regards,
>
>
>     Alex Lai
>     OMI SIPS DBA ADNET Systems , Inc. 7515 Mission Drive, Suite A100
>     Lanham, MD 20706 301-352-4657 (phone) 301-352-0437 (fax)
>     alai@sesda2.com <mailto:alai@sesda2.com>
>
>
>
>
> --
> --
> Andrew Schetinin
Hi Andrew,

I am interested in see your query.

--
Best regards,


Alex Lai
OMI SIPS DBA ADNET Systems , Inc.
7515 Mission Drive,
Suite A100 Lanham, MD 20706
301-352-4657 (phone)
301-352-0437 (fax)
alai@sesda2.com