| From: | Dennis Bjorklund <db(at)zigo(dot)dhs(dot)org> |
|---|---|
| To: | Gaetano Mendola <mendola(at)bigfoot(dot)com> |
| Cc: | "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org> |
| Subject: | Re: 7.4 vs 7.3 ( hash join issue ) |
| Date: | 2004-09-22 06:48:09 |
| Message-ID: | Pine.LNX.4.44.0409220844010.9559-100000@zigo.dhs.org |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-patches pgsql-performance |
On Wed, 22 Sep 2004, Gaetano Mendola wrote:
> Now my question is why the 7.4 choose the hash join ? :-(
It looks to me that the marge join is faster because there wasn't really
anything to merge, it resulted in 0 rows. Maybe the hash join that is
choosen in 7.4 would have been faster had there been a couple of result
rows (just a guess).
It would be interesting to compare the plans in 7.4 with and without
hash_join active and see what costs it estimates for a merge join compared
to a hash join.
--
/Dennis Björklund
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Dominic Mitchell | 2004-09-22 07:05:40 | doc patch for ssl in server |
| Previous Message | Dominic Mitchell | 2004-09-22 06:42:34 | SSL Error Code logging. |
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Gaetano Mendola | 2004-09-22 08:22:05 | Re: 7.4 vs 7.3 ( hash join issue ) |
| Previous Message | Gaetano Mendola | 2004-09-21 22:52:06 | 7.4 vs 7.3 ( hash join issue ) |