| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
| Cc: | Volker Grabsch <vog(at)notjusthosting(dot)com>, pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: Calculation of unused columns |
| Date: | 2009-10-18 02:19:33 |
| Message-ID: | 28393.1255832373@sss.pgh.pa.us |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-performance |
Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> On Sat, Oct 17, 2009 at 9:41 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> I've been thinking about this since your earlier mail, and I think it
>> would probably be possible to suppress unused columns in a non-flattened
>> subquery. I remain unconvinced that it's worth the trouble though.
>> A real (not handwavy) example would help make the case here.
> Are there any situations where this would enable join removal that
> otherwise wouldn't be possible?
Hmm, yeah maybe, now that we have some join removal logic. Seems a bit
of a stretch to claim that's a common real-world case though.
regards, tom lane
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Karl Denninger | 2009-10-18 03:55:43 | Re: Are folks running 8.4 in production environments? and 8.4 and slon 1.2? |
| Previous Message | Robert Haas | 2009-10-18 01:53:11 | Re: Calculation of unused columns |