|From:||"Simon Riggs" <simon(at)2ndquadrant(dot)com>|
|To:||"Marshall, Steve" <smarshall(at)wsi(dot)com>|
|Cc:||"ITAGAKI Takahiro" <itagaki(dot)takahiro(at)oss(dot)ntt(dot)co(dot)jp>, "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>, <pgsql-hackers(at)postgresql(dot)org>|
|Subject:||Re: Allow use of immutable functions operating onconstants with constraint exclusion|
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On Tue, 2007-05-08 at 08:08 -0400, Marshall, Steve wrote:
> I think the optimization could work if you could exclude prepared
> statements. However, I looked at the planning code and found no clear
> way to distinguish between a statement being prepared for later
> execution, and a statement being planned only for immediate execution.
> As a result, I don't think stable functions can (or should) be
> expanded to help optimize queries using constraint exclusion.
I think it should be possible to tell the difference between planned and
immediate-execution queries. Anything coming thru exec_simple_query can
be tagged as immediate-execution, so should be allowed to make the
evaulation of stable functions in the planner as being accurate for the
rest of the statement execution also.
|Next Message||Tom Lane||2007-05-11 18:27:49||Re: [PATCHES] Arrays of Complex Types|
|Previous Message||Gregory Stark||2007-05-11 15:55:10||Concurrent psql patch|