| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Mark Mielke <mark(at)mark(dot)mielke(dot)cc> |
| Cc: | Jeroen Vermeulen <jtv(at)xs4all(dot)nl>, Alex Hunsaker <badalex(at)gmail(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Greg Stark <gsstark(at)mit(dot)edu>, Bart Samwel <bart(at)samwel(dot)tk>, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Avoiding bad prepared-statement plans. |
| Date: | 2010-02-26 19:57:56 |
| Message-ID: | 3138.1267214276@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Mark Mielke <mark(at)mark(dot)mielke(dot)cc> writes:
> There must be some way to lift the cost of planning out of the plan
> enumeration and selection phase, such that only plan enumeration and
> selection is run at execute time. In most cases, plan enumeration and
> selection, provided that all data required to make these decisions is
> all cached in data structures ready to go, should be very fast? Right?
Huh? What exactly do you think the cost of planning is, if not
enumeration and selection? There isn't very much that's cacheable,
at least not in any sanely-sized cache.
> By "not worth it", do you mean development effort or run time?
Run time. The development cost of what you are proposing is negligible:
just rip out the plan cache altogether. I don't believe it would be a
performance win though.
regards, tom lane
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