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Re: Avoiding bad prepared-statement plans.

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Mark Mielke <mark@mark.mielke.cc>, Jeroen Vermeulen <jtv@xs4all.nl>, Alex Hunsaker <badalex@gmail.com>, Greg Stark <gsstark@mit.edu>, Bart Samwel <bart@samwel.tk>, Pavel Stehule <pavel.stehule@gmail.com>, pgsql-hackers@postgresql.org
Date: 2010-02-28T04:22:00Z
Lists: pgsql-hackers 
Robert Haas <robertmhaas@gmail.com> writes:
> On Fri, Feb 26, 2010 at 7:03 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> Wouldn't it be better if it just did the right thing automatically?
>> 
>> The sort of heuristic I'm envisioning would essentially do "replan every
>> time" for some number of executions, and give up only if it noticed that
>> it wasn't getting anything better than the generic plan. So you'd have
>> a fixed maximum overhead per session when the custom plan was useless,
>> and the Right Thing when it wasn't.

> Which is likely useless for my use case.

[ shrug... ]  You'd better explain exactly why, if you want me to take
that objection seriously.

			regards, tom lane