Re: Avoiding bad prepared-statement plans.

Alex Hunsaker <badalex@gmail.com>

From: Alex Hunsaker <badalex@gmail.com>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Jeroen Vermeulen <jtv@xs4all.nl>, Greg Stark <gsstark@mit.edu>, Bart Samwel <bart@samwel.tk>, Pavel Stehule <pavel.stehule@gmail.com>, pgsql-hackers@postgresql.org
Date: 2010-02-26T20:02:40Z
Lists: pgsql-hackers
On Fri, Feb 26, 2010 at 09:50, Robert Haas <robertmhaas@gmail.com> wrote:
> On Fri, Feb 26, 2010 at 1:29 AM, Alex Hunsaker <badalex@gmail.com> wrote:
>> Prepared plans + exec plan (new guc/ protocol thing):
>>  Use: not quite sure
>>  Problems: slow because it would replan every time
>>  Solutions: use a prepared plan with the appropriate things not
>> parametrized...?
>>
>> [ aka we already have this, its called dont use a prepared statement ]
>
> The point is sometimes you'd like to replan every time, but not
> reparse every time.  There's no way to do that ATM.

So what you save on parse time?  Maybe that's worth it.  I've never
run the numbers nor have I seen them in this thread.  I probably
missed em...  My _hunch_ is planning will on average take
significantly longer than parse time (read in the noise of plan time).
 But that's unfounded :)  I can certainly imagine cases where you have
HUGE queries where the parse time too slow-- wont the plan most of the
time be an order of magnitude slower?  Anyway Ill stop until I get a
chance to do _some_ kind of benchmarking, I'm really quite clueless
here.