Re: Stopgap solution for table-size-estimate updatingproblem - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Stopgap solution for table-size-estimate updatingproblem
Date
Msg-id 18457.1101742652@sss.pgh.pa.us
Whole thread Raw
In response to Re: Stopgap solution for table-size-estimate updatingproblem  ("Zeugswetter Andreas DAZ SD" <ZeugswetterA@spardat.at>)
Responses Re: Stopgap solution for table-size-estimate updatingproblem  (Greg Stark <gsstark@mit.edu>)
Re: Stopgap solution for table-size-estimate  (Simon Riggs <simon@2ndquadrant.com>)
List pgsql-hackers
"Zeugswetter Andreas DAZ SD" <ZeugswetterA@spardat.at> writes:
> Tom wrote:
>>> But I am used to applications
>>> that prepare a query and hold the plan for days or weeks. If you happen to 
>>> create the plan when the table is by chance empty you lost.
>> 
>> You lose in either case, since this proposal doesn't change when
>> planning occurs or doesn't occur.

> This is not true in my case, since I only "update statistics"/analyze
> when the tables have representative content (i.e. not empty).

I'm unsure why you feel you need a knob to defeat this.  The only time
when the plan would change from what you think of as the hand-tuned
case is when the physical table size is greatly different from what it
was when you analyzed.  The entire point of wanting to make this change
is exactly that in that situation the plan *does* need to change.
        regards, tom lane


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