Re: execution plan and poor statistics
From: Jonathan Lewis <jonathan_at_jlcomp.demon.co.uk>
Date: Tue, 12 Apr 2011 16:36:41 +0100
Message-ID: <peadnSCoQL4Z7DnQnZ2dnUVZ8nCdnZ2d_at_bt.com>
Date: Tue, 12 Apr 2011 16:36:41 +0100
Message-ID: <peadnSCoQL4Z7DnQnZ2dnUVZ8nCdnZ2d_at_bt.com>
"onedbguru" <onedbguru_at_yahoo.com> wrote in message news:cc278a1b-de27-4353-9c46-57340c25cf90_at_r14g2000vbm.googlegroups.com... This is an easy fix. Stop collecting statistics on the table. - with a caveat.
- while the table is full - gather statistics - do this one time
- save these statistics somewhere
- when your table is full again, restore those statistics.
- If you never run stats against it again, then it is unlikely that you will collect stats while the table is empty thereby averting your problem.
Doesn't necessarily work - sometimes you have to keep updating the states
if you want the plans to stay the same.
This is a side effect of the "linear decay" algorithm that the optimizer
uses to pro-rate statistics when the query predicates move outside the
low/high column values. If the user has time-based (or sequence-based)
data then there may be cases where (in the absence of hinted paths) he will
see execution plans change as time passes.
-- Regards Jonathan Lewis http://jonathanlewis.wordpress.comReceived on Tue Apr 12 2011 - 10:36:41 CDT