Re: optimizer_index_caching and optimizer_index_cost_adj deprecated by system stats?
Date: 14 Mar 2008 08:35:56 GMT
On Thu, 13 Mar 2008 13:44:50 -0700, Mark D Powell wrote:
> I am against modifying the parameters away from the defaults on any
> release. Jonathan has written about some of the side effects that are
> possible when you do change the parameters.
I have no compunction about modifying the optimizer_index_caching because this parameter does supply realistic information which doesn't have a smart default. I usually do not set optimizer_index_cost_adj as this information can be manipulated through system statistics, if needed. Optimizer has no other way to figure the portion of index that is cached and you provide a default that is much "truthier" (sorry Mr. Colbert, I just had to use your word) then the default which says that index is not cached at all. I find this particular parameter useful in OLTP environments.
-- Mladen Gogala http://mgogala.freehostia.comReceived on Fri Mar 14 2008 - 03:35:56 CDT