RE: So how big is your buffer cache ?
- From: "Gogala, Mladen" <Mladen.Gogala@xxxxxxxx>
- To: "'oracle-l@xxxxxxxxxxxxx'" <oracle-l@xxxxxxxxxxxxx>
- Date: Mon, 30 Aug 2004 10:37:43 -0400
Well, free buffer waits mean that the waiting session is waiting on
free buffer. It can be waiting because there isn't a sufficient number of
buffers, or it can wait for DBWR write buffers to the data file. Of course,
it needs to be investigated, but if the buffer cache is too small, then
waits will not be grouped around a small set of tables used by many users,
but will be more randomly distributed. Specifically, to answer your
question, increasing buffer cache will help in cases when the session is
waiting for any free buffer, and it can't get it, because there simply
aren't enough to go around. I don't recommend increasing DB_BUFFER_CACHE
whenever you see a single free buffer wait, but seeing that event on a
regular basis will warrant an investigation. One of the results of such
investigation might be a recommendation for a larger buffer cache.
--
Mladen Gogala
A & E TV Network
Ext. 1216
> -----Original Message-----
> From: Cary Millsap [mailto:cary.millsap@xxxxxxxxxx]
> Sent: Monday, August 30, 2004 10:21 AM
> To: oracle-l@xxxxxxxxxxxxx
> Subject: RE: So how big is your buffer cache ?
>
>
> But, whoa, wait! Seeing 'free buffer waits' waits in your
> session is an indication that your session is waiting for
> DBWR to do its job. How does increasing the database buffer
> cache size help the DBWR do its job more efficiently?! It doesn't.
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