Re: MTS and Memory

From: <ctcgag_at_hotmail.com>
Date: 10 Sep 2004 17:30:03 GMT
Message-ID: <20040910133003.520$q6@newsreader.com>

hjr_at_dizwell.com (Howard J. Rogers) wrote:

> But in any case, that doesn't get you off the hook. You asked a
> generic question about how far you can 'bump up' your SGA. You were
> told, I think, that the official recommendation from Oracle is that
> the SGA should never consume more than 50% of available physical RAM.

I've heard this many times here, but I've not seen it in Oracle documentation. So I spent more time than I'd care to admit on tahiti searching for their SGA sizing recommendations (9.2), and I couldn't find such advice. Usually they just say that it should be set "appropriately" (Gee thanks, guys.) or they tell you to go look in some other document (which of course just refers you to yet another document). The most specific advice I could find is that it should not be so large as to cause swapping.

> You were also told (by me) that unless you are suffering lots of
> ORA-4031 errors (indicating that you are running out of memory in the
> shared and/or large pools) you don't (probably) need to increase the
> size of your SGA (specifically the large or shared pools) in the first
> place.

If there are excessive disk sort or hash operations, would that also indicate that more memory is needed? IOW, if I can't grab my sort_area_size or hash_area_size worth of memory from the large pool, would I throw an error or would I make do with less memory and go to disk?

Xho

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Received on Fri Sep 10 2004 - 12:30:03 CDT