RE: Free Memory in v$sgastat

Hi Mladen,

I try to understand 8i, and I am not using MTS, my current understanding is UGA and PGA only exists (I mean in use or in the picture) when you are using MTS.

Oracle themselves said "'free memory' are more properly thought of as wasted space"

I just wondering why this million dollar RDBMS can't make use of this space? everything are in terms of Oracle Block, you can release and reuse the blocks. Well maybe quite difficult to get long continuous blocks, but it still free space, I am so blur now....

Sinardy

-----Original Message-----
Sent: 16 December 2003 12:54
To: Multiple recipients of list ORACLE-L

Sinardy, you've attended wrong database tuning course. You need free memory in your shared pool. There is no such thing as "sga fragmentation" unless there is not enough free memory to satisfy average request. While oracle is not monitoring the size of an average shared pool request. you have things like session_uga_memory and session_pga_memory in v$mystat. In v9 there is also "session_stored_procedure_space". If the instance doesn't have enough room to load the next thing to execute (SQL, PL/SQL, Java), it will have to make room. Generally speaking, making room hurts. You want to have enough room to load your stuff into the shared pool and then some. That "room" is also known as "free space". Look into the tuning manual on the OTN and make sure that your buffer cache hit ratio is high enough (sorry folks, I couldn't resist).

On 2003.12.15 23:19, Sinardy Xing wrote:
> Hi all,
>
> Why free memory in v$sgastat is a symptom of the fragmentation?
>
> Why these "free memory" are more properly thought of as wasted space?
>
>
>
> Thanks
>
> Sinardy
>

-- 
Mladen Gogala
Oracle DBA
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