Re: question on SGA/PGA/UGA/SEP relationship

In dedicated server: When a user connects a dedicated server process is started. this process is outside of the SGA. If you monitor the memory on the server as people connect you will see the free memory decline. If someone issues a query that causes a sort(and you have sort_area_size set to a reasonably large number and the sort is large) then you will see the free memory shrink further. So in a dedicated server process the process is outside.

In the MTS the emory allocations occur in the SGA and so you would not see the same free memory usage.
Jim

"Cantonese Boy" <cantoneseboy_at_netscape.net> wrote in message news:3A7429B0.5AC44FE3_at_netscape.net...
> Hi
>
> I got a little bit confuse about the relationship between
> SGA/PGA/UGA/SEP.
>
> Form my book, it said:
>
> "The SGA also contains the sort extent pool (SEP) in
> non-MTS instances;in MTS instances, the user global area(UGA)
> contains the SEP"
>
> So, is that SEP inside non-MTS instances=dedicated server ?
> Where is it reside?
>
> But in another paragraph , it said:
>
> "In dedicated server environments, the shared pool can
> be smaller than the equivalent MTS environment. This happens because,
> in a dedicated server system, the sort areas used by each process are
> kept in the user's program global area(PGA), whereas in an MTS
> environment , the UGA extents used for sorting are tracked using the
> SEP, which is a part of the shared pool. Any time a process needs a
> temporary segment for sorting , it checks the SEP first before
> allocating a new segment."
>
>
> Is the "sort areas" here refer the SEP?
> If the first paragraph I quoted is correct, which means
> the "SGA also contains the sort extent pool (SEP) in non-MTS instances",
> then it got some contradiction with the second paragraph.
>
> My question is "IS UGA inside SGA?"
>
> Here is my unstanding about difference between dedicated server and
> MTS server doing sorting.
>
> Dedicated server:
> the PGA contain the sort area , so user process will use it's
> own PGA to do the sorting first, if not enough use temporary segement.
> MTS server:
> all the prcoess share the UGA which contain the SEP(I don't know if it
> is the only existing sort area for all process) and use it to do the
> sorting.
>
> Please correct me if I'm wrong.
>
> Thanks
>
> W
Received on Sun Jan 28 2001 - 10:33:15 CST