question on SGA/PGA/UGA/SEP relationship

From: Cantonese Boy <cantoneseboy_at_netscape.net>
Date: Sun, 28 Jan 2001 22:16:16 +0800
Message-ID: <3A7429B0.5AC44FE3@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 - 08:16:16 CST