Since no-one's answered this, I'll propose my theory,
although I'm not sure it's right.

The session_cached_cursors is just an array in the
UGA (session memory), which means it will be stored
in the SGA when using the multi-threaded server.

The function of the cache is to maintain pointers
into the shared pool so that on reuse of a closed
cursor, Oracle has the option of finding the cursor
very rapidly if it is still available, rather than going
through all the processing (and particularly latching)
needed to find if the 'new' SQL is sharable.

I believe the cost is actually a very small increment
in memory, plus a CPU cost for scanning the array,
which means that an array size over about 100 may
put you in the position of losing more CPU than you
would otherwise save.




Jonathan Lewis
http://www.jlcomp.demon.co.uk

Host to The Co-Operative Oracle Users' FAQ
http://www.jlcomp.demon.co.uk/faq/ind_faq.html

Author of:
Practical Oracle 8i: Building Efficient Databases

Screen saver or Life saver: http://www.ud.com
Use spare CPU to assist in cancer research.

-----Original Message-----
To: Multiple recipients of list ORACLE-L <[EMAIL PROTECTED]>
Date: 03 October 2001 22:03


Does anyboby know how this parameter really works?

Does it use PGA memory to cache parsed statements or
it uses SHARED_POOL memory for that.

If the case is the first one, imagine that cursor1 is
flushed out from the Shared Pool, and the session A
has it cached (in its PGA I assume), then, in order to
use it again, what must the session A do?
(it has to place the cursor into the shared pool again
and do a soft parse or that would not be
necessary...??)

thanks


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