RE: Pinning/keeping plans in shared pool
- From: "Allen, Brandon" <Brandon.Allen@xxxxxxxxxxx>
- To: "Bobak, Mark" <Mark.Bobak@xxxxxxxxxxxxxxx>, "Boris Dali" <boris_dali@xxxxxxxx>, <rjamya@xxxxxxxxx>, <tanel.poder.003@xxxxxxx>
- Date: Mon, 10 Jul 2006 08:48:16 -0700
Thanks Mark - you were right on, I did miss the lower portion of Boris'
email. I had read Tanel's comments earlier though and also the white
paper that Tanel referenced, and my understanding from both was that
cursor_space_for_time=true *does* make the plan/heap6 stay pinned along
with the metadata/heap0, but *only* as long as the cursor is open - here
are the pertinent statements from the white paper (available here:
http://download-west.oracle.com/oowsf2005/003wp.pdf):
p.18: "Cursor_space_for_time is an initialization parameter which can be
used for optimizing the repeated execution of cursors that are parsed
once and kept open. The distinction is important: the cursor must
remain open for cursor_space_for_time to apply" . . . "Unlike
session_cached_cursors where only heap 0 of the cursor is pinned, with
cursor_space_for_time we pin the entire cursor in the pool until the
cursor is closed"
So if this white paper is correct, then cursor_space_for_time=true won't
help in my case because the cursor is closed after execution. I might
test it though just to be sure - maybe there is some special effect that
the white paper fails to mention when cursor_space_for_time=true is used
in conjunction with dbms_shared_pool.keep.
Regards,
Brandon
-----Original Message-----
From: Bobak, Mark [mailto:Mark.Bobak@xxxxxxxxxxxxxxx]
Sent: Monday, July 10, 2006 6:34 AM
To: Allen, Brandon; Boris Dali; rjamya@xxxxxxxxx;
tanel.poder.003@xxxxxxx
Cc: oracle-l@xxxxxxxxxxxxx
Subject: RE: Pinning/keeping plans in shared pool
Brandon,
I think Boris's reply, where he asked if you have cursor_space_for_time
= true, explains why he thinks it will help.
If you look at that posting more carefully, after he asks the question,
there is a bunch of quoted material from Tanel as well as some of
Boris's comments. (I suspect you just read his one-liner question, and
assumed everything below the "------" was old quoted material, which
isn't the case.)
I think you ought to try cursor_space_for_time=true.
-Mark
--
Mark J. Bobak
Senior Oracle Architect
ProQuest Information & Learning
Ours is the age that is proud of machines that can think and suspicious
of men who try to. --H. Mumford Jones, 1892-1980
-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Allen, Brandon
Sent: Saturday, July 08, 2006 5:20 PM
To: Boris Dali; rjamya@xxxxxxxxx; tanel.poder.003@xxxxxxx
Cc: oracle-l@xxxxxxxxxxxxx
Subject: RE: Pinning/keeping plans in shared pool
I have cursor_space_for_time set to false (default). I thought about
trying with it set to true, but if I understand the documentation
correctly, this only affects cursors that are still open - which won't
help in my case. Someone please correct me if I'm wrong on that.
Thanks
-----Original Message-----
From: Boris Dali [mailto:boris_dali@xxxxxxxx]
Sent: Saturday, July 08, 2006 9:55 AM
To: Allen, Brandon; rjamya@xxxxxxxxx; tanel.poder.003@xxxxxxx
Cc: oracle-l@xxxxxxxxxxxxx
Subject: RE: Pinning/keeping plans in shared pool
Brandon,
What's your cursor_space_for_time setting? Does setting it true make any
difference?
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