Considerable overhead? Not really, but I only said "overhead", not
"considerable overhead". There are, as you are well aware, potential
issues with ST locking on very busy systems with dictionary managed
tablespaces. Pre-fragmenting can (not "will") reduce the duration of the ST
lock hold. Extent allocation becomes a delete from FET$ and an insert into
UET$ rather than an update to FET$ and an insert into UET$. (I hope I got
that right!) Its a rather minor tweaker's thing that probably only makes
any detectable difference on a handful of systems.
-Don Granaman
[certifiable OraSaurus]
----- Original Message -----
To: "Multiple recipients of list ORACLE-L" <[EMAIL PROTECTED]>
Sent: Monday, July 23, 2001 10:46 AM
> Is there really any considerable overhead involved in dynamically
> allocating an extent? By creating free space chunks in a tablespace
> of uniform extent size, will you really reduce the amount of time and
> resources spent when a segment allocates those extents?
>
> I doubt it, but statistics from v$sesstat could convince me otherwise.
>
> --
> Jeremiah Wilton
> http://www.speakeasy.net/~jwilton
>
> On Sun, 22 Jul 2001, Don Granaman wrote:
>
> > If you are using uniform extents in LMT, you don't want to coalesce
> > - ever. Since every extent will be the same size, it is useless
> > overhead. This is even more true if you have adopted a "uniform
> > extents" policy in any dictionary managed tablespaces. In fact, to
> > reduce the overhead of throwing a new extent in the latter, you
> > might try "pre-fragmenting" the tablespace by creating a junk table
> > in it and manually allocating new extents, then dropping the table -
> > during a low activity period of course.
>
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.com
> --
> Author: Jeremiah Wilton
> INET: [EMAIL PROTECTED]
>
> Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
> San Diego, California -- Public Internet access / Mailing Lists
> --------------------------------------------------------------------
> To REMOVE yourself from this mailing list, send an E-Mail message
> to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in
> the message BODY, include a line containing: UNSUB ORACLE-L
> (or the name of mailing list you want to be removed from). You may
> also send the HELP command for other information (like subscribing).
--
Please see the official ORACLE-L FAQ: http://www.orafaq.com
--
Author: Don Granaman
INET: [EMAIL PROTECTED]
Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
San Diego, California -- Public Internet access / Mailing Lists
--------------------------------------------------------------------
To REMOVE yourself from this mailing list, send an E-Mail message
to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in
the message BODY, include a line containing: UNSUB ORACLE-L
(or the name of mailing list you want to be removed from). You may
also send the HELP command for other information (like subscribing).
