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Home -> Community -> Mailing Lists -> Oracle-L -> RE: full usefullness of CURRENT OF ???
Locking if something oracle is very good at. It happens all over the place
and it happens quickly...there is very little overhead to it.
Block headers. ...each block in the affected table.
By updating the table by rowid, you get the best of both worlds assuming no one is re-orging the table (or somehow altering rowid to row value relationship) and that there is no need prevent users from touching the table while you are doing the update.
Cursor c_crud is select rowid, col1 from t_crud;
For v_crud in c_crud loop
Update t_crud
Set col1=whatever
where rowid = v_crud.rowid;
End loop;
(I remember reading about this in Guy Harrison's SQL tuning book...if you have a copy, I'd check that out....because I am very prone to memory recall error :) )
-----Original Message-----
Sent: Friday, July 11, 2003 3:09 PM
To: Multiple recipients of list ORACLE-L
OK, fair enough.
> The second example has to run the update statement seperately.
> CURRENT OF can go directly to the row(s) affected. CURRENT OF
> still has to modify each block header in the table to lock which
> is a small performance hit.
So CURRENT OF has to lock, so its slower, right? Does it have any advantages after all?
>To prevent that you could update by rowid
How? How can I update by ROWID? I was thinking to update
by PRIMARY_KEY...
> and avoid the header updates.
... what "header" updates?
thx
maa
-- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: MaryAnn Atkinson INET: maryann_30_at_yahoo.com Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (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.net -- Author: Chris Stephens INET: ChrisStephens_at_affina.com Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (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).Received on Fri Jul 11 2003 - 15:34:25 CDT
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