"Mark J. Bobak" wrote: > > Um, no. Select for update will lock whatever rows it selects. If it > happens to select all the rows in a table, then all the rows in the > table will be locked. But, you could select for update where > primary_key=1 and select (and lock) just one row. As with other DML > locks, the lock will be released when you commit or rollback. > > See the concepts manual for more details. > > Hope that helps, > > -Mark > > On Fri, 2002-09-27 at 20:33, tony ynot wrote: > > Is Select ... For Update; > > a cheap table lock? > > It seems whenever code uses this statement > > all the records in the cursor are locked > > until the cursor is closed. > >
IMHO SELECT .. FOR UPDATE is something which, in most cases where I see it used, is perfectly dispensable. It's a relic of Oracle 5 when there was no real row lock (only exclusive table locks and 'intent' row locks) and the difficulty was to hold them for as short a period as possible - hence SELECT ... FOR UPDATE to get the rowid, then a very fast UPDATE using the rowid and commit. Since Oracle6, unless you intend to 'reserve' a row, run a 3 hours process and be certain to find the same value when you're done, you can directly execute the update, it will spare you a select. -- Regards, Stephane Faroult Oriole Software -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Stephane Faroult INET: [EMAIL PROTECTED] 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: [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).
