Well you certainly could do that. I think it would have to be a very
special circumstance where you would want to do that.
Jim
"Francesco Marchioni" <fmarchioni_at_libero.it> wrote in message
news:_r6%6.2691$F85.96823_at_news.infostrada.it...
> > > 2) When I issue a SELECT FOR UPDATE the transaction level switches
> > > automatically to TRANSACTIONS_SERIALIZABLE ?
> Hi Fumi,
> well this looks surprising a bit, (though I'm not a big expert of Oracle
!)
> but I imagined that if you issue a SELECT for UPDATE on the WHOLE table
> then you lock enterely the table, so nobody else can for example insert
> or modify other records on the table 'til you issue a commit...so the
> isolation
> level should be higher...I expect it to be TRANSACTION_SERIALIZABLE...
> please correct me if I'm wrong (as I said I have just a basic Oracle
> knowledge!)
> Regards
> Francesco
>
> "fumi" <fumi_at_tpts5.seed.net.tw> ha scritto nel messaggio
> news:9hfkhm$f68$8_at_news.seed.net.tw...
> >
> > "Francesco Marchioni" <fmarchioni_at_libero.it> ¼¶¼g©ó¶l¥ó
> > news:jSl_6.5944$363.259102_at_news.infostrada.it...
> > > Hi all,
> > > I'm studying transactions isolation levels.
> > > I have some questions, hope somebody will help me:
> > >
> > > 1) How can I change the transaction isolation level via SQL - PL/SQL ?
> > > ( I mean without administrator's tools)
> >
> >
> > Oracle supports only SERIALIZABLE and READ COMMITTED.
> > Use the SQL command:
> >
> > ALTER SESSION SET ISOLATION_LEVEL= {SERIALIZABLE | READ COMMITTED}
> >
> > By the way, I think no tools support this rare used statement.
> >
> > > 2) When I issue a SELECT FOR UPDATE the transaction level switches
> > > automatically to TRANSACTIONS_SERIALIZABLE ?
> >
> >
> > No, after you issue a SELECT FOR UPDATE command,
> > you still in (default) READ COMMITTED level.
> >
> > > 3) I understand row locking and table locking but what does it mean
"page"
> > > locking ??
> >
> >
> > Oracle doesn't use page lock.
> > Page lock means that if you locks one or more rows in a page (block),
> > then all rows in the page (block) are locked.
> >
> >
> >
>
>
Received on Fri Jun 29 2001 - 20:56:42 CDT
