Database block sizes are determined when you create the database.(in Oracle,
in SQL Server you cannot specify the database block size.) You do not have
control over it; that is it just happens. This is not the behavior in
Oracle. Unlike a lot of databases in Oracle readers don't block writers
and writers don't block readers and Oracle does not take out page level
locks. Page level locks are not a good thing.
Jim
"Francesco Marchioni" <fmarchioni_at_libero.it> wrote in message
news:UOA_6.3664$z11.403456_at_news.infostrada.it...
> Hi Jim,
> thanks for your answer. May I ask how do you define a database block, in
> order to
> lock a certain number of rows ?
> via a SQL command ?
> Thanks
> Francesco
>
> "Jim Kennedy" <kennedy-family_at_home.com> ha scritto nel messaggio
> news:4lv_6.260536$p33.5211963_at_news1.sttls1.wa.home.com...
> > For 1 an 2 I'd have to refer to the manual (which I don't have with me
right
> > now.)
> > A "page" typically refers to a database block. A database block usually
has
> > more than 1 row in it. Some databases lock data by the page. Thus if
you
> > update a record in block 5 all the other records in block 5 are locked
also
> > (not in Oracle, but in quite a few other databases this is true.)
> > Is that helpful?
> > Jim
> > "Francesco Marchioni" <fmarchioni_at_libero.it> wrote in message
> > 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)
> > >
> > > 2) When I issue a SELECT FOR UPDATE the transaction level switches
> > > automatically to TRANSACTIONS_SERIALIZABLE ?
> > >
> > > 3) I understand row locking and table locking but what does it mean
"page"
> > > locking ??
> > >
> > > Thanks a lot in advance
> > > Francesco
> > >
> > >
> > >
> >
> >
>
>
Received on Thu Jun 28 2001 - 07:41:48 CDT
