[Zope-DB] Concurrenct updates in a table, column, row

[Federico Di Gregorio]

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On Wed, 2001-12-12 at 17:25, Dario Lopez-K=E4sten wrote:
> >
> > If you use SELECT ... FOR UPDATE you will lock the columns you select s=
o
> > they cannot be updated by another query until your transaction commits
> > (ie it should be pessimistic locking, vs Oracle's normal optimistic
> > locking strategy).
> >
>=20
> thanks, matt - got a followup question:
>=20
> if I am in the same request, and I do this i zsqlmeth1 and then do the
> actual update in zsqlmeth2 and do the commit in zsqlmeth3, all using the
> same db-connection object, will it work?

if i understand zope correctly, you should *never* commit explicitly in
a zsql method. zope will call da's _begin method before executing the
first sql and _finish just before returning from the request. (_abort is
called if there is a non-trapped error in the page).=20

that is, zope will open a transaction for you and commit or rollback
just before the end of the request (presuming the da support zope
transaction stuff, not all da do.)

hope this helps,
federico

--=20
Federico Di Gregorio
Debian GNU/Linux Developer & Italian Press Contact        fog@debian.org
INIT.D Developer                                           fog@initd.org
              La felicit=E0 =E8 una tazza di cioccolata calda. Sempre. -- I=
o

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