--- "Jim C. Nasby" <jnasby@xxxxxxxxxxxxx> wrote: > On Wed, Aug 24, 2005 at 09:26:10AM +0930, Jeff > Eckermann wrote: > > The ctid value can be useful in a multi user > application, to check whether a > > record has been changed by another user, before > committing changes. > > Whenever a record is updated the ctid value will > be changed, so by storing > > the ctid value when first fetching the record, > that can be compared with the > > current ctid value before doing the update. > > I believe that's not necessarily true. If you select > a tuple and it's > ctid and it's updated more than once with a vacuum > in-between I believe > it could end up back in the same position, which > would mean the same > ctid. True. But the probability of that happening would generally be low enough not to bother the designers of most applications. > -- > Jim C. Nasby, Sr. Engineering Consultant > jnasby@xxxxxxxxxxxxx > Pervasive Software http://pervasive.com > 512-569-9461 > __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com ---------------------------(end of broadcast)--------------------------- TIP 6: explain analyze is your friend
