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. -- Jim C. Nasby, Sr. Engineering Consultant [EMAIL PROTECTED] Pervasive Software http://pervasive.com 512-569-9461 ---------------------------(end of broadcast)--------------------------- TIP 9: In versions below 8.0, the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match
