Re: ctid access is slow

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      jnasby@pervasive.com
Pervasive Software        http://pervasive.com        512-569-9461