> -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On > Behalf Of Ed Loehr > > mikeo wrote: > > > > thanks for the response. oid is equivalent to oracle rowid. IMHO,tid is equivalent to Oracle's rowid. > > rownum can be used similar to the limit option of select in postgres > > but in oracle it can also be used in a where clause, or as an assigment > > in an update statement for instance. > > > > eg: update ctmaster set bsc_id = mod(rownum,3) +1; > > > > this gives me a way to assign streams to rows in a load balanced manner > > on the fly, for example. i use it in other more involved ways than this > > also. i cannot do this with limit. i could do this with sequence with > > a max value but i'd have to define a sequence each time i wanted to do > > something "on the fly" or for what ifs. > > > > what i'm also interested in is how to find reference to these type of > > pseudo-columns, even just the names of them, if they're listed > somewhere. > > I think this might be the list, but you might query pgsql-hackers for > more info. There was a recent thread involving this.. > > ctid > oid > xmin (minimum transaction number) > xmax > cmin (minimum command number) > cmax > > ctid may be what you're looking for, but I don't understand very well how > these are used. Maybe someone else can say or you can experiment... > AFAIK,there's no pseudo-column like Oracle's rownum which is dynamically allocated at execution time. Regards. Hiroshi Inoue [EMAIL PROTECTED]