mikeo wrote:
>
> thanks for the response. oid is equivalent to oracle 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...
Regards,
Ed Loehr
(PS: Posting to only one of -general or -sql will almost always be
sufficient.)