On Thu, Dec 4, 2014 at 1:27 PM, Peter Geoghegan <p...@heroku.com> wrote: > On Thu, Dec 4, 2014 at 3:04 AM, Craig Ringer <cr...@2ndquadrant.com> wrote: >> Yes, I think that's pretty important. With a negative attno so it's >> treated as a "hidden" col that must be explicitly named to be shown and >> won't be confused with user columns. > > I think that the standard for adding a new system attribute ought to > be enormous. The only case where a new one was added post-Postgres95 > was "tableoid". I'm pretty sure that others aren't going to want to do > it that way.
+1. System attributes are a mess; a negative attribute number implies not only that the column is by default hidden from view but also that it is stored in the tuple header rather than the tuple data. Using one here, where we're not even talking about a property of the tuple per se, would be a pretty goofy solution. > Besides, I'm not entirely convinced that this is actually > an important distinction to expose. I think it's probably an important distinction, for the kinds of reasons Anssi mentions, but we should look for some method other than a system column of indicating it. Maybe there's a magic function that returns a Boolean which you can call, or maybe some special clause, as with WITH ORDINALITY. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
