Re: Special column trivia

Greg Smith <greg(at)2ndquadrant(dot)com> writes:
> I was just reading
> http://www.postgresql.org/docs/9.0/static/ddl-system-columns.html and
> noted that the second part about the ctid being unstable: "a row's ctid
> will change if it is updated or moved by VACUUM FULL" is probably not
> true anymore. Is that worth updating?

It's still true. VACUUM FULL still reassigns ctids.

> What got me reading that section was a rather weird documentation
> question/addition from Edmund Horner. He noted that the following works
> on PG8.4 and 9.0:

> postgres=# select (row(1,2)).name;

This is the cast-a-composite-type-to-string-type issue that's come up in
several guises before, eg most recently at
http://archives.postgresql.org/pgsql-general/2010-05/msg01126.php

regards, tom lane