Bear Giles <bgi...@coyotesong.com> writes: > Hi, I'm working on a FDW for the unix/linux user database - think > /etc/passwd and /etc/group although I'm actually using system calls that > could be quietly redirected to LDAP or other backends. It's easy to create > the FDW and a table associated with it, something like
> CREATE TABLE passwd ( > name text, > passwd text, > uid int, > ... > The problem is the user could decide to reorder or remove columns so I > can't make the assumption that values[0] is always going to be the username. > I have a solution that requires looking at the rel, extracting the atts, > and then doing a loop where I check the attname against all possible values > for each column. Anything that doesn't match is set to null. This isn't too > bad here but it would be a pain if there are many columns. > Is there a cleaner way? The only thing that comes to mind is that you could probably amortize the figure-out-the-mapping overhead over multiple tuples. There's surely no reason to do it more often than once per query; and if that's not good-enough performance you could think about caching it longer, with some sort of invalidation logic. Take a look at src/include/access/tupconvert.h and src/backend/access/common/tupconvert.c for inspiration, or maybe even code you can use directly. regards, tom lane -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers