Re: psql \l error

"Hiroshi Inoue" <Inoue@tpf.co.jp> writes:
> What I wanted was to know official opinions about backward
> compatibility of clients(not only psql)included in PostgreSQL's
> release.

"Official" opinions?  I think we all just have our own opinions around
here :-).

> As for psql it isn't a generic client software as Peter mentioned.
> It's a part of backend in a sense. At least it could talk to pre-7.0
> backend and it isn't so critical that \l,\df and \dd doesn't work for 
> pre-7.0 backends. I'm not so much eager to change psql myself.

My opinion is that we'd be boxing ourselves in far too much to commit
to never having any system-catalog changes across versions.  So I'm
not particularly disturbed that functions that involve system catalog
queries sometimes are version-specific.  We should avoid breaking
essential functions of psql, but I don't think \df and friends are
essential...
        regards, tom lane