Joshua,
I've moved this discussion to pgsql-advocacy where it belongs.
> Aside from Drupal core, its too soon to know if there will be problems
> with D7 contrib but there are a few major bugs about other D6 contrib
> modules. The biggest one, which I think need movement to get fixed is in
> the Views module. The Views module has a bit of a hard time trying to
> please both databases and its surrounding the use of DISTINCT and
> restricting duplicate results. They've opted for a solution that really
> hits hard on PostgreSQL's performance. Bascially, when a DISTINCT clause
> is used, all other fields being selected get a custom functional called
> FIRST rapped around them: SELECT DISTINCT(nid), FIRST(title),
> FIRST(body), ..... The function merely returns the first value when two
> values are present for that row. This is the alternate instead of
> grouping by each field. Its stupid and needs to be fixed. The issue is
> here: http://drupal.org/node/460838
What's the obstacle to fixing it? It seems like just changing to SELECT
DISTINCT ON ... would do the trick, and would allow cutting code.
--Josh Berkus