Rails core - Aug 2006 - Forwarding a bug, following an IRC conversation with <bitsweat> -- HACK ALERT

Hello all -

I was asked to forward a bug found in Active Record 1.14.4 when I upgraded 
to Rails 1.1.5 today by <bitsweat>. He also suggested the ''HACK
ALERT''...
hope that''s okay :)

The post in it''s entirety is below.

Please let me know what else I can do to help resolve this...
>From rails@philip.pjkh.com Wed Aug  9 10:17:46 2006
Date: Wed, 9 Aug 2006 15:17:46 -0500 (CDT)
From: Philip Hallstrom <rails@philip.pjkh.com>
To: rails@lists.rubyonrails.org
Bcc: Philip Hallstrom <philip@cardplayer.com>
Subject: Bug in ActiveRecord 1.14.4 and select_limited_ids_list method using
mysql?!?!

All -

I just upgraded to rails 1.1.5 (per the announcement) which also updated
active record to 1.14.4 (was 1.14.2).  I know have a problem...

Author has many Articles...

   @authors = Author.find(:all, :limit => 10,
                                :offset => 0
                                :include => [:articles],
                                :conditions => ["hide = ?", false],
                                :order => "lname ASC, fname ASC,
articles.created_at asc")


This used to generate this query:

   SELECT DISTINCT authors.id
   FROM authors LEFT OUTER JOIN articles ON articles.author_id = authors.id
   WHERE (hide = 0)
   ORDER BY lname ASC, fname ASC, articles.created_at asc
   LIMIT 0, 10

and now it generates this query:

   SELECT DISTINCT authors.id, lname, fname, articles.created_at
   FROM authors LEFT OUTER JOIN articles ON articles.author_id = authors.id
   WHERE (hide = 0)
   ORDER BY lname ASC, fname ASC, articles.created_at asc
   LIMIT 0, 10


The next query generated (the one that actually gets my data) is the
same except for the "authors.id IN" section, since the new query
returns
a lot more rows since articles.created_at is pretty much different all
the time.

So, I used to get a list of 10 authors.  Now depending on how many
articles each author has, I get about 2.

In active records changelog I see the following commit for 1.14.3:

   Associations#select_limited_ids_list adds the ORDER BY columns to the
SELECT DISTINCT List for postgresql. [Rick]

And looking through the code in
activerecord-1.14.4/lib/active_record/associations.rb (line 1117)
I see where and why that is happening (I''m ordering by a field not in
the model''s table).

But what I don''t understand is why this change was made, nor why it
says
"for postgresql", but I don''t see any casing to only do it
for
postgresql.  I also don''t understand why the original query
isn''t the
desired behaviour.

Anyway, am I missing something obvious?  Or is this a bug?  Is there any
other info I can provide?

Thanks!

-philip