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POActiveRecord 3.2 vs. 3.0 Uniq Method Ignored in Join Statement
 

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  1. POActiveRecord 3.2 vs. 3.0 Uniq Method Ignored in Join Statement
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    <p>About two weeks ago I updated my Rails app from 3.0 to 3.2 (just in time for 4! Sigh.). Anyway, I've just noticed something odd — a query that returned correctly-ordered results in the old version is returning consistently-incorrect results in 3.2.</p> <p>Here's the query:</p> <pre><code>@sessions = user.email_sessions.joins(:email_stats) .where('email_stats.event_type = "open"') .order('email_stats.created_at DESC') .uniq </code></pre> <p>This query in Rails 3.2 returns these timestamps:</p> <pre><code>2013-06-18 12:02:05 -0400 2013-06-18 11:24:22 -0400 2013-06-18 10:41:52 -0400 2013-06-18 12:09:42 -0400 2013-06-18 10:02:26 -0400 2013-06-18 10:24:40 -0400 2013-06-18 08:59:19 -0400 2013-06-18 08:59:19 -0400 2013-06-18 08:51:39 -0400 2013-06-14 15:47:28 -0400 </code></pre> <p>Whereas in 3.0, I get this:</p> <pre><code>2013-06-18 12:09:42 -0400 2013-06-18 12:03:23 -0400 2013-06-18 12:02:05 -0400 2013-06-18 11:24:22 -0400 2013-06-18 10:41:52 -0400 2013-06-18 10:24:40 -0400 2013-06-18 10:02:26 -0400 2013-06-18 08:59:19 -0400 2013-06-18 08:59:19 -0400 2013-06-18 08:51:39 -0400 </code></pre> <p>That's good! Rails 3.2 is bad! Can anyone shed some light on this issue?</p> <p><strong>Update:</strong> It just occurred to me to check Rails 3.1, which I slid through briefly on my way to 3.2. I checked out the latest commit of that branch, and the dates are good there. It's only on 3.2 that this problem occurs.</p> <p><strong>Update 2:</strong> Thanks to Dhurv's question below, I've gotten the raw SQL being generated in both versions of Rails. I used the .to_sql method on the first, and I pulled the latter from the log. <strong>The difference: the .uniq method is only there in 3.2</strong> Why?</p> <p>Rails 3.2</p> <blockquote> <p>SELECT DISTINCT <code>email_sessions</code>.* FROM <code>email_sessions</code> INNER JOIN <code>email_stats</code> ON <code>email_stats</code>.<code>email_session_id</code> = <code>email_sessions</code>.<code>id</code> WHERE <code>email_sessions</code>.<code>user_id</code> = 374 AND (email_stats.event_type = "open") ORDER BY email_stats.created_at DESC</p> </blockquote> <p>Rails 3.0</p> <blockquote> <p>SELECT <code>email_sessions</code>.* FROM <code>email_sessions</code> INNER JOIN <code>email_stats</code> ON <code>email_stats</code>.<code>email_session_id</code> = <code>email_sessions</code>.<code>id</code> WHERE (<code>email_sessions</code>.user_id = 374) AND (email_stats.event_type = "open") ORDER BY email_stats.created_at DESC</p> </blockquote>
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    1. PTQuestion
    1. USAaron Vegh
    1. USAaron Vegh
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    1. CODoes the raw sql generated by rails differ from 3.0 to 3.2? You can tack on a '.to_sql' to the end of your query to find out.
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      1. POActiveRecord 3.2 vs. 3.0 Uniq Method Ignored in Join Statement
      1. USDhruv
    2. CO@Dhurv -- good idea, but the to_sql method doesn't exist in Rails 3.0 to compare it to! However, I got the SQL output from the log. There are differences, which I'll add to in my question above.
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      1. POActiveRecord 3.2 vs. 3.0 Uniq Method Ignored in Join Statement
      1. USAaron Vegh
 

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