eager loading duplicates conditions unnecessarily
Reported by Smilinguy | July 17th, 2008 @ 02:08 PM | in 2.x
I noticed that when querying for limited numbers of results, that the eager loading of objects with have has_and_belongs_to_many and has_many :through associations appears to run a pre-query to obtain object ids then performs the eager loading of those objects by id with the included associations.
The issue I saw was that the conditions block was run on both the pre-query for IDs and the eager loading query. Perhaps I'm missing something, but if you already have the object ids, and you are really just querying by ID why do you need to run the conditions again? It slows things down and it looks to me to be unnecessary.
I'm not sure how to make a patch, but the method that I think needs to be changed is construct_finder_sql_with_included_associations.
I changed the lines
add_conditions!(sql, options[:conditions], scope)
add_limited_ids_condition!(sql, options, join_dependency) if !using_limitable_reflections?(join_dependency.reflections) && ((scope && scope[:limit]) || options[:limit])
to
if !using_limitable_reflections?(join_dependency.reflections) && ((scope && scope[:limit]) || options[:limit])
add_limited_ids_condition!(sql, options, join_dependency)
else
add_conditions!(sql, options[:conditions], scope)
end
Not sure what other impacts this will have or if I'm correct in my assumptions. Any comments or feedback would be appreciated.
Please Login or create a free account to add a new comment.
You can update this ticket by sending an email to from your email client. (help)
Create your profile
Help contribute to this project by taking a few moments to create your personal profile. Create your profile »
Source available from github
The Git repository resides at http://github.com/rails
Check out the current development trunk (Edge Rails) with:
git clone git://github.com/rails/rails.git
The latest development for the 1.2.x and 2.0.x releases are on the 1-2-stable and 2-0-stable branches.
Creating a bug report
When creating a bug report, be sure to include as much relevant information as possible. Post the code sample that causes the problem. Preferably, alter the unit tests and show through either changed or added tests how the expected behavior is not occuring.
Security vulnerabilities should be reported via an email to security@rubyonrails.org, do not use trac for reporting security vulnerabilities. All content in trac is publicly available as soon as it is posted.
Then don't get your hopes up. Unless you have a "Code Red, Mission Critical, The World is Coming to an End" kinda bug, you're creating this ticket in the hope that others with the same problem will be able to collaborate with you on solving it. Do not expect that the ticket automatically will see any activity or that others will jump to fix it. Creating a ticket like this is mostly to help yourself start on the path of fixing the problem and for others to sign on to with a "I'm having this problem too".
