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.
