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Adapters can specify maximum number of ids they support in a list of …

…expressions

(default is nil meaning unlimited but Oracle imposes a limit of 1000)
Limit is used to make multiple queries when preloading associated has_many or habtm records
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1 parent 77fc0cc commit c5a284f8eb6113f06030ea7a18543905146e8768 @alexrothenberg alexrothenberg committed with tenderlove Nov 8, 2010
@@ -193,13 +193,17 @@ def preload_has_and_belongs_to_many_association(records, reflection, preload_opt
conditions = "t0.#{reflection.primary_key_name} #{in_or_equals_for_ids(ids)}"
conditions << append_conditions(reflection, preload_options)
- associated_records = reflection.klass.unscoped.where([conditions, ids]).
+ associated_records_proxy = reflection.klass.unscoped.
includes(options[:include]).
joins("INNER JOIN #{connection.quote_table_name options[:join_table]} t0 ON #{reflection.klass.quoted_table_name}.#{reflection.klass.primary_key} = t0.#{reflection.association_foreign_key}").
select("#{options[:select] || table_name+'.*'}, t0.#{reflection.primary_key_name} as the_parent_record_id").
- order(options[:order]).to_a
+ order(options[:order])
- set_association_collection_records(id_to_record_map, reflection.name, associated_records, 'the_parent_record_id')
+ all_associated_records = associated_records(ids) do |some_ids|
+ associated_records_proxy.where([conditions, ids]).to_a
+ end
+
+ set_association_collection_records(id_to_record_map, reflection.name, all_associated_records, 'the_parent_record_id')
end
def preload_has_one_association(records, reflection, preload_options={})
@@ -358,13 +362,14 @@ def find_associated_records(ids, reflection, preload_options)
find_options = {
:select => preload_options[:select] || options[:select] || Arel::SqlLiteral.new("#{table_name}.*"),
:include => preload_options[:include] || options[:include],
- :conditions => [conditions, ids],
:joins => options[:joins],
:group => preload_options[:group] || options[:group],
:order => preload_options[:order] || options[:order]
}
- reflection.klass.scoped.apply_finder_options(find_options).to_a
+ associated_records(ids) do |some_ids|
+ reflection.klass.scoped.apply_finder_options(find_options.merge(:conditions => [conditions, some_ids])).to_a
+ end
end
@@ -382,6 +387,17 @@ def append_conditions(reflection, preload_options)
def in_or_equals_for_ids(ids)
ids.size > 1 ? "IN (?)" : "= ?"
end
+
+ # Some databases impose a limit on the number of ids in a list (in Oracle its 1000)
+ # Make several smaller queries if necessary or make one query if the adapter supports it
+ def associated_records(ids)
+ max_ids_in_a_list = connection.ids_in_list_limit || ids.size
+ records = []
+ ids.each_slice(max_ids_in_a_list) do |some_ids|
+ records += yield(some_ids)
+ end
+ records
+ end
end
end
end
@@ -91,6 +91,11 @@ def prefetch_primary_key?(table_name = nil)
false
end
+ # Does this adapter restrict the number of ids you can use in a list. Oracle has a limit of 1000.
+ def ids_in_list_limit
+ nil
+ end
+
# QUOTING ==================================================
# Override to return the quoted table name. Defaults to column quoting.
@@ -79,6 +79,58 @@ def test_duplicate_middle_objects
end
end
+ def test_preloading_has_many_in_multiple_queries_with_more_ids_than_database_can_handle
+ Post.connection.expects(:ids_in_list_limit).at_least_once.returns(5)
+ posts = Post.find(:all, :include=>:comments)
+ assert_equal 7, posts.size
+ end
+
+ def test_preloading_has_many_in_one_queries_when_database_has_no_limit_on_ids_it_can_handle
+ Post.connection.expects(:ids_in_list_limit).at_least_once.returns(nil)
+ posts = Post.find(:all, :include=>:comments)
+ assert_equal 7, posts.size
+ end
+
+ def test_preloading_habtm_in_multiple_queries_with_more_ids_than_database_can_handle
+ Post.connection.expects(:ids_in_list_limit).at_least_once.returns(5)
+ posts = Post.find(:all, :include=>:categories)
+ assert_equal 7, posts.size
+ end
+
+ def test_preloading_habtm_in_one_queries_when_database_has_no_limit_on_ids_it_can_handle
+ Post.connection.expects(:ids_in_list_limit).at_least_once.returns(nil)
+ posts = Post.find(:all, :include=>:categories)
+ assert_equal 7, posts.size
+ end
+
+ def test_load_associated_records_in_one_query_when_adapter_has_no_limit
+ Post.connection.expects(:ids_in_list_limit).at_least_once.returns(nil)
+ Post.expects(:i_was_called).with([1,2,3,4,5,6,7]).returns([1])
+ associated_records = Post.send(:associated_records, [1,2,3,4,5,6,7]) do |some_ids|
+ Post.i_was_called(some_ids)
+ end
+ assert_equal [1], associated_records
+ end
+
+ def test_load_associated_records_in_several_queries_when_many_ids_passed
+ Post.connection.expects(:ids_in_list_limit).at_least_once.returns(5)
+ Post.expects(:i_was_called).with([1,2,3,4,5]).returns([1])
+ Post.expects(:i_was_called).with([6,7]).returns([6])
+ associated_records = Post.send(:associated_records, [1,2,3,4,5,6,7]) do |some_ids|
+ Post.i_was_called(some_ids)
+ end
+ assert_equal [1,6], associated_records
+ end
+
+ def test_load_associated_records_in_one_query_when_a_few_ids_passed
+ Post.connection.expects(:ids_in_list_limit).at_least_once.returns(5)
+ Post.expects(:i_was_called).with([1,2,3]).returns([1])
+ associated_records = Post.send(:associated_records, [1,2,3]) do |some_ids|
+ Post.i_was_called(some_ids)
+ end
+ assert_equal [1], associated_records
+ end
+
def test_including_duplicate_objects_from_belongs_to
popular_post = Post.create!(:title => 'foo', :body => "I like cars!")
comment = popular_post.comments.create!(:body => "lol")

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