debian-mirror-gitlab/lib/gitlab/sql/union.rb

35 lines
1 KiB
Ruby
Raw Normal View History

2015-11-26 14:37:03 +05:30
module Gitlab
module SQL
# Class for building SQL UNION statements.
#
# ORDER BYs are dropped from the relations as the final sort order is not
# guaranteed any way.
#
# Example usage:
#
# union = Gitlab::SQL::Union.new(user.personal_projects, user.projects)
# sql = union.to_sql
#
# Project.where("id IN (#{sql})")
class Union
def initialize(relations)
@relations = relations
end
def to_sql
# Some relations may include placeholders for prepared statements, these
# aren't incremented properly when joining relations together this way.
# By using "unprepared_statements" we remove the usage of placeholders
# (thus fixing this problem), at a slight performance cost.
fragments = ActiveRecord::Base.connection.unprepared_statement do
@relations.map do |rel|
rel.reorder(nil).to_sql
end
end
fragments.join("\nUNION\n")
end
end
end
end