43 lines
1.2 KiB
Ruby
43 lines
1.2 KiB
Ruby
# frozen_string_literal: true
|
|
|
|
module FromUnion
|
|
extend ActiveSupport::Concern
|
|
|
|
class_methods do
|
|
# Produces a query that uses a FROM to select data using a UNION.
|
|
#
|
|
# Using a FROM for a UNION has in the past lead to better query plans. As
|
|
# such, we generally recommend this pattern instead of using a WHERE IN.
|
|
#
|
|
# Example:
|
|
# users = User.from_union([User.where(id: 1), User.where(id: 2)])
|
|
#
|
|
# This would produce the following SQL query:
|
|
#
|
|
# SELECT *
|
|
# FROM (
|
|
# SELECT *
|
|
# FROM users
|
|
# WHERE id = 1
|
|
#
|
|
# UNION
|
|
#
|
|
# SELECT *
|
|
# FROM users
|
|
# WHERE id = 2
|
|
# ) users;
|
|
#
|
|
# members - An Array of ActiveRecord::Relation objects to use in the UNION.
|
|
#
|
|
# remove_duplicates - A boolean indicating if duplicate entries should be
|
|
# removed. Defaults to true.
|
|
#
|
|
# alias_as - The alias to use for the sub query. Defaults to the name of the
|
|
# table of the current model.
|
|
# rubocop: disable Gitlab/Union
|
|
extend FromSetOperator
|
|
define_set_operator Gitlab::SQL::Union
|
|
# rubocop: enable Gitlab/Union
|
|
end
|
|
end
|