blob: f05592fc3a330192f415964543a357ab544bf23d (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
|
# frozen_string_literal: true
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, remove_duplicates: true)
@relations = relations
@remove_duplicates = remove_duplicates
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 { |rel| rel.reorder(nil).to_sql }.reject(&:blank?)
end
if fragments.any?
fragments.join("\n#{union_keyword}\n")
else
'NULL'
end
end
def union_keyword
@remove_duplicates ? 'UNION' : 'UNION ALL'
end
end
end
end
|
