gitlab-org--gitlab-foss/lib/gitlab/sql/union.rb
gfyoung f93f8f569d Enable even more frozen string for lib/gitlab
Enables frozen string for the following:

* lib/gitlab/patch/**/*.rb
* lib/gitlab/popen/**/*.rb
* lib/gitlab/profiler/**/*.rb
* lib/gitlab/project_authorizations/**/*.rb
* lib/gitlab/prometheus/**/*.rb
* lib/gitlab/query_limiting/**/*.rb
* lib/gitlab/quick_actions/**/*.rb
* lib/gitlab/redis/**/*.rb
* lib/gitlab/request_profiler/**/*.rb
* lib/gitlab/search/**/*.rb
* lib/gitlab/sherlock/**/*.rb
* lib/gitlab/sidekiq_middleware/**/*.rb
* lib/gitlab/slash_commands/**/*.rb
* lib/gitlab/sql/**/*.rb
* lib/gitlab/template/**/*.rb
* lib/gitlab/testing/**/*.rb
* lib/gitlab/utils/**/*.rb
* lib/gitlab/webpack/**/*.rb

Partially addresses gitlab-org/gitlab-ce#47424.
2018-11-19 18:24:22 -08:00

43 lines
1.3 KiB
Ruby

# 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