Redmine

The change from #21608 should be reverted because it's a speed regression:

1/ current version

EXISTS (SELECT 1 AS one FROM enabled_modules em WHERE em.project_id = projects.id AND em. NAME = 'issue_tracking')

2/ previous version (actually faster even without an index on enabled modules)

projects.id IN (SELECT project_id FROM enabled_modules em WHERE em.project_id = projects.id AND em. NAME = 'issue_tracking'

3/ fastest version (in some cases better indexes were used)

INNER JOIN `enabled_modules` ON `enabled_modules`.`project_id` = `projects`.`id` WHERE `enabled_modules`.`name` = 'issue_tracking'

INNER JOIN `enabled_modules` ON `enabled_modules`.`project_id` = `projects`.`id` AND `enabled_modules`.`name` = 'issue_tracking'

• revert of #21608, because the previous version was faster (about 30%)
• new index "enabled_modules_name", but it's not very helpful unless you have many projects (3000+)
• implementation of visible conditions with inner join instead of subselect, it passes all tests, but it should be refactored. I want to know what do you think about it first

Rails version             4.2.8
Ruby version              2.1.9-p490 (x64-mingw32)
RubyGems version          2.6.12
Rack version              1.6.8
Middleware                Rack::Sendfile, Rack::ContentLength, ActionDispatch::Static, Rack::Lock, #<ActiveSupport::Cache::Strategy::LocalCache::Middleware:0x00000007745610>, Rack::Runtime, Rack::MethodOverride, ActionDispatch::RequestId, Rails::Rack::Logger, ActionDispatch::ShowExceptions, ActionDispatch::DebugExceptions, ActionDispatch::RemoteIp, ActionDispatch::Reloader, ActionDispatch::Callbacks, ActiveRecord::ConnectionAdapters::ConnectionManagement, ActiveRecord::QueryCache, ActionDispatch::Cookies, ActionDispatch::Session::CookieStore, ActionDispatch::Flash, ActionDispatch::ParamsParser, ActionDispatch::XmlParamsParser, Rack::Head, Rack::ConditionalGet, Rack::ETag, RequestStore::Middleware, OpenIdAuthentication
Environment               development
Database adapter          mysql2
Database schema version   20170607051650