Roll your own SQL session store
Posted 19 Dec 2005
The alert reader may have noticed that I'm using my own SQL session store, which provides much better performance than the default ActiveRecordStore shipping with Rails.
I have decided to publish the source code here. If you are using Mysql, simply unpack the files into your lib directory and make SQLSessionStore your session storage.
require 'sql_session_store'
require 'mysql_session'
ActionController::CgiRequest::DEFAULT_SESSION_OPTIONS.
update(:database_manager => SQLSessionStore)
SQLSessionStore.session_class = MysqlSession
MysqlSession.eager_session_creation = true
The improved performance is due to a number of factors:
- fixed number of known DB columns
- retrieve only fields into the session that are actually used to create the session for a controller
- offloading most of the work to the DB, including updating the created_at and updated_at fields
- hard coded Mysql statements
As a consequence, if you want another DB, other DB column names, don't want created_at or updated_at fields, you'll have to change the code.
I have uploaded HTML representations of the call trees for ActiveRecordStore and SQLSessionStore. If you inspect them closely, you'll see how much time ActiveRecordStore spends in just creating the SQL statements and how much simpler the call tree is for SQLSessionStore.
If you adapt the provided code for other database systems, I'd be happy if you sent me the code, and I'll add it to the download after reviewing. The required changes are probably pretty small, but I currently don't have the time to test other DB systems.
Enjoy!
