将会话数据存储在数据库和内存缓存中

Question

Google App Engine for PHP stores session data in memcache, which is nice and fast (and cheap), but session data from memcache seems to be clearing out after 8-10 min, which is much less than I need it. Following Google's advice,

...data in App Engine memcache may be flushed periodically, meaning any session information will be lost. For longer-lived sessions, it may be preferable to use an alternative storage service such as Cloud SQL. ( https://developers.google.com/appengine/docs/php/#PHP_Sessions )

I'm using Zend_Session_SaveHandler_DbTable to store session data in the database. However, the downside to this, as far as I can tell, is having to access the database every page request (with latency and cost both going up).

my question

Is there a way to persist session data in the database but also use memcache so the database isn't hit every single time? (I'm using Zend Framework 1.12)

Answer 1

Sure. Just specify a custom session_set_save_handler that saves to both, and checks memcache first for loads, falling back to the database if it's not found.

Now, the session will still need to be saved to both (otherwise you might lose data when memcache is cleared), so the cost will probably remain similar, but it'll reduce latency since session saves are after the page is rendered, and thus not included in user-visible latency. It'll also reduce the number of reads needed to load the session.