Using Plone 4 and pas.plugins.sqlalchemy with many users

I've been using pas.plugins.sqlalchemy to provide an RDBMS backend for authentication and memberdata storage, using MySQL. Authentication works perfectly and member data is correctly stored and retrived on the RDBMS. The current users are over 20.000

However, user enumeration takes ages. I have checked the "Many users" in the Plone Control Panel / Users and Groups section but even a simple user search takes a near infinite amount of time. By debugging the plugin.py script I noticed that enumerateUsers() is called as many times as the number of users stored; therefore, an enormous amount of CPU time is needed to complete a simple sear开发者_JS百科ch request, as the query is matched against each username, one user at a time, one query at a time.

Am I missing something here? Isn't pas.plugins.sqlalchemy useful especially when you have a very large number users? Currently, I have the sql plugin as top priority in my *acl_users/plugins/User Enumeration* setup. Should I change this?

I've pretty much inherited maintenance pas.plugins.sqlalchemy - but I haven't personally used it for more than a handful of users, yet. If you file a bug at https://github.com/auspex/pas.plugins.sqlalchemy/issues, I'll see what I can do.

I don't think it can make much difference what order the enumeration occurs - it still has to enumerate all the users in the SQL db. So it either does them before the ones found in the ZODB, or after. It sounds as if the problem begins with Zope - calling enumerateUsers() once per user seems excessive - but even so, it shouldn't be necessary to make a request to the relational db per enumeration.