[wp-hackers] 10K Users?

[Otto]

On Tue, Jan 31, 2012 at 9:37 PM, Rafael Ehlers <rafaehlers at gmail.com> wrote:
> This kind of problem came to me, in my last project, where we have 175K
> users and 55 usermeta for each user, THAT is problem, because you can't
> even access the wp-admin, we haven't figured yet why.
> Maybe because WP is making some kind of caching on this usermeta, don't
> know yet.
>
> But still, the site (user end) runs smoothly! It's kind of impressive!

It's unlikely to be an issue with the users table or the number of
users or even the number of meta. WordPress.org has a tad under 3
million registered users, with something like 20 million rows of meta
on the main usermeta table and dozens of other similar tables for
various things. Now, this is mirrored across a bunch of separate
database servers, but it scales fine.

The number of rows or size of your tables is rarely the main problem.
MySQL scales quite well in that respect, as do all other modern
databases. The real scaling problems lie in concurrency. The database
can be as big as creation and still serve things lightning fast thanks
to indexing, but even small databases will choke when you start making
thousands of requests per second to them.

If you're unable to load the back end at all, then it's unlikely to be
a table holding a mere few million rows that is the problem. Databases
with *billions* of rows can easily be made and will generally work
fine. Instead, it's more likely that you have a misbehaving
plugin/theme or other form of code causing the system to choke.

-Otto