[wp-hackers] Max number of WP sites per MySQL DB

[Elizabeth Buckwalter]

On Tue, May 11, 2010 at 2:35 PM,
<wp-hackers-request at lists.automattic.com> wrote:
> Message: 7
> Date: Tue, 11 May 2010 15:42:23 -0500
> From: Andy Skelton <skeltoac at gmail.com>
> Subject: Re: [wp-hackers] Max number of WP sites per MySQL DB
> To: wp-hackers at lists.automattic.com
> Message-ID:
>        <AANLkTimziBYnyz32A4Y4yMU83XepJ4Gs8cQa1IW6QpCL at mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1
>
> On Tue, May 11, 2010 at 12:58 PM, Otto <otto at ottodestruct.com> wrote:
>> You might ask the WordPress.com folks. They're running one big
>> installation, they can probably tell you how they've subdivided to
>> help performance.
>
> Very low-precision numbers follow.
>
> We have 10^8 blogs spread across 10^2 master servers, each containing
> 10^3 databases.
>
> So the number of blogs per database is about 10^3.
>
> We developed a custom database class to deal with this and we released
> the main parts of that code as HyperDB:
> http://wordpress.org/extend/plugins/hyperdb/
>
> Andy

1000 blogs per database and 1000 databases per server.  Are these
physical servers or  otherwise?  And is there one master database
server that uses the slaves or are there several masters per site
group?

I'm interested in knowing at what the physical limitations are to the
quantity of sites in a single database instance.  I understand that it
depends on the OS, but I can't seem to find the actual number.  Like
linux is limited to this number of database tables and windows is
limited to this number.  Is there a chart or graph anywhere?  It seems
like this is something that should be in a sys admin "manual"
somewhere, so others can rtfm.

If 1000 blogs per database is what you guys are doing, then it seems
that I would have to worry about memory before site limitations.  I
just don't want to have to scramble if we hit up that limitation
before expected.

-- 
Thanks,
Elizabeth Buckwalter