[HyperDB] Partitioning wpmu data

Felix Gushansky felix.gushansky at internetbrands.com
Mon Apr 27 17:40:35 GMT 2009 

Right, I did this initially, Callum, and here is what I saw:

- if I exclude *both* the define('WPMU', true); and the
require('db-settings.php'); then everything works fine. If at that point
it's already using db.php, as you seem to suggest, then we're in good shape.

- if in wp-config.php I include one of the two statements - or both - I get
the error described below. This is unexpected, since, according to readme in
the package, I should be able to just include define('WPMU', true); and
everything should work using the default settings. In my case it does not.

Not sure if it's a symptom of another problem, which could be the reason I
can not make it work with require('db-settings.php');

Thanks,
-- Felix


> From: Callum Macdonald <lists.automattic.com at callum-macdonald.com>
> Reply-To: <hyperdb at lists.automattic.com>
> Date: Mon, 27 Apr 2009 10:19:13 -0700
> To: <hyperdb at lists.automattic.com>
> Subject: Re: [HyperDB] Partitioning wpmu data
> 
> Felix, you're absolutely right, you do need to include db-settings.php
> in wp-config.php.
> 
> As I understand it, you don't need to configure the default db settings.
> HyperDB will automatically pick up the settings in wp-config.php and use
> those. So if you just want to test, install db.php in wp-content/ and
> don't include db-settings.php.
> 
> Then you can try adding db-settings.php and see if it works as you
> expect.
> 
> Cheers - Callum.
> 
> On Mon, 2009-04-27 at 09:31 -0700, Felix Gushansky wrote:
>> Hm, but the add_db_server (a function in db.php) is being called from
>> db-settings.php, which I think *won't* get executed unless I require it in
>> the wp-config, no? That add_db_server call carries the info about my (in
>> this case default) database.
>> 
>> Thanks,
>> -- Felix
>> 
>>> From: Callum Macdonald <lists.automattic.com at callum-macdonald.com>
>>> Reply-To: <hyperdb at lists.automattic.com>
>>> Date: Sun, 26 Apr 2009 19:18:14 -0700
>>> To: <hyperdb at lists.automattic.com>
>>> Subject: Re: [HyperDB] Partitioning wpmu data
>>> 
>>> I don't think you need to do add any require() calls. WordPress will
>>> automatically pick up a file called db.php in wp-content.
>>> 
>>> As far as I'm aware, you can drop in the HyperDB class and it will
>>> automatically fall back on the default db details, in effect changing
>>> almost nothing.
>>> 
>>> Cheers - Callum.
>>> 
>>> On Fri, 2009-04-24 at 11:01 -0700, Felix Gushansky wrote:
>>>> Hi, folks. Before getting into the depths of db partitioning I am having
>>>> trouble making the thing to work with just my default db. Seemingly the
>>>> simplest thing in the world: added define and require lines to wp-config
>>>> (at
>>>> the top), dropped in db-settings.php, uncommented the default add_db_server
>>>> ('global') line in it, made sure all variables are defined and good,
>>>> dropped
>>>> in db.php in the wp-content dir -- just like prescribed. Croaking in the
>>>> wpmu-settings.php - I think 'SELECT * FROM sites' does not give back the
>>>> data resulting in 'count( $sites )' to be equal to 1 -- which is what seems
>>>> to be expected. As soon as I disable the plugin (commenting out the define
>>>> and the require lines in the wp-config.php) everything is back to normal.
>>>> 
>>>> Any ideas what could be wrong?
>>>> 
>>>> Thanks,
>>>> -- Felix
>>>> 
>>>> 
>>>>> From: Callum Macdonald <lists.automattic.com at callum-macdonald.com>
>>>>> Reply-To: <hyperdb at lists.automattic.com>
>>>>> Date: Thu, 23 Apr 2009 11:57:29 -0700
>>>>> To: <hyperdb at lists.automattic.com>
>>>>> Subject: Re: [HyperDB] Partitioning wpmu data
>>>>> 
>>>>> As Andy said, HyperDB is about on the money for what you want.
>>>>> 
>>>>> The biggest challenge you'll face will be moving the data. You have 11k
>>>>> tables in one database right now, you need to move those to new
>>>>> databases. The MultiDB class uses the same method as HyperDB did
>>>>> originally, 4096 databases, first 3 digits of the md5 of the blog_id
>>>>> (the NNN number).
>>>>> 
>>>>> I think your best bet will be to use HyperDB and create your own system
>>>>> for managing which blog is in which database (maybe a lookup table like
>>>>> Andy mentioned). That way you'll be able to migrate the data over time.
>>>>> 
>>>>> Other options that occur to me:
>>>>> 
>>>>> Migrate all the data at once. Take the whole system down for a few hours
>>>>> and move all the tables as you need to. Pray nothing goes wrong. :-)
>>>>> 
>>>>> You could add some logic that checks if the table is found in the new
>>>>> target database, and if not, fall back on the global database. That
>>>>> would allow you to move blogs one at a time, without changing any code.
>>>>> If the blog tables are in the new database, the queries go there, if
>>>>> not, the queries go to the master table.
>>>>> 
>>>>> If you're looking for help, you could speak to the guys at Incsub. I'm a
>>>>> (present and about to be) retired staffer there, so I'm biased. :-)
>>>>> 
>>>>> Best of luck with the project.
>>>>> 
>>>>> Cheers - Callum.
>>>>> 
>>>>> On Thu, 2009-04-23 at 10:32 -0700, Felix Gushansky wrote:
>>>>>> Hello, folks. We have just inherited the site that uses wordpress MU (ver
>>>>>> 2.5.1) with MySQL 5 on the back. Soon we have learned that the blog db is
>>>>>> huge. Not size wise necessarily (it is slightly over a gig), but table
>>>>>> wise.
>>>>>> That db contains over 11,000 tables with the total of over 40,000 files
>>>>>> in
>>>>>> the same directory. That hugely affects performance AND maintenance ­ to
>>>>>> the
>>>>>> point in fact that we can not backup the db using mysqldump. We had to
>>>>>> write
>>>>>> a script dumping a table at a time.
>>>>>> 
>>>>>> So, we need to scale somehow. That¹s why he have looked at HyperDB, which
>>>>>> seems to have been built just for that. However, the problem we are
>>>>>> seeing
>>>>>> is that in our case the tables in the blog db are created and named
>>>>>> dynamically. For each new user wpmu creates multiple tables (8?) in the
>>>>>> database and names them like wp_<nnnn>_comments, wp_<nnnn>_links,
>>>>>> wp_<nnnn>_options, wp_<nnnn>_postmeta, wp_<nnnn>_posts, etc, where <nnnn>
>>>>>> is
>>>>>> a four digit integer. Can we take advantage of HyperDB in this case? And
>>>>>> if
>>>>>> not what are our options?
>>>>>> 
>>>>>> Thanks very much folks. Your help is very much appreciated.
>>>>>> 
>>>>>> -- Felix
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>>>>>> HyperDB at lists.automattic.com
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