Mediawiki custom namespaces id change - namespaces

Question

I am currently working on an internal Mediawiki and we are using a lot of custom written extensions.
Because we did no know better, defined custom namespaces for our own extensions and articles with an id that is smaller than 3000.
For example:
define('NS_bla', 1100);
$wgExtraNamespaces[NS_bla] = "bla";
define('NS_bla_TALK', 1101);
$wgExtraNamespaces[NS_bla_TALK] = "bla Talk";
We did this with several different extensions. Now we read on the official documentation (http://www.mediawiki.org/wiki/Extension_default_namespaces) that custom namespaces should use id's that are 3000+.
Therefore my question: How can we easily change the IDs of the namespaces on the production instance, without messing up with our current dataset? How could we tackle this problem? I could not find any information on the Mediawiki documentation.
Thank's a lot in advance and
Cheers from Germany,
Fabian

Answer 1

To answer the question, you would need to update the page table with the new namespace ID:
http://www.mediawiki.org/wiki/Manual:Using_custom_namespaces#Use_a_database_query
To fit this to your occassion, it would be:
UPDATE page
SET page_namespace = 3000
WHERE page_namespace = 1100
You shouldn't have to replace the page_title since these articles are already in another namespace.
Just please remember to back up your database before trying this.