Manual:$wgVirtualDomainsMapping

Database settings: $wgVirtualDomainsMapping
Mapping of virtual database domains to actual databases.
Introduced in version:	1.41.0 (Gerrit change 963291; git #8bae6836)
Removed in version:	Still in use
Allowed values:	(array)
Default value:	[]
Other settings: Alphabetical | By function

Details

Mapping of virtual database domains to actual databases.

Virtual database domains are listed under the DatabaseVirtualDomains property in extensions' extension.json file. Extensions will use a virtual domain name when connecting to a table, which they expect might not be in the wiki's main database. This mapping will determine what actual database to connect to.

Usually, virtual database domains are used either because on a wiki farm, multiple wikis should share the same table or because the table contains a lot of data and the extension wants to allow for the flexibility of storing it separately. It's up to the extension to document the expected usage patterns of its virtual DB domains.

If no entry is set, the virtual database domain will be mapped to the main database of the wiki. For example, to send read-write queries of virtual domain 'virtual-example' to 'myexample' database in 'mycluster' cluster. The config should be like this:

[ 'virtual-example' => [ 'cluster' => 'mycluster', 'db' => 'myexample' ] ]

If the domain should use tables in the local database (for each wiki separately), set the 'db' to false.

If you want to use a database in your main (or only) cluster, omit 'cluster'. For example:

[ 'virtual-centralauth' => [ 'db' => 'centralauth' ] ]