Use tag as dynamic database name

[sgohl]

Consider a fluent configuration 30-ish lines starting with this:

  <store>
    @type couch
    host couch
    port 5984
    database <tag-name>

   ... more stuff

now imagine your application want to log messages having hundrets of different tags.
You don't want to copy the same configuration all over and over again, as only the database name changes. How to take the tag out of the message to set the database name ?