selective_cache_purge_redis_database per server?

[livid]

Is it possible to specify different selective_cache_purge_redis_database per server?

Why I needed this is that one of the servers has too many cached items, it slows everything down. If it is possible to use selective_cache_purge_redis_database per server, purging on other servers with fewer cached items could become faster.

Currently when I set different selective_cache_purge_redis_database for different server, I get this error message:

nginx: [emerg] "selective_cache_purge_redis_database" directive is duplicate in ...

[wandenberg]

Not in the current version. It would require some refactoring on both ends, composing the index on Redis an on the purge location.
One quick/temporary solution using the current code is splitting your Nginx instance with multiple servers to 1 + n instances, one instance to each server and Redis database and another instance doing the routing to the servers based on the domain/port.
I know that is probably not the answer you want to, but will allow you to solve the issue without having to change the module code.