I have a bunch of Drupal 7 sites which all contain data related to our organization. Let's say Events and News. My ultimate goal is that each site can be searched independently and also searched from a central location where all sites can be searched.

For this, I am thinking of using Elasticsearch (but I am open to Solr too) and I installed Search API and the Elasticsearch Connector on my sites.

I set Elasticsearch to have one index and two types (one form News and one for Events).

The problem is that Elasticsearch Connector uses the nid as the _id under which content is indexed and my many sites will attempt to index nodes under the same nid.

Does anyone have experience doing this? Am I going about it completely wrong?