can we use cassandra / couchdb / mongodb with google app engine infrastructure?

Question

Is there anyway we can use Google App Engine but do not use google's bigtable?

Like for storing my data, I would prefer to use cassandra and have the ability to plug and unplug additional database servers.

And say if I would like to use CouchDb/MongoDb instead is it supported in the GAE's infrastructure?

Answer 1

Short answer: No.

Longer answer: It depends how you want/need to use the database systems. There is no way you could run those system directly on AppEngine. But if low-latency was not a prerequisite (as would be the case with infrequent/periodical fetches of data) then you could set them up on another host with some kind of HTTP API, and query your services from appengine using urlfetch.