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

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

Li开发者_运维技巧ke 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?

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.

Just my two cents:

I dont think you can do what you want on Google App Engine directly. If you really need other databases, then Amazon's EC2 may e what you are looking for.

Also, Take a look at this: Using Quercus® to Run the WordPress PHP blog on Google App Engine

Yes, you can use Cassandra database on Google App Engine but in its flexible environment. But, as of now, flexible environment is in Beta version and is not recommended for production use.