Maximum number of databases supported by MongoDB

Question

I would like to create a database for each customer. But before, I would like to know how many databases can be created in a single instance of MongoDB ?

Answer 1

By default, you can run some 12,000 collections in a single instance of MongoDB( that is, if each collection also has 1 index).

If you want to create more number of collections, then use --nssize when you run mongod process. You can see this link for more details:

http://www.mongodb.org/display/DOCS/Using+a+Large+Number+of+Collections

Answer 2

There's no explicit limit, but there are probably some implicit limits due to max number of open file handles / files in a directory on the host OS/filesystem.

see: http://groups.google.com/group/mongodb-user/browse_thread/thread/01727e1af681985a?fwc=2