limits of number of collections in databases

Question

Can anyone say are there any practical limits for the number of collections in mongodb? They write here https://docs.mongodb.com/manual/core/data-model-operations/#large-num

Answer 1

No More Limits!

As other answers have stated - this is determined by the size of the namespace file. This was previously an issue, because it had a default limit of 16mb and a max of 2gb. However with the release of MongoDB 3.0 and the WiredTiger storage engine, it looks like this limit has been removed. WiredTiger seems to be better in almost every way, so I see little reason for anyone to use the old engine, except for legacy support reasons. From the site:

For the MMAPv1 storage engine, namespace files can be no larger than 2047 megabytes.

By default namespace files are 16 megabytes. You can configure the size using the nsSize option.

The WiredTiger storage engine is not subject to this limitation.

http://docs.mongodb.org/manual/reference/limits/