Appropriate database for web analytics? I am working on the web analytics it is similar to google analytics,  Currently i am using the mongoDB.
Problem using MongoDB
Writing and reading is performed at the same time so after some point writing is bit slow. So i am looking for appropriate database which is suitable for following requirement.
Requirements

Open Source

Can adapt large volume of data.

Better performance while aggregating the data.

Time based aggregation.

Real time processing.

Driver support for node.js and java.


Database should be scalable with node.js and java
 Saving the data using java.

 Fetching the data using node.js
I think you are looking for DBs that are designed for analytics.
May be you should check these solutions:.
some data storage solutions specific to realtime analytics

Druid
Spark
Cassandra
Hbase
hypertable
accumulo

reference:

http://kkovacs.eu/cassandra-vs-mongodb-vs-couchdb-vs-redis
http://relistan.com/cassandra-vs-mongo/