We have discussed hadoop and its HDFS management tools for big data system, which works horizontal scaling for data distribution and can be used for data warehousing. can manage big data/heavy data
There is another BIG Data system called MongoDB, which is again an open source. this is very developer friendly NoSQL system. as you know about RDBMS it has pre defined record structure and rows size is static. so for developer if they want to think and make some changes in the metadata by adding any columns or make changes in data type of the column will intern has to make the changes into the complete data and its related indexes. MongoDB is document oriented NoSQL.
MongoDB consider record as a document and you can dynamically add the columns into it and for developer its not necessary to input all the column information into one record/document. this way developer likes this database system.
MongoDB is written in C, C++, and java scripts. and it works same as developments.