The first public release of the MangoDB project is available, offering a layer with an implementation of the MongoDB document-oriented DBMS protocol running on top of the PostgreSQL DBMS. The project aims to provide the ability to migrate applications using the MongoDB DBMS to PostgreSQL and a completely open software stack. The code is written in Go and distributed under the Apache 2.0 license.
The program works as a proxy that translates calls to MangoDB into SQL queries to PostgreSQL, using PostgreSQL as the actual storage. The project is compatible with drivers for MongoDB, but is still at the prototype stage and does not support the advanced features of the MongoDB protocol, although it is already suitable for translating simple applications.
The need to avoid using the MongoDB DBMS may arise due to the transition of the project to a non-free SSPL license, which is based on the AGPLv3 license, but is not open, since it contains a discriminatory requirement to supply under the SSPL license not only the application code itself, but also the source codes of all components involved in providing cloud services.
Recall that MongoDB occupies a niche between fast and scalable systems that operate on data in the key / value format, and relational DBMS, functional and convenient in generating queries. MongoDB supports storing documents in a JSON-like format, has a fairly flexible language for generating queries, can create indexes for various stored attributes, efficiently provides storage of large binary objects, supports logging of operations to change and add data to the database, can work in accordance with the paradigm Map/Reduce, supports replication and building fault-tolerant configurations.
Source: opennet.ru