Couchdb Interview Questions

CouchDB is an open-source non-relational NoSQL database by Apache. It is written in ‎Erlang‎, ‎JavaScript‎, ‎C‎, ‎C++

Uses of CouchDB are as stated;

• It can be used directly to write a client’s application without the use of any other server reducing the development time.
• It helps to replicate the database of client and the filter feature helps to replicate the database of the specific user.

The key features of CouchDB are as stated below.

• JSON documents – Each and every data is stored in JSON document.
• RESTful interface- Each and every data task and management can be done via HTTP.
• N-Master replication- Unlimited amount of masters can be used for replication topologies.
• Built for offline – This database can replicate to devices (e.g. Android phones) and can be used in offline mode. But the data will be in sync when the device is back online.
• Replication filters – Filters can be applied to replicate different nodes in the database.

  There are several reasonsfor CouchDB not using Mnesia. Few of them are:

• The overall storage limits up to 2 gigs per file.
• There is a requirement of validation and fix up of cycle once there is crashes or power hence, for large file fix up time is prohibitive.
• Sometimes Mnesia is not suitable for large-scale database hence it creates a hindrance.

Earlier when CouchDB was started it was written in C ++, but soon it got replace by Erlang. Erlang OTP platform has been an appropriate match till date. The default view server of this database uses Mozilla’s spidermonkey javascript etc. 

CloudDB is a framework for python application, helps to access and manage CouchDB data. It allows the user to manage CouchDB server, database, and doc management and to view access. Each and every objective here reflects python objects for convenience.

 ETL testing is the basic procedure of writing scripts for the automated testing process, there is no need of any additional technical knowledge other than the software knows how. This testing is one of the fast and systematic testing that gives the top result.

Manual testing uses other testing and seeing the procedure and requires a technical knowledge of SQL and shell scripting. It is a time and efforts consuming procedure and is prone to errors.

Cubes are the data processing units that comprise facts and dimensions from the database. Gives the multi-dimensional analysis.
OLAP stands for Online Analytics processing and it stores a large amount of data in a multi-dimensional form that can be used for reporting purposes.

Elements in couchbase Nodes are;

1. Index service
2. Data service
3. Cluster manager component
4. Query service

  This server involves two functional blocks, which are;

1. Data manager
2. Cluster manager

MongoDB and CouchDB are traditionally open sources No SQL, document-oriented database.   Apart from storing the data outside, they have nothing in common. Even their interface storage and replication methods are different in each and every approach.

CouchDB is simple and easy to maintain no additional cost or efforts are given by the user to maintain this Database. It is flexible and has more scalability, which makes it a better product among others.

Based on the requirements and assumptions in the project a particular kind of database is chosen. CouchDB offers few out of the box features and this leads to the high demand of this database irrespective of challenges. Discussing the replication, multi-master replication seems attractive to the clients in the context of using this database in their project.

Still, the challenge remains in replication is conflict resolution. Maintenance of this database is quite simple and affordable. It doesn’t require too much caring and attention. This is considered as one of the most stable and user-friendly DB and crashes only in critical situations. But it is not always possible to save and protect the whole data after a crash, sometimes data can be lost forever if the proper process not followed. One of the other advantages is as it only uses JSON and HTTP, it reduces the use of middle server and cut downs the cost and is used directly from browser JavaScript.

Best example, which can be given here, is when the user does not wish to change the document data too frequently and without this can define all possible queries in advance.  Apart from these services the CouchBase server can fulfill several other requirements like SQL integration, scale-out architecture, core database engine etc. 

Couchbase is a Server, also known as Membase, is an open-source, distributed (shared-nothing architecture) multi-model NoSQL document-oriented database software package that is optimized for interactive applications. These applications may serve many concurrent users by creating, storing, and retrieving, aggregating, manipulating and presenting data. And also, Couchbase Server is designed to provide easy-to-scale key-value or JSON document access with low latency and high sustained throughput. It is developed to be clustered from a single machine to very large-scale deployments spanning many machines. A version originally called Couchbase Lite was later marketed as Couchbase Mobile combined with other software.