Why isn’t a private blockchain effectively a ‘fancy’ database?

A private blockchain could be considered a database with the notion that it does store data, but much more than calling it a fancy database, it’d be better considered a degraded version of our modern day database.

Our Modern day to day databases options are mainly split between SQL like and NoSQL for majority of purposes that we encounter.

Each one of them has specific use cases and scenarios where it makes sense to use a particular database. Blockchain isn’t any different.
Similarly, a private Blockchain would prove to be a rather shitty database as you scale up for all your data isn’t properly arranged. 
Data is scattered all around and it is quite hard to make sense of dirty mismanaged data while running analysis and extracting analytics.

NoSQL databases make use of not having to chalk up a structure, draw tables and columns in the very beginning. NoSQL exhibits no structure, now imagine a blockchain to be that times ten.

Databases are designed for a specific purpose or rather used on whichever suits best for their necessity, quite similar to how the whole entirety of Blockchain was developed as a proof of concept for Bitcoin.

I have previously worked with MongoDB and have heard people criticize it and move on to postgresql (SQL like) for security reasons and varied memory usage.
I find mongoDB perfect for prototyping on and hence I decided to stick with MongoDB. It ultimately boils down to what utility satisfies your needs.

I’m going to address a private Blockchain’s use case specifically since it certainly is a lot better than making a case study of all the databases there ever existed.

Private Blockchains or consortium networks are built to enhance communication between major entities where there usually a mix of small volume of large importance decisions to be taken and large volume of small importance decisions to be taken in mutual interest.

It is highly unlikely that you see a school or a design company use a private blockchain to document internal operations, but it is quite likely to see Banks and multimillion dollar corporations implement private consortium networks to take decisions. Private blockchains, just as a public blockchain require that transactions(usually containing metadata) are mined. This whole setup isn’t as expensive as compared to Public blockchain, but rather writing permissions are restricted to the elite group alone.

Mining forms an integral part of any blockchain. 
In consortium blockchains, there are a limited few that act as endorsers that are given writing permission to write on the blockchain. Public Blockchains incentivize mining by providing block rewards and transaction fees, but private blockchains have no need for block rewards, but rather choose to implement the notion of transaction fees for better accountability. 
Members involved in usage of private consortium blockchains aren’t incentivized or focussed on transaction fees or block rewards, but are invested in using blockchain as a utility to carry out their necessary function of documenting decisions and operations.

Banks, Multimillion and Multibilliondollar corporations have a need to document private data, operations and justify the same within the consortium network alone and hence have a need to use private blockchain network to facilitate the same.

I’ve known IBM’s hyperledger to be of great help in setting up in setting up a private consortium blockchain. It is well recommended to try it out for implementing your very own Private consortium network.

Good Luck

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I hope this was helpful.