Can blockchain be stored in SQL or even noSQL database?

Question

From what i know, blockchain database isn’t stored in any single location, meaning the records it keeps are truly public and easily verifiable. No centralized version of this information exists for a hacker to corrupt. Hosted by millions of computers simultaneously, its data is accessible to anyone on the internet.
So my question is can we store blockchain in for example sql? or it can only be stored in a database that works on its own?

Answer 1

As a matter of fact, the currently available blockchain applications present users with only a few decentralized options to store data. These options include storing in the blockchain itself, peer to peer file systems like IPFS Decentralized cloud file storage, Distributed Databases like Cassandra, Rethink DB, and BigChainDB and Ties DB. 

However, there are pros and cons associated with each of them. Let’s dive deep into all of them. 

Although storing all data within the blockchain is the most simple and widely used process, there are enormous drawbacks that pertain to this storage process. This is because transactions take a lot of time to confirm, and blockchain networks are immutable. Immutability undoubtedly makes blockchain networks secure but is not efficient when it comes to data storage. When all blocks store and update data within blockchain, the blockchain size grows tremendously, thereby exceeding available hard drive capacity. Therefore, it is not advisable for users to store rich application content within blockchain ledgers. 

When it comes to IPFS, files are shared on client computers and all clients are united in a global system. Based on BitTorrent protocol and distributed hash tables, IPFS is content addressable and therefore it is impossible to forge content by a given address. But, users should stay online for sharing files and it is impossible to modify or remove files once uploaded. 

With Decentralized cloud file storage, some of IPFS’ predicaments are addressed. Here data is stored in the user’s systems as rent as opposed to the IPFS version of storing data in data centers. Examples of decentralized cloud file storage systems are Sia, Storj, and Ethereum Swarm. Despite being fast, reliable and capacitive, these file storage systems cater to static files only. Plus, they are not free. 

Next, come Distributed Databases. With Distributed NoSQL Databases, it is possible to store structured data and seek advanced querying capabilities. However traditional SQL databases cannot be distributed as the CAP theorem restricts them. In NoSQL databases, availability is chosen over consistency. But, all nodes become consistent over a period of time. Distributed databases are fast, efficient, fault-tolerant (not byzantine proof), and support rich query language. The only constraint is that even one malicious node can destroy the whole distributed system. 

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