Is blockchain a decentralised database?

Question

I understand bitcoin uses blockchain technology to maintain a decentralised ledger of all transactions. I have also read many posts eluding to future applications of blockchain technology, none of which have been very clear to me.

Is blockchain technology simply a decentralised database with consensus validation of the data? If this was the case surely the db would grow to be too large to be effectively decentralised?

To help me understand, can anyone point me to a clear example of a non-bitcoin blockchain application?

Answer 1

Yes, its true that the blockchain database would grow overtime which is what is called "blockchain bloat". Currently the blockchain growth of Bitcoin is roughly less than 100mb a day. Today (2016) the bitcoin blockchain takes up about 60-100GB of space which took about 6 years to accumulate. It is indeed growing faster, but also limited by the blocksize cap of 1MB per block (every 10 minutes). Some proposed solutions have been:

• SPV nodes: This is how your phone doesn't need to download the entire blockchain, but retrieve its data from SPV nodes that have the entire blockchain.
• Lightning network - This is how Bitcoin can overcome the 1MB memory cap.

Those are just some of the solutions for bitcoin that I know of, as for altcoin related solutions. NXT/Ardor has implemented the solution of pruned data, because NXT/Ardor gives the ability to upload arbitrary data and messages onto its blockchain, the bloat is much more apparent in this scenario. The NXT/Ardor blockchain has the ability to delete previous data every 2 weeks and only keep the hash of its data on the blockchain which only takes a few KB. They also have the ability to retain all of the blockchain data with the pruning turned off which would mark a node as an Archival Node and other nodes can replicate this node and become an Archival node.

From my understanding NXT/Ardor has been one of the few blockchains that has production ready decentralized data storage system, marketplace, stock exchange, and messaging system built into its blockchain.

Answer 2

Blockchain is combination of p2p network, decentralised database and asymmetric cryptography P2P network means you can transfer data between two deferent network nodes without any middleman, decentralised db means every nodes of network has one replica of network db and asymmetric cryptography means you can use digital signature to validate the authenticity and integrity of a messages