Storing Data in a Blockchain
A blockchain handles data differently than a traditional database. One of the biggest differences is that a blockchain does not support CRUD operations. The only database operations are Write, which is the same as Create, followed by populating data before writing, and Read. After data has been placed in a block and added to the blockchain, that data cannot change. A blockchain does not have Update and
Delete operations.
The other big difference between blockchain data storage and databases is their location. A complete copy of the blockchain is stored on every full blockchain node. Much of the difficulty in maintaining a blockchain network is ensuring that all blockchain nodes store the same data. Each blockchain implementation has strict rules for maintaining a synchronized blockchain across the network, and those rules make detecting differences between nodes easy (and quick).
This distributed storage property of a blockchain makes it extremely resilient, because the failure of any node or nodes will have a negligible effect on the rest of the blockchain network. Blockchain storage was never designed for high-performance situations. The storage method does support fast traversals through the block tree, but accessing individual data items within blocks takes some time. Remember that blocks can contain data in different formats, which must be filtered for searching.
