Mastering Blockchain Programming with Solidity

Limited storage

When your smart contract stores some variables/states, it has to be stored on the blockchain's ledger. The storage space of smart contracts is limited and costly. As the gas limit per block is limited, so is the execution of a transaction. The Ethereum blockchain should not be used as data storage or a replacement database. The blockchain is a kind of decentralized database; however, at the moment, the Ethereum blockchain cannot handle the processing of loads of data in a transaction. Blockchain technology is still evolving; in the future, it might be possible to even store large amounts of data and processes in a single transaction.

If you want to store big files or data on decentralized blockchains, you should look for Swarm, ...