How is Blockchain a distributed database

Question

In most places blockchain is cited as a distributed database. Does it mean we can store any type of data in blockchain like audio, video, pdf?

Answer 1

Think of blockchain as a relatively slow, very expensive database that provides excellent resistance to hacking and corruption. It's a Write-Once, Read Mostly (WORM) system.

You absolutely could store any data you want in a hypothetical blockchain. The practical limits are, you don't want to store very large chunks of data (so, not video); you probably don't want to store frequently changing data (so, not a thesis paper you're revising) -- unless it's important somehow to record every single change forever.

Because, its other feature is, once something is written to a blockchain, it's there forever.

Need to fix a typo? Then you add a new record with a correction.

Need to delete a record? Too bad, you can't. Best you can do is enter a new record saying that the record you wish to delete is "obsolete" or "repudiated" or "no longer valid" or "should be considered as deleted."

In short, it's wise to treat your blockchain as a permanent record.

1. Slow: the Bitcoin blockchain runs about 3 transactions per second (tps) and the Ethereum blockchain runs about 30 tps.
2. Expensive: the Bitcoin blockchain cost an average of US$ 8.22 per transaction in November 2017

To learn more about the blockchain, join Blockchain Course today.

Answer 2

Yes, it is possible. The simplest way would be to define a contract with two attributes, an address used for access control (so that only an account that you control can write to the contract) and a byte array for the actual storage container:

contract Storage {

   address owner = 0xdeadbeef...; // <= define the address you control (have the private key to)

   bytes32[] storageContainer;

   function pushByte(bytes32 b) {
      storageContainer.push(b);
   }

}

You don't really need a getter method as it is sufficient to synchronize with the block chain in order to retrieve the data stored in the contract.

Answer 3

Systems like Storj, Sia, Filecoin, and Bittorrent break files up into little pieces and store them in computers all over the Internet. They all use technologies commonly used in blockchain systems (merkle trees, hashes, digital signatures). None of them are actually blockchains.

Answer 4

You can’t store digital documents on the blockchain per-se. If you mean to store in the sense of Dropbox then no, but there are a few companies who use the blockchain in order to support file storage.

Answer 5

What you can do though is store a file and hash it. That hash is what is saved in the blockchain. You upload a file, the blockchain takes that file and uses a unique algorithm to generate a hash. Although you can’t retrieve the file because of the nature of hashes, which is a one way encryption, it can only be used as a digital stamp as to say “This file was uploaded”.