Where to store data when creating a blockchain based solution?

Question

I have a question regarding the storage of data when creating a Dapp. For example i create a real estate website on ethereum blockchain where people will buy or sell properties on the basis of tokens or any traditional currency. Now where should I store all of my data. Should I store all of my data on blockchain using mapping or should i store all of my data in the database like "MySql" and store only the proof of it on the ethereum network. I have heard that its not a good idea to store all of the data on blockchain but then where should we store it if we want to maintain decentralization. Storing data on databases like MySql and MongoDB depicts decentralization. By data in a real estate website I mean:

1. Property information
2. Information regarding which user owns how many properties.
3. User information.
4. Information of the total number of tokens owned by a user.
5. etc

I would be very thankful for an answer.

Answer 1

Blockchain is a public ledger, which means whatever data you are going to store is visible. Storing sensitive data in blockchain would not be a good idea. Secondly storing data in the blockchain is expensive and cost money so its up to you how much data you are ready to store. On such application like yours its good practices to store less data and use blockchain for the payment with the help of Smart Contract.

If you want to store the data in the blockchain then you can use Mapping, Strucutre, Arrays and other data type. Where as storing of data should be tricky too so you can easily extract the relevant data which you can easily achieve by using mapping and structure.