What is a data query? The role of data queries for blockchain

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2022-12-04 00:46:42

What is a data query?

Data query is searching and displaying data, including 2 main activities: indexing and querying, in which:

  • Querying (also known as querying) is the operation of finding data by filtering specific criteria.
  • Indexing is a way to sort data to maximize the efficiency of querying.

If you are looking to read a book, finding books in a library will be much faster and easier than finding books in a warehouse with many different stacks of books. Because the books in the library are clearly classified (what genre the books are in) and are arranged in order (volumes 1 to 2, books that start with the letter A, through the letter B…), and books in Warehouses are not arranged in a certain order.

In the context that data is considered the new oil of the 21st century and the amount of data is increasing rapidly on a global scale, Indexing and querying are playing an increasingly important role.

Problems and solutions for the ability to query data from blockchain

The problem of blockchain in querying data

Blockchain is a breakthrough technology in bringing transparency and decentralization. Essentially, a blockchain is a ledger containing data that cannot be modified and anyone has access to view the data in that ledger. The emergence of new ideas such as smart contract, oracle is the premise for many development branches such as: DeFi, NFT, SocialFi… Accordingly, the demand for data querying on blockchain is also increasing.

Although it also plays the role of storing data, blockchain has a different design from the databases (where data is stored) in use today. It is this that gives rise to problems related to querying data on the blockchain.

The main issues affecting data query efficiency on the blockchain include:

  • Platform Design: The blockchain structure consists of many data blocks (blocks) linked together to form a chain. This structure does not allow storing data entirely into a block. Therefore, finding certain information in a sea of ​​data is time consuming and inefficient.
  • Missing query language: Usually, each type of database has a query language that helps answer questions according to specific criteria. Because blockchains use a new programming language, they are not compatible with any current query languages. Information retrieval with high technical difficulty requires dapp developers to have good export programming ability.
  • Restrictions related to API: API is a method to help connect data systems together. However, currently the connected data part is quite simple and has not been utilized to high efficiency.

The above problems make blockchain a safe “bookstore”, but not so ideal as a “library” where anyone can easily find information. Therefore, if it wants to be widely applied, blockchain needs solutions that make information retrieval easier.

Solution to improve the ability to query data from blockchain

From the above problems, we can identify the main characteristics of solutions that improve the ability to query data from the blockchain. These include:

  • Use centralized storage, where information is comprehensively stored and easily searchable.
  • Develop and use a programming language that helps query data from the blockchain.
  • Ensure transparency in data storage order for easy querying in the system.

The solution being applied to improve the ability to query data

To improve the ability to query data from blockchain, current solutions possess the following main characteristics:

Using the services of centralized parties

Currently, there are many companies that provide centralized database services and APIs for blockchain, typically Infura, Alchemy… However, in essence, these services violate the goal of achieving Decentralization of blockchain in general and dapps in particular. Another limitation is that centralized services are likely to be affected by external actors.

Use a decentralized party service

There have been projects developed to solve the problem of data query but still ensure decentralization, typical of which is The Graph.

The Graph allows users to create Subgraphs (child nodes of The Graph). The developer will choose the data to be indexed, the Subgraph will be in charge of indexing and storing the indexed data from the blockchain. The Graph uses the GraphQL query language which makes it easy to connect or leverage indexed data from subgraphs with dapps.


Build your own storage system

Building your own storage system is a reasonable solution if you want to optimize performance and data query ability. However, such a storage system requires a large investment and high maintenance costs.


The demand for data querying on the blockchain is growing. Improving the ability to query data is a necessary condition for blockchain to accelerate integration in the current information age.

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