Ethereum: What keys are used in blockchain levelDB (i.e. what are the key:value pairs)?

I’ll provide an article on Ethereum’s blockchain structure, specifically focusing on LevelDB and node.js.

Ethereum’s Blockchain Structure: A Deep Dive into LevelDB

The Ethereum blockchain is a decentralized, public record-keeping system that enables transactions to be verified and stored on the network. To understand how this works, we need to break down its underlying architecture.

Blockchain Structure

The Ethereum blockchain consists of several layers:

• Block

  : A block is a collection of transactions. Each transaction consists of a sender, recipient, amount, and other relevant data.

• Chain: The chain is the sequence of blocks that make up the Ethereum blockchain. Each block contains a hash of the previous block’s hexadecimal representation.

• Header

  

  : The header is a unique identifier for each block. It includes metadata such as the timestamp, number of confirmations, and more.

LevelDB: A Distributed Database

To store the blockchain data efficiently, LevelDB, a distributed database, is used. LevelDB allows for fast lookups, writes, and updates to large datasets with low latency.

In Ethereum’s blockchain architecture, LevelDB is used to store the block headers and other metadata. This means that you can access specific blocks by their unique header ID.

Key/Value Pairs

To understand how key-value pairs work in LevelDB, let’s consider an example:

Suppose we want to retrieve a block’s header with the following key-value pairs: block_number, timestamp, and nonce.

• block_number is a unique identifier for the block.

• timestamp represents when the block was created (in seconds since the Unix epoch).

• nonce is an optional value that determines how many times the block’s creator can submit transactions before it’s confirmed.

To access this data in LevelDB, we would use the following key-value pairs:

| Key | Value |

| — | — |

| block_number | 1234567890 (the actual block number) |

| timestamp | 1643723400.000Z (the timestamp) |

| nonce | 42 (optional value) |

In LevelDB, this data is stored as a hash of the key-value pairs:

{

  "block_number": "1234567890",

  "timestamp": "1643723400.000Z",

  "nonce": "42"

}

Node.js and LevelDB

To access the blockchain database directly using node.js, you can use the leveldb package. Here’s a simplified example:

const level = require('level');


// Create a new LevelDB instance

const db = level(':memory:'); // ':memory:' is a special key that allows for memory-only databases


// Insert some data into the database

db.set('block_number', '1234567890', { timestamp: 1643723400.000Z, nonce: 42 });

db.set('transaction_hash', 'abcdefg');


// Retrieve a specific block's header using its ID

const blockHeader = db.get('block_number');

console.log(blockHeader);


// Update the data in LevelDB (optional)

db.update('block_number', { timestamp: 1643723401.000Z, nonce: 43 });

In this example, we create a new LevelDB instance and insert some data into it using set(). We then retrieve a specific block’s header using its ID and update the data if needed.

Conclusion

Ethereum’s blockchain structure is built on top of LevelDB for efficient storage and retrieval. By understanding how key-value pairs work in LevelDB, you can access the Ethereum blockchain database directly using node.js. However, keep in mind that this requires a LevelDB instance to be created and maintained properly.