LevelDB is a library that provides a high-performance key-value storage store. It is an open source, cross-platform storage library developed by Google with the goal of creating a fast and reliable data store for application developers. LevelDB was designed to work efficiently on large, disk-based stores, and so it is perfect for storing Bitcoin data.
In the case of Bitcoin, LevelDB is used to store the transaction history and account balances for every Bitcoin address. All account balances are stored as a key-value pair, with the address being the key and the balance being the value. LevelDB also stores transaction information, such as sending and receiving addresses, amounts, and timestamps.
This data is stored on each full node and is then synchronized across the blockchain. The use of LevelDB ensures that data is stored securely and efficiently, allowing for a faster retrieval process. LevelDB is also highly scalable, allowing it to easily read and write large amounts of data quickly.
As the technology continues to develop, more applications are using LevelDB due to its high performance and scalability. With the increasing popularity of cryptocurrencies such as Bitcoin, the use of LevelDB is becoming more prevalent.