Here is an article on the format of the contents of a block key in Bitcoind’s LevelDB:
Understanding the format of the block key contents in Bitcoind’s LevelDB
When working with Bitcoind’s LevelDB block index files, it is important to understand the format of the block keys and their contents. This is crucial for efficiently searching for specific blocks in the database.
What are block keys?
Block keys, also known as block IDs or block numbers, are unique identifiers assigned to each block in a Bitcoin blockchain. They serve as labels that help Bitcoind identify which block to process next during the block validation and verification process.
Format of a block key’s contents
The format of a block key’s contents is typically represented by a 64-bit integer (8 bytes) containing various fields, including:
0x01: A bit flag indicating whether the block key is valid
0x00-0x7F: Additional information about the block, such as its timestamp and/or other metadata
The more commonly used format of a block key’s contents in Bitcoind’s LevelDB is:
0x01 (validity)
| 0x00 0x00 0x00 0x00 (timestamp)
seconds since the start of the epoch| 0x01 (metadata, e.g. timestamp, size, etc.)
0x08-0x07 (block ID, a 64-bit integer)
0x00-0x7F (additional metadata or flags)
Byte position of specific blocks
To find the byte position of specific blocks within the database, you can use the blk field in the block key contents. This field specifies the starting address of a block.
For example, if you have a block key with a validity flag of 0x01 and metadata specifying a block ID of 0x12345678, the byte position of that particular block would be:
0x08-0x07 (block ID: 0x12345678)
starting addressExample use case
Suppose you want to search for a specific block in the database. You can create a blk field with the desired byte position and metadata, such as:
blk00029.dat | 0x01 (validity) | 0x08-0x07 (block ID: 0x12345678)
Then you can use Bitcoind’s LevelDB command line tool (bitcoind -db path/to/db -query blk00029.dat | grep block_id:0x12345678) to search for the specified block.
By understanding the format of the contents of a block key and using the blk field with the desired byte position, you can efficiently find specific blocks in Bitcoind’s LevelDB database.