pub const EXECUTION_WITNESSES: &str = "execution_witnesses";
Execution witnesses column family: Vec<u8> => Vec<u8>
Vec<u8>
// let mut composite_key = Vec::with_capacity(8 + 32); // composite_key.extend_from_slice(&block_number.to_be_bytes()); // composite_key.extend_from_slice(block_hash.as_bytes());
serde_json::to_vec(&witness)