Identifying Exchange-By-Fee (RBF) Transactions in Bitcoin Core

As a Bitcoin enthusiast, monitoring the mempool for specific transaction patterns can be valuable in analyzing network behavior, optimizing node performance, or even identifying potential blockchain issues. One such pattern is the Replace-By-Fee (RBF) mechanism, which allows miners to update their transactions on the chain without incurring a rejoining fee. However, this feature requires a methodical approach to identifying when a transaction in the mempool uses RBF.

What is Replace-by-Fee (RBF)?

At the core of Bitcoin, RBF is a mechanism that allows miners to update their transactions before they are included in the next block. When a miner adds a new transaction to the mempool, it must be confirmed by other nodes before it is accepted into the blockchain. If the added transaction is deemed invalid or has insufficient fees, it will be rejected and a rejoin fee will be charged. However, if the transaction meets the requirements, it can be added to the next block without triggering a rejoin.

Does Bitcoin have a core method that identifies RBF transactions in the mempool?

You will need to use a combination of manual analysis and programming to identify transactions that use RBF. One approach is to store current transactions in the mempool and compare them with newly added transactions. Here is an example Python code snippet:

import queries
def check_rbf_transactions(mempool_url):









Initialize lists to store RBF transactions
rbf_transactions = []

Loop through each transaction in mepool
for transaction in mempool.get_transaction_list():

Check if the transaction uses fee swapping (RBF)
if transaction.get('rbf'):

Add the RBF transaction to the list
rbf_transactions.append(transaction['data'])
return rbf_transactions

Example usage:
mempool_url = '
rfb_transactions = check_rbf_transactions(mempool_url)
print("RBF transactions:")
for i, transaction in enumerate(rbf_transactions):
print(f"Transaction {i+1}: {transaction['data']}")

This code snippet uses the Bitcoin API to load mempool transactions and check RBF transactions. The check_rbf_transactions function takes a URL pointing to the mempool as input and returns a list of RBF transactions.

Manual Analysis

Alternatively, you can manually analyze the mempool data by comparing each transaction to newly added transactions. This approach requires significant manual effort, but produces accurate results. Here is an example Python code snippet:

def check_rbf_transactions_manual(mempool_url):

Initialize lists to store RBF transactions
rbf_transactions = []

Loop through each new transaction in mempool
for i, transaction in enumerate(mempool.get_transaction_list()):

Compare the current transaction with the newly added ones
if i > 0 and all(transaction['data'] != x['data'] for x in mpool.get_transaction_list()[:i]):

Append the RBF transaction to the list
rbf_transactions.append(transaction)
return rbf_transactions

Usage example:
mempool_url = '
rfb_transactions = check_rbf_transactions_manual(mempool_url)
print("RBF transactions (manual analysis):")
for i, transaction in enumerate(rfb_transactions):
print(f"Transaction {i+1}: {transaction['data']}")

This code snippet compares each new transaction with all previous ones and identifies cases where the current transaction uses RBF.

Conclusion

Identifying transactions that use Replace-By-Fee (RBF) is a difficult task, but can be accomplished through a combination of manual analysis and programming.