How Does a Node Decide Which Low-Fee Transactions to Drop from Its Mempool?
Nodes have a finite amount of memory to store unconfirmed transactions. When the Mempool becomes full, nodes must prune or drop transactions to make space for new, higher-fee ones.
The decision is typically based on the transaction's fee-per-byte (or fee-per-gas). Transactions below a certain minimum fee threshold or those that have been pending for an excessive duration are usually the first to be dropped.
Glossar
Node
Entity ⎊ A Node is an individual participant computer that validates transactions, maintains a copy of the ledger, and contributes to the overall security and decentralization of the cryptocurrency Network.
Minimum Fee Threshold
Threshold ⎊ The Minimum Fee Threshold represents the lowest acceptable fee rate, often enforced by node relay policies, required for a transaction to be considered valid and propagated across the network.