Network, Relay & Client Sync • Estimated 35m

Mempool Unbroadcast Set

protocol.mempool-unbroadcast-set

Bitcoin Core tracks locally submitted transactions that are in the mempool but not yet verified as seen by the wider network in an unbroadcast set. This explains why nodes remember some txids for later rebroadcast attempts instead of treating mempool admission as proof of propagation.

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Curated resources (3)

• Bitcoin Core Academy: Mempool Unbroadcast Set (article) Primary explanation of m_unbroadcast_txids, removal conditions, and periodic rebroadcast attempts.
• Bitcoin Core Academy: Transaction Relay (article) Provides the surrounding relay and rebroadcast context that makes the unbroadcast set useful.
• Mastering Bitcoin (book) Broad technical reference for transaction relay, mempool handling, and node behavior around unconfirmed transactions.

Direct prerequisites (2)

• Mempool
• Transaction Relay (inv/getdata)

Direct dependents (1)

• Transaction Rebroadcast Privacy

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