getTransactions2 (56)

The getTransactions2 message is used to request the full binary data for a list of transactions when the requester already knows their transaction IDs (TxIDs). This is a common operation after receiving a block header, which contains the TxIDs but not the full transaction bodies.

If the list of requested TxIDs is large, the request will be automatically split into multiple getTransactions2 messages.

Core Data Types

• IxiVarInt / IxiVarUInt: See IxiVarInt Encoding.
• IxiBytes: See IxiBytes Encoding.

Payload Structure

Field	Data Type	Min	Max	Description
Entire Payload	byte[]		50MB	The total size of the message payload must not exceed the global maximum.
blockNum	IxiVarInt			The block number context for this request. 0 can be used for mempool transactions.
txCount	IxiVarUInt	1	5000*	The number of transaction IDs that follow in this message.
transactionIDs	IxiBytes[]			An array of txCount transaction IDs (hashes) being requested.

* The maximum value for txCount is determined by the node configuration (CoreConfig.maximumTransactionsPerChunk), which defaults to 5000.

Behavioral Notes

• A node sends this message to download the bodies of transactions it needs for block validation or for a light client's wallet.
• The blockNum field provides important context. A positive blockNum indicates a request for confirmed transactions from a specific block and is treated as a high-priority message. A blockNum of 0 or less may indicate a request for unconfirmed transactions from the mempool.
• Upon receiving this message, a peer should look up each transaction by its ID.
• The full transaction data for all found transactions should be sent back to the requester in one or more transactionsChunk3 messages.