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15 sats \ 2 replies \ @Murch 4 May \ parent \ on: Quick questions about OP_RETURN? Quick answers here. bitcoin
The consensus rules specify what a node must accept in a block. These rules must match perfectly across all node implementations. If a block or a transaction in a block are evaluated differently by some nodes, the network would experience a consensus failure as some nodes accept the block while others fork off.
A node’s mempool policy defines what the node will relay and consider for the block templates it produces. We use mempool policy to e.g. discourage transactions that are expensive to validate or might trigger security issues for some nodes, and the premature use of upgrade hooks. Generally, mempool policy is more strict than consensus rules and may diverge across nodes. When many nodes agree on mempool policy, it reduces the amount of bandwidth necessary to propagate transactions and blocks across the network, and reduces the overall latency of block propagation, because most nodes can reconstruct the full block from compact block announcements.
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Consensus rules define valid transactions and a nodes mempool policy defines what it considers standard?
Yes, that’s right. Whatever a node accepts to its mempool, it will use to build block templates and relay to peers. The name is derived from a function called
isStandard(…)
in the Bitcoin Core code base, which implemented some of the mempool policies.Are there any consensus rules surrounding the size of op_return?
OP_RETURN outputs are not limited by consensus rules other than indirectly per the block size limit.
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