[Bitcoin-development] Increasing the OP_RETURN maximum payload size

Flavien Charlon flavien.charlon at coinprism.com
Sun Nov 16 16:21:27 UTC 2014


The data that can be embedded as part of an OP_RETURN output is currently
limited to 40 bytes. It was initially supposed to be 80 bytes, but got
reduced to 40 before the 0.9 release to err on the side of caution.

After 9 months, it seems OP_RETURN did not lead to a blockchain
catastrophe, so I think it might be time to discuss increasing the limit.

There are a number of proposals:

   1. Allow two OP_RETURN outputs per transaction (PR
   2. Increase the default maximum payload size from 40 bytes to 80 bytes (
   PR <https://github.com/bitcoin/bitcoin/pull/5286>)
   Note that the maximum can be configured already through the
   'datacarriersize' option - this is just changing the default.
   3. Make the maximum OP_RETURN payload size proportional to the number of
   outputs of the transaction
   4. A combination of the above

3 sounds the most interesting, and 2 would be the second best.

1 is also good to have as long as the "space budget" is shared between the
two outputs.

Can we discuss this and agree on a plan?

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