Miners should prioritise transactions in forked chains #6574

It would be nice if there was an option to download non-best blockchains and prioritise (even replacing existing mempool txns) anything confirmed in them. This would make confirmed transactions somewhat stronger.

What's the rationale for this feature? So that if a user sees that a transaction is confirmed in a block that is then orphaned, it's likely to get reconfirmed quickly?

@casey at least, ideally, that seems to be the intended effect. Although no incentive exists, default policy can be powerful enough that this may be worth doing.

I wouldnt consider it "stronger" unless its also rational to prioritise those transactions, which it is not.

Fraudulent double-spending clearly harms the Bitcoin economy, so I would say miners have a light incentive to make an attempt to prevent it when practical. (Non-fraudulent double-spending does not, AFAIK, have any case harmed by this behaviour.)

There is a subtle risk to this behaviour I should document: if a transaction is the cause of the stale chain being non-best, we would not want to re-mine that transaction. I don't know if there's a good way to determine and prevent this.

I would have no problem with this as long as the transactions you are replacing have lower fee rates, and if you never prioritize transactions above others which have a higher fee rate (making the decision to do so irrational). I really dont think we should be adding new behavior which is not in a rational miner's best interest, we should be moving the other way (ie eventual RBF, etc).

Doesn't the fact that transactions are mostly ordered by fee provide enough likeliness that a replacement block has mostly the same transactions?

Discussion should probably move to the mailing list