Light client library to monitor mempool about bdk HOT 5 CLOSED

Fee estimation is actually pretty hard if you only look at the mempool, because you don't know the value of the inputs that are being spent. You might be able to estimate it by downloading the latest x blocks and only considering txs spending outputs from these blocks (or the mempool itself), but it might not be optimal.

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Fee estimation is actually pretty hard if you only look at the mempool, because you don't know the value of the inputs that are being spent.

Also you have no idea whether the stuff in your mempool is actually valid at all. How would you filter out invalid transaction spam?

Ah interesting. The UTXO set is needed I assume?

I think so.

I am curious how utreexo would handle this then?

It's a good question. I don't know if the vision for utreexo nodes is to have a mempool at all. You could do it you just have to have inclusion proofs for each output being spent being broadcast by the "bridge node" as the enter the mempool.

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Well, the fact that they could be invalid is pretty much unavoidable with light clients. Even when you download blocks you are just checking the PoW, but the transactions they contain could be invalid in any sort of ways.

For some use cases that isn't a problem though, if you are a watchtower for instance. You don't care about transactions being valid, you are just looking for some specific txids.

For fee estimation specifically, I think what most light clients do is rely on centralized (trusted) services. I'm pretty sure LND does it when using neutrino and I was planning to add this here to BDK too, since currently the fee estimation in the CompactFilters blockchain is a TODO. I'm not sure about utreexo, I've never looked too much into it.

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Closing this for now since there doesn't seem to be a good way to monitor the mempool in light clients. A better approach for fee estimation based on prior blocks is described in the blog post series "Fee estimation for light-clients".

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