[bitcoin-dev] Using a storage engine without UTXO-index

Tomas tomas at tomasvdw.nl
Sat Apr 8 19:56:18 UTC 2017

> I don’t fully understand your storage engine. So the following deduction
> is just based on common sense.
> a) It is possible to make unlimited number of 1-in-100-out txs
> b) The maximum number of 100-in-1-out txs is limited by the number of
> previous 1-in-100-out txs
> c) Since bitcrust performs not good with 100-in-1-out txs, for anti-DoS
> purpose you should limit the number of previous 1-in-100-out txs. 
> d) Limit 1-in-100-out txs == Limit UTXO growth
> I’m not surprised that you find an model more efficient than Core. But I
> don’t believe one could find a model that doesn’t become more efficient
> with UTXO growth limitation.

My efficiency claims are *only* with regards to order validation. If we
assume all transactions are already pre-synced and verified, bitcrust's
order validation is very fast, and (only slightly) negatively effected
by input-counts.

Most total time is spend during base load script validation, and UTXO
growth is the definitely the limiting factor there, as the model here
isn't all that different from Core's.

> Maybe you could try an experiment with regtest? Make a lot 1-in-100-out
> txs with many blocks, then spend all the UTXOs with 100-in-1-out txs.
> Compare the performance of bitcrust with core. Then repeat with
> 1-in-1-out chained txs (so the UTXO set is always almost empty)

Again, this really depends on whether we focus on full block validation,
in which case the 100-1, 1-100 distinction will be the similar to Core,
or only regard order validation, in which case Bitcrust will have this
odd reversal. 

> One more question: what is the absolute minimum disk and memory usage in
> bitcrust, compared with the pruning mode in Core?

As bitcrust doesn't support this yet, I cannot give accurate numbers,
but I've provided some numbers estimates earlier in the thread.

Rereading my post and these comments, I may have stepped on some toes
with regards to SegWit's model. I like SegWit (though I may have a
slight preference for BIP140), and I understand the reasons for the
"discount", so this was not my intention. I just think that the reversal
of costs during peak load order validation is a rather interesting
feature of using spend-tree  based validation. 


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