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Show HN: My experimental take on a decentralized ledger

github.com

48 pointsbuhrmi27 comments

Needs a brief documentation "how it works" or something... I really don't understand the concept, I'm very familiar with bitcoin and somewhat familiar with ripple/stellar. How is the ledger maintained? How do we form the consensus on the valid ledger? What are the incentives for running nodes? etc.

How would this prevent a flood attack ? What I mean is in Bitcoin and presumably Stellar, you need coins to create transactions. There is therefore a cost to spamming the system.

It doesn't prevent a flood attack. The challenge in this approach does not lie in "preventing it" but in "dealing with it".

Do you have some ideas on how to deal with it?

Yeah

Stellar is 100% centralized. In fact, its owners took it down at some point to change some rules.

It's interesting that it says that "Warning: Requires Postgres 9.5. You WILL lose sync if you run against an earlier version. YOU HAVE BEEN WARNED."

Which PostgreSQL features new in 9.5 are being used that cause that? Or are earlier versions somehow buggy?

I'm using upserts... The reason I'm using upserts is basically just lazyness because I didn't feel like refactoring the source code to work around requiring upserts. Also, I'm not very confident in C++ so I did not want to take on that task.

You can fix this with basic SQL

IF record EXISTS then UPDATE else INSERT

No. Conccurrency makes it way harder than that.

In PostgreSQL, you can set the SERIALIZABLE isolation level for the whole database, put a retry loop around all database transactions and completely stop worrying about concurrency issues.

I think all database applications should be written like this at least until performance starts being an issue.

Entirely depends on the the type of workload / application architecture. In some cases the rollback ratios will be massive (I've seen 70%). In other cases adding such a retry loop is unattractive because the latency jitter. Or retaining all involved data for a retry is unattrictive.

Yet Another problem is that you need to enforce all sessions potentially involved in a data race need to use serializable; that can be easy or hard, depending on the scenario.

Use UPSERT, it's correct -and- fast rather than just correct.

Increasing the transaction isolation level shouldn't be done out of laziness.

> Transactions are FREE (the fee is always zero)

How would you deal with DDoS attacks? Taking down a ledger like this could be easy...

> How would you deal with DDoS attacks?

That's the open question.

Cloudflare doesn't have to charge a fee for every http request, although transaction fees do seem like the elegant solution.

Cloudflare is a massive, well-funded, centralized entity.

How is it protected from Sybil attacks on consensus algo? The algo description is definitely needed.

Is there any interesting lecture that got you this far or did you study source code?

Check out https://morph.is/v0.8/ if you haven't seen it, decentralized encrypted file storage and email, exciting stuff.

> Distributed Spam Proof Mail! Uncensorable, inherently spam proof and transparently encrypted and sender authenticated messaging! Secure enough for Edward Snowden! Easy and fool-proof enough for a child!

43 exclamation points on the front page. He has the hype cranked up pretty high. Still, it's nice to see all of these P2P efforts.

very cool! thanks!

Cool. I really liked the idea of Stellar, but I just cant get over the premined coin distribution. Nice to have a truly decentralized alternative!

What do you like about Stellar? It's not decentralized at all. Being premined is just the icing on the cake.

Stellar is indeed decentralized but not distributed [1]. What I like about Stellar is the concept of gateways and trust. It adds a whole new dimension for transactions.

[1] http://web.cs.ucla.edu/classes/cs217/Baran64.pdf

Basically, `Bitcoin - Politics`. A nice idea.

It's also `Bitcoin - all_the_hard_problems_bitcoin_solves`. Still nice but you can't compare it with Bitcoin. This is more the sort of service banks could use to track loans.

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