3 ms·

Replication, atomicity and order in distributed systems

138 points by strlen 15y ago

fleitz 15y ago
Why not use the bitcoin protocol, longest block chain wins, missing transactions are just replayed. Use difficulty settings to tweak the transaction latency. It even solves the split brain issue, which ever brain has the longest block chain wins when the network is unified.
- jchrisa 15y ago
  That's sorta how CouchDB does it's default conflict resolution. In a conflict, by default CouchDB picks the revision with the longest edit chain. Couch doesn't throw out the other conflicts, it hangs on to them so applications can make their own decisions about resolution.
- smanek 15y ago
  That provides the same functionality of just using vector clocks, at ludicrously higher cost and complexity (and only addresses half the problem that Alex is discussing). A big problem is that arbitrary DB writes after split brain (aka network partition) situations are much harder to 'unify' than bitcoin transactions. Check out the Dynamo paper (or Riak docs like: http://blog.basho.com/2010/01/29/why-vector-clocks-are-easy/ http://blog.basho.com/2010/01/29/why-vector-clocks-are-easy/) for details. In some cases (e.g., shopping carts) conflict resolution is as easy as it is in bitcoin - but in most common applications it's far more difficult, if not impossible.
- xiaoqmabsc 15y ago
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- maurycy 15y ago
  In a word, the cap.
cema 15y ago
A good review, thanks!
jorangreef 15y ago
A related problem is anti-entropy, synchronizing replica sets across nodes, for which Merkle Trees are useful: http://en.wikipedia.org/wiki/Merkle_signature_scheme http://en.wikipedia.org/wiki/Merkle_signature_scheme

138 points by strlen 15y ago

Why not use the bitcoin protocol, longest block chain wins, missing transactions are just replayed. Use difficulty settings to tweak the transaction latency. It even solves the split brain issue, which ever brain has the longest block chain wins when the network is unified.

jchrisa 15y ago
That's sorta how CouchDB does it's default conflict resolution. In a conflict, by default CouchDB picks the revision with the longest edit chain. Couch doesn't throw out the other conflicts, it hangs on to them so applications can make their own decisions about resolution.
smanek 15y ago
That provides the same functionality of just using vector clocks, at ludicrously higher cost and complexity (and only addresses half the problem that Alex is discussing). A big problem is that arbitrary DB writes after split brain (aka network partition) situations are much harder to 'unify' than bitcoin transactions. Check out the Dynamo paper (or Riak docs like: http://blog.basho.com/2010/01/29/why-vector-clocks-are-easy/ http://blog.basho.com/2010/01/29/why-vector-clocks-are-easy/) for details. In some cases (e.g., shopping carts) conflict resolution is as easy as it is in bitcoin - but in most common applications it's far more difficult, if not impossible.
xiaoqmabsc 15y ago
welcometo: http://www.fullmalls.com http://www.fullmalls.com The website wholesale for many kinds of fashion shoes, like the nike,jordan,prada,, also including the jeans,shirts,bags,hat and the decorations. All the products are free shipping, and the the price is competitive, and also can accept the paypal payment.,after the payment, can ship within short time. free shippingcompetitive priceany size availableaccept the paypal ===== http://www.fullmalls.com http://www.fullmalls.com ===== jordan shoes $32nike shox $32Christan Audigier bikini $23 Ed Hardy Bikini $23Smful short_t-shirt_woman $15ed hardy short_tank_woman $16Sandal $32christian loubo utin $80 Sunglass $15 COACH_Necklace $27handbag $33AF tank woman $17puma slipper woman $30 ===== http://www.fullmalls.com http://www.fullmalls.com ===== ===== http://www.fullmalls.com http://www.fullmalls.com ===== ===== http://www.fullmalls.com http://www.fullmalls.com ===== ===== http://www.fullmalls.com http://www.fullmalls.com ===== ===== http://www.fullmalls.com http://www.fullmalls.com ===== ===== http://www.fullmalls.com http://www.fullmalls.com =====
maurycy 15y ago
In a word, the cap.

cema 15y ago

A good review, thanks!

jorangreef 15y ago

A related problem is anti-entropy, synchronizing replica sets across nodes, for which Merkle Trees are useful: http://en.wikipedia.org/wiki/Merkle_signature_scheme http://en.wikipedia.org/wiki/Merkle_signature_scheme