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> Does Cassandra actually support transactions? He means in the sense that databases have typically been divided into "transaction processing" (doing a small s
by jbellis 17y ago
> Does Cassandra actually support transactions?
He means in the sense that databases have typically been divided into "transaction processing" (doing a small set of operations over and over with large concurrency) and "analytics" (doing potentially monstrous ad-hoc queries w/ very low concurrency).
> You could easily have this in a distributed system that has a single master (implemented as a distributed state machine), without all the disadvantages of a gossip-protocol.
Sure, but then you have all the disadvantages of a single master system. :)
For most systems the single master system and its potential for catastrophic downtime if failover goes badly (which it _always_ does eventually; if you claim otherwise you are a novice or selling snake oil) is the worse choice.
> a P2P system will in most cases be slower than a hierarchical one.
I call BS. An O(1) routing p2p system like Cassandra has no inherent speed disadvantage over a heirarchical system.
Case in point: Cassandra is substantially faster than HBase, its closest heirarchical competitor. There's also Hypertable, but to a first approximation nobody uses it so I don't know of any benchmarks.
- cx01 17y ago> For most systems the single master system and its potential for catastrophic downtime if failover goes badly (which it _always_ does eventually; if you claim otherwise you are a novice or selling snake oil) is the worse choice. I don't know what you're talking about. If implemented correctly, a hierarchical system is extremely unlikely to fail. I mean, if your network is split into 3 partitions, the master will be unavailable, but in that situation you're going to have worse problems than availability, because your web-servers are unlikely to be even reachable from outsite the datacenter. > I call BS. An O(1) routing p2p system like Cassandra has no inherent speed disadvantage over a heirarchical system. Nope. If you have a master that stores the dictionary, then all lookups are also O(1). Even better, you can randomly distribute keys across the nodes and are not bound by the hashing algorithm. I don't know about the performance between HBase and Cassandra; I'm strictly talking about theoretical performance.
- jbellis 17y ago> If implemented correctly, a hierarchical system is extremely unlikely to fail. You should go show google how they're doing it wrong so they can keep app engine up.