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by voidmain
2830 days ago
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FoundationDB uses a consensus algorithm for reconfiguration, but not in the (happy path) transaction pipeline. It provides (by default) strict serializability (i.e. serializability and external consistency/linearizability) for arbitrary, ad hoc, interactive transactions, and it's expected to provide excellent performance when every single transaction is cross node (so e.g. indexes can be efficiently updated this way). It provides better fault tolerance than consensus replicated databases typically can because it needs only N+1 replicas instead of 2N+1 to survive N faults (it keeps 2N+1 replicas of tiny configuration for consensus, if course). It has the best testing story in the industry and is used at scale by, among others, the largest company in the world. Because it doesn't have consensus in the datapath it can have lower latencies than consensus replicated databases in multi region deployments, it also supports asynchronous replication, and an upcoming feature will provide a unique option for multi region failover with sub geographic write latencies, maintaining full transaction durability in failover, as if in synchronous replication, except for the exceptionally rare case where the failure of multiple datacenters in a region are exactly simultaneous. Besides its extensive documentation, you can read its source code and run its deterministic simulation tests yourself if you are interested (it's Apache licensed). Skepticism on these points was reasonable when we originally launched it in 2012 but is getting a little silly in 2018. |
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