Anna: A Fast, Scalable, Flexibly Consistent Key-Value Store

Actually I would prefer such kind of database (just the engine).

1. Expose it to network via what ever framework you like. Thrift, Rest, grpc, ... You don't have to include different kind of libraries for each network service. I would love to connect to every network service (Redis, Elasticsearch, Cassandra, MySQL, ...) via a single framework (say grpc).

2. In most large scale scenarios, there is already some kind of log service (DistributedLog, NATS, Kafka, ...). Why not take benefit of that for replication? Isn't it great to separate the engine layer from replication layer? Currently we are doing double replication actually. Replicate data from master DB to slave DB. Then replicate the same data, from any DB to cache, search, ... components. The data is already there on log. Let everyone (slave DB as well as cache/search module) consume it. This is basically state machine replication idiom. PNUTS[0], Twitter K/V database, LinkedIn Espresso [1] (as well as Ambry[2] which is their internal object store), ... use this approach for replication.

3. I would agree with that, they only support basic low level operations.

[0] http://www.vldb.org/pvldb/1/1454167.pdf

[1] http://www.csce.uark.edu/~xintaowu/BDAM/p1135-qiao.pdf

[2] http://dprg.cs.uiuc.edu/docs/SIGMOD2016-a/ambry.pdf

So... is that kind of like Riak where (I believe Riak would do this) would send all conflicting values to the client for resolution, but instead you provide resolution strategies as part of the query? My understanding of vector clocks is admittedly pretty shitty though.

Why so much focus on Key Value stores? That's the easy part of the problem.

I would like to know more about the interesting ones: secondary indexes, range scans, performance on mixed workloads, robustness, operational complexity.

> it was up to 700x faster than Masstree, up to 800x Intel’s “lock-free” TBB hash table. In fairness, those systems provide linearizable consistency and Anna does not. But Anna was still up to 126x faster than a “hogwild”-style completely inconsistent C++ hashtable due to cache locality for private state, while providing quite attractive coordination-free consistency.