NoSQL WideTable system which supports Column Value based Queries?

I'm currently evaluating possible NoSQL WideTable systems for use as a storage backend for an experimental project I'm working on but I'm struggling with the fact that many of these seem to have vague/incomplete documentation and it's hard to determine whether a specific feature is supported.

Specifically I need to be able to do queries which return rows which have certain values for a specific Column and this needs to be doable without relying on a complete row scan (which afaict means Cassandra is out as an option).

What systems are there that have this feature? Sytems with a RESTful HTTP API 开发者_如何学Cor a .Net Client/Driver library are also preferable.

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Cassandra calls this "secondary index support." It is available in the 0.7b2 release.

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Take a look at ESE which is one of Microsoft's least known storage offerings... it is a sparse-table model (NOSQL), is free, ships with every server version since 2000 (? IIRC), is vastly scalable and highly performant. It is used by multiple Microsoft products such as WINS, DNS, Active Directory and Exchange - this is no toy.

Recently Ayende released RavenDB, a document database (written in c#, w00t!) which uses ESE internally for storage.