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answers:

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How does Voldemort compare to Cassandra?

I'm not talking about size of community and only want to hear from people who have actually used both.

Especially I'm interested in:

  • How they dynamically scale when adding and removing nodes
  • Query performance
  • How they scale when adding nodes (linear)?
  • Write speed
+13  A: 

Voldemort's support for adding nodes was just added recently (this month). So I would expect Cassandra's to be more robust given the longer time to cook and a larger community testing.

Both are fast (> 10k ops/s per machine). Because of their storage designs, I would expect Cassandra to be faster at writes, and Voldemort to be faster at reads. I would also expect Cassandra's performance to degrade less as the amount of data per node increases. And of course if you need more than just a key/value data model Cassandra's ColumnFamily model wins.

I don't know of any head-to-head benchmarks since the one done for NoSQL SF last June, which found Cassandra to be somewhat faster at whatever workload mix he was using. (The "vpork" talk from http://blog.oskarsson.nu/2009/06/nosql-debrief.html) 8 months is an eternity with projects under this much development, though.

jbellis
At last, someone who knows what they are talking about. Thanks jbellis, I thought this would never get answered! :)
Zubair
+1  A: 

Some additional comments:

  • Regarding write speed, Cassandra should be faster -- it is designed to be faster to write than read (you can avoid immediate disk hit for writes due to specialized way storage is done)

But main difference I think is actually not performance but feature set: Voldemort is strictly a key/value store (currently anyway), whereas Cassandra can offer range queries (with order-preserving partitioner), and bit more structure around data (column families etc). Former is an important consideration for design; latter IMO less so, you can always structure BLOB data on client side.

StaxMan