Netuality

Well, not all Twitter runs on Cassandra Alex Payne explains how they build Hawkwind, a distributed search system written in Scala. Take a look at the slide 18, where you can clearly see that they use HBase as backend:

Also from the great guys at Twitter: gizzard. Interesting and appropriate name for a database sharding framework. Gizzard uses range-based partitioning and replication tree and knows to rely on a large range of data stores: RDBMSes, Lucene or Redis – you name it. But I wonder about the operational overhead when you have a really large gizzard cluster.

Michael Stonebraker has a short essay on CAP published in the ACM blogs. He identifies a series of use cases where the CAP theorem simply does not apply and cannot be appealed to for guidance:

Obviously, one should write software that can deal with load spikes without failing; for example, by shedding load or operating in a degraded mode. Also, good monitoring software will help identify such problems early, since the real solution is to add more capacity. Lastly, self-reconfiguring software that can absorb additional resources quickly is obviously a good idea.

In summary, one should not throw out the C so quickly, since there are real error scenarios where CAP does not apply and it seems like a bad tradeoff in many of the other situations.

Great nosqlEu coverage on Alex Popescu’s blog MyNoSQL. Read it to get all the presentations, tons of links and Twitter quotes.

Because every self-respecting blog should mention some info about the newly released iPad, here’s mine. According to the O’Reilly Radar, iPad is not ready for the cloud integration:

I am hoping for a future where all I need to supply a device with is my identity, and everything else falls into place. This doesn’t even have to be me trusting in a third-party cloud: there’s no reason similar mechanisms couldn’t be used privately in a home network setting.

I think the iPad is an amazing piece of hardware, and the most pleasant web browsing experience available. It is still very much a 1.0 device though, and its best days certainly lie ahead of it. I hope part of that improvement is a simple story for synchronization and cloud access.

Guess I’ll be waiting for the release of iPad Pro:

Seven signs you need to accept NoSQL in your life according to the High Scalability blog. I especially like sign #6 “Maintaining a completely separate object caching system on top of an already beefy table storage system“. There are companies making serious bucks from selling exactly this type of caching systems. I find that a bit ironic, don’t you?

Twitter has just decided to adopt Cassandra as their main storage. I roughly estimated the status table to having  more than 9 billion rows – it’s a good table size to start thinking about the benefits of NoSQL. I would have been interested in seeing a comparison with other existing solutions and a rationale of their choice. According to some sources, Ryan King rejected HBase because if a region server is down, writes will be blocked for affected data until the data is redistributed – unlike Cassandra’s “write never fail” policy. According to other sources, this will be solved in a future version of HBase but I think Twitter needed a solution sooner rather than later. I hope for two things:

• That the Twitter dudes will blog about their migration experience
• That I’ll be able to access and search through all my older tweets, fer’ God sake!

Forrester Research thinks that NoSQL and Elastic Caching Platforms are very similar. So similar that “NoSQL Wants To Be Elastic Caching When It Grows Up“. According to Forrester “Ultimately, the real difference between NoSQL and elastic caching now may be in-memory versus persistent storage on disk.” Yeah sure: transactions, durability, indexing, security model – who needs this crap anyway?

Oh and let’s not forget about today’s GAE unscheduled downtime. Waiting forward for the post mortem, for sure there will be a thing or two to learn…