Well they did say that Cassandra is better than all the others - especially when compared to HBase - on nearly all measurements (except for high write scenario latencies.)
This makes the decision of Facebook to go with HBase for their new messaging platform back in 2010 all the more strange. Though that was two years ago so things might have changed in Cassandra's favor since then.
> This makes the decision of Facebook to go with HBase for their new messaging platform back in 2010 all the more strange.
Speed isn't everything to a database. AFAIK they chose HBase over Cassandra because of consistency guarantees: eventual consistency is a bad choice for a messaging platform.
eventual consistency is a bad choice for a messaging platform
Strange you would mention that in the context of Cassandra, since it allows for per-read/write configuration of consistency, from "eventual" to "strong". You get exactly what you ask for with Cassandra, whether its availability or consistency.
This is not the main reason people would choose HBase. For time series data HBase is much better at load balancing the data and at storing the same data in sequential blocks so that in a single operation you can fetch all of the data points that are interesting. Cassandra supports range queries but the last time I saw it wasn't super awesome at load balancing data across nodes when using the OrderedPartitioner. Do I remember wrong?
I won't put too many words into the mouths of the Facebook fellows, but I meet with them every now and then, and they very much care about "speed" (latency and throughput, best and worst case).
This paper does not reflect what I have seen in production setups.
I was once informed by an FB employee that federal agents are ensconced at the FB premises to monitor users' communications and shut down / censor FB groups and venues for "hate" speech and terroristic threats.
What position did this Facebook employee hold at the company? In which office did they work? Is it possible they weren't really a Facebook employee? What sort of censorship are you talking about?
I ask because I've never heard anything like that, despite working with the teams that build tools to fight spam, scams, fake accounts, and to assist the User Operations team to handle reports from people who encounter harassment, bullying, and other anti-social or criminal activity.
What position was he recruiting for, and roughly when (let's say, which quarter and year)? How likely was he a new recruiter?
I'm not sure I can express my skepticism about this enough - our security, safety, and site integrity teams are some of the most privacy-conscious people I know, and even a hint of something like this happening here would lead to very pointed questions asked at the weekly Q&A every week until it was resolved.
This was last year, and the recruiter was an old timer, so to speak; he wasn't new to FB. He was recruiting for the software engineering positions.
Really, are you surprised that there are federal agents on the premises, or just upset at the thought that FB users' privacy could be compromised in such a situation? To the degree that FB forum and groups ToS conforms with federal law and moreover seeks to go above and beyond the letter of the law then FB in this regard could be thought of as an extension of the federal government in such matters with regards to its own users. In this light it is no more relevant whether federal agents look at private or group communications, as opposed to bona fide FB employees. It doesn't matter. This is a private company; the first amendment doesn't apply. In any case, FB as a company isn't exactly widely respected for its position on its users' data, nor is it known to play nice with its users' privacy.
Let's not forget that of the companies whom the federal government sought to extract users' accounts' data from with regards to the Wikileaks issue 18 months ago, only Twitter publicized the compelled exposure of its users' data. Facebook happily gave the feds all the users' info they sought without telling us about it.
Although IIRC you have said that you've worked with the FB spam and fake account / phishing detection team, FB is a large enough organization at this point that the team responsible for complying with federal mandates and managing FB's relation with federal law enforcement is separate. Tao Stein and team have no bearing on this particular matter, nor should they care that real users happen to talk about and discuss real issues that federal agents think should be taken down. This is a separate matter entirely from what you've worked on.
This makes the decision of Facebook to go with HBase for their new messaging platform back in 2010 all the more strange. Though that was two years ago so things might have changed in Cassandra's favor since then.