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You're assuming that the difficulty is linear in time, while it could easily be exponential.

IIRC, we started working on Distributed Log at least a year before that post.

If 2M requests result in 1 Gb network traffic, each message is 500 bits (~60 bytes). Theoretically, that's 1K messages per batch.

Even if practically that number is much lower (around 100 per batch), the cost ends up becoming around $3,000 for the messages and $9,000 for the network, so roughly $12,000 per month.

Yes, but if I'm reading their blog post correctly, their individual messages are much smaller than 64K

"Pub/Sub passed the test with flying colours. We published 2M messages without any service degradation and received almost no server errors from the Pub/Sub backend. Enabling batching and compression on the Event Service machines resulted in ~1Gbps of network traffic towards Pub/Sub."

You're making a big assumption here - that they don't batch events before publishing to Google's Pub/Sub system.

The blog post says "We also added queuing and batching in the client. (This wasn’t first time that we needed to roll our sleeves up and reimplement a Google Cloud API client: in another project we implemented a high performance client for the Datastore API.)"

I've used OEIS a number of times for obscure mathematical problems in programming competitions. It's a pretty useful resource!

I've found these video lectures by professor Seif Haridi to be really useful. http://www.ict.kth.se/courses/ID2203/video_lectures.html

Edit : https://www.youtube.com/playlist?list=PL700757A5D4B3F368

"The login id and password combination is invalid. Please verify the credentials."

I get this error - "You can't take this test now. Please contact support@hackerrank.com for more details."

Edit : https://www.hackerrank.com/tests/gfmhcts2 seems to be the actual link, but when I try logging in, the error message says that my credentials are invalid.

The system is still available if your ring gets an acknowledgement of receipt. The latency for the request to be served is a design metric and has no impact on "availability"

https://code.google.com/codejam/contest/2974486/dashboard The questions in case anyone's interested.

Actually deleting content would be a very expensive operation at Facebook's scale. Flagging it as deleted is the most optimal way. What's troubling is that this content somehow got undeleted on its own. Not once, but twice.

>>This rings some alarm bells as some of the larger SV companies have found themselves on the business end of a law suit for this.

Any citations for this?

There are lots of message queues that overcome this. A good example is Apache Kafka (http://incubator.apache.org/kafka/)

Perhaps I wasn't clear. What I meant was that if you enqueue the job directly and the job is idempotent, using approach 2 will introduce dependencies like the ones you pointed out.

Isn't this the same as a message queue? Why would you want to rewrite this using a database? Also point/trick 2 seems unnecessary if you are using 3 (idempotent jobs). By queuing job ids you now have a consistency dependency between your message queue and database.

Anyone who has taken Computer Security 101 would know that security through obscurity is not the smartest thing to do. Calling it "near-ridiculous level of security." is downright blasphemy.

Google is a direct competitor to Facebook when it comes to Ads. It doesn't really matter if the advertising is search based or social. They are vying for a piece of the same pie.

The really high valuation of Facebook is partly because investors expect it to grow substantially, at least in the short term. The fact that it's growth is lower than that of it's direct competitors (who have a much lower P/E) is not a good sign for the stock in days to come.

I am talking about growth, not numbers. Google's Y/Y revenue growth was 35% and Facebook's is around 32.

Interesting to see that Google's Y/Y revenue growth beats Facebook's for Q2 2012.

(Edit : Google's Y/Y revenue growth was 35% and Facebook's 32%. In contrast, Google's market cap is about two times that of $FB)

Apple is fighting Steve Jobs' battle. If it weren't for Jobs and his overly bloated ego, we wouldn't have had these stupid patent wars.

It would be interesting to know if their definition of an "Active Google+ user" has changed. Otherwise those stats don't mean a thing.