It sounds like you have a lot to teach us about query writing, but gratuitously putting someone else down, even when they don't know as much as you do, is not ok here. It violates both important rules of HN comments: civility (it truly is gratuitously negative) and substance, because it impedes the absorption of real information in your comment.

In the future, please edit that stuff out and stick to the substance when commenting here.

https://news.ycombinator.com/newsguidelines.html

https://news.ycombinator.com/newswelcome.html

Yea, the guy that goes into the source code of the optimizer to figure out the cause for a poorly optimized query plan is the amateur!

So sad I can't see or reply to that comment anymore - I'm the author. Sorry, HN, my personal blog rarely gets that wide circulation, I should've done better job at introducing the context.

This was just one of many systems that thousands of facebook engineers build and they did not think of some edge cases. We do know how to write queries or to operate our databases, in general.