[alecco]

Funny how everything Google does is dogma. They move from complicated hash DS to B+trees, a decade later, and everyone follows. Better DS are currently Log-merge for heavy writes and data parallel BSTs for read-most.

At least they are not stubborn for long, I give them that.

[yongjik]

I don't know how you got that impression, but inside Google people use hash tables far, far more often than B+trees. In fact, I don't think I ever used B+tree once in my entire career inside Google.

It's pretty hard to beat "expected O(1)".