Ken sat near Jeff, Sanjay, and co while they were designing Spanner, and he regularly consults in an informal capacity on people's projects. I wasn't there, but it wouldn't surprise me at all if Ken's unique insight contributed to Spanner's design.

I'm familiar with Ken Thompson, so I'm more puzzled than someone who isn't familiar with his work might be.

What exactly is his unique insight? Do you know any specifics or are you just speaking on behalf of the fact that he's a famous programmer?

I say this as someone whose Planetside2 character is named: "KenThompsonHackerExtraordinaire"

Enneff works with ken in the Go team at Google.

As for his particular insight, if you are familiar with his work, that should be enough.

For those not familiar with his work, this interview might be a good starting point:

http://genius.cat-v.org/ken-thompson/interviews/unix-and-bey...

This is golden:

"The aggressive use of a small number of abstractions is, I think, the direct result of a very small number of people who interact closely during the implementation."

It's from 1997 I guess ? Seems like he was wrong about Linux and maybe Microsoft :)

Ken's mind just works in a different way to most people. You explain your problem to him and he'll respond with some question or statement that turns your entire perspective inside out.

When I was in the platforms group looking at storage issues the Spanner requirements had a lot of commentary from Ken in them, so much so that I thought it was his idea/project until someone corrected me a bit later. That was why I was surprised he wasn't acknowledged, from where I sat it seemed like he was one of the architects of the effort. Apparently that wasn't the case.