No, it wasn't legendary.

That's just one data warehouse application.

The one I administered, just as big, was Saturn. And it was MySQL.

Source: worked at Yahoo, saw way more MySQL than PG.

You just said you never saw Postgres at Yahoo. Yet Yahoo had possibly the world’s largest Postgres installation. I consider that legendary. I’ve certainly been aware of it for over a decade. It was also an early (?) columnar store which is now commonplace among OLAP databases. Seems like if it didn’t start a trend it was at least an early adopter. I’d say that’s legendary too. Even today the scale is impressive.

Now you say you did see some Postgres but there was more MySQL. Fine, you were there, I’ll take your word for it. But I can’t reconcile your own statements on this. Yahoo very clearly used Postgres.

You ran a 2PB MySQL install. Cool, I’d love to hear about that, truly. Do you have any written accounts or talks about that?

I believe the database described is Greenplum[0], which was a fork of PostgreSQL at 8.3, I think. It handles truly enormous datasets.

There's been an ongoing multi-year project to merge Greenplum up to the mainline so that it's no longer a hard fork.

Disclosure: I work for VMware, which sponsors development and sells commercial offerings of Greenplum.

[0] https://greenplum.org/

The article says Yahoo bought Mahat Technologies for their columnar version of Postgres. That sounds similar to Redshift or Greenplum but I think it is different. I can’t find a clear history of Greenplum’s origins or what happened to Mahat. Looks like Redshift came from ParAccel which was a separate project. From what I can find there were a lot of similar projects at the time.