Again, my qualifier is "to PostgreSQL". I couldn't see such a connection on a brief skim of the A/S wikipedia entry.

I was the PM for the software side of Greenplum DB for a while. I also don't know of an earlier example of a separate column oriented storage option on top of a Postgres base. Vertica and ParAccel (which became Redshift) both also started from a Postgres base (though Vertica claims otherwise in marketing material) but were a little later. In any case, "Column oriented storage for Postgres" is almost 20 years old. This also isn't the first open source implementation.

Nice to meet you :-)

You're right that Addamark wasn't open source and wasn't a storage option, but it was indeed built with a Postgres base.

Here's the paper (2002):

https://www.usenix.org/legacy/events/lisa2002/tech/full_pape...

There were non-Postgres SQL columnar stores as well, most notably Sybase IQ, which dates to the 1990s: https://en.m.wikipedia.org/wiki/SAP_IQ