Most users know that PostgreSQL has a 23-year development history. But did you know that Postgres code is used for over a dozen other database systems? Thanks to our liberal licensing, many companies and open source projects over the years have taken the Postgres or PostgreSQL code, changed it, added things to it, and/or merged it into something else. Illustra, Truviso, Aster, Greenplum, and others have seen the value of Postgres not just as a database but as some darned good code they could use. We'll explore the lineage of these forks, and go into the details of some of the more interesting ones.