Bruce Momjiam say's "PostgreSQL's ancestor was Ingres" but I haven't found anything concrete one way or the other on whether Postgres started from scratch or from Ingres code (the name comes from 'post' 'gres' - after Ingres)
My understanding is that we started from Ingres in the sense that we are derived from ideas that are better then Ingres, thus Postgres... I do not believe we share any code.
Joshua D. Drake
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