Postgres has window functions, and I believe it supports the full ANSI windowing function feature set. Nothing like Oracle's flashback queries. It used to have

Postgres has window functions, and I believe it supports the full ANSI windowing function feature set. Nothing like Oracle's flashback queries. It used to have a feature called time travel which allowed you to look at historical versions of data, something they could do thanks to MVCC. It was removed, presumably because it caused performance issues or was too complex to maintain.