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by sixdimensional 2075 days ago
This sounds like temporal tables, does it not - except deep inside the storage engine?? The historical copy goes to a separate table, the current row is in the current table.

I wonder if there is a logical overlap in the ideas between temporal table handling and this low level storage engine optimization.
2 comments
atombender 2075 days ago
Indeed, Postgres used to have "time travel" [1] — allowing you to view the table as it was a given point in time. It was removed in 6.2, though some of

Of course, support doesn't require Postgres-style MVCC. Oracle has time travel, which it calls Flashback ("SELECT AS OF"), even though it uses a different type of concurrency control.

[1] https://www.postgresql.org/docs/6.3/c0503.htm

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jacques_chester 2075 days ago
PostgreSQL used to have a limited form of unitemporalism by exploiting its MVCC implementation. You could retrieve unvacuumed rows through some additional magic.

For true bitemporalism you need more than current-row/historical-row separations, though.

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