Funny historical and architecture fact about PostgreSQL. It actually can do this, for all tables without special features. Unfortunately the facility to perform

Funny historical and architecture fact about PostgreSQL. It actually can do this, for all tables without special features. Unfortunately the facility to perform a query like this is no longer exposed but it shouldn't be impossible to re-add in a more modern way. Essentially PostgreSQL has copy-on-write semantics, so historical records exist unless a vacuum marks them as no longer needed and subsequent insert/updates overwrite the values. In the past when PostgreSQL had the postquel language (before SQL was added) there was special syntax to access data at specific points in time: This is nicely outlined in "THE IMPLEMENTATION OF POSTGRES" by Michael Stonebraker, Lawrence A. Rowe and Michael Hirohama[1]. Go ahead open the PDF and search for "time travel" or read the quotes below. > The second benefit of a no-overwrite storage manager is the possibility of time travel. As noted earlier, a user can ask a historical query and POSTGRES will automatically return information from the record valid at the correct time. Quoting the paper again: > For example to find the salary of Sam at time T one would query: retrieve (EMP.salary) using EMP [T] where EMP.name = "Sam" > POSTGRES will automatically find the version of Sam’s record valid at the correct time and get the appropriate salary. [1] - https://dsf.berkeley.edu/papers/ERL-M90-34.pdf https://dsf.berkeley.edu/papers/ERL-M90-34.pdf