MVCC not only tracks row history but also records the search-key space. To better understand PostgreSQL MVCC, it's useful to look at some alternatives. One is zheap, which introduced out-of-place undo logging to rebuild historical row versions by storing old tuples in an undo log instead of the...
Source: [Dev.to](https://dev.to/franckpachot/orioledb-multi-version-concurrency-control-43d)