This any help, a bit old, but seems to have some interesting points:
How old is that? Could not find MVCC there. I believe that is an upper hand for PostgreSQL when you compare to many implementations e.g. DB2 or SQL Server. Both of them rely on reading back (which not to mention is possible because of recording MVCC info) in transaction logs.
Best Regards,
Sameer Kumar | Database Consultant
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