zlacker

>>andren+(OP)
> Oracle and MySQL do not have this problem in their MVCC implementation because their secondary indexes do not store the physical addresses of new versions. Instead, they store a logical identifier (e.g., tuple id, primary key) that the DBMS then uses to look up the current version’s physical address.

This doesn’t have anything to do with MVCC. I’m sure PostgreSQL could implement an index format that piggybacks on another index rather than pointing at the physical page directly, without overhauling MVCC.

>>zeroim+Up1
And this is wrong. Oracle stores the physical address in the index. The ROWID is the relative file number (in the tablespace) + block offset in the file + an index in the block row directory. The difference is that Oracle rows usually don't move and are updated in place. Because old version diff goes to undo segments.