Thomas Kellerer <spam_eater@xxxxxxx> writes: > Martijn van Oosterhout, 28.08.2012 10:02: >> I'm not sure how oracle avoids the same issues: >> - The index has no visibility information, so you can't tell if an >> index entry refers to a row you can actually see in your session. >> The visibility map might help here in the future. > In Oracle an index (entry) has the information about transactional visibility. You sure about that? What I always understood about Oracle is that the main table (and by implication, also the indexes) has *only* the most up-to-date version of any row. If you want back versions, you have to go trawling for them in the rollback segments. That approach has its pluses and minuses compared to ours, but it doesn't seem to lead to keeping visibility info in the index. regards, tom lane -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
