Ryan Kelly <rpkelly22@xxxxxxxxx> writes: > I'm having trouble understanding why it is necessary to generate a new > tuple even when nothing has changed. It seems that the OP understands > that MVCC is at work, but is questioning why this exact behavior occurs. > I too have the same question. It's not *necessary* to do so. However, avoiding it would require sitting there and comparing the old and new tuples, which would be a waste of cycles for most applications, which don't do useless updates. We'd be trading off a small loss on every update for a moderate gain on a few updates, with all of the benefit going to poorly-coded applications. This has come up before and we've always judged that it would be a net loss not gain of performance to check for useless updates. 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
