On Wed, 2010-12-22 at 10:45 -0500, Tom Lane wrote: > Aidan Van Dyk <ai...@highrise.ca> writes: > > With this statement, you just moved the goal posts on the checksumming > > ideas. In fact, you didn't just move the goal posts, you picked the > > ball up and teleported it to another stadium. > > What he said. I can't imagine that anyone will be interested in any > case other than "set the CRC immediately before writing, and check it > upon first reading the page in". Maintaining it continuously while the > page is in shared memory is completely insane from a cost-versus-benefit > perspective.
If you insist on setting hint-bits, then that is probably true. Many people experience almost no I/O these days, and there's a strong correlation between people caring about their data and also being willing to spend big $s on cache. We need to protect our users, however much money they spent on cache; I would argue the more money they spent on cache the harder we should be trying to protect them. I'm sure it will take a little while for everybody to understand why a full CRC implementation is both necessary and now possible. Paradigm shifts of thought do seem like teleports, but they can be beneficial. -- Simon Riggs http://www.2ndQuadrant.com/books/ PostgreSQL Development, 24x7 Support, Training and Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
