On Tue, 2011-01-25 at 09:41 -0600, Kevin Grittner wrote: > Yep. For the visual thinkers out there, the whole concept can be > understood by looking at the jpeg file that's in the Wiki page: > > http://wiki.postgresql.org/images/e/eb/Serialization-Anomalies-in-Snapshot-Isolation.png
Yes, that helped a lot throughout the review process. Good job keeping it up-to-date! > Yes, that would work. It would lower one type of overhead a little > and allow RO transactions to be released from SSI tracking earlier. > The question is how to determine it without taking too much time > scanning the finished transaction list for every active read write > transaction every time you start a RO transaction. I don't think > that it's a trivial enough issue to consider for 9.1; it's certainly > one to put on the list to look at for 9.2. It's OK to leave it to 9.2. But if it's a RO deferrable transaction, it's just going to go to sleep in that case anyway; so why not look for an opportunity to get a safe snapshot right away? Regards, Jeff Davis -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers