On 2013-04-12 20:02:07 +0300, Tarvi Pillessaar wrote: > On 12.04.2013 17:04, Andres Freund wrote: > >On the other hand, at > >least in the first example you haven't even committed the transaction so > >there's nothing that could flush the transaction unless we we would > >*always* flush nextval() immediately if needs to get new values which > >doesn't seem reasonable. > Yes, i know that i haven't commited anything and also i agree that flushing > always is not reasonable. > I'm not sure that i understand all the details in sequence.c, but there > seems to be some sort of cache used for sequences, so instead of flushing > always maybe flush should only happen if next batch of values are written to > cache.
Flushing everytime the cache is used up will have a far too high overhead. Consider bulk loading new data into a table. If we would flush wal every 32 new rows that would be disastrous from a performance perspective. Greetings, Andres Freund -- Andres Freund http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-bugs mailing list (pgsql-bugs@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-bugs
