[ Replying to a very old thread ] Indeed, fsync = off just means that the WAL isn't fsync'd at all, which can cause permanent corruption after a crash. Postgr

[ Replying to a very old thread ] Indeed, fsync = off just means that the WAL isn't fsync'd at all, which can cause permanent corruption after a crash. PostgreSQL does support a "deferred logging" mode, in which one or more transactions can avoid fsync'ing the WAL without risking data corruption -- the only risk is that those particular transactions might not be durable if the system crashes before the next fsync. This allows you to mix must-be-durable transactions with more transient ones, which is a nice feature.