> AFAIK we don't truncate the log file created by the log_filename GUC
> on every unclean crash and every clean shutdown.
That's not a remotely relevant analogy. A log file is not a database table.
If we allow a database table to become corrupted due to being unsynched
at the time of shutdown, it's not a matter of "missing a few rows". The
table is *unreadable*, and may cause the backend or even the whole
server to crash when you try to read it.
Anyway, per discussion on hackers, unlogged tables (or "volatile tables"
as they're now being called) include two modes in the spec; one which
checkpoints (and thus can survive a planned restart) and one which
doesn't (and will truncate on every restart, but doesn't cause physical
I/O). We may or may not have both modes for 9.1.
--
-- Josh Berkus
PostgreSQL Experts Inc.
http://www.pgexperts.com