Re: Survey on backing up unlogged tables: help us with PostgreSQL development!

On Tue, Nov 16, 2010 at 8:15 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> Scott Mead <scott(at)scottrmead(dot)com> writes:
> > +1 -- Is there a technical reason to do a TRUNCATE on restart? I'd feel
> > better if I could just have unlogged tables that survive unless something
> > like a power-outage etc... I'm in the exact same boat here, lots of big
> > logging tables that need to survive reboot, but are frustrating when it
> > comes to WAL generation.
>
> Keep in mind that these tables are *not* going to survive any type of
> backend crash.

Not surviving a crash is fine. IMHO, if we'd lose data in myisam files,
I'm happy to lose them on pg nologging tables. I just want it to survive a
stop / start operation. The benefits (think of multi-host syslog
consolidation with FTS <drools> ) on these tables FAR outweigh the
off-chance that a crash will cause me some heartache.

> Maybe my perceptions are colored because I deal with
> Postgres bugs all the time, but I think of backend crashes as pretty
> common, certainly much more common than an OS-level crash. I'm afraid
> you may be expecting unlogged tables to be significantly more robust
> than they really will be.
>

Bugs? What bugs :)

Honestly, I've only had a couple of *Prod* crashes (knocks on wood), but
the need to restart occurs every now and then.

--Scott

>
> regards, tom lane
>