Re: How to determine a database is intact?

On 9/3/04 3:11 AM, "Richard Huxton" <dev(at)archonet(dot)com> wrote:

> You shouldn't have to verify anything. PG's job is to never corrupt your
> data, and providing your hardware is good it should do so. If you are
> getting problems almost daily that would suggest a RAM/disk problem to
> me (sig 11 usually implies RAM). Can't guarantee it's not PG but it's
> record of reliability is pretty good.

I believe SEGV typically just indicates it de-referenced a bad pointer (i.e.
NULL or out of range). The problem is not occurring on a daily basis. The
database has been in service since December of last year. It's just that
the symptoms progressed from no apparent symptoms, to a clearly corrupt DB.
My guess is that some minor corruption fed upon itself until the DB couldn't
even be dumped.

> Steps I'd take:
> 1. Check your version number against the release notes and see if you
> should upgrade. You don't mention your version, but it's always worth
> having the last dot-release (7.2.5, 7.3.7, 7.4.5)
> 2. Schedule time to run memory/disk tests against your hardware. Finding
> 48 hours might not be easy, but you need to know where you stand.
> 3. Setup slony or some other replication so I can schedule my downtime.

I thought I mentioned the level in my original mail - 7.4.1. We are
planning on running some diagnostics.

Whether there is a bug in PostgreSQL, or there was a memory hit, or whatever
doesn't really matter to the original question. The database can become
corrupt. How can I tell that a database is fully intact at any given point
in time? If I reload from a system backup before the known corruption, how
can I be sure that the original corruption that precipitated the failure is
not still there and will again rear its ugly head?

Wes