Re: Data recovery - URGENT

From: Jan Wieck <JanWieck(at)Yahoo(dot)com>
To: Peter Galantha <argosz(at)tensa(dot)net>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: Data recovery - URGENT
Date: 2003-06-16 00:12:54
Message-ID: 3EED0B86.3000908@Yahoo.com
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Peter Galantha wrote:
> Hello,
>
> is there a way to recover data from a damaged database if
> a.) we have some but not all datafiles
> b.) we have all datafiles but system tables are currupted
>
> The situation is extremely critical so we're interested in all possible
> solutions even if it's time consuming or if we need to pay for it!

Okay, data in lost datafiles will be lost (surprise, surprise).

But for the other parts ...

Corrupt or missing index files are no big deal (as long as they are user
indexes.

Corrupt system index files ... hmmm ... don't remember if v7.1 did a
good job on system index recovery. Worst case we might have to consider
that a corrupt catalog.

If system tables are corrupted, the complete schema of the database must
be known otherwise. If not, this will become some detective work to
figure out the table structures. Maybe another, older backup exists and
the schema didn't change after that.

The real key is the commitlog. If that is available, the data files that
can be recovered could be injected into some sort of emergency room
database system at least.

I am already constructing a v7.1 testbed, and will be able to answer
more detailed questions in a few minutes. For speed you can reach me on
+1 978-697-7733.

Jan

>
> Version: Postgres v7.1
> OS: Debian Linux 3.0
> Storage: RAID 5 and RAID 1 (the array is dead and we might not be able to
> restore all data, but there are good chances to recover about 90% of the
> data)
>
> Thanks & regards,
> Peter Galantha
> argosz(at)tensa(dot)net
>
>
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