Re: DB fails to start: "Could not read from file "pg_clog/0003" at offset 212992: No error.

[Craig Ringer <ringerc@xxxxxxxxxxxxx>]

On 07/16/2012 09:55 PM, raghu ram wrote:

On Mon, Jul 16, 2012 at 5:44 PM, Olga Vingurt <olgavi@xxxxxxxxxxxxxx> wrote:

Hi,

 

We are using PostgreSQL 8.3 on Windows Server.

The db crashed and now it fails to start up.

Crashed how? Did the *server* crash, or the database?

When is your last backup from?

Have you made a complete file-system level copy of the database yet? See:

http://wiki.postgresql.org/wiki/Corruption

There's no sign of corruption and an issue with the clog doesn't imply data coruption, but you should still take a complete copy before proceeding unless your backups are current and trusted.

Raghu: It may be best to advise people with DB damage issues to make a full file-system level copy before attempting repair. Once they start trying to fix things it's much harder to go back to the start if something breaks worse.

Please perform below steps:

1. Backup the current pg_clog/0003 file in different directory

2. Create a file  by assumption of  make the uncommitted record as they haven't been committed. command as follows:

dd if=/dev/zero of=<data directory location>/pg_clog/0003   bs=256K count=1

This is just a 256k zero-byte file. Here's one I made earlier:

  http://www.postnewspapers.com.au/~craig/0003.zip

I don't know if the above advice is safe, but so long as you've made a backup of your datadir it's worth a go.

--
Craig Ringer