ERROR: missing chunk number 0 for toast value 382548694 in pg_toast_847386

Hi,

We have a PG 8.4 database approx 5TB in size.

We were recently testing our restore procedure against our latest dump. The dumps are taken using the Continuous Archiving method with base dumps taken using tar. Our tar script is set up to ignore missing/modified files but should stop on all other errors.

We are testing the restore on a completely separate machine of a similar spec to the server on which the dumps are made.

On our first attempt we were using PG 8.4.0. We struck problems on restore with the error 'Unexpected timeline ID 0 in log file'. After some googling we identified that this was a known bug in PG 8.4.0 so we upgraded the target machine to 8.4.7 and began the recovery again.

On the second attempt the recovery went through smoothly. However, after starting the application again we started to get the following error:

ERROR: missing chunk number 0 for toast value 382548694 in pg_toast_847386

The table it is trying to access is one in which our application stores various schema information that is used each time the application starts up.

As far as we know the base dump is good and the DB did not complain about any of the WAL files. We are now nervous that our backups are no good, so we want to get to the bottom of it. What can be the reason that these backups are not restoring properly?

Thanks in advance,

Regards
Mike Harris