Connect to and reindex Postgres database with system table errors

Question

I've got a Postgres database that crashed (as well as the disk) and suffered some data errors (per http://serverfault.com/questions/156152/after-db-disk-failure-now-cache-lookup-failed-for-index).

The initial problem seems to be the system tables, as the answer in that question suggests. However it's been impossible to even try to reindex the database.

Trying postgres -P -D datadir dbname yields the same error, FATAL: cache lookup failed for index 2662 - isn't that what the -P flag is supposed to get around?

How do you connect to the database to reindex the database if you can't ignore the system tables? Or is something else going on?

Answer 1

In this case, where the -P flag still results in errors, the database is almost certainly beyond (reasonable) recovery.

This:

postgres -O -P -D /data/dir -c log_error_verbosity=verbose dbname

yields additional information. In this instance it meant corruption beyond the pg_class table.

More info on the pgsql-admin list.