Re: Is it possible to recover the schema from the raw files? - Mailing list pgsql-general

Please note, in cases of this kind, it is always pertinent to provide the PostgreSQL version and O/S, especially if the possibility exists
it might be related to an existing bug.

>The raw files were backed up separately outside of the original data folder upon discovery of the issue.

That's not going to help you, as the files you need are already corrupted at that point.

If, however, you have a backup of the raw files _prior_ to the crash, you might be in luck.
So, since you verified it is only one database that is the problem, but the PostgreSQL server can access the others, do the following:

SELECT oid, datname FROM pg_database WHERE datname = 'your_bad_db_name';

The oid is the directory file under the base directory that needs to be restored.
That is the directory (and all sub files) that needs to be restored.

First, stop the PostgreSQL server.
Back up that current (but bad) directory and all sub files.
Then restore the good backup of that directory only!
Restart the PostgreSQL server and hopefully you will then have access to an old version of the corrupted database.
If successful, immediately take a SQL dump of that database.