Re: Data corruption while taking backup of database

Pushker Chaubey wrote:
> We took back up of a database using the following command
> pg_dump -a
> Please note that when we took the back the database was available for
> use simultaneously from various clients.
>
> In the back up file that was generated we found some data that was
> violating foreign key constraints. And there fore we were not able to
> restore database back with this back up file.
>
> What may be the possible reasons?
>
> Also please tell me, is it safe if we allow concurrent modification of
> data through DMLs and the same time take the back up using pg_dump?

Yes, that is safe. pg_dump takes a coherent snapshot of the database as
it is when the backup starts; modifications during the backup don't show
up in the backup. But clearly something has corrupted your database
either before the backup or during it.

Are the rows that violate the foreign key constraint still there in the
original database? When was the last time you backed up? Can you check
if the foreign key violation present in the previous backup as well?

What does the schema of the tables involved look like? Can you post the
offending rows?

(this has nothing to do with JDBC, BTW. pgsql-general mailing list would
be more appropriate)

--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com