How to restore a single table from a .sql postgresql backup?

Question

A table's rows were mistakenly deleted from the database. We have a db backup which results in a sql file that can restored like so:

psql -h localhost -d proddump -f /Users/U/Desktop/prod_db_backup/PostgreSQL/site_prod.sql

This ends up doing a full restore locally. But what we need is to restore a single table's rows to production. Any tips on how to make this work with PostgreSQL 9.1?

Thanks

Answer 1

I'm not aware of any tool for this, but this one-liner extracts precious_table from my_backup.sql file:

sed -n '/^COPY precious_table /,/^\\\.$/p' my_backup.sql

Answer 2

Don't do SQL backups if you need single table restore, etc. Use pg_dump's -Fc option - the "custom" format. This can be restored using pg_restore. Selective restore is possible, as are all sorts of other handy features. pg_restore can convert a custom-format dump into an SQL dump later if you need it.

If you're stuck with an existing dump, your only options are:

• Use a text editor to extract the target table data to a separate file and just restore that; or

• Restore the dump to a throwaway database then use pg_dump to take a selective dump including just that table. Since it's throwaway, you can use a separate Pg instance on some unloaded fast-but-unsafe machine where you turn on all the "make it fast but eat my data if you like" options like fsync=off. You should NEVER set that in production.