How is the process of restoring a PostgreSQL database from backups carried out?

Restoring a PostgreSQL database from backups typically occurs as follows:

1. Full restore from a dump (pg_dump):

   • A backup is created using pg_dump.
   • Restoration is performed using the psql command or pg_restore (for archive formats).

   pg_dump -U user -F c -b -v -f backup.dump dbname
   pg_restore -U user -d dbname -v backup.dump
   

2. Restoring from a file copy (pg_basebackup):

   • A physical copy of the data is created using pg_basebackup.
   • The copy is placed in the PostgreSQL data directory for restoration.

3. Point-in-Time Recovery (PITR):

   • Used when WAL (transaction log) archives are available.
   • Restoration occurs to a specific point in time, using a base backup and WAL files.

The restoration process depends on the type of backup and the requirements for recovery time and accuracy.