Sample Exam Questions

From the objective of OSS-DB Exam Silver
S2.4 Backup and restore (Non-exclusive low level backup)

Sample Question


Choose two incorrect descriptions for non-exclusive low-level backups.

  1. Connect to a running PostgreSQL server and use the pg_start_backup() and pg_stop_backup() functions.

  2. After running the pg_stop_backup() function, two files are automatically generated: backup_label and tablespace_map.

  3. If no options are specified for the pg_start_backup() or pg_stop_backup() functions, they operate in exclusive mode.

  4. Exclusive mode is not recommended.

  5. Backups taken with non-exclusive low-level backups are not available for PITR.

※This sample exam is different from those that appear in the actual OSS-DB Exam.

Answer and Explanation

One way to obtain a base backup for use with PITR is to use a non-exclusive low-level backup. Non-exclusive low-level backups use the low-level API to take backups.
Connect to a running PostgreSQL server, execute the pg_start_backup() function, then backup (copy) the database cluster directory and execute the pg_stop_backup() function. Note that you must be a superuser or a user who has been granted EXECUTE permission on the function. In non-exclusive low-level backups, you need to create a file at the backup destination.

If you are using backup_label and tablespaces to store backup information, create a file called tablespace_map to store tablespace information.
The file contains the output of the pg_stop_backup() function.
Exclusive and non-exclusive modes exist, and the default is to run in exclusive mode, which is not officially recommended.

The correct answers are B and E because it is a question to choose the wrong ones.