From the objective of OSS-DB Exam Gold
- Advanced Server Administration - Commands for database administration
Sample Question
1.05
Choose two statements that are NOT accurate descriptions of the pg_basebackup command.
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You can obtain a base backup of a PostgreSQL database cluster running on a separate server.
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The pg_start_backup command must be executed before the pg_basebackup command is executed.
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In the case of fetch method, the max_wal_senders parameter should be set to at least 1.
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WAL is included in the backup if the command is executed without explicitly specifying options.
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If an additional tablespace is created, the data within the tablespace is not included in the backup.
※This sample exam is different from those that appear in the actual OSS-DB Exam.
2025/05/29
Answer and Explanation
[Option A]
Replication protocols are used for backups, and base backups can be obtained from another server running remotely.
[Option B]
The pg_basebackup command automatically handles the execution of pg_start_backup, the transfer of data within the database cluster, and the execution of pg_stop_backup. Therefore, it is unnecessary to execute pg_start_backup beforehand.
[Option C]
At least one max_wal_senders is required for backups using the fetch method, and two slots are used with the stream method. In practice, the value of max_wal_senders should be set high enough to accommodate other replication connections, etc.
[Option D]
WAL is included in the backup even when executed without explicitly specifying options like -x.
[Option E]
Even if additional tablespaces have been created, backups can be taken that include data within those tablespaces.
Therefore, statements B and E are not accurate.
Refer to the official documentation for details. (Please note that there are parts of the specifications that differ depending on the Version.)
https://www.postgresql.org/docs/10/app-pgbasebackup.html
The correct answers are B and E.