From the objective of OSS-DB Exam Silver
- Operation and Management - actual operation management task (concept and action of automatic vacuum)
Sample Question
1.27
Choose two appropriate descriptions for autovacuum.
- Automatic vacuum is started regularly and vacuum processing is executed for all tables in the database.
- Although it is possible to operate the database without executing automatic vacuum, it is strongly recommended to execute it.
- When setting to execute automatic vacuum, it is better not to perform manual vacuum processing.
- Automatic vacuum is activated only when the load on the database is relatively small.
- Automatic vacuum automatically not only vacuum (VACUUM) but also ANALYZE processing.
※This sample exam is different from those that appear in the actual OSS-DB Exam.
2019/03/04
Answer and Explanation
Automatic vacuum is executed by periodically starting automatic vacuum worker from a daemon called automatic vacuum launcher which always exists. It is started automatically at regular intervals and does not take into consideration the load situation etc of the server. Automatic vacuum processes VACUUM and ANALYZE, but only the tables whose update exceeds a certain threshold are processed.
Automatic vacuum is set appropriately to run by default, and the development group of PostgreSQL strongly recommends that this be done.
If you are running automatic vacuuming, the need for manual vacuum vacuuming is low, but there are situations where it is desirable to perform vacuum, such as immediately after updating or deleting a large amount of data.
Therefore, the correct answers are B and E.