Sample Exam Questions

From the objective of OSS-DB Exam Silver
S2.5 Basic server administration (Autovacuum concepts and behavior)

Sample Question


Choose the three best descriptions of autovacuum.

  1. VACUUM operation is performed on all tables at regular intervals.

  2. VACUUM is performed on a table where the amount of data updates exceeds a certain threshold.

  3. It is designed to be executed only during periods when the database load is low.

  4. It is designed to prevent many concurrent VACUUM executions.

  5. Temporary tables are not subject to autovacuum, so you must issue SQL to run VACUUM if necessary.

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

Answer and Explanation

Autovacuum is intended to automate the running of VACUUM and ANALYZE, and enabling it is strongly recommended (it is enabled by default). Based on the collected statistics, VACUUM and ANALYZE will run on tables where the amount of data inserted, updated, and deleted is greater than a certain threshold. However, temporary tables are not subject to autovacuum, so separate SQL commands must be issued if VACUUM or ANALYZE needs to be done.

When autovacuum is enabled, the autovacuum launcher process resides on the system, from which the autovacuum worker process is started at regular intervals. Worker processes inspect the tables in the database and run VACUUM and ANALYZE on the tables that are heavily updated.

To manage the system load caused by autovacuum, there is a parameter autovacuum_max_workers that prevents more than a specified number of worker processes from starting.

So the correct answers are B, D, and E.