From the objective of OSS-DB Exam Gold
- Performance Tuning - Parameters related to performance
Sample Question
3.12
Choose the one INCORRECT description of a GUC parameter.
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shared_buffers sets the size of the shared memory buffers used by the PostgreSQL server.
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max_connections sets the maximum number of concurrent client connections allowed to the PostgreSQL server.
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work_mem sets the maximum amount of memory used for maintenance tasks like VACUUM and CREATE INDEX.
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Setting ssl to on enables SSL connections.
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wal_level is a parameter that controls the level of information written to the WAL.
※This sample exam is different from those that appear in the actual OSS-DB Exam.
2025/06/02
Answer and Explanation
The correct answer is C.
work_mem specifies the amount of memory used by each query process for operations like sorting and hashing. Note that complex queries, especially when multiple sessions are active, can consume significantly more memory than the work_mem setting.
maintenance_work_mem specifies the amount of memory used by maintenance operations like VACUUM and CREATE INDEX.
The default values for work_mem and maintenance_work_mem vary depending on the PostgreSQL version; in version 12, they are 4MB and 64MB, respectively.