ORDER BY
CREATE INDEX
Merge Join
VACUUM
Automatic VACUUM
※This sample exam is different from those that appear in the actual OSS-DB Exam.
2025/06/02
work_mem specifies the amount of memory used in sorting (internal sorting) and hashing processes.
Therefore, tuning work_mem is expected to improve the performance of "ORDER BY" and "MERGE JOIN" that involve sorting processes. On the other hand, the amount of memory used by "VACUUM" and "CREATE INDEX" is specified by maintenance_work_mem.
Also, the amount of memory used by "automatic VACUUM" (the amount of memory used by the autovacuum worker process) is specified by autovacuum_work_mem.
However, by default, maintenance_work_mem is set to be used.
Therefore, the correct answers are A and C.