Ron Johnson <ronljohnsonjr@gmail.com> writes: > Why is VACUUM FULL recommended for compressing a table, when CLUSTER does > the same thing (similarly doubling disk space), and apparently runs just as > fast?
CLUSTER makes the additional effort to sort the data per the ordering of the specified index. I'm surprised that's not noticeable in your test case.
It's in a freshly restored database. However, regular deletions of old records, and normal vacuums would have led me to expect that the "fresh" public.log would have been in relatively random order.