Re: CLUSTER vs. VACUUM FULL - Mailing list pgsql-general

From Ron Johnson
Subject Re: CLUSTER vs. VACUUM FULL
Date
Msg-id CANzqJaAj9TRMKOwOv9pNjf7n5+e0bbd8ERZB2Zb8sdazVRmRwg@mail.gmail.com
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In response to Re: CLUSTER vs. VACUUM FULL  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-general
On Sun, Apr 21, 2024 at 6:45 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
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.

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