Re: vacuum full, why multiple times ?

Gaetano Mendola wrote:
>
> # vacuum full verbose url;
> INFO: vacuuming "public.url"
> INFO: "url": found 74 removable, 21266 nonremovable row versions in 8550 pages
> DETAIL: 2 dead row versions cannot be removed yet.
> [SNIP]
> INFO: "url": moved 11 row versions, truncated 8550 to 8504 pages
>
>
> and in the next run:
>
>
> # vacuum full verbose url;
> INFO: vacuuming "public.url"
> INFO: "url": found 13 removable, 21264 nonremovable row versions in 8504 pages
> DETAIL: 0 dead row versions cannot be removed yet.
> [SNIP]
> INFO: "url": moved 5666 row versions, truncated 8504 to 621 pages

If page number 8549 was the one being held, I don't think vacuum can
truncate the file. The empty space can be re-used, but the rows can't be
moved to a lower page while a transaction is using them.

--
Richard Huxton
Archonet Ltd