Can't, it generates huge IO spikes.
But....
Few hours ago i manually started vacuum verbose on pg_attribute, now its finished and i have some outputs:
INFO: "pg_attribute": found 554728466 removable, 212058 nonremovable row versions in 44550921 out of 49326696 pages
DETAIL: 178215 dead row versions cannot be removed yet.
There were 53479 unused item pointers.
0 pages are entirely empty.
CPU 1097.53s/1949.50u sec elapsed 6337.86 sec.
Query returned successfully with no result in 01:47:3626 hours.
what do you think?
select count(*) on pg_attribute returns:
158340 rows
So as i understand vacuum full will create new pg_attribute and will wrote those amount of "valid" rows, but still it will scan 300GB old table?
So estimate will be even ~same compering with regular vacuum?
2018-03-26 17:17 GMT+03:00 hubert depesz lubaczewski <depesz@xxxxxxxxxx>:
On Mon, Mar 26, 2018 at 05:15:14PM +0300, Artem Tomyuk wrote:
> For now pg_attribute bloated to 300GB in size, and we have only 260GB's of
> free space on disk.
> In normal situation pg_attribute takes 50mb in size for our DB...
> Can we assume that if we will run vacuum full on pg_attribute it will take
> additional 50MB on disk?
You can estimate by doing:
create table z as select * from pg_Attribute;
and then checking size of z.
bloat there suggests that you have huge churn in tables - like: create
table, drop table, lots of times.
Best regards,
depesz
