AW: AW: [Extern] Re: autovacuum on pg_catalog tables - Mailing list pgsql-general
| From | Zwettler Markus (OIZ) |
|---|---|
| Subject | AW: AW: [Extern] Re: autovacuum on pg_catalog tables |
| Date | |
| Msg-id | e9101119a6d74174b9b249ddefebc9fe@zuerich.ch Whole thread Raw |
| Responses |
Re: AW: AW: [Extern] Re: autovacuum on pg_catalog tables
(Tom Lane <tgl@sss.pgh.pa.us>)
|
| List | pgsql-general |
I have some hundred (user) tables where only a small subset of them requires a more aggressive autovacuum.
Setting table level parameters on this small subset seems more straightforward to me.
Loosing this setting on pg_dump / pg_upgrade would be ok for me. Doesn't happen that often.
I tried this on postgres 9.6:
postgresql.conf -> allow_system_table_mods=on + pg_ctl restart
# alter table pg_catalog.pg_shdepend set (autovacuum_vacuum_scale_factor = 0, autovacuum_vacuum_threshold = 1000);
ERROR: shared tables cannot be toasted after initdb
Time: 0.618 ms
# alter table pg_catalog.pg_largeobject set (autovacuum_vacuum_scale_factor = 0, autovacuum_vacuum_threshold = 1000);
ERROR: AccessExclusiveLock required to add toast table.
Time: 0.590 ms
# alter table pg_catalog.pg_largeobject_metadata set (autovacuum_vacuum_scale_factor = 0, autovacuum_vacuum_threshold = 1000);
ERROR: AccessExclusiveLock required to add toast table.
Time: 1.601 ms
Any idea?
Thanks, Markus
Von: Zwettler Markus (OIZ) <Markus.Zwettler@zuerich.ch>
Gesendet: Freitag, 4. Juni 2021 17:44
An: Vijaykumar Jain <vijaykumarjain.github@gmail.com>
Cc: pgsql-general@lists.postgresql.org
Betreff: AW: [Extern] Re: autovacuum on pg_catalog tables
Thanks for the info.
I have a lot of LO manipulation and want a more aggressive autovacuum on some pg_catalog tables therefore.
I do not see any reason why this should not work or be at risk?
Markus
Von: Vijaykumar Jain <vijaykumarjain.github@gmail.com>
Gesendet: Freitag, 4. Juni 2021 17:37
An: Zwettler Markus (OIZ) <Markus.Zwettler@zuerich.ch>
Cc: pgsql-general@lists.postgresql.org
Betreff: [Extern] Re: autovacuum on pg_catalog tables
ok, what i am sharing, DO NOT DO IT.
it is just to answer why it is not working :)
postgres=# alter table pg_catalog.pg_largeobject_metadata set (AUTOVACUUM_VACUUM_COST_DELAY = 1);
ERROR: permission denied: "pg_largeobject_metadata" is a system catalog
postgres=# show allow_system_table_mods;
allow_system_table_mods
-------------------------
off
(1 row)
postgres=# set allow_system_table_mods TO 1;
SET
postgres=# show allow_system_table_mods;
allow_system_table_mods
-------------------------
on
(1 row)
postgres=# alter table pg_catalog.pg_largeobject_metadata set (AUTOVACUUM_VACUUM_COST_DELAY = 1);
ALTER TABLE
but you can always run vacuum manually on the table.
vacuum (verbose,analyze) pg_catalog.pg_largeobject_metadata;
INFO: vacuuming "pg_catalog.pg_largeobject_metadata"
INFO: index "pg_largeobject_metadata_oid_index" now contains 0 row versions in 1 pages
DETAIL: 0 index row versions were removed.
0 index pages have been deleted, 0 are currently reusable.
CPU: user: 0.00 s, system: 0.00 s, elapsed: 0.00 s.
INFO: "pg_largeobject_metadata": found 0 removable, 0 nonremovable row versions in 0 out of 0 pages
DETAIL: 0 dead row versions cannot be removed yet, oldest xmin: 8083775
There were 0 unused item identifiers.
Skipped 0 pages due to buffer pins, 0 frozen pages.
0 pages are entirely empty.
CPU: user: 0.00 s, system: 0.00 s, elapsed: 0.00 s.
INFO: analyzing "pg_catalog.pg_largeobject_metadata"
INFO: "pg_largeobject_metadata": scanned 0 of 0 pages, containing 0 live rows and 0 dead rows; 0 rows in sample, 0 estimated total rows
VACUUM
On Fri, 4 Jun 2021 at 20:10, Zwettler Markus (OIZ) <Markus.Zwettler@zuerich.ch> wrote:
I would like to start a more aggressive autovacuum on pg_catalog tables like pg_largeobject.
So I tried as a superuser:
# alter table pg_catalog.pg_largeobject_metadata set (autovacuum_vacuum_scale_factor = 0, autovacuum_vacuum_threshold = 5000);
ERROR: permission denied: "pg_largeobject_metadata" is a system catalog
(How) Is it possible to change such table attributes on pg_catalog tables?
Thanks, Markus
--
Thanks,
Vijay
Mumbai, India
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