Re: Tooling for per table autovacuum tuning

Hi,

Following on from Michael's idea, you could write a function to split up
the tables based upon size.  As an example, you could do this (using the
pg_stat_all_tables):

DO
$$
DECLARE
        tab_rec RECORD;
BEGIN

        FOR tab_rec IN SELECT   schemaname,
                                relname tablename,
                                pg_catalog.pg_table_size(relid) bytes,
pg_catalog.pg_size_pretty(pg_catalog.pg_table_size(relid)) size
                        FROM    pg_stat_all_tables
                        WHERE   schemaname NOT IN
('pg_catalog','information_schema')
                        AND     schemaname = 'public'
                        ORDER BY bytes
        LOOP
                RAISE NOTICE 'schemaname % tablename % bytes: %
Table_size: %', tab_rec.schemaname, tab_rec.tablename, tab_rec.bytes,
tab_rec.size;

                IF tab_rec.bytes < 10000 THEN
                        RAISE NOTICE 'ALTER TABLE %.% SET
(autovacuum_vacuum_cost_limit = 1000);', tab_rec.schemaname,
tab_rec.tablename;
                ELSE
                        RAISE NOTICE 'ALTER TABLE %.% SET
(autovacuum_vacuum_cost_limit = 10000);', tab_rec.schemaname,
tab_rec.tablename;
                END IF;

        END LOOP;
END;
$$

NOTICE: schemaname public tablename event_check3 bytes: 0 Table_size: 0
bytes
NOTICE:  ALTER TABLE public.event_check3 SET
(autovacuum_vacuum_cost_limit = 1000);
NOTICE:  schemaname public tablename event_check bytes: 0 Table_size: 0
bytes
NOTICE:  ALTER TABLE public.track_ddl SET (autovacuum_vacuum_cost_limit
= 10000);
NOTICE:  schemaname public tablename audit_ddl_cmds bytes: 16384
Table_size: 16 kB
NOTICE:  ALTER TABLE public.audit_ddl_cmds SET
(autovacuum_vacuum_cost_limit = 10000);
NOTICE:  schemaname public tablename c1 bytes: 16384 Table_size: 16 kB

You'd have to define the parameters in the IF statements but it could be
split up into the "t-shirt" sizes that you want.  The pg_catalog table
could also be changed to something else but this is the general idea.

KR,

Matt

On 12/03/2023 20:43, MichaelDBA wrote:
> Why don't you just monitor pg_stat_user_tables.n_dead_tup on a 
> regular basis and increase autovacuum aggressiveness based on that at
> the global level (postgresql.conf - thresholds) or set autovacuum
> parms at the table level for customized cases.
>
> Regards,
> Michael Vitale
>
>
> Joseph Hammerman wrote on 3/12/2023 4:34 PM:
>> Hi all,
>>
>> Apologies for any confusion I may have caused. What I am imagining is
>> per table tuning that buckets the tables based on their relative sizes.
>>
>> Something like:
>>
>> Up to 1Gb - Small
>> Up to 4Gb - Medium
>> Up to 8Gb - L
>> Bigger - XL
>>
>> And an accordant autovacuum_scale_factor associated with each size.
>>
>> The motivation for this is to make sure large tables get regularly
>> vacuumed.
>>
>> I hope that clears thing up!
>> Joe
>>
>> On Sun, Mar 12, 2023 at 9:56 AM Wolfgang Wilhelm
>> <wolfgang20121964(at)yahoo(dot)de> wrote:
>>
>> I think Mr Hammerman is referring to T-shirts for user stories.
>>
>> But even when I'm right I don't get what is meant with that. I
>> don't get what Joe means with "autovacuuming profiles per table".
>> Joe, can you elaborate on that?
>>
>> Yours
>> Wolfgang
>>
>> Am Sonntag, 12. März 2023 um 14:47:42 MEZ hat Laurenz Albe
>> <laurenz(dot)albe(at)cybertec(dot)at> Folgendes geschrieben:
>>
>>
>> On Sat, 2023-03-11 at 10:49 -0800, Joseph Hammerman wrote:
>>
>> > I would like to define t-shirt sizes and have an
>> autovacuuming profile associated with each t-shirt size.
>> >
>> > Is there any tooling out there that assists in the execution
>> side of this? Or are all of you rolling your own?
>>
>>
>> Isn't that question 21 days early?
>>
>> Yours,
>> Laurenz Albe
>>
>>
>>
>
>
> Regards,
>
> Michael Vitale
>
> Michaeldba(at)sqlexec(dot)com <mailto:michaelvitale(at)sqlexec(dot)com>
>
> 703-600-9343
>
>
>
>
--
Pythian
Matt Pearson | Database Consultant - PostgreSQL & Oracle | LinkedIn
mpearson2(at)pythian(dot)com
www.pythian.com
Pythian

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