RE: Monitoring multixact members growth - Mailing list pgsql-general

From Vido Vlahinic
Subject RE: Monitoring multixact members growth
Date
Msg-id SYYP282MB1294AC64BADA3A4A3B8636C7806C9@SYYP282MB1294.AUSP282.PROD.OUTLOOK.COM
Whole thread Raw
In response to Monitoring multixact members growth  (Vido Vlahinic <Vido.Vlahinic@milestonegroup.com>)
Responses Re: Monitoring multixact members growth
List pgsql-general

Hello everyone,

 

Is there a way to monitor multixact members growth per table ?

 

There is this query:

 

SELECT relname, relminmxid, mxid_age(relminmxid) AS age

FROM pg_class

WHERE relkind = 'r'

AND relnamespace::regnamespace::text = 'public'

ORDER BY 3 DESC

 

However it is not quite clear to me how I can interpret results from the above and e.g. conclude: my_table accumulates x more multixact members since I measured it last.

 

My goal here is to predict where multixact members are growing the fastest so I can perform manual VACUUM FREEZE only on those tables

(typically with multi-billion row count) when system is relatively idle as opposed to just sit and wait for wraparound protection to take over

when autovacuum_multixact_freeze_max_age threshold is reached (slowing the whole system down).

 

Please advise on how to achieve this.

 

Best regards,

Vido

 

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