From: | "Peter J(dot) Holzer" <hjp-pgsql(at)hjp(dot)at> |
---|---|
To: | pgsql-general(at)lists(dot)postgresql(dot)org |
Subject: | Re: Purging few months old data and vacuuming in production |
Date: | 2023-01-07 11:29:46 |
Message-ID: | 20230107112946.pamp3ot44sa7aylk@hjp.at |
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Lists: | pgsql-general |
On 2023-01-07 05:33:33 +0000, Ranjith Paliyath wrote:
>
> > This is because the deletion step is executed record
> > by record in main table, with its connected record(s)
> > delete executions in rest of tables?
>
> > I don't know if you have ON DELETE CASCADE. Even if you do,
> > you'll have to manually delete the tables not linked by FK.
> > I'd write a PL/pgSQL procedure: pass in a PK and then delete
> > records from the 9 tables in the proper order so as to not
> > throw FK constraint errors.
>
> Ok, in the case of our specific 9 tables it would finding and deleting
> linked records in 8 tables based on the record chosen in the main
> table. That is going and deleting records one by one.
If I understood correctly, you have to delete about 3 million records
(worst case) from the main table each day. Including the other 8 tables
those are 27 million DELETE queries each of which deletes only a few
records. That's about 300 queries per second. I'd be worried about
impacting performance on other queries at this rate.
I'd go for a middle ground: Instead of expiring once per day, use a
shorter interval, maybe once per hour or once per minute. That will
(probably) make each expire job really quick but still create much less
load overall.
hp
--
_ | Peter J. Holzer | Story must make more sense than reality.
|_|_) | |
| | | hjp(at)hjp(dot)at | -- Charles Stross, "Creative writing
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