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* Max tables in a cluster?
@ 2023-04-05 07:07 Karthik Krishnakumar <karthikk@zohocorp.com>
0 siblings, 2 replies; 3+ messages in thread
From: Karthik Krishnakumar @ 2023-04-05 07:07 UTC (permalink / raw)
To: pgsql-admin <pgsql-admin@lists.postgresql.org>
Hi admins,
Is there a limit to number of tables that a cluster can support?
At the moment, one of my clusters has about 250k user tables (plus 150k toast tables) across a hundred schemas within a single database.
My application team wants to double the number of schemas (and with it the tables)
I am looking for both pros and cons of doing this and what tuning can help this cluster perform acceptably.
My questions are
1. Is there a limit to number of tables a cluster can support effectively?
2. My guess is autovacuum would have to be tuned. Current gucs for this are
max_autovacuum_workers = 6
maintenance_work_mem = 1GB
autovacuum_vacuum_scale_factor = 0.2
autovacuum_vacuum_cost_delay = 20ms
Are there any potential problems that I need to think about ?
My machine specs are as below.
RAM 256GB
32-core CPU
7TB SSD
thanks
karthik
^ permalink raw reply [nested|flat] 3+ messages in thread
* Re: Max tables in a cluster?
@ 2023-04-05 07:20 Ron <ronljohnsonjr@gmail.com>
parent: Karthik Krishnakumar <karthikk@zohocorp.com>
1 sibling, 0 replies; 3+ messages in thread
From: Ron @ 2023-04-05 07:20 UTC (permalink / raw)
To: pgsql-admin@lists.postgresql.org
On 4/5/23 02:07, Karthik Krishnakumar wrote:
> Hi admins,
>
> Is there a limit to number of tables that a cluster can support?
https://www.postgresql.org/docs/13/limits.html
> At the moment, one of my clusters has about 250k user tables (plus 150k
> toast tables) across a hundred schemas within a single database.
> My application team wants to double the number of schemas (and with it the
> tables)
> I am looking for both pros and cons of doing this and what tuning can help
> this cluster perform acceptably.
>
> My questions are
> 1. Is there a limit to number of tables a cluster can support effectively?
> 2. My guess is autovacuum would have to be tuned. Current gucs for this are
> max_autovacuum_workers = 6
> maintenance_work_mem = 1GB
> autovacuum_vacuum_scale_factor = 0.2
> autovacuum_vacuum_cost_delay = 20ms
>
> Are there any potential problems that I need to think about ?
>
> My machine specs are as below.
> RAM 256GB
> 32-core CPU
> 7TB SSD
>
> thanks
> karthik
>
--
Born in Arizona, moved to Babylonia.
^ permalink raw reply [nested|flat] 3+ messages in thread
* Re: Max tables in a cluster?
@ 2023-04-05 10:21 hubert depesz lubaczewski <depesz@depesz.com>
parent: Karthik Krishnakumar <karthikk@zohocorp.com>
1 sibling, 0 replies; 3+ messages in thread
From: hubert depesz lubaczewski @ 2023-04-05 10:21 UTC (permalink / raw)
To: Karthik Krishnakumar <karthikk@zohocorp.com>; +Cc: pgsql-admin <pgsql-admin@lists.postgresql.org>
On Wed, Apr 05, 2023 at 12:37:41PM +0530, Karthik Krishnakumar wrote:
> Is there a limit to number of tables that a cluster can support?
Well, yes.
For starters: https://www.postgresql.org/docs/current/limits.html
But more important is: with large number of tables certain operations
become VERY slow. Specifically getting schema dump. Which is used, for
example, by pg_upgrade.
In my experience hitting 1 million rows in pg_class made it
realistically impossible to use pg_dump. But there have been
many improvements to pg_dump over the years
(https://why-upgrade.depesz.com/show?from=9.5&to=15.2&keywords=pg_dump)
to it's possible that the problem is gone now.
Try taking `pg_dump -s` of the db, and see how long it takes...
Best regards,
depesz
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2023-04-05 07:07 Max tables in a cluster? Karthik Krishnakumar <karthikk@zohocorp.com>
2023-04-05 07:20 ` Ron <ronljohnsonjr@gmail.com>
2023-04-05 10:21 ` hubert depesz lubaczewski <depesz@depesz.com>
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