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Date: Wed, 8 Oct 2025 12:54:44 -0700
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Subject: Re: Alerting on memory use and instance crash
To: sud <suds1434@gmail.com>, Ron Johnson <ronljohnsonjr@gmail.com>
Cc: pgsql-general <pgsql-general@lists.postgresql.org>
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From: Adrian Klaver <adrian.klaver@aklaver.com>
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On 10/8/25 11:58, sud wrote:
> Thank you.
> My understanding may be wrong here.And my apology as I am using the 
> example of Oracle again even though these two are not the same. But 
> being worked for a long time in Oracle so trying to understand exactly 
> how it's different.
> 
> In oracle RAC(real application cluster) database, we have single 
> databases with multiple nodes/instances/memory, which means the 
> underlying storage is same but the memory/cpu of each of those instances 
> are different and any of the instances can be down but the database 
> still operates routing the application traffic of the downed node to 
> others. Similarly even in AWS Aurora postgres also there can be multiple 
> instances like Writer and Reader instances/nodes and the underlying 
> storage being the same. So I was thinking of any such cluster level pg_* 
> views available by querying which we would be able to know if any one of 
> the nodes is down ?   Also , I don't see any such pg_* view which can 
> show the statistics of all the instances combinely i.e. cluster level 
> statistics.
> 
> Do you mean in normal Postgres it's alway a single instance/memory and 
> single storage attached? then I also do not see any such cluster level 
> views in aws aurora postgres too? Pardon if it's a silly one to ask.
> 

It would be helpful if you specified exactly what variety of Postgres 
you are using and it's version.

If you are using AWS Aurora Postgres then you will need to look at pages 
like this:

https://docs.aws.amazon.com/AmazonRDS/latest/AuroraUserGuide/AuroraPostgreSQL.Managing.html

This list is for the community version of Postgres and it's been a long 
time since AWS saw fit to have someone on the list and when they where 
here they did not really provide answers.

-- 
Adrian Klaver
adrian.klaver@aklaver.com