Re: Alerting on memory use and instance crash
| От | sud |
|---|---|
| Тема | Re: Alerting on memory use and instance crash |
| Дата | |
| Msg-id | CAD=mzVVBHZ6480qrbPYhvpkkKqGeBpahV-+=r0xXU7O0XXQ5zw@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: Alerting on memory use and instance crash (Adrian Klaver <adrian.klaver@aklaver.com>) |
| Ответы |
Re: Alerting on memory use and instance crash
Re: Alerting on memory use and instance crash |
| Список | pgsql-general |
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.
On Wed, Oct 8, 2025 at 9:52 PM Adrian Klaver <adrian.klaver@aklaver.com> wrote:
On 10/8/25 08:42, sud wrote:
> Hi Experts,
>
> It's postgres version 16. I have two questions on alerting as below.
>
> 1)If we want to have alerting on any node/instance that gets crashed :-
> In other databases like Oracle the catalog Views like "GV$Instance" used
> to give information on whether the instances are currently active/down
> or not. But in postgres it seems all the pg_* views are instance
> specific and are not showing information on the global/cluster level but
> are restricted to instance level only. So is there any other way to
> query the pg_* views to have alerts on the specific instance crash?
1) When you say instance do you mean database?
2) Not all system tables/views are database only.
For instance:
https://www.postgresql.org/docs/current/catalog-pg-database.html
https://www.postgresql.org/docs/current/catalog-pg-auth-members.html
https://www.postgresql.org/docs/current/catalog-pg-authid.html
https://www.postgresql.org/docs/current/view-pg-roles.html
> 2)Is there a way to fetch the data from pg_* view to highlight the
> specific connection/session/sqls which is using high memory in postgres?
>
> Appreciate your guidance.
>
> Regards
> Sud
--
Adrian Klaver
adrian.klaver@aklaver.com
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