Hello, I had an RDS instance with a “lot” of CPU and a “lot” of memory. I was studying tuning parameters for a particular application. I wanted to change instance type to have less CPU and less memory. There were no way to do it. The instance had to be erased an recreated. At the beginning, It was possible to choose an instance type with bigger RAM and more CPUs. Regards Michel SALAIS Consultant Oracle, PostgreSQL MSYM 23 rue du Départ Boîte 37 75014 Paris +33 6 68 94 19 60 msalais@xxxxxxx www.msym.fr De : Wells Oliver <wells.oliver@xxxxxxxxx>
Envoyé : mercredi 20 octobre 2021 22:36
À : Michel SALAIS <msalais@xxxxxxx>
Cc : John Scalia <jayknowsunix@xxxxxxxxx>; Tom Lane <tgl@xxxxxxxxxxxxx>; pgsql-admin <pgsql-admin@xxxxxxxxxxxxxx>
Objet : Re: Understanding was terminated by signal 9: Killed For posterity: RDS will definitely allow you to downgrade instance type. Be careful!
I am not sure but upgrade for a larger instance can't be temporary. I think you can't downgrade to the original instance class thereafter...
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Michel SALAIS
-----Message d'origine-----
De : John Scalia <jayknowsunix@xxxxxxxxx>
Envoyé : mercredi 20 octobre 2021 01:12
À : Tom Lane <tgl@xxxxxxxxxxxxx>
Cc : Wells Oliver <wells.oliver@xxxxxxxxx>; pgsql-admin <pgsql-admin@xxxxxxxxxxxxxx>
Objet : Re: Understanding was terminated by signal 9: Killed
You could always change the size of the RDS instance to something larger than what it currently is running, even just temporarily.
Sent from my iPad
> On Oct 19, 2021, at 6:01 PM, Tom Lane <tgl@xxxxxxxxxxxxx> wrote:
>
> Wells Oliver <wells.oliver@xxxxxxxxx> writes:
>> In an RDS instance with 16GB RAM, I ran a long query which started by
>> setting temp_buffers to 16GB, so I think I plum ran out of memory,
>> but can anyone point me in a different direction if the following log
>> messages indicate something else is awry?
>
> Yeah, this:
>
>> 2021-10-19 21:10:37 UTC::@:[24752]:LOG: server process (PID 25813)
>> was terminated by signal 9: Killed
>
> almost certainly indicates the Linux OOM killer at work. If you were
> running your own system I'd point you to [1], but I doubt that RDS
> lets you put your hands on the relevant knobs.
>
> regards, tom lane
>
> [1]
> https://www.postgresql.org/docs/current/kernel-resources.html#LINUX-ME
> MORY-OVERCOMMIT
>
>
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