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Subject: Re: [EXTERNAL] RDS IO Read time
From: Christophe Pettus <xof@thebuild.com>
In-Reply-To: <PA6PR03MB102418866F5C140FB0604E1EBBBAD2@PA6PR03MB10241.eurprd03.prod.outlook.com>
Date: Mon, 31 Mar 2025 10:43:19 -0700
Cc: "pgsql-general@lists.postgresql.org" <pgsql-general@lists.postgresql.org>
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To: Eden Aharoni <edena@legitsecurity.com>
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> On Mar 31, 2025, at 10:32, Eden Aharoni <edena@legitsecurity.com> =
wrote:
>=20
> First, thanks for the reply :)
> So, I do know which part is taking a lot of IO time and it's to be =
honest any node that reads from the disk.. of course, we're running =
EXPLAIN on our queries (to be more specific we use auto_explain) but we =
can't seem to find what could cause an index scan that reads 34 MB to =
take more than a second (1.2 sec).. we do know that our dataset doesn't =
fit the memory and we were ok with that but with IO being so slow we =
just don't know what to do anymore. Any other suggestions other than =
contact AWS (which we did but it seems this path won't lead anywhere).

The performance of EBS is definitely a question for AWS.  I can say =
that, in our experience, EBS mounts for RDS almost never approach the =
stated maximum throughput, although io2 tends to be closer than gp2 or =
gp3.=