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From: Jeremy Smith <jeremy@musicsmith.net>
Date: Wed, 5 Jun 2024 08:09:34 -0400
Message-ID: <CAM8SmLUMREu3MOSpfh58EoV9ysgWi8sFkbj_BnBJQjeJn3C+7Q@mail.gmail.com>
Subject: Re: Poor performance after restoring database from snapshot on AWS RDS
To: Sam Kidman <sam@fresho.com>
Cc: pgsql-general@lists.postgresql.org
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On Wed, Jun 5, 2024 at 4:23=E2=80=AFAM Sam Kidman <sam@fresho.com> wrote:

> We get very poor performance in the staging environment after this
> restore takes place - after some usage it seems to get better perhaps
> because of caching.
>

This is due to the way that RDS restores snapshots.

From the docs (https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_=
RestoreFromSnapshot.html):

You can use the restored DB instance as soon as its status is
available. The DB instance continues to load data in the background.
This is known as lazy loading.

If you access data that hasn't been loaded yet, the DB instance
immediately downloads the requested data from Amazon S3, and then
continues loading the rest of the data in the background.


  -Jeremy