Re: RDS IO Read time

On 3/31/25 06:54, Eden Aharoni wrote:
> Hi all,
>
> Hopefully, someone here could help us understand whats going on with our
> deployment..
>
> We are running Postgres 17.4 on AWS RDS on an ec2 instance that has:
>
> * 32vCPU
> * 128GB RAM
> * gp3 with 25K IOPS and 4000MiB/s throughput
> * the instance supports up to 3125GB/s of throughput.
>
> Whenever a query fetches data from the disk (index scan, bitmap scans,
> etc.) we’re reaching 23 – 30MB/s of IO Read time.
>
> We changed our autovacuum settings to be more aggressive (0 scale factor
> and 10K threshold) so our index only scans will (hopefully) read data
> from the disk rarely. However, we can’t optimize all the queries to use
> index-only-scan since our users can dynamically select which columns to
> see and filtering.
>
> Is this expected IO read rate? I can’t help but feel we’re missing
> something here..

RDS is a black box controlled by AWS, you are going to need to reach out
to their tech support.

>
> Thanks a lot! 😊
>

--
Adrian Klaver
adrian(dot)klaver(at)aklaver(dot)com