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.klaver@aklaver.com