Re: Change prefetch and read strategies to use range in pg_prewarm ... and raise a question about posix_fadvise WILLNEED

Hi,

On Thu, 7 Mar 2024 at 15:26, Cédric Villemain
<Cedric.Villemain@abcsql.com> wrote:
>
> On 07/03/2024 12:19, Nazir Bilal Yavuz wrote:
> >
> > I did not test read performance but I am planning to do that soon.

I did not have the time to check other things you mentioned but I
tested the read performance. The table size is 5.5GB, I did 20 runs in
total.

When the OS cache is cleared:

Master -> Median: 2266.293ms, Avg: 2265.5038ms
Patched -> Median: 2166.493ms, Avg: 2183.6208ms

When the buffers are in the OS cache:

Master -> Median: 585.719ms, Avg: 583.5032ms
Patched -> Median: 533.071ms, Avg: 532.7119ms

Patched version is better on both. ~4% when the OS cache is cleared,
~%9 when the buffers are in the OS cache.

--
Regards,
Nazir Bilal Yavuz
Microsoft