Re: Streaming read-ready sequential scan code

On 01/04/2024 22:58, Melanie Plageman wrote:
> Attached v7 has version 14 of the streaming read API as well as a few
> small tweaks to comments and code.

I saw benchmarks in this thread to show that there's no regression when
the data is in cache, but I didn't see any benchmarks demonstrating the
benefit of this. So I ran this quick test:

-- create table ~1 GB table with only 1 row per page.
CREATE TABLE giga (i int, filler text) with (fillfactor=10);
insert into giga select g, repeat('x', 900) from generate_series(1,
140000) g;
vacuum freeze giga;

\timing on
select count(*) from giga;

The SELECT takes about 390 ms on 'master', and 230 ms with the patch.

This is pretty much the best case for this patch, real world gains will
be much smaller. Nevertheless, nice speedup!

--
Heikki Linnakangas
Neon (https://neon.tech)