Re: Using read_stream in index vacuum

Hi Andrey,

I ran the following test with
v7-0001-Prototype-B-tree-vacuum-streamlineing.patch
to measure the performance improvement.

--Table size of approx 2GB (Fits in RAM)
postgres=# create unlogged table x_big as select i from
generate_series(1,6e7) i;
SELECT 60000000
postgres=# create index on x_big(i);
CREATE INDEX
-- Perform updates to create dead tuples.
postgres=# do $$
declare
var int := 0;
begin
for counter in 1 .. 1e7 loop
var := (SELECT floor(random() * (1e7 - 1 + 1) * 1));
UPDATE x_big SET i = i + 5 WHERE i = var;
end loop;
end;
$$;
postgres=# CREATE EXTENSION pg_buffercache;
CREATE EXTENSION
-- Evict Postgres buffer cache for this relation.
postgres=# SELECT DISTINCT pg_buffercache_evict(bufferid)
FROM pg_buffercache
WHERE relfilenode = pg_relation_filenode('x_big');
pg_buffercache_evict
----------------------
t
(1 row)

postgres=# \timing on
Timing is on.
postgres=# vacuum x_big;
VACUUM

The timing does not seem to have improved with the patch.
Timing with the patch: Time: 9525.696 ms (00:09.526)
Timing without the patch: Time: 9468.739 ms (00:09.469)

While writing this email, I realized I evicted buffers for the table
and not the index. I will perform the test again. However,
I would like to know your opinion on whether this looks like
a valid test.

Thank you,
Rahila Syed

On Thu, Oct 24, 2024 at 4:45 PM Andrey M. Borodin <x4mmm(at)yandex-team(dot)ru>
wrote:

>
>
> > On 24 Oct 2024, at 10:15, Andrey M. Borodin <x4mmm(at)yandex-team(dot)ru>
> wrote:
> >
> > I've also added GiST vacuum to the patchset.
>
> I decided to add up a SP-GiST while having launched on pgconf.eu.
>
>
> Best regards, Andrey Borodin.
>