Re: Change GUC hashtable to use simplehash?

On Fri, Jan 5, 2024 at 6:54 PM John Naylor <johncnaylorls@gmail.com> wrote:
>
> On Thu, Jan 4, 2024 at 10:01 AM jian he <jian.universality@gmail.com> wrote:
> >
> > I still cannot git apply your patch cleanly. in
>
> I don't know why you're using that -- the git apply man page even says
>
> "Use git-am(1) to create commits from patches generated by
> git-format-patch(1) and/or received by email."
>
> Or, if that fails, use "patch".
>
> > http://cfbot.cputube.org/ i cannot find your patch.
> > ( so, it might be that I test based on incomplete information).
> > but only hashfn_unstable.h influences bench_hash/bench_hash.c.
> >
> > so I attached the whole patch that I had git applied, that is the
> > changes i applied for the following tests.
>
> Well, aside from the added text-editor detritus, it looks like this
> has everything except v11-0008, without which I still get improvement
> for the pgstat hash.
>
> >   Model name:            Intel(R) Core(TM) i5-14600K
>
> > The following is tested with another machine, also listed machine spec below.
> > I tested 3 times, the results is very similar as following:
> > select * from bench_cstring_hash_aligned(100000);        4705.686 ms
> > select * from bench_cstring_hash_unaligned(100000);    6835.753 ms
> > select * from bench_pgstat_hash(100000);                       2678.978 ms
> > select * from bench_pgstat_hash_fh(100000);                  6199.017 ms
> > select * from bench_string_hash(100000);                        847.699 ms
>
> I was fully prepared to believe something like 32-bit Arm would have
> difficulty with 64-bit shifts/multiplies etc., but this makes no sense
> at all. In this test, on my machine, HEAD's pgstat_hash is 3x faster
> than HEAD's "strlen + hash_bytes", but for you it's 3x slower. To
> improve reproducibility, I've added the .sql files and a bench script
> to v13. I invite you to run bench_hash.sh and see if that changes
> anything.

git apply has a verbose option.
also personally I based on vscode editor, the color to view the changes.

jian@jian:~/Desktop/pg_src/src4/postgres$ git apply
$PATCHES/v13-0006-Add-benchmarks-for-hashing.patch
/home/jian/Downloads/patches/v13-0006-Add-benchmarks-for-hashing.patch:81:
indent with spaces.
        if (/^PG_KEYWORD\("(\w+)"/)
/home/jian/Downloads/patches/v13-0006-Add-benchmarks-for-hashing.patch:82:
indent with spaces.
        {
/home/jian/Downloads/patches/v13-0006-Add-benchmarks-for-hashing.patch:87:
indent with spaces.
        }
/home/jian/Downloads/patches/v13-0006-Add-benchmarks-for-hashing.patch:89:
trailing whitespace.

/home/jian/Downloads/patches/v13-0006-Add-benchmarks-for-hashing.patch:92:
trailing whitespace.

warning: squelched 11 whitespace errors
warning: 16 lines add whitespace errors.


jian@jian:~/Desktop/pg_src/src4/postgres$ bash runbench.sh
select * from bench_string_hash(100000);

latency average = 875.482 ms
select * from bench_cstring_hash_unaligned(100000);
latency average = 6539.231 ms
select * from bench_cstring_hash_aligned(100000);
latency average = 4401.278 ms
select * from bench_pgstat_hash(100000);
latency average = 2679.732 ms
select * from bench_pgstat_hash_fh(100000);

latency average = 5711.012 ms
jian@jian:~/Desktop/pg_src/src4/postgres$ bash runbench.sh
select * from bench_string_hash(100000);

latency average = 874.261 ms
select * from bench_cstring_hash_unaligned(100000);
latency average = 6538.874 ms
select * from bench_cstring_hash_aligned(100000);
latency average = 4400.546 ms
select * from bench_pgstat_hash(100000);
latency average = 2682.013 ms
select * from bench_pgstat_hash_fh(100000);

latency average = 5709.815 ms

meson:

meson setup ${BUILD} \
        -Dprefix=${PG_PREFIX} \
        -Dpgport=5459 \
        -Dplperl=enabled \
        -Dplpython=enabled \
        -Dssl=openssl \
        -Dldap=enabled \
        -Dlibxml=enabled \
        -Dlibxslt=enabled \
        -Duuid=e2fs \
        -Dzstd=enabled \
        -Dlz4=enabled \
        -Dsystemd=enabled \
        -Dcassert=true \
        -Db_coverage=true \
        -Dicu=enabled \
        -Dbuildtype=debug \
        -Dwerror=true \
        -Dc_args='-Wunused-variable
                -Wuninitialized
-Werror=maybe-uninitialized
                -Wreturn-type
                -DWRITE_READ_PARSE_PLAN_TREES
                -DCOPY_PARSE_PLAN_TREES
                -DREALLOCATE_BITMAPSETS
                -DRAW_EXPRESSION_COVERAGE_TEST -fno-omit-frame-pointer' \
        -Ddocs_pdf=disabled \
        -Dllvm=disabled \
        -Ddocs_pdf=disabled