Re: Change GUC hashtable to use simplehash?

John Naylor <johncnaylorls@gmail.com>

From: John Naylor <johncnaylorls@gmail.com>

To: "Anton A. Melnikov" <a.melnikov@postgrespro.ru>

Cc: Tom Lane <tgl@sss.pgh.pa.us>, Jeff Davis <pgsql@j-davis.com>, Ants Aasma <ants.aasma@cybertec.at>, Heikki Linnakangas <hlinnaka@iki.fi>, Junwang Zhao <zhjwpku@gmail.com>, jian he <jian.universality@gmail.com>, Andres Freund <andres@anarazel.de>, Gurjeet Singh <gurjeet@singh.im>, pgsql-hackers@postgresql.org

Date: 2025-01-17T09:50:37Z

Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

Silence warning in older versions of Valgrind
- fde7c0164ea2 17.5 landed
- 0600d276d485 18.0 landed
Revert "Speed up tail processing when hashing aligned C strings, take two"
- 6555fe197914 17.3 landed
- 235328ee4ae4 18.0 landed
Speed up tail processing when hashing aligned C strings, take two
- a365d9e2e8c1 17.0 landed
Teach fasthash_accum to use platform endianness for bytewise loads
- 0c25fee35903 17.0 landed
Add macro to disable address safety instrumentation
- db17594ad73a 17.0 landed
Convert uses of hash_string_pointer to fasthash equivalent
- f956ecd0353b 17.0 landed
Speed up tail processing when hashing aligned C strings
- 07f0f6abfc7f 17.0 landed
Add helper functions for dshash tables with string keys.
- 42a1de3013ea 17.0 cited
Fix warnings in cpluspluscheck
- 257998508672 17.0 landed
Further cosmetic review of hashfn_unstable.h
- b83033c3cff5 17.0 landed
Simplify initialization of incremental hash state
- 9ed3ee5001b6 17.0 landed
Add optimized C string hashing
- 0aba2554409e 17.0 landed
Add inline incremental hash functions for in-memory use
- e97b672c88f6 17.0 landed
Make all Perl warnings fatal
- c5385929593d 17.0 cited

On Wed, Jan 15, 2025 at 7:08 PM Anton A. Melnikov
<a.melnikov@postgrespro.ru> wrote:
> It was x86 AMD Laptop: HP Probook 455 g7 with AMD Ryzen 7 4700U and 64GB DDR4 RAM.
> OS: Linux 5.15.0-130-generic #140~20.04.1-Ubuntu SMP Wed Dec 18 21:35:34 UTC 2024 x86_64 x86_64 x86_64 GNU/Linux.
>
> ~$ valgrind --version
> valgrind-3.15.0

Thanks for getting back to us! 3.24 on x86_64 doesn't raise a warning.
If anyone believes the difference from a release six years ago
represents a regression in diagnostic ability, perhaps that warrants a
bug report to Valgrind?

> > I'd be inclined to just remove the pg_rightmost_one_pos64 call
> > in favor of the other coding you suggest.
>
> Here is a patch like that.

It would be a lot more readable to revert the offending commit
instead, since its predecessor had a much simpler bytewise loop.

--
John Naylor
Amazon Web Services