Re: [PATCH] avoid double scanning in function byteain

Поиск
Список
Период
Сортировка
От Stepan Neretin
Тема Re: [PATCH] avoid double scanning in function byteain
Дата
Msg-id CA+Yyo5Ta=wdcObw+y9_F9MuP6vTduu9PCHD6RWk5vGuNR5q8RA@mail.gmail.com
обсуждение исходный текст
Ответ на Re: [PATCH] avoid double scanning in function byteain  (Aleksander Alekseev <aleksander@timescale.com>)
Список pgsql-hackers
Дерево обсуждения


On Fri, May 9, 2025 at 7:43 PM Aleksander Alekseev <aleksander@timescale.com> wrote:
Hi Stepan,

> Sorry for the noise — I'm resending the patch because I noticed a compiler warning related to mixed declarations and code, which I’ve now fixed.
>
> Apologies for the oversight in the previous submission.

Thanks for the patch.

As Kirill pointed out above, it would be nice if you could prove that
your implementation is actually faster. I think something like a
simple micro-benchmark will do.

--
Best regards,
Aleksander Alekseev


Hi,

Thanks for the feedback.

I’ve done a simple micro-benchmark using PL/pgSQL with a large escaped input string (\\123 repeated 100,000 times), converted to bytea in a loop:

DO $$
DECLARE    start_time TIMESTAMP;    end_time TIMESTAMP;    i INTEGER;    dummy BYTEA;    input TEXT := repeat(E'\\123', 100000);    elapsed_ms DOUBLE PRECISION;
BEGIN    start_time := clock_timestamp();
    FOR i IN 1..1000 LOOP        dummy := input::bytea;    END LOOP;
    end_time := clock_timestamp();    elapsed_ms := EXTRACT(EPOCH FROM end_time - start_time) * 1000;    RAISE NOTICE 'Average time per call: % ms', elapsed_ms / 1000;
END
$$;

Here are the results from NOTICE output:

Without patch:

NOTICE:  Average time per call: 0.49176600000000004 ms
NOTICE:  Average time per call: 0.47658999999999996 ms

With patch:

NOTICE:  Average time per call: 0.468231 ms
NOTICE:  Average time per call: 0.463909 ms

The gain is small but consistent. Let me know if a more rigorous benchmark would be useful.

Best regards,
Stepan Neretin

В списке pgsql-hackers по дате отправления: