public inbox for [email protected]  

help / color / mirror / Atom feed

From: jian he <[email protected]>
To: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Subject: Re: Row pattern recognition
Date: Sat, 4 Jul 2026 09:22:24 +0800
Message-ID: <CACJufxFDkF0_JjHh--d4cbakaCG6X=c7RHYENGMyrudKnBT1-g@mail.gmail.com> (raw)
In-Reply-To: <CAAAe_zBMvzn6ZwmTPhsi0mP6FPVv3hZ2cb1Xe3KD8brT5EPTFg@mail.gmail.com>
References: <CAAAe_zChW=nM9J18wdF2wMa2KesFO53fkbVRudkJ_bstdxzfOQ@mail.gmail.com>
	<[email protected]>
	<[email protected]>
	<[email protected]>
	<CAAAe_zBMvzn6ZwmTPhsi0mP6FPVv3hZ2cb1Xe3KD8brT5EPTFg@mail.gmail.com>

On Sat, Jul 4, 2026 at 6:22 AM Henson Choi <[email protected]> wrote:
>
> Hi Tatsuo,
>
> > In v50-0006-tidy-plumbing.patch, the planner cost model seems slightly
> > changed. Before the cost was charged according to the number of
> > pattern variables in PATTERN clause. But now it is charged according
> > to the number of pattern variables in DEFINE clause. Maybe I missed
> > the discussion on the changing. Can you please explain the reason of
> > the change?
>
> The change is a simplification that came out of Jian's v48 review, and it
> does not change the cost the model produces.
>
> It follows Jian's suggestion from 2026-06-15 [1]:
>
> ....
>
> This also matches the premise of the cost model we settled on back in
> February: the NFA executor evaluates every DEFINE expression once per row,
> so the natural unit for the per-tuple charge is the DEFINE variable.
>
> [1] https://www.postgresql.org/message-id/CACJufxFAQhbOD9EVCTAy-VwDbG4446N10GsxCcgdpFnjHO1Efw%40mail.gma...
>
> Best regards,
> Henson

I am wondering if we can have one query to enable (COSTS ON) for testing.

For many rpr tests, the table size is small, EXPLAIN ANALYZE won't
take long, and probably all rows will be sampled.
Of course, once the patch is in committable shape, we need to switch it to OFF.

view thread (181+ messages)  latest in thread

reply

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Reply to all the recipients using the --to and --cc options:
  reply via email

  To: [email protected]
  Cc: [email protected], [email protected], [email protected], [email protected], [email protected], [email protected], [email protected], [email protected], [email protected], [email protected], [email protected]
  Subject: Re: Row pattern recognition
  In-Reply-To: <CACJufxFDkF0_JjHh--d4cbakaCG6X=c7RHYENGMyrudKnBT1-g@mail.gmail.com>

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

This inbox is served by agora; see mirroring instructions
for how to clone and mirror all data and code used for this inbox