Horton

Re: pgsql: dshash: Add sequential scan support.

Thomas Munro <thomas.munro@gmail.com>

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From: Thomas Munro <thomas.munro@gmail.com>
To: Andres Freund <andres@anarazel.de>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Kyotaro HORIGUCHI <horiguchi.kyotaro@lab.ntt.co.jp>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2022-07-05T03:21:40Z
Lists: pgsql-hackers

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On Tue, Jul 5, 2022 at 11:25 AM Andres Freund <andres@anarazel.de> wrote:
> On 2022-07-05 11:20:54 +1200, Thomas Munro wrote:
> > Since there were 6 places with I-hold-no-lock assertions, I shoved the
> > loop into a function so I could do:
> >
> > -               Assert(!status->hash_table->find_locked);
> > +               assert_no_lock_held_by_me(hash_table);
>
> I am a *bit* wary about the costs of that, even in assert builds - each of the
> partition checks in the loop will in turn need to iterate through
> held_lwlocks. But I guess we can also just later weaken them if it turns out
> to be a problem.

Maybe we should add assertion support for arrays of locks, so we don't
need two levels of loop?  Something like the attached?

Commits

  1. Fix lock assertions in dshash.c.

  2. dshash: Add sequential scan support.