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In-Reply-To: <77FA04FE-1F84-4DA1-8855-8BBFD8CC889A@gmail.com>
From: Amit Langote <amitlangote09@gmail.com>
Date: Tue, 31 Mar 2026 18:17:16 +0900
Message-ID: 
 <CA+HiwqHpVtP485wEKuXdOkdoZWhvVvfFH40-og07Jp3MPx21eg@mail.gmail.com>
Subject: Re: Eliminating SPI / SQL from some RI triggers - take 3
To: Chao Li <li.evan.chao@gmail.com>
Cc: Junwang Zhao <zhjwpku@gmail.com>, Haibo Yan <tristan.yim@gmail.com>,
	Pavel Stehule <pavel.stehule@gmail.com>,
	PostgreSQL-development <pgsql-hackers@postgresql.org>,
 Tomas Vondra <tomas@vondra.me>
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Hi,

On Tue, Mar 31, 2026 at 6:09=E2=80=AFPM Chao Li <li.evan.chao@gmail.com> wr=
ote:
> > On Mar 30, 2026, at 19:15, Amit Langote <amitlangote09@gmail.com> wrote=
:
> >
> > On Mon, Mar 30, 2026 at 1:55=E2=80=AFPM Amit Langote <amitlangote09@gma=
il.com> wrote:
> >> Junwang pointed out off-list that FK tuples added to
> >> RI_FastPathEntry.batch[] were being copied into TopTransactionContext
> >> rather than flush_cxt, so they would accumulate until the batch was
> >> exhausted rather than being reclaimed per flush. Fixed in
> >> ri_FastPathBatchAdd() in 0002.
> >>
> >> Also added a couple of comments in trigger.c that were missing: an
> >> Assert and explanation in RegisterAfterTriggerBatchCallback()
> >> clarifying the query_depth >=3D 0 precondition, a comment at the
> >> AfterTriggerEndQuery call site explaining why
> >> FireAfterTriggerBatchCallbacks() must precede the query_depth
> >> decrement and AfterTriggerFreeQuery, and brief intent comments at the
> >> AfterTriggerFireDeferred and AfterTriggerSetState call sites.
> >>
> >> Plan is to commit 0001 tomorrow barring objections and let it sit for
> >> a bit before committing 0002. Feedback on 0002, particularly on the
> >> AfterTriggerBatchCallback mechanism in trigger.c, welcome in the
> >> meantime.
> >
> > Kept looking at 0002 and found a couple of things to improve or change
> > my thoughts about.  I decided to move the permission check from fast
> > path cache entry creation into ri_FastPathBatchFlush(), alongside the
> > snapshot, so that permission changes between flushes are respected
> > rather than checked once at batch start; the check happens for every
> > row in the SPI and non-batched fast path.  Also, improved comments in
> > a few places to mention design decisions better.
> >
> > 0001 is mostly unchanged from v11 except I updated its commit message
> > to explain why only RI_FKey_check is covered and not the action
> > triggers as the topic has come up in previous threads about this
> > topic.
> >
> > Still planning to commit 0001 tomorrow.
> >
> > --
> > Thanks, Amit Langote
> > <v12-0001-Add-fast-path-for-foreign-key-constraint-checks.patch><v12-00=
02-Batch-FK-rows-and-use-SK_SEARCHARRAY-for-fast-pa.patch>
>
> Hi Amit,
>
> While reading the recent commits, I saw that 0001 has been pushed as 2da8=
6c1ef9b5446e0e22c0b6a5846293e58d98e3. However, I also just noticed a use-af=
ter-free issue in ri_LoadConstraintInfo(). It dereferences conForm after Re=
leaseSysCache(tup), which is unsafe. I am attaching a tiny patch to fix tha=
t.

Thanks.  I noticed that too and pushed the fix an hour ago:

https://www.postgresql.org/message-id/E1w7U6V-002H6n-0o%40gemulon.postgresq=
l.org

--=20
Thanks, Amit Langote