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From: Tender Wang <tndrwang@gmail.com>
Date: Tue, 24 Mar 2026 09:10:07 +0800
Message-ID: 
 <CAHewXNkO0NO4+98=E=QodAUz_mkX2YOB0rD_C3Yz7o383aRhVQ@mail.gmail.com>
Subject: Re: Fix "could not find memoization table entry"
To: David Rowley <dgrowleyml@gmail.com>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
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David Rowley <dgrowleyml@gmail.com> =E4=BA=8E2026=E5=B9=B43=E6=9C=8824=E6=
=97=A5=E5=91=A8=E4=BA=8C 08:12=E5=86=99=E9=81=93=EF=BC=9A
>
> On Mon, 23 Mar 2026 at 19:30, Tender Wang <tndrwang@gmail.com> wrote:
> > Recently, I encountered an error: could not find memoization table
>
> > The hkeys returned by datum_image_hash() are different, so we can't
> > find the entry in the hash table.
> >
> > In the datum_image_hash(), if typByVal is true, calling
> > result =3D hash_bytes((unsigned char *) &value, sizeof(Datum));
> >
> > I think we should use typLen here, not sizeof(Datum).
> > I tried this way and didn't encounter any errors again.
>
> The Datum values should be the same. You can't just compare the lowest
> attlen bytes of a Datum.

Thanks for pointing this out.
Actually, I haven't quite figured out why `typLen` cannot be used here.

>
> It looks to me like the bug is in hash_numeric(). Seems like it has no
> idea what type it's meant to return. hash_numeric_extended() doesn't
> seem to be much better.
>
> Do you still get the ERROR after patching with the attached?

No error anymore with your patch.


--=20
Thanks,
Tender Wang