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From: Ron Johnson <ronljohnsonjr@gmail.com>
Date: Sat, 14 Dec 2024 13:13:55 -0500
Message-ID: <CANzqJaCngKMjcxtzHPggWV3mQU8U2E0zqxDtkznSpQbmPgTCgg@mail.gmail.com>
Subject: Re: Allowed to return possibly TOASTed datums?
To: "pgsql-generallists.postgresql.org" <pgsql-general@lists.postgresql.org>
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On Sat, Dec 14, 2024 at 12:02=E2=80=AFPM Tom Lane <tgl@sss.pgh.pa.us> wrote=
:

> Jan Behrens <jbe-mlist@magnetkern.de> writes:
> > Is it allowed to use the following function, assuming the data type is
> > TOASTable?
>
> > PG_FUNCTION_INFO_V1(mytype_pos);
> > Datum mytype_pos(PG_FUNCTION_ARGS) {
> >   PG_RETURN_DATUM(GETARG_DATUM(0));
> > }
>
> Absolutely.  You can find things equivalent to that in the
> core code, I think.
>

(I'm not a developer, so this is a curiosity question, not a challenge.)

Since the purpose of TOAST is just (I think) to store "large field values"
on disk by dividing into multiple chunks, what would be the purpose of
returning the TOASTed value to Jan's function?

--
Death to <Redacted>, and butter sauce.
Don't boil me, I'm still alive.
<Redacted> lobster!

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<div dir=3D"ltr"><div dir=3D"ltr">On Sat, Dec 14, 2024 at 12:02=E2=80=AFPM =
Tom Lane &lt;<a href=3D"mailto:tgl@sss.pgh.pa.us">tgl@sss.pgh.pa.us</a>&gt;=
 wrote:</div><div class=3D"gmail_quote gmail_quote_container"><blockquote c=
lass=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px soli=
d rgb(204,204,204);padding-left:1ex">Jan Behrens &lt;<a href=3D"mailto:jbe-=
mlist@magnetkern.de" target=3D"_blank">jbe-mlist@magnetkern.de</a>&gt; writ=
es:<br>
&gt; Is it allowed to use the following function, assuming the data type is=
<br>
&gt; TOASTable?<br>
<br>
&gt; PG_FUNCTION_INFO_V1(mytype_pos);<br>
&gt; Datum mytype_pos(PG_FUNCTION_ARGS) {=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0=
 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0<br>
&gt;=C2=A0 =C2=A0PG_RETURN_DATUM(GETARG_DATUM(0));<br>
&gt; }<br>
<br>
Absolutely.=C2=A0 You can find things equivalent to that in the<br>
core code, I think.<br></blockquote><div><br class=3D"gmail-Apple-interchan=
ge-newline">(I&#39;m not a developer, so this is a curiosity question, not =
a challenge.)</div><div><br></div><div></div></div><div>Since the purpose o=
f TOAST is just (I think) to store &quot;large field values&quot; on disk b=
y dividing into multiple chunks, what would be the purpose of returning the=
 TOASTed value to Jan&#39;s function?</div><div><br></div><div>--</div><div=
 dir=3D"ltr" class=3D"gmail_signature"><div dir=3D"ltr">Death to &lt;Redact=
ed&gt;, and butter sauce.<div>Don&#39;t boil me, I&#39;m still alive.<br><d=
iv><div>&lt;Redacted&gt; lobster!</div></div></div></div></div></div>

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