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From: Andy Fan <zhihui.fan1213@gmail.com>
Date: Thu, 3 Aug 2023 22:27:34 +0800
Message-ID: <CAKU4AWp8ab61e96v57OaB-Gm1bMfBNVLVy+s17U6_Ne3veB84g@mail.gmail.com>
Subject: Re: Extract numeric filed in JSONB more effectively
To: Pavel Stehule <pavel.stehule@gmail.com>
Cc: jian he <jian.universality@gmail.com>, 
	pgsql-hackers <pgsql-hackers@postgresql.org>
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Hi:


>  If you use explicit cast, then the code should not be hard, in the
> rewrite stage all information should be known.
>

Can you point to me where the code is for the XML stuff?  I thought
this is a bad idea but I may accept it if some existing code does
such a thing already.   "such thing"  is  typeA:typeB is
converted something else but user can't find out an entry in
pg_cast for typeA to typeB.


> It would be cool but still I didn't see a way to do that without making
>> something else complex.
>>
>
>  The custom @-> operator you can implement in your own custom extension.
> Builtin solutions should be generic as it is possible.
>

I agree, but actually I think there is no clean way to do it, at least I
dislike the conversion of typeA to typeB in a cast syntax but there
is no entry in pg_cast for it.  Are you saying something like this
or I misunderstood you?

>

-- 
Best Regards
Andy Fan

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<div dir=3D"ltr"><div>Hi:=C2=A0</div><div class=3D"gmail_quote"><div dir=3D=
"ltr" class=3D"gmail_attr"><br></div><blockquote class=3D"gmail_quote" styl=
e=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);paddin=
g-left:1ex"><div dir=3D"ltr"><div class=3D"gmail_quote"><div><br></div><div=
>=C2=A0If you use explicit cast, then the code should not be hard, in the r=
ewrite stage all information should be known.</div></div></div></blockquote=
><div><br></div><div>Can you point to me where the code is for the XML stuf=
f?=C2=A0 I thought</div><div>this is a bad idea but I may accept it if some=
 existing code does</div><div>such a thing already.=C2=A0 =C2=A0&quot;such =
thing&quot;=C2=A0 is=C2=A0 typeA:typeB is</div><div>converted something els=
e but user can&#39;t find out an entry in</div><div>pg_cast for typeA to ty=
peB.=C2=A0</div><div>=C2=A0</div><blockquote class=3D"gmail_quote" style=3D=
"margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-le=
ft:1ex"><div dir=3D"ltr"><div class=3D"gmail_quote"><blockquote class=3D"gm=
ail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,=
204,204);padding-left:1ex"><div dir=3D"ltr"><div class=3D"gmail_quote"><div=
>It would be cool but still I didn&#39;t see a way to do that without makin=
g</div><div>something else complex.=C2=A0</div></div></div></blockquote><di=
v><br></div><div>=C2=A0The custom @-&gt; operator you can=20
implement in your own custom extension. Builtin solutions should be=20
generic as it is possible.</div></div></div></blockquote><div><br></div><di=
v>I agree, but actually I think there is no clean way to do it, at least I<=
/div><div>dislike the conversion of=C2=A0typeA to typeB in a cast syntax=C2=
=A0but there</div><div>is no entry in pg_cast for it.=C2=A0 Are you saying =
something like this=C2=A0</div><div>or I misunderstood you?=C2=A0</div><blo=
ckquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left=
:1px solid rgb(204,204,204);padding-left:1ex"><div dir=3D"ltr"><div class=
=3D"gmail_quote"><blockquote class=3D"gmail_quote" style=3D"margin:0px 0px =
0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
</blockquote></div></div>
</blockquote></div><br clear=3D"all"><div><br></div><span class=3D"gmail_si=
gnature_prefix">-- </span><br><div dir=3D"ltr" class=3D"gmail_signature"><d=
iv dir=3D"ltr">Best Regards<div>Andy Fan</div></div></div></div>

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