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From: Ron Johnson <ronljohnsonjr@gmail.com>
Date: Fri, 10 Jan 2025 09:39:10 -0500
Message-ID: <CANzqJaDrj6mYQ0zoXL=q1aWFE117zeExYzmyqnNDHPcnaB+SVg@mail.gmail.com>
Subject: Re: Display Bytea field
To: Daniel Verite <daniel@manitou-mail.org>
Cc: Andy Hartman <hartman60home@gmail.com>, pgsql-general@lists.postgresql.org
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On Fri, Jan 10, 2025 at 7:49=E2=80=AFAM Daniel Verite <daniel@manitou-mail.=
org>
wrote:
[snip]

> Alternatively, you could compare image checksums before and
> after moving them into postgres. The advantage is that you
> don't need to export or view any file, and you compare globally
> all your images. If the checksums are identical, the data are identical.
> On the MSSQL side, checksums can be computed with hashbytes()
> as suggested in this stackoverflow answer: [3]
> On the postgres side, use functions like md5() or sha256()
> directly on the bytea column.
>

This is what I did when migrating Oracle xLOB columns to bytea.  Had to use
upper(md5()).

I didn't suggest this earlier, since I don't know the details of MSSQL's
Image data type.

--=20
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 Fri, Jan 10, 2025 at 7:49=E2=80=AFAM D=
aniel Verite &lt;<a href=3D"mailto:daniel@manitou-mail.org">daniel@manitou-=
mail.org</a>&gt; wrote:</div><div class=3D"gmail_quote gmail_quote_containe=
r"><div>[snip]=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-left:1ex"=
>Alternatively, you could compare image checksums before and<br>
after moving them into postgres. The advantage is that you<br>
don&#39;t need to export or view any file, and you compare globally<br>
all your images. If the checksums are identical, the data are identical.<br=
>
On the MSSQL side, checksums can be computed with hashbytes()<br>
as suggested in this stackoverflow answer: [3]<br>
On the postgres side, use functions like md5() or sha256()<br>
directly on the bytea column.<br></blockquote><div><br></div><div>This is w=
hat I did when migrating Oracle xLOB columns to bytea.=C2=A0 Had to use upp=
er(md5()).</div><div><br></div><div>I didn&#39;t suggest this earlier, sinc=
e I don&#39;t know the details of MSSQL&#39;s Image data type.</div><div><b=
r></div></div><span class=3D"gmail_signature_prefix">-- </span><br><div dir=
=3D"ltr" class=3D"gmail_signature"><div dir=3D"ltr">Death to &lt;Redacted&g=
t;, and butter sauce.<div>Don&#39;t boil me, I&#39;m still alive.<br><div><=
div>&lt;Redacted&gt; lobster!</div></div></div></div></div></div>

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