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From: Greg Sabino Mullane <htamfids@gmail.com>
Date: Wed, 25 Sep 2024 16:22:31 -0400
Message-ID: <CAKAnmmLDpwgqu071t_Q7Fq349dYAgQim1x46U1DCAiiTcUmU2A@mail.gmail.com>
Subject: Re: Repeatable Read Isolation Level "transaction start time"
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Ron Johnson <ronljohnsonjr@gmail.com>, 
	"pgsql-generallists.postgresql.org" <pgsql-general@lists.postgresql.org>
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On Wed, Sep 25, 2024 at 1:53=E2=80=AFPM Tom Lane <tgl@sss.pgh.pa.us> wrote:

> Because we're not going to analyze the statement in the amount of depth
> needed to make that distinction before we crank up the
> transactional machinery.  If it says SELECT, it gets a snapshot.
>

Ok, thanks. So to the original poster's point, perhaps the path with the
least side effects / best Principle of Least Surprise (POLS) support is to
start the transaction, and immediately call a "SELECT 1;" or perhaps better
still, a 'SELECT timeofday();'

Cheers,
Greg

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<div dir=3D"ltr"><div dir=3D"ltr">On Wed, Sep 25, 2024 at 1:53=E2=80=AFPM T=
om Lane &lt;<a href=3D"mailto:tgl@sss.pgh.pa.us">tgl@sss.pgh.pa.us</a>&gt; =
wrote:<br></div><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">Because we&#39;re not going to analyze the statement in t=
he amount of depth needed to make that distinction before we crank up the<b=
r>
transactional machinery.=C2=A0 If it says SELECT, it gets a snapshot.<br></=
blockquote><div><br></div><div>Ok, thanks. So to the original poster&#39;s =
point, perhaps the path with the least side effects / best Principle of Lea=
st Surprise (POLS) support is to start the transaction, and immediately cal=
l a &quot;SELECT 1;&quot; or perhaps better still, a &#39;SELECT timeofday(=
);&#39;</div><div><br></div><div>Cheers,</div><div>Greg</div><div><br></div=
></div></div>

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