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Date: Tue, 11 Aug 2015 14:51:28 +0300
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Subject: Re: 36.3 Writing Tigger Functions in C
From: Dmitry Igrishin <dmitigr@gmail.com>
To: Marko Tiikkaja <marko@joh.to>
Cc: pgsql-docs <pgsql-docs@postgresql.org>
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2015-08-11 14:32 GMT+03:00 Marko Tiikkaja <marko@joh.to>:

> On 8/11/15 12:47 PM, Dmitry Igrishin wrote:
>
>> tg_trigtuple:
>> I'm not sure why "skip the operation" is here:
>> "if you don't want to replace the row with a different one (in the
>> case of INSERT) or skip the operation"
>>
>
> Returning NULL from a row-level BEFORE trigger skips the operation which
> fired the trigger.  So for an INSERT, any triggers which would otherwise
> fire after the current trigger are not fired, and the row is not INSERTed
> into the table.

Yes, but it's absolutely unclear in this place of the documentation.
Thus,
"If this trigger was fired for an INSERT or DELETE then this is what you
should return from the function if you don't want to replace the row with a
different one (in the case of INSERT) or skip the operation."
should be replaced with something like
"If this trigger was fired for an INSERT or DELETE then this is what you
should return from the function if you don't want to replace the row with a
different one (in the case of INSERT). (To skip the operation you should
return NULL.)" ?

-- 
// Dmitry.

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<div dir=3D"ltr"><br><div class=3D"gmail_extra"><br><div class=3D"gmail_quo=
te">2015-08-11 14:32 GMT+03:00 Marko Tiikkaja <span dir=3D"ltr">&lt;<a href=
=3D"mailto:marko@joh.to" target=3D"_blank">marko@joh.to</a>&gt;</span>:<br>=
<blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1p=
x #ccc solid;padding-left:1ex"><span class=3D"">On 8/11/15 12:47 PM, Dmitry=
 Igrishin wrote:<br>
<blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1p=
x #ccc solid;padding-left:1ex">
tg_trigtuple:<br>
I&#39;m not sure why &quot;skip the operation&quot; is here:<br>
&quot;if you don&#39;t want to replace the row with a different one (in the=
<br>
case of INSERT) or skip the operation&quot;<br>
</blockquote>
<br></span>
Returning NULL from a row-level BEFORE trigger skips the operation which fi=
red the trigger.=C2=A0 So for an INSERT, any triggers which would otherwise=
 fire after the current trigger are not fired, and the row is not INSERTed =
into the table.</blockquote><div>Yes, but it&#39;s absolutely unclear in th=
is place of the documentation.</div><div>Thus,</div><div>&quot;If this trig=
ger was fired for an INSERT or DELETE then this is what you</div><div>shoul=
d return from the function if you don&#39;t want to replace the row with a<=
/div><div>different one (in the case of INSERT) or skip the operation.&quot=
;</div><div>should be replaced with something like</div><div>&quot;If this =
trigger was fired for an INSERT or DELETE then this is what you</div><div>s=
hould return from the function if you don&#39;t want to replace the row wit=
h a</div><div>different one (in the case of INSERT). (To skip the operation=
 you should</div><div>return NULL.)&quot; ?</div></div><div><br></div>-- <b=
r><div class=3D"gmail_signature"><div dir=3D"ltr"><div>// Dmitry.<br><br></=
div></div></div>
</div></div>

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