Re: Ancient comment in rules.sgml

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От Tatsuo Ishii
Тема Re: Ancient comment in rules.sgml
Дата
Msg-id 20190212.094549.652427794253296707.t-ishii@sraoss.co.jp
обсуждение исходный текст
Ответ на Re: Ancient comment in rules.sgml  (Tom Lane <tgl@sss.pgh.pa.us>)
Ответы Re: Ancient comment in rules.sgml  (Michael Paquier <michael@paquier.xyz>)
Список pgsql-docs
> Tatsuo Ishii <ishii@sraoss.co.jp> writes:
>> There's a comment beginning with:
>> <!-- What's happening with this?  If it doesn't come back, remove this section. -->
>> in rules.sgml around line 2437. It seems this has been there since 2003.
>> Do we need to keep this?
> 
> Well, the point is that the whole para after that is commented out.

Yes, so my question was we could safely remove the whole comment or
not.

> The para in question seems to have shown up in 20a071326, and
> at the time it began
> 
> +<Para>
> +    Another situation are cases on UPDATE where it depends on the
> +    change of an attribute if an action should be performed or
> +    not. In <ProductName>Postgres</ProductName> version 6.4, the
> +    attribute specification for rule events is disabled (it will have
> +    it's comeback latest in 6.5, maybe earlier 
> +    - stay tuned). So for now the only way to
> +    create a rule as in the shoelace_log example is to do it with
> +    a rule qualification. That results in an extra query that is
> +    performed allways, even if the attribute of interest cannot
> 
> I think it's a safe bet at this point that that feature isn't ever
> coming back, so I'd be good with ripping out the whole para.

Ok, I will remove the comment in all supported branches (after next
moinor releases are out). Patch attached.
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese:http://www.sraoss.co.jp
diff --git a/doc/src/sgml/rules.sgml b/doc/src/sgml/rules.sgml
index 3372b1ac2b..4e20664ea1 100644
--- a/doc/src/sgml/rules.sgml
+++ b/doc/src/sgml/rules.sgml
@@ -2434,30 +2434,6 @@ Nestloop
     in a command.
 </para>
 
-<!-- What's happening with this?  If it doesn't come back, remove this section. -->
-<!--
-<para>
-    Another situation is cases on <command>UPDATE</command> where it depends on the
-    change of an attribute if an action should be performed or
-    not. The only way to
-    create a rule as in the shoelace_log example is to do it with
-    a rule qualification. That results in an extra query that is
-    performed always, even if the attribute of interest cannot
-    change at all because it does not appear in the target list
-    of the initial query. When this is enabled again, it will be
-    one more advantage of rules over triggers. Optimization of
-    a trigger must fail by definition in this case, because the
-    fact that its actions will only be done when a specific attribute
-    is updated is hidden in its functionality. The definition of
-    a trigger only allows to specify it on row level, so whenever a
-    row is touched, the trigger must be called to make its
-    decision. The rule system will know it by looking up the
-    target list and will suppress the additional query completely
-    if the attribute isn't touched. So the rule, qualified or not,
-    will only do its scans if there ever could be something to do.
-</para>
--->
-
 <para>
     The summary is, rules will only be significantly slower than
     triggers if their actions result in large and badly qualified

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