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Add ALSO keyword to CREATE RULE.

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Fabien COELHO
This commit is contained in:
Bruce Momjian
2004-03-09 05:05:41 +00:00
parent 53cd7cd8a9
commit 943eae92fb
6 changed files with 29 additions and 21 deletions
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8
doc/src/sgml/keywords.sgml
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@ -1,4 +1,4 @@
<!-- $PostgreSQL: pgsql/doc/src/sgml/keywords.sgml,v 2.12 2003/11/29 19:51:37 pgsql Exp $ -->
<!-- $PostgreSQL: pgsql/doc/src/sgml/keywords.sgml,v 2.13 2004/03/09 05:05:40 momjian Exp $ -->
<appendix id="sql-keywords-appendix">
<title><acronym>SQL</acronym> Key Words</title>
@ -170,6 +170,12 @@
<entry>reserved</entry>
<entry>reserved</entry>
</row>
<row>
<entry><token>ALSO</token></entry>
<entry>non-reserved</entry>
<entry></entry>
<entry></entry>
</row>
<row>
<entry><token>ALTER</token></entry>
<entry>non-reserved</entry>

18
doc/src/sgml/rules.sgml
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@ -1,4 +1,4 @@
<!-- $PostgreSQL: pgsql/doc/src/sgml/rules.sgml,v 1.33 2003/12/13 23:59:06 neilc Exp $ -->
<!-- $PostgreSQL: pgsql/doc/src/sgml/rules.sgml,v 1.34 2004/03/09 05:05:40 momjian Exp $ -->
<Chapter Id="rules">
<Title>The Rule System</Title>
@ -873,7 +873,7 @@ SELECT t1.a, t2.b, t1.ctid FROM t1, t2 WHERE t1.a = t2.a;
<ListItem>
<Para>
They can be <literal>INSTEAD</> or not.
They can be <literal>INSTEAD</> or <literal>ALSO</> (default).
</Para>
</ListItem>
@ -904,7 +904,7 @@ SELECT t1.a, t2.b, t1.ctid FROM t1, t2 WHERE t1.a = t2.a;
<ProgramListing>
CREATE RULE <replaceable>rule_name</> AS ON <replaceable>event</>
TO <replaceable>object</> [WHERE <replaceable>rule_qualification</>]
DO [INSTEAD] [<replaceable>action</> | (<replaceable>actions</>) | NOTHING];
DO [ALSO|INSTEAD] [<replaceable>action</> | (<replaceable>actions</>) | NOTHING];
</ProgramListing>
in mind.
@ -920,7 +920,7 @@ CREATE RULE <replaceable>rule_name</> AS ON <replaceable>event</>
Initially the query-tree list is empty.
There can be zero (<literal>NOTHING</> key word), one, or multiple actions.
To simplify, we will look at a rule with one action. This rule
can have a qualification or not and it can be <literal>INSTEAD</> or not.
can have a qualification or not and it can be <literal>INSTEAD</> or <literal>ALSO</> (default).
</Para>
<Para>
@ -937,7 +937,7 @@ CREATE RULE <replaceable>rule_name</> AS ON <replaceable>event</>
<variablelist>
<varlistentry>
<term>No qualification and not <literal>INSTEAD</></term>
<term>No qualification and <literal>ALSO</></term>
<listitem>
<para>
the query tree from the rule action with the original query
@ -957,7 +957,7 @@ CREATE RULE <replaceable>rule_name</> AS ON <replaceable>event</>
</varlistentry>
<varlistentry>
<term>Qualification given and not <literal>INSTEAD</></term>
<term>Qualification given and <literal>ALSO</></term>
<listitem>
<para>
the query tree from the rule action with the rule
@ -980,7 +980,7 @@ CREATE RULE <replaceable>rule_name</> AS ON <replaceable>event</>
</varlistentry>
</variablelist>
Finally, if the rule is not <literal>INSTEAD</>, the unchanged original query tree is
Finally, if the rule is <literal>ALSO</>, the unchanged original query tree is
added to the list. Since only qualified <literal>INSTEAD</> rules already add the
original query tree, we end up with either one or two output query trees
for a rule with one action.
@ -1111,7 +1111,7 @@ INSERT INTO shoelace_log VALUES (
</Para>
<Para>
The rule is a qualified non-<literal>INSTEAD</> rule, so the rule system
The rule is a qualified <literal>ALSO</> rule, so the rule system
has to return two query trees: the modified rule action and the original
query tree. In step 1, the range table of the original query is
incorporated into the rule's action query tree. This results in:
@ -1190,7 +1190,7 @@ INSERT INTO shoelace_log VALUES (
</para>
<para>
That's it. Since the rule is not <literal>INSTEAD</>, we also output the
That's it. Since the rule is <literal>ALSO</>, we also output the
original query tree. In short, the output from the rule system
is a list of two query trees that correspond to these statements: