diff options
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/ref/create_rule.sgml | 19 |
1 files changed, 10 insertions, 9 deletions
diff --git a/doc/src/sgml/ref/create_rule.sgml b/doc/src/sgml/ref/create_rule.sgml index dbf4c937841..4871a896dc3 100644 --- a/doc/src/sgml/ref/create_rule.sgml +++ b/doc/src/sgml/ref/create_rule.sgml @@ -59,15 +59,16 @@ CREATE [ OR REPLACE ] RULE <replaceable class="parameter">name</replaceable> AS </para> <para> - Presently, <literal>ON SELECT</literal> rules must be unconditional - <literal>INSTEAD</literal> rules and must have actions that consist - of a single <command>SELECT</command> command. Thus, an - <literal>ON SELECT</literal> rule effectively turns the table into - a view, whose visible contents are the rows returned by the rule's - <command>SELECT</command> command rather than whatever had been - stored in the table (if anything). It is considered better style - to write a <command>CREATE VIEW</command> command than to create a - real table and define an <literal>ON SELECT</literal> rule for it. + Presently, <literal>ON SELECT</literal> rules can only be attached + to views. Such a rule must be named <literal>"_RETURN"</literal>, + must be an unconditional <literal>INSTEAD</literal> rule, and must have + an action that consists of a single <command>SELECT</command> command. + This command defines the visible contents of the view. (The view + itself is basically a dummy table with no storage.) It's best to + regard such a rule as an implementation detail. While a view can be + redefined via <literal>CREATE OR REPLACE RULE "_RETURN" AS + ...</literal>, it's better style to use <literal>CREATE OR REPLACE + VIEW</literal>. </para> <para> |