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Diffstat (limited to 'doc/src/sgml/rules.sgml')
| -rw-r--r-- | doc/src/sgml/rules.sgml | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/doc/src/sgml/rules.sgml b/doc/src/sgml/rules.sgml index 7e98f5694b4..9fdf8b1d917 100644 --- a/doc/src/sgml/rules.sgml +++ b/doc/src/sgml/rules.sgml @@ -1646,6 +1646,23 @@ CREATE RULE shoelace_ins AS ON INSERT TO shoelace </para> <para> + Note that in the <literal>RETURNING</literal> clause of a rule, + <literal>OLD</literal> and <literal>NEW</literal> refer to the + pseudorelations added as extra range table entries to the rewritten + query, rather than old/new rows in the result relation. Thus, for + example, in a rule supporting <command>UPDATE</command> queries on this + view, if the <literal>RETURNING</literal> clause contained + <literal>old.sl_name</literal>, the old name would always be returned, + regardless of whether the <literal>RETURNING</literal> clause in the + query on the view specified <literal>OLD</literal> or <literal>NEW</literal>, + which might be confusing. To avoid this confusion, and support returning + old and new values in queries on the view, the <literal>RETURNING</literal> + clause in the rule definition should refer to entries from the result + relation such as <literal>shoelace_data.sl_name</literal>, without + specifying <literal>OLD</literal> or <literal>NEW</literal>. + </para> + + <para> Now assume that once in a while, a pack of shoelaces arrives at the shop and a big parts list along with it. But you don't want to manually update the <literal>shoelace</literal> view every |