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Improve docs on updatable views

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Introduce the options before going into details, and add a link to the
CREATE TRIGGER documentation.

Author: David Johnston
Reviewed-By: Anastasia Lubennikova
Discussion: https://postgr.es/m/CAKFQuwYLLRhheo0_Y4Jp=vJ_YDsz1KoRuTpX1A_bUxmHTmLe-A@mail.gmail.com
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Magnus Hagander
2021-03-06 17:36:48 +01:00
parent f1516ad7b3
commit e045565dae
1 changed files with 6 additions and 1 deletions
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7
doc/src/sgml/rules.sgml
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@ -797,6 +797,10 @@ SELECT t1.a, t2.b, t1.ctid FROM t1, t2 WHERE t1.a = t2.a;
relation points at a subquery range-table entry, which will not relation points at a subquery range-table entry, which will not
work. There are several ways in which <productname>PostgreSQL</productname> work. There are several ways in which <productname>PostgreSQL</productname>
can support the appearance of updating a view, however. can support the appearance of updating a view, however.
In order of user-experienced complexity those are: automatically substitute
in the underlying table for the view, execute a user-defined trigger,
or rewrite the query per a user-defined rule.
These options are discussed below.
</para> </para>
<para> <para>
@ -812,7 +816,8 @@ SELECT t1.a, t2.b, t1.ctid FROM t1, t2 WHERE t1.a = t2.a;
<para> <para>
Alternatively, the operation may be handled by a user-provided Alternatively, the operation may be handled by a user-provided
<literal>INSTEAD OF</literal> trigger on the view. <literal>INSTEAD OF</literal> trigger on the view
(see <xref linkend="sql-createtrigger"/>).
Rewriting works slightly differently Rewriting works slightly differently
in this case. For <command>INSERT</command>, the rewriter does in this case. For <command>INSERT</command>, the rewriter does
nothing at all with the view, leaving it as the result relation nothing at all with the view, leaving it as the result relation