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Modify UPDATE/DELETE WHERE CURRENT OF to use the FOR UPDATE infrastructure to

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locate the target row, if the cursor was declared with FOR UPDATE or FOR
SHARE.  This approach is more flexible and reliable than digging through the
plan tree; for instance it can cope with join cursors.  But we still provide
the old code for use with non-FOR-UPDATE cursors.  Per gripe from Robert Haas.
This commit is contained in:
Tom Lane
2008-11-16 17:34:28 +00:00
parent 30f272a79b
commit 18004101ac
9 changed files with 246 additions and 70 deletions
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15
doc/src/sgml/ref/delete.sgml
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@@ -1,5 +1,5 @@
<!--
$PostgreSQL: pgsql/doc/src/sgml/ref/delete.sgml,v 1.34 2008/11/14 10:22:46 petere Exp $
$PostgreSQL: pgsql/doc/src/sgml/ref/delete.sgml,v 1.35 2008/11/16 17:34:28 tgl Exp $
PostgreSQL documentation
-->
@@ -148,10 +148,13 @@ DELETE FROM [ ONLY ] <replaceable class="PARAMETER">table</replaceable> [ [ AS ]
<para>
The name of the cursor to use in a <literal>WHERE CURRENT OF</>
condition. The row to be deleted is the one most recently fetched
from this cursor. The cursor must be a simple (non-join, non-aggregate)
from this cursor. The cursor must be a non-grouping
query on the <command>DELETE</>'s target table.
Note that <literal>WHERE CURRENT OF</> cannot be
specified together with a Boolean condition.
specified together with a Boolean condition. See
<xref linkend="sql-declare" endterm="sql-declare-title">
for more information about using cursors with
<literal>WHERE CURRENT OF</>.
</para>
</listitem>
</varlistentry>
@@ -244,14 +247,14 @@ DELETE FROM films WHERE kind &lt;&gt; 'Musical';
Clear the table <literal>films</literal>:
<programlisting>
DELETE FROM films;
</programlisting>
</programlisting>
</para>
<para>
Delete completed tasks, returning full details of the deleted rows:
<programlisting>
DELETE FROM tasks WHERE status = 'DONE' RETURNING *;
</programlisting>
</programlisting>
</para>
<para>
@@ -259,7 +262,7 @@ DELETE FROM tasks WHERE status = 'DONE' RETURNING *;
<literal>c_tasks</> is currently positioned:
<programlisting>
DELETE FROM tasks WHERE CURRENT OF c_tasks;
</programlisting>
</programlisting>
</para>
</refsect1>