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Allow WITH clauses to be attached to INSERT, UPDATE, DELETE statements.

Browse Source 
This is not the hoped-for facility of using INSERT/UPDATE/DELETE inside
a WITH, but rather the other way around.  It seems useful in its own
right anyway.

Note: catversion bumped because, although the contents of stored rules
might look compatible, there's actually a subtle semantic change.
A single Query containing a WITH and INSERT...VALUES now represents
writing the WITH before the INSERT, not before the VALUES.  While it's
not clear that that matters to anyone, it seems like a good idea to
have it cited in the git history for catversion.h.

Original patch by Marko Tiikkaja, with updating and cleanup by
Hitoshi Harada.
This commit is contained in:
Tom Lane
2010-10-15 19:53:59 -04:00
parent 6ab42ae367
commit 07f1264dda
14 changed files with 333 additions and 44 deletions
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16
doc/src/sgml/queries.sgml
View File

@ -472,7 +472,7 @@ FROM <replaceable>table_reference</replaceable> <optional>, <replaceable>table_r
(1 row)
</screen>
This is because a restriction placed in the <literal>ON</>
clause is processed <emphasis>before</> the join, while
clause is processed <emphasis>before</> the join, while
a restriction placed in the <literal>WHERE</> clause is processed
<emphasis>after</> the join.
</para>
@ -1139,7 +1139,7 @@ SELECT a "value", b + c AS sum FROM ...
<para>
The naming of output columns here is different from that done in
the <literal>FROM</> clause (see <xref
linkend="queries-table-aliases">). It is possible
linkend="queries-table-aliases">). It is possible
to rename the same column twice, but the name assigned in
the select list is the one that will be passed on.
</para>
@ -1539,7 +1539,7 @@ SELECT <replaceable>select_list</replaceable> FROM <replaceable>table_expression
<para>
<literal>WITH</> provides a way to write subqueries for use in a larger
<literal>SELECT</> query. The subqueries can be thought of as defining
query. The subqueries can be thought of as defining
temporary tables that exist just for this query. One use of this feature
is to break down complicated queries into simpler parts. An example is:
@ -1791,12 +1791,20 @@ SELECT n FROM t LIMIT 100;
However, the other side of this coin is that the optimizer is less able to
push restrictions from the parent query down into a <literal>WITH</> query
than an ordinary sub-query. The <literal>WITH</> query will generally be
evaluated as stated, without suppression of rows that the parent query
evaluated as written, without suppression of rows that the parent query
might discard afterwards. (But, as mentioned above, evaluation might stop
early if the reference(s) to the query demand only a limited number of
rows.)
</para>
<para>
The examples above only show <literal>WITH</> being used with
<command>SELECT</>, but it can be attached in the same way to
<command>INSERT</>, <command>UPDATE</>, or <command>DELETE</>.
In each case it effectively provides temporary table(s) that can
be referred to in the main command.
</para>
</sect1>
</chapter>

16
doc/src/sgml/ref/delete.sgml
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@ -21,6 +21,7 @@ PostgreSQL documentation
<refsynopsisdiv>
<synopsis>
[ WITH [ RECURSIVE ] <replaceable class="parameter">with_query</replaceable> [, ...] ]
DELETE FROM [ ONLY ] <replaceable class="PARAMETER">table</replaceable> [ [ AS ] <replaceable class="parameter">alias</replaceable> ]
[ USING <replaceable class="PARAMETER">using_list</replaceable> ]
[ WHERE <replaceable class="PARAMETER">condition</replaceable> | WHERE CURRENT OF <replaceable class="PARAMETER">cursor_name</replaceable> ]
@ -83,6 +84,18 @@ DELETE FROM [ ONLY ] <replaceable class="PARAMETER">table</replaceable> [ [ AS ]
<title>Parameters</title>
<variablelist>
<varlistentry>
<term><replaceable class="parameter">with_query</replaceable></term>
<listitem>
<para>
The <literal>WITH</literal> clause allows you to specify one or more
subqueries that can be referenced by name in the <command>DELETE</>
query. See <xref linkend="queries-with"> and <xref linkend="sql-select">
for details.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>ONLY</></term>
<listitem>
@ -272,7 +285,8 @@ DELETE FROM tasks WHERE CURRENT OF c_tasks;
<para>
This command conforms to the <acronym>SQL</acronym> standard, except
that the <literal>USING</literal> and <literal>RETURNING</> clauses
are <productname>PostgreSQL</productname> extensions.
are <productname>PostgreSQL</productname> extensions, as is the ability
to use <literal>WITH</> with <command>DELETE</>.
</para>
</refsect1>
</refentry>

25
doc/src/sgml/ref/insert.sgml
View File

@ -21,6 +21,7 @@ PostgreSQL documentation
<refsynopsisdiv>
<synopsis>
[ WITH [ RECURSIVE ] <replaceable class="parameter">with_query</replaceable> [, ...] ]
INSERT INTO <replaceable class="PARAMETER">table</replaceable> [ ( <replaceable class="PARAMETER">column</replaceable> [, ...] ) ]
{ DEFAULT VALUES | VALUES ( { <replaceable class="PARAMETER">expression</replaceable> | DEFAULT } [, ...] ) [, ...] | <replaceable class="PARAMETER">query</replaceable> }
[ RETURNING * | <replaceable class="parameter">output_expression</replaceable> [ [ AS ] <replaceable class="parameter">output_name</replaceable> ] [, ...] ]
@ -84,6 +85,26 @@ INSERT INTO <replaceable class="PARAMETER">table</replaceable> [ ( <replaceable
<title>Parameters</title>
<variablelist>
<varlistentry>
<term><replaceable class="parameter">with_query</replaceable></term>
<listitem>
<para>
The <literal>WITH</literal> clause allows you to specify one or more
subqueries that can be referenced by name in the <command>INSERT</>
query. See <xref linkend="queries-with"> and <xref linkend="sql-select">
for details.
</para>
<para>
It is possible for the <replaceable class="parameter">query</replaceable>
(<command>SELECT</command> statement)
to also contain a <literal>WITH</literal> clause. In such a case both
sets of <replaceable>with_query</replaceable> can be referenced within
the <replaceable class="parameter">query</replaceable>, but the
second one takes precedence since it is more closely nested.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="PARAMETER">table</replaceable></term>
<listitem>
@ -287,7 +308,9 @@ INSERT INTO distributors (did, dname) VALUES (DEFAULT, 'XYZ Widgets')
<para>
<command>INSERT</command> conforms to the SQL standard, except that
the <literal>RETURNING</> clause is a
<productname>PostgreSQL</productname> extension. Also, the case in
<productname>PostgreSQL</productname> extension, as is the ability
to use <literal>WITH</> with <command>INSERT</>.
Also, the case in
which a column name list is omitted, but not all the columns are
filled from the <literal>VALUES</> clause or <replaceable>query</>,
is disallowed by the standard.

16
doc/src/sgml/ref/update.sgml
View File

@ -21,6 +21,7 @@ PostgreSQL documentation
<refsynopsisdiv>
<synopsis>
[ WITH [ RECURSIVE ] <replaceable class="parameter">with_query</replaceable> [, ...] ]
UPDATE [ ONLY ] <replaceable class="PARAMETER">table</replaceable> [ [ AS ] <replaceable class="parameter">alias</replaceable> ]
SET { <replaceable class="PARAMETER">column</replaceable> = { <replaceable class="PARAMETER">expression</replaceable> | DEFAULT } |
( <replaceable class="PARAMETER">column</replaceable> [, ...] ) = ( { <replaceable class="PARAMETER">expression</replaceable> | DEFAULT } [, ...] ) } [, ...]
@ -79,6 +80,18 @@ UPDATE [ ONLY ] <replaceable class="PARAMETER">table</replaceable> [ [ AS ] <rep
<title>Parameters</title>
<variablelist>
<varlistentry>
<term><replaceable class="parameter">with_query</replaceable></term>
<listitem>
<para>
The <literal>WITH</literal> clause allows you to specify one or more
subqueries that can be referenced by name in the <command>UPDATE</>
query. See <xref linkend="queries-with"> and <xref linkend="sql-select">
for details.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="PARAMETER">table</replaceable></term>
<listitem>
@ -345,7 +358,8 @@ UPDATE films SET kind = 'Dramatic' WHERE CURRENT OF c_films;
<para>
This command conforms to the <acronym>SQL</acronym> standard, except
that the <literal>FROM</literal> and <literal>RETURNING</> clauses
are <productname>PostgreSQL</productname> extensions.
are <productname>PostgreSQL</productname> extensions, as is the ability
to use <literal>WITH</> with <command>UPDATE</>.
</para>
<para>