Re: Relax requirement for INTO with SELECT in pl/pgsql - Mailing list pgsql-hackers

Anyways, here's the patch with documentation adjustments as promised.
I ended up keeping the 'without result' section because it contained
useful information about plan caching,

merlin

diff --git a/doc/src/sgml/plpgsql.sgml b/doc/src/sgml/plpgsql.sgml
new file mode 100644
index 9786242..512eaa7
*** a/doc/src/sgml/plpgsql.sgml
--- b/doc/src/sgml/plpgsql.sgml
*************** my_record.user_id := 20;
*** 904,910 ****
      <title>Executing a Command With No Result</title>

      <para>
!      For any SQL command that does not return rows, for example
       <command>INSERT</> without a <literal>RETURNING</> clause, you can
       execute the command within a <application>PL/pgSQL</application> function
       just by writing the command.
--- 904,910 ----
      <title>Executing a Command With No Result</title>

      <para>
!      For any SQL command, for example
       <command>INSERT</> without a <literal>RETURNING</> clause, you can
       execute the command within a <application>PL/pgSQL</application> function
       just by writing the command.
*************** my_record.user_id := 20;

*** 925,972 ****
       <xref linkend="plpgsql-plan-caching">.
      </para>

-     <para>
-      Sometimes it is useful to evaluate an expression or <command>SELECT</>
-      query but discard the result, for example when calling a function
-      that has side-effects but no useful result value.  To do
-      this in <application>PL/pgSQL</application>, use the
-      <command>PERFORM</command> statement:
-
- <synopsis>
- PERFORM <replaceable>query</replaceable>;
- </synopsis>
-
-      This executes <replaceable>query</replaceable> and discards the
-      result.  Write the <replaceable>query</replaceable> the same
-      way you would write an SQL <command>SELECT</> command, but replace the
-      initial keyword <command>SELECT</> with <command>PERFORM</command>.
-      For <command>WITH</> queries, use <command>PERFORM</> and then
-      place the query in parentheses.  (In this case, the query can only
-      return one row.)
-      <application>PL/pgSQL</application> variables will be
-      substituted into the query just as for commands that return no result,
-      and the plan is cached in the same way.  Also, the special variable
-      <literal>FOUND</literal> is set to true if the query produced at
-      least one row, or false if it produced no rows (see
-      <xref linkend="plpgsql-statements-diagnostics">).
-     </para>
-
      <note>
       <para>
!       One might expect that writing <command>SELECT</command> directly
!       would accomplish this result, but at
!       present the only accepted way to do it is
!       <command>PERFORM</command>.  A SQL command that can return rows,
!       such as <command>SELECT</command>, will be rejected as an error
!       unless it has an <literal>INTO</> clause as discussed in the
!       next section.
       </para>
      </note>

      <para>
       An example:
  <programlisting>
! PERFORM create_mv('cs_session_page_requests_mv', my_query);
  </programlisting>
      </para>
     </sect2>
--- 925,944 ----
       <xref linkend="plpgsql-plan-caching">.
      </para>

      <note>
       <para>
!       In older versions of PostgreSQL, it was mandatory to use
!       <command>PERFORM</command> instead of <command>SELECT</command>
!       when the query could return data that was not captured into
!       variables.  This requirement has been relaxed and usage of
!       <command>PERFORM</command> has been deprecated.
       </para>
      </note>

      <para>
       An example:
  <programlisting>
! SELECT create_mv('cs_session_page_requests_mv', my_query);

  </programlisting>
      </para>
     </sect2>
*************** GET DIAGNOSTICS integer_var = ROW_COUNT;
*** 1480,1491 ****
            </listitem>
            <listitem>
             <para>
!             A <command>PERFORM</> statement sets <literal>FOUND</literal>
              true if it produces (and discards) one or more rows, false if
              no row is produced.
             </para>
            </listitem>
            <listitem>
             <para>
              <command>UPDATE</>, <command>INSERT</>, and <command>DELETE</>
              statements set <literal>FOUND</literal> true if at least one
--- 1452,1471 ----
            </listitem>
            <listitem>
             <para>
!             A <command>SELECT</> statement sets <literal>FOUND</literal>
              true if it produces (and discards) one or more rows, false if
              no row is produced.
             </para>

            </listitem>
            <listitem>
+            <para>
+             A <command>PERFORM</> statement sets <literal>FOUND</literal>
+             true if it produces (and discards) one or more rows, false if
+             no row is produced.  This statement is equivalent to
+             <command>SELECT</> without INTO.
+            </para>
+           </listitem>
+           <listitem>
diff --git a/doc/src/sgml/plpgsql.sgml b/doc/src/sgml/plpgsql.sgml
new file mode 100644
index 9786242..512eaa7

diff --git a/src/pl/plpgsql/src/pl_exec.c b/src/pl/plpgsql/src/pl_exec.c
new file mode 100644
index b63ecac..975e8fe
*** a/src/pl/plpgsql/src/pl_exec.c
--- b/src/pl/plpgsql/src/pl_exec.c
*************** exec_stmt_assign(PLpgSQL_execstate *esta
*** 1557,1562 ****
--- 1557,1563 ----
   * exec_stmt_perform      Evaluate query and discard result (but set
   *                            FOUND depending on whether at least one row
   *                            was returned).
+  *                            This syntax is deprecated.
   * ----------
   */
  static int
*************** exec_stmt_execsql(PLpgSQL_execstate *est
*** 3647,3658 ****
    }
    else
    {
!       /* If the statement returned a tuple table, complain */
        if (SPI_tuptable != NULL)
!           ereport(ERROR,
!                   (errcode(ERRCODE_SYNTAX_ERROR),
!                    errmsg("query has no destination for result data"),
!                    (rc == SPI_OK_SELECT) ? errhint("If you want to
discard the results of a SELECT, use PERFORM instead.") : 0));
    }

    return PLPGSQL_RC_OK;
--- 3648,3656 ----
    }
    else
    {
!       /* If the statement returned a tuple table without INTO, free it. */
        if (SPI_tuptable != NULL)
!           SPI_freetuptable(SPI_tuptable);
    }

    return PLPGSQL_RC_OK;