PL/pgSQL functions can return sets. Neil Conway's patch, modified so

that the functionality is available to anyone via ReturnSetInfo, rather
than hard-wiring it to PL/pgSQL.

Author: tglsfdc

contrib/intagg/int_aggregate.c

@@ -16,14 +16,13 @@
 #include "postgres.h"
 
 #include <ctype.h>
-#include <stdio.h>
 #include <sys/types.h>
-#include <string.h>
-#include "postgres.h"
+
 #include "access/heapam.h"
 #include "catalog/catname.h"
 #include "catalog/indexing.h"
 #include "catalog/pg_proc.h"
+#include "catalog/pg_type.h"
 #include "executor/executor.h"
 #include "utils/fcache.h"
 #include "utils/sets.h"
@@ -97,7 +96,7 @@ static PGARRAY * GetPGArray(int4 state, int fAdd)
 		p->a.size = cb;
 		p->a.ndim = 0;
 		p->a.flags = 0;
-		p->a.elmtype = INT4OID;
+		p->a.elemtype = INT4OID;
 		p->items = 0;
 		p->lower= START_NUM;
 	}
@@ -150,7 +149,7 @@ static PGARRAY *ShrinkPGArray(PGARRAY *p)
 			pnew->a.size = cb;
 			pnew->a.ndim=1;
 			pnew->a.flags = 0;
-			pnew->a.elmtype = INT4OID;
+			pnew->a.elemtype = INT4OID;
 			pnew->lower = 0;
 		}
 		else
@@ -171,11 +170,11 @@ Datum int_agg_state(PG_FUNCTION_ARGS)
 	PGARRAY *p = GetPGArray(state, 1);
 	if(!p)
 	{
-		elog(ERROR,"No aggregate storage\n");
+		elog(ERROR,"No aggregate storage");
 	}
 	else if(p->items >= p->lower)
 	{
-		elog(ERROR,"aggregate storage too small\n");
+		elog(ERROR,"aggregate storage too small");
 	}
 	else
 	{
@@ -202,32 +201,24 @@ Datum int_agg_final_array(PG_FUNCTION_ARGS)
 /* This function accepts an array, and returns one item for each entry in the array */
 Datum int_enum(PG_FUNCTION_ARGS)
 {
-	CTX *pc;
 	PGARRAY *p = (PGARRAY *) PG_GETARG_POINTER(0);
+	CTX *pc;
 	ReturnSetInfo *rsi = (ReturnSetInfo *)fcinfo->resultinfo;
 
+	if (!rsi || !IsA(rsi, ReturnSetInfo))
+		elog(ERROR, "No ReturnSetInfo sent! function must be declared returning a 'setof' integer");
+
 	if(!p)
 	{
-		elog(WARNING, "No data sent\n");
-		return 0;
-	}
-	if(!rsi)
-	{
-		elog(ERROR, "No ReturnSetInfo sent! function must be declared returning a 'setof' integer");
+		elog(WARNING, "No data sent");
 		PG_RETURN_NULL();
-
 	}
+
 	if(!fcinfo->context)
 	{
 		/* Allocate a working context */
 		pc = (CTX *) palloc(sizeof(CTX));
 
-		if(!pc)
-		{
-			elog(ERROR, "CTX Alocation failed\n");
-			PG_RETURN_NULL();
-		}
-
 		/* Don't copy atribute if you don't need too */
 		if(VARATT_IS_EXTENDED(p) )
 		{
@@ -236,7 +227,7 @@ Datum int_enum(PG_FUNCTION_ARGS)
 			pc->flags = TOASTED;
 			if(!pc->p)
 			{
-				elog(ERROR, "Error in toaster!!! no detoasting\n");
+				elog(ERROR, "Error in toaster!!! no detoasting");
 				PG_RETURN_NULL();
 			}
 		}

doc/src/sgml/plpgsql.sgml

@@ -1,5 +1,5 @@
 <!--
-$Header: /cvsroot/pgsql/doc/src/sgml/plpgsql.sgml,v 1.4 2002/08/29 04:12:02 tgl Exp $
+$Header: /cvsroot/pgsql/doc/src/sgml/plpgsql.sgml,v 1.5 2002/08/30 00:28:40 tgl Exp $
 -->
 
 <chapter id="plpgsql"> 
@@ -1142,11 +1142,20 @@ GET DIAGNOSTICS <replaceable>variable</replaceable> = <replaceable>item</replace
 RETURN <replaceable>expression</replaceable>;
 </synopsis>
 
+     RETURN with an expression is used to return from a
+     <application>PL/pgSQL</> function that does not return a set.
      The function terminates and the value of
-     <replaceable>expression</replaceable> will be returned to the
-     upper executor.
+     <replaceable>expression</replaceable> is returned to the caller.
+    </para>
+
+    <para>
+     To return a composite (row) value, you must write a record or row
+     variable as the <replaceable>expression</replaceable>.  When
+     returning a scalar type, any expression can be used.
      The expression's result will be automatically cast into the
      function's return type as described for assignments.
+     (If you have declared the function to return <type>void</>,
+     then the expression can be omitted, and will be ignored in any case.)
     </para>
 
     <para>
@@ -1155,6 +1164,28 @@ RETURN <replaceable>expression</replaceable>;
      the function without hitting a RETURN statement, a run-time error
      will occur.
     </para>
+
+    <para>
+     When a <application>PL/pgSQL</> function is declared to return
+     <literal>SETOF</literal> <replaceable>sometype</>, the procedure
+     to follow is slightly different.  The individual items to be returned
+     are specified in RETURN NEXT commands, and then a final RETURN with
+     no argument is given to indicate that the function is done generating
+     items.
+
+<synopsis>
+RETURN NEXT <replaceable>expression</replaceable>;
+</synopsis>
+
+     RETURN NEXT does not actually return from the function; it simply
+     saves away the value of the expression (or record or row variable,
+     as appropriate for the datatype being returned).
+     Execution then continues with the next statement in the
+     <application>PL/pgSQL</> function.  As successive RETURN NEXT
+     commands are executed, the result set is built up.  A final
+     RETURN, which need have no argument, causes control to exit
+     the function.
+    </para>
    </sect2>
 
    <sect2 id="plpgsql-conditionals">
@@ -1531,8 +1562,8 @@ END LOOP;
     to worry about that, since FOR loops automatically use a cursor
     internally to avoid memory problems.) A more interesting usage is to
     return a reference to a cursor that it has created, allowing the
-    caller to read the rows. This provides a way to return row sets
-    from functions.
+    caller to read the rows. This provides an efficient way to return
+    large row sets from functions.
    </para>
 
    <sect2 id="plpgsql-cursor-declarations">
@@ -1794,19 +1825,27 @@ COMMIT;
 RAISE <replaceable class="parameter">level</replaceable> '<replaceable class="parameter">format</replaceable>' <optional>, <replaceable class="parameter">variable</replaceable> <optional>...</optional></optional>;
 </synopsis>
 
-    Possible levels are DEBUG (write the message into the postmaster log),
-    NOTICE (write the message into the postmaster log and forward it to
-    the client application) and EXCEPTION (raise an error,
-    aborting the transaction).
+    Possible levels are <literal>DEBUG</literal> (write the message to
+    the server log), <literal>LOG</literal> (write the message to the
+    server log with a higher priority), <literal>INFO</literal>,
+    <literal>NOTICE</literal> and <literal>WARNING</literal> (write
+    the message to the server log and send it to the client, with
+    respectively higher priorities), and <literal>EXCEPTION</literal>
+    (raise an error and abort the current transaction). Whether error
+    messages of a particular priority are reported to the client,
+    written to the server log, or both is controlled by the
+    <option>SERVER_MIN_MESSAGES</option> and
+    <option>CLIENT_MIN_MESSAGES</option> configuration variables. See
+    the <citetitle>PostgreSQL Administrator's Guide</citetitle> for more
+    information.
    </para>
 
    <para>
-    Inside the format string, <literal>%</literal> is replaced by the next
-    optional argument's external representation.
-    Write <literal>%%</literal> to emit a literal <literal>%</literal>.
-    Note that the optional arguments must presently
-    be simple variables, not expressions, and the format must be a simple
-    string literal.
+    Inside the format string, <literal>%</literal> is replaced by the
+    next optional argument's external representation. Write
+    <literal>%%</literal> to emit a literal <literal>%</literal>. Note
+    that the optional arguments must presently be simple variables,
+    not expressions, and the format must be a simple string literal.
    </para>
 
    <!--
@@ -1820,8 +1859,9 @@ RAISE <replaceable class="parameter">level</replaceable> '<replaceable class="pa
 <programlisting>
 RAISE NOTICE ''Calling cs_create_job(%)'',v_job_id;
 </programlisting>
-    In this example, the value of v_job_id will replace the % in the
-    string.
+
+    In this example, the value of v_job_id will replace the
+    <literal>%</literal> in the string.
    </para>
 
    <para>
@@ -1852,12 +1892,12 @@ RAISE EXCEPTION ''Inexistent ID --> %'',user_id;
     </para>
 
     <para>
-     Thus, the only thing <application>PL/pgSQL</application> currently does when it encounters
-     an abort during execution of a function or trigger
-     procedure is to write some additional NOTICE level log messages
-     telling in which function and where (line number and type of
-     statement) this happened.  The error always stops execution of
-     the function.
+     Thus, the only thing <application>PL/pgSQL</application>
+     currently does when it encounters an abort during execution of a
+     function or trigger procedure is to write some additional
+     <literal>NOTICE</literal> level log messages telling in which
+     function and where (line number and type of statement) this
+     happened.  The error always stops execution of the function.
     </para>
   </sect2>
  </sect1>

doc/src/sgml/release.sgml

@@ -1,5 +1,5 @@
 <!--
-$Header: /cvsroot/pgsql/doc/src/sgml/release.sgml,v 1.154 2002/08/29 03:22:00 tgl Exp $
+$Header: /cvsroot/pgsql/doc/src/sgml/release.sgml,v 1.155 2002/08/30 00:28:40 tgl Exp $
 -->
 
 <appendix id="release">
@@ -24,6 +24,7 @@ CDATA means the content is "SGML-free", so you can write without
 worries about funny characters.
 -->
 <literallayout><![CDATA[
+Substantial improvements in functionality for functions returning sets
 Client libraries older than 6.3 no longer supported (version 0 protocol removed)
 PREPARE statement allows caching query plans for interactive statements
 Type OPAQUE is now deprecated in favor of pseudo-types cstring, trigger, etc

doc/src/sgml/runtime.sgml

@@ -1,5 +1,5 @@
 <!--
-$Header: /cvsroot/pgsql/doc/src/sgml/runtime.sgml,v 1.128 2002/08/29 19:53:58 momjian Exp $
+$Header: /cvsroot/pgsql/doc/src/sgml/runtime.sgml,v 1.129 2002/08/30 00:28:40 tgl Exp $
 -->
 
 <Chapter Id="runtime">
@@ -921,7 +921,8 @@ env PGOPTIONS='-c geqo=off' psql
         built (see the configure option
         <literal>--enable-cassert</literal>). Note that
         <literal>DEBUG_ASSERTIONS</literal> defaults to on if
-        <productname>PostgreSQL</productname> has been built this way.
+        <productname>PostgreSQL</productname> has been built with
+	assertions enabled.
        </para>
       </listitem>
      </varlistentry>

doc/src/sgml/xfunc.sgml

@@ -1,5 +1,5 @@
 <!--
-$Header: /cvsroot/pgsql/doc/src/sgml/xfunc.sgml,v 1.58 2002/08/29 17:14:32 tgl Exp $
+$Header: /cvsroot/pgsql/doc/src/sgml/xfunc.sgml,v 1.59 2002/08/30 00:28:40 tgl Exp $
 -->
 
  <chapter id="xfunc">
@@ -315,9 +315,7 @@ ERROR:  function declared to return emp returns varchar instead of text at colum
      function, as described below.  It can also be called in the context
      of an SQL expression, but only when you
      extract a single attribute out of the row or pass the entire row into
-     another function that accepts the same composite type.  (Trying to
-     display the entire row value will yield 
-     a meaningless number.)  For example,
+     another function that accepts the same composite type.  For example,
 
 <programlisting>
 SELECT (new_emp()).name;