Support "variadic" functions, which can accept a variable number of arguments

so long as all the trailing arguments are of the same (non-array) type.
The function receives them as a single array argument (which is why they
have to all be the same type).

It might be useful to extend this facility to aggregates, but this patch
doesn't do that.

This patch imposes a noticeable slowdown on function lookup --- a follow-on
patch will fix that by adding a redundant column to pg_proc.

Pavel Stehule

1 files changed, 30 insertions, 3 deletions

diff --git a/src/backend/commands/functioncmds.c b/src/backend/commands/functioncmds.c
index 9831692eea0..cb249d9c7d1 100644
--- a/src/backend/commands/functioncmds.c
+++ b/src/backend/commands/functioncmds.c
@@ -10,7 +10,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/functioncmds.c,v 1.95 2008/07/12 10:44:56 petere Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/functioncmds.c,v 1.96 2008/07/16 01:30:22 tgl Exp $
  *
  * DESCRIPTION
  *	  These routines take the parse tree and pick out the
@@ -173,6 +173,7 @@ examine_parameter_list(List *parameters, Oid languageOid,
 	Datum	   *paramModes;
 	Datum	   *paramNames;
 	int			outCount = 0;
+	int			varCount = 0;
 	bool		have_names = false;
 	ListCell   *x;
 	int			i;
@@ -228,15 +229,41 @@ examine_parameter_list(List *parameters, Oid languageOid,
 					 errmsg("functions cannot accept set arguments")));
 
 		if (fp->mode != FUNC_PARAM_OUT)
+		{
+			/* only OUT parameters can follow a VARIADIC parameter */
+			if (varCount > 0)
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+						 errmsg("VARIADIC parameter must be the last input parameter")));
 			inTypes[inCount++] = toid;
+		}
 
-		if (fp->mode != FUNC_PARAM_IN)
+		if (fp->mode != FUNC_PARAM_IN && fp->mode != FUNC_PARAM_VARIADIC)
 		{
 			if (outCount == 0)	/* save first OUT param's type */
 				*requiredResultType = toid;
 			outCount++;
 		}
 
+		if (fp->mode == FUNC_PARAM_VARIADIC)
+		{
+			varCount++;
+			/* validate variadic parameter type */
+			switch (toid)
+			{
+				case ANYARRAYOID:
+				case ANYOID:
+					/* okay */
+					break;
+				default:
+					if (!OidIsValid(get_element_type(toid)))
+						ereport(ERROR,
+								(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+								 errmsg("VARIADIC parameter must be an array")));
+					break;
+			}
+		}
+
 		allTypes[i] = ObjectIdGetDatum(toid);
 
 		paramModes[i] = CharGetDatum(fp->mode);
@@ -253,7 +280,7 @@ examine_parameter_list(List *parameters, Oid languageOid,
 	/* Now construct the proper outputs as needed */
 	*parameterTypes = buildoidvector(inTypes, inCount);
 
-	if (outCount > 0)
+	if (outCount > 0 || varCount > 0)
 	{
 		*allParameterTypes = construct_array(allTypes, parameterCount, OIDOID,
 											 sizeof(Oid), true, 'i');