Add a WINDOW attribute to CREATE FUNCTION, and teach pg_dump about it,

so that user-defined window functions are possible.  For the moment you'll
have to write them in C, for lack of any interface to the WindowObject API
in the available PLs, but it's better than no support at all.

There was some debate about the best syntax for this.  I ended up choosing
the "it's an attribute" position --- the other approach will inevitably be
more work, and the likely market for user-defined window functions is
probably too small to justify it.

6 files changed, 35 insertions, 11 deletions

diff --git a/src/backend/catalog/pg_aggregate.c b/src/backend/catalog/pg_aggregate.c
index 414366bc54e..8aad4a0ea44 100644
--- a/src/backend/catalog/pg_aggregate.c
+++ b/src/backend/catalog/pg_aggregate.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/catalog/pg_aggregate.c,v 1.99 2008/12/18 18:20:33 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/catalog/pg_aggregate.c,v 1.100 2008/12/31 02:25:03 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -217,6 +217,7 @@ AggregateCreate(const char *aggName,
 							  "aggregate_dummy",		/* placeholder proc */
 							  NULL,		/* probin */
 							  true,		/* isAgg */
+							  false,	/* isWindowFunc */
 							  false,	/* security invoker (currently not
 										 * definable for agg) */
 							  false,	/* isStrict (not needed for agg) */
diff --git a/src/backend/catalog/pg_proc.c b/src/backend/catalog/pg_proc.c
index 8ff22c23c9e..d11a067a5d9 100644
--- a/src/backend/catalog/pg_proc.c
+++ b/src/backend/catalog/pg_proc.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/catalog/pg_proc.c,v 1.158 2008/12/28 18:53:54 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/catalog/pg_proc.c,v 1.159 2008/12/31 02:25:03 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -53,7 +53,7 @@ static bool match_prosrc_to_literal(const char *prosrc, const char *literal,
  *
  * Note: allParameterTypes, parameterModes, parameterNames, and proconfig
  * are either arrays of the proper types or NULL.  We declare them Datum,
- * not "ArrayType *", to avoid importing array.h into pg_proc.h.
+ * not "ArrayType *", to avoid importing array.h into pg_proc_fn.h.
  * ----------------------------------------------------------------
  */
 Oid
@@ -67,6 +67,7 @@ ProcedureCreate(const char *procedureName,
 				const char *prosrc,
 				const char *probin,
 				bool isAgg,
+				bool isWindowFunc,
 				bool security_definer,
 				bool isStrict,
 				char volatility,
@@ -80,8 +81,6 @@ ProcedureCreate(const char *procedureName,
 				float4 prorows)
 {
 	Oid			retval;
-	/* XXX we don't currently have a way to make new window functions */
-	bool		isWindowFunc = false;
 	int			parameterCount;
 	int			allParamCount;
 	Oid		   *allParams;
diff --git a/src/backend/commands/functioncmds.c b/src/backend/commands/functioncmds.c
index 8963f981178..13f1debf669 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 1.104 2008/12/28 18:53:55 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/functioncmds.c,v 1.105 2008/12/31 02:25:03 tgl Exp $
  *
  * DESCRIPTION
  *	  These routines take the parse tree and pick out the
@@ -503,6 +503,7 @@ static void
 compute_attributes_sql_style(List *options,
 							 List **as,
 							 char **language,
+							 bool *windowfunc_p,
 							 char *volatility_p,
 							 bool *strict_p,
 							 bool *security_definer,
@@ -513,6 +514,7 @@ compute_attributes_sql_style(List *options,
 	ListCell   *option;
 	DefElem    *as_item = NULL;
 	DefElem    *language_item = NULL;
+	DefElem    *windowfunc_item = NULL;
 	DefElem    *volatility_item = NULL;
 	DefElem    *strict_item = NULL;
 	DefElem    *security_item = NULL;
@@ -540,6 +542,14 @@ compute_attributes_sql_style(List *options,
 						 errmsg("conflicting or redundant options")));
 			language_item = defel;
 		}
+		else if (strcmp(defel->defname, "window") == 0)
+		{
+			if (windowfunc_item)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("conflicting or redundant options")));
+			windowfunc_item = defel;
+		}
 		else if (compute_common_attribute(defel,
 										  &volatility_item,
 										  &strict_item,
@@ -578,6 +588,8 @@ compute_attributes_sql_style(List *options,
 	}
 
 	/* process optional items */
+	if (windowfunc_item)
+		*windowfunc_p = intVal(windowfunc_item->arg);
 	if (volatility_item)
 		*volatility_p = interpret_func_volatility(volatility_item);
 	if (strict_item)
@@ -735,7 +747,8 @@ CreateFunction(CreateFunctionStmt *stmt, const char *queryString)
 	ArrayType  *parameterNames;
 	List	   *parameterDefaults;
 	Oid			requiredResultType;
-	bool		isStrict,
+	bool		isWindowFunc,
+				isStrict,
 				security;
 	char		volatility;
 	ArrayType  *proconfig;
@@ -756,6 +769,7 @@ CreateFunction(CreateFunctionStmt *stmt, const char *queryString)
 					   get_namespace_name(namespaceId));
 
 	/* default attributes */
+	isWindowFunc = false;
 	isStrict = false;
 	security = false;
 	volatility = PROVOLATILE_VOLATILE;
@@ -766,7 +780,8 @@ CreateFunction(CreateFunctionStmt *stmt, const char *queryString)
 	/* override attributes from explicit list */
 	compute_attributes_sql_style(stmt->options,
 								 &as_clause, &language,
-								 &volatility, &isStrict, &security,
+								 &isWindowFunc, &volatility,
+								 &isStrict, &security,
 								 &proconfig, &procost, &prorows);
 
 	/* Convert language name to canonical case */
@@ -892,6 +907,7 @@ CreateFunction(CreateFunctionStmt *stmt, const char *queryString)
 					prosrc_str, /* converted to text later */
 					probin_str, /* converted to text later */
 					false,		/* not an aggregate */
+					isWindowFunc,
 					security,
 					isStrict,
 					volatility,
diff --git a/src/backend/commands/proclang.c b/src/backend/commands/proclang.c
index 3188156c4d1..ea37352b419 100644
--- a/src/backend/commands/proclang.c
+++ b/src/backend/commands/proclang.c
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/proclang.c,v 1.82 2008/12/18 18:20:33 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/proclang.c,v 1.83 2008/12/31 02:25:03 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -140,6 +140,7 @@ CreateProceduralLanguage(CreatePLangStmt *stmt)
 										 pltemplate->tmplhandler,
 										 pltemplate->tmpllibrary,
 										 false, /* isAgg */
+										 false,	/* isWindowFunc */
 										 false, /* security_definer */
 										 false, /* isStrict */
 										 PROVOLATILE_VOLATILE,
@@ -174,6 +175,7 @@ CreateProceduralLanguage(CreatePLangStmt *stmt)
 										 pltemplate->tmplvalidator,
 										 pltemplate->tmpllibrary,
 										 false, /* isAgg */
+										 false,	/* isWindowFunc */
 										 false, /* security_definer */
 										 false, /* isStrict */
 										 PROVOLATILE_VOLATILE,
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 34dc40a1056..011041f3037 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -11,7 +11,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.649 2008/12/31 00:08:36 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.650 2008/12/31 02:25:04 tgl Exp $
  *
  * HISTORY
  *	  AUTHOR			DATE			MAJOR EVENT
@@ -4801,6 +4801,10 @@ createfunc_opt_item:
 				{
 					$$ = makeDefElem("language", (Node *)makeString($2));
 				}
+			| WINDOW
+				{
+					$$ = makeDefElem("window", (Node *)makeInteger(TRUE));
+				}
 			| common_func_opt_item
 				{
 					$$ = $1;
diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index 4a44b733cf3..f48ee4ae96d 100644
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -9,7 +9,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/ruleutils.c,v 1.292 2008/12/31 00:08:37 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/ruleutils.c,v 1.293 2008/12/31 02:25:04 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1466,6 +1466,8 @@ pg_get_functiondef(PG_FUNCTION_ARGS)
 	/* Emit some miscellaneous options on one line */
 	oldlen = buf.len;
 
+	if (proc->proiswindow)
+		appendStringInfoString(&buf, " WINDOW");
 	switch (proc->provolatile)
 	{
 		case PROVOLATILE_IMMUTABLE: