Simplify transformJsonAggConstructor() API

There's no need for callers to pass aggregate names so that the function
can resolve them to OIDs, when callers can just pass aggregate OIDs
directly to begin with.

Author: alvherre

src/backend/parser/parse_expr.c

@@ -3611,21 +3611,17 @@ transformJsonArrayQueryConstructor(ParseState *pstate,
 static Node *
 transformJsonAggConstructor(ParseState *pstate, JsonAggConstructor *agg_ctor,
 							JsonReturning *returning, List *args,
-							const char *aggfn, Oid aggtype,
+							Oid aggfnoid, Oid aggtype,
 							JsonConstructorType ctor_type,
 							bool unique, bool absent_on_null)
 {
-	Oid			aggfnoid;
 	Node	   *node;
 	Expr	   *aggfilter;
 
 	aggfilter = agg_ctor->agg_filter ? (Expr *)
 		transformWhereClause(pstate, agg_ctor->agg_filter,
 							 EXPR_KIND_FILTER, "FILTER") : NULL;
 
-	aggfnoid = DatumGetInt32(DirectFunctionCall1(regprocin,
-												 CStringGetDatum(aggfn)));
-
 	if (agg_ctor->over)
 	{
 		/* window function */
@@ -3703,7 +3699,7 @@ transformJsonObjectAgg(ParseState *pstate, JsonObjectAgg *agg)
 	Node	   *key;
 	Node	   *val;
 	List	   *args;
-	const char *aggfnname;
+	Oid			aggfnoid;
 	Oid			aggtype;
 
 	key = transformExprRecurse(pstate, (Node *) agg->arg->key);
@@ -3717,33 +3713,33 @@ transformJsonObjectAgg(ParseState *pstate, JsonObjectAgg *agg)
 	{
 		if (agg->absent_on_null)
 			if (agg->unique)
-				aggfnname = "pg_catalog.jsonb_object_agg_unique_strict";
+				aggfnoid = F_JSONB_OBJECT_AGG_UNIQUE_STRICT;
 			else
-				aggfnname = "pg_catalog.jsonb_object_agg_strict";
+				aggfnoid = F_JSONB_OBJECT_AGG_STRICT;
 		else if (agg->unique)
-			aggfnname = "pg_catalog.jsonb_object_agg_unique";
+			aggfnoid = F_JSONB_OBJECT_AGG_UNIQUE;
 		else
-			aggfnname = "pg_catalog.jsonb_object_agg";
+			aggfnoid = F_JSONB_OBJECT_AGG;
 
 		aggtype = JSONBOID;
 	}
 	else
 	{
 		if (agg->absent_on_null)
 			if (agg->unique)
-				aggfnname = "pg_catalog.json_object_agg_unique_strict";
+				aggfnoid = F_JSON_OBJECT_AGG_UNIQUE_STRICT;
 			else
-				aggfnname = "pg_catalog.json_object_agg_strict";
+				aggfnoid = F_JSON_OBJECT_AGG_STRICT;
 		else if (agg->unique)
-			aggfnname = "pg_catalog.json_object_agg_unique";
+			aggfnoid = F_JSON_OBJECT_AGG_UNIQUE;
 		else
-			aggfnname = "pg_catalog.json_object_agg";
+			aggfnoid = F_JSON_OBJECT_AGG;
 
 		aggtype = JSONOID;
 	}
 
 	return transformJsonAggConstructor(pstate, agg->constructor, returning,
-									   args, aggfnname, aggtype,
+									   args, aggfnoid, aggtype,
 									   JSCTOR_JSON_OBJECTAGG,
 									   agg->unique, agg->absent_on_null);
 }
@@ -3760,7 +3756,7 @@ transformJsonArrayAgg(ParseState *pstate, JsonArrayAgg *agg)
 {
 	JsonReturning *returning;
 	Node	   *arg;
-	const char *aggfnname;
+	Oid			aggfnoid;
 	Oid			aggtype;
 
 	arg = transformJsonValueExpr(pstate, agg->arg, JS_FORMAT_DEFAULT);
@@ -3770,19 +3766,17 @@ transformJsonArrayAgg(ParseState *pstate, JsonArrayAgg *agg)
 
 	if (returning->format->format_type == JS_FORMAT_JSONB)
 	{
-		aggfnname = agg->absent_on_null ?
-			"pg_catalog.jsonb_agg_strict" : "pg_catalog.jsonb_agg";
+		aggfnoid = agg->absent_on_null ? F_JSONB_AGG_STRICT : F_JSONB_AGG;
 		aggtype = JSONBOID;
 	}
 	else
 	{
-		aggfnname = agg->absent_on_null ?
-			"pg_catalog.json_agg_strict" : "pg_catalog.json_agg";
+		aggfnoid = agg->absent_on_null ? F_JSON_AGG_STRICT : F_JSON_AGG;
 		aggtype = JSONOID;
 	}
 
 	return transformJsonAggConstructor(pstate, agg->constructor, returning,
-									   list_make1(arg), aggfnname, aggtype,
+									   list_make1(arg), aggfnoid, aggtype,
 									   JSCTOR_JSON_ARRAYAGG,
 									   false, agg->absent_on_null);
 }