From 59a85323d9d5927a852939fa93f09d142c72c91a Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter_e@gmx.net>
Date: Mon, 9 Jul 2018 13:58:08 +0200
Subject: [PATCH] Add UtilityReturnsTuples() support for CALL

This ensures that prepared statements for CALL can return tuples.
---
 src/backend/commands/functioncmds.c | 24 ++++++++++++++++++++++++
 src/backend/tcop/utility.c          |  9 +++++++++
 src/include/commands/defrem.h       |  1 +
 3 files changed, 34 insertions(+)

diff --git a/src/backend/commands/functioncmds.c b/src/backend/commands/functioncmds.c
index acc08b1990..84daa19e06 100644
--- a/src/backend/commands/functioncmds.c
+++ b/src/backend/commands/functioncmds.c
@@ -51,6 +51,7 @@
 #include "commands/proclang.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
+#include "funcapi.h"
 #include "miscadmin.h"
 #include "optimizer/clauses.h"
 #include "optimizer/var.h"
@@ -2340,3 +2341,26 @@ ExecuteCallStmt(CallStmt *stmt, ParamListInfo params, bool atomic, DestReceiver
 
 	FreeExecutorState(estate);
 }
+
+/*
+ * Construct the tuple descriptor for a CALL statement return
+ */
+TupleDesc
+CallStmtResultDesc(CallStmt *stmt)
+{
+	FuncExpr   *fexpr;
+	HeapTuple   tuple;
+	TupleDesc   tupdesc;
+
+	fexpr = stmt->funcexpr;
+
+	tuple = SearchSysCache1(PROCOID, ObjectIdGetDatum(fexpr->funcid));
+	if (!HeapTupleIsValid(tuple))
+		elog(ERROR, "cache lookup failed for procedure %u", fexpr->funcid);
+
+	tupdesc = build_function_result_tupdesc_t(tuple);
+
+	ReleaseSysCache(tuple);
+
+	return tupdesc;
+}
diff --git a/src/backend/tcop/utility.c b/src/backend/tcop/utility.c
index 4e1c21298e..b5804f64ad 100644
--- a/src/backend/tcop/utility.c
+++ b/src/backend/tcop/utility.c
@@ -1744,6 +1744,12 @@ UtilityReturnsTuples(Node *parsetree)
 {
 	switch (nodeTag(parsetree))
 	{
+		case T_CallStmt:
+			{
+				CallStmt   *stmt = (CallStmt *) parsetree;
+
+				return (stmt->funcexpr->funcresulttype == RECORDOID);
+			}
 		case T_FetchStmt:
 			{
 				FetchStmt  *stmt = (FetchStmt *) parsetree;
@@ -1794,6 +1800,9 @@ UtilityTupleDescriptor(Node *parsetree)
 {
 	switch (nodeTag(parsetree))
 	{
+		case T_CallStmt:
+			return CallStmtResultDesc((CallStmt *) parsetree);
+
 		case T_FetchStmt:
 			{
 				FetchStmt  *stmt = (FetchStmt *) parsetree;
diff --git a/src/include/commands/defrem.h b/src/include/commands/defrem.h
index 8fc9e424cf..6b837236d4 100644
--- a/src/include/commands/defrem.h
+++ b/src/include/commands/defrem.h
@@ -64,6 +64,7 @@ extern void IsThereFunctionInNamespace(const char *proname, int pronargs,
 						   oidvector *proargtypes, Oid nspOid);
 extern void ExecuteDoStmt(DoStmt *stmt, bool atomic);
 extern void ExecuteCallStmt(CallStmt *stmt, ParamListInfo params, bool atomic, DestReceiver *dest);
+extern TupleDesc CallStmtResultDesc(CallStmt *stmt);
 extern Oid	get_cast_oid(Oid sourcetypeid, Oid targettypeid, bool missing_ok);
 extern Oid	get_transform_oid(Oid type_id, Oid lang_id, bool missing_ok);
 extern void interpret_function_parameter_list(ParseState *pstate,