0003-Free-space-allocated-by-copy_plpgsql_datums.patch

From 4375046f8b1f376e404b6ed65a358ee6d55d3b41 Mon Sep 17 00:00:00 2001
From: Tomas Vondra <tomas@2ndquadrant.com>
Date: Sat, 13 May 2023 13:19:49 +0200
Subject: [PATCH 3/3] Free space allocated by copy_plpgsql_datums

During PL/pgSQL execution, we allocate a local copy for calls. When
executing triggers, this gets allocated in ExecutorState, so it'd be
kept until query completes.

Free it explicitly, as part of cleanup.
---
 src/pl/plpgsql/src/pl_exec.c | 39 +++++++++++++++++++++++++++++++-----
 1 file changed, 34 insertions(+), 5 deletions(-)

diff --git a/src/pl/plpgsql/src/pl_exec.c b/src/pl/plpgsql/src/pl_exec.c
index 4b76f7699a6..99283d354f4 100644
--- a/src/pl/plpgsql/src/pl_exec.c
+++ b/src/pl/plpgsql/src/pl_exec.c
@@ -264,6 +264,8 @@ static void coerce_function_result_tuple(PLpgSQL_execstate *estate,
 static void plpgsql_exec_error_callback(void *arg);
 static void copy_plpgsql_datums(PLpgSQL_execstate *estate,
 								PLpgSQL_function *func);
+static void free_plpgsql_datums(PLpgSQL_execstate *estate,
+								PLpgSQL_function *func);
 static void plpgsql_fulfill_promise(PLpgSQL_execstate *estate,
 									PLpgSQL_var *var);
 static MemoryContext get_stmt_mcontext(PLpgSQL_execstate *estate);
@@ -788,6 +790,8 @@ plpgsql_exec_function(PLpgSQL_function *func, FunctionCallInfo fcinfo,
 	exec_eval_cleanup(&estate);
 	/* stmt_mcontext will be destroyed when function's main context is */
 
+	free_plpgsql_datums(&estate, func);
+
 	/*
 	 * Pop the error context stack
 	 */
@@ -1142,6 +1146,8 @@ plpgsql_exec_trigger(PLpgSQL_function *func,
 	exec_eval_cleanup(&estate);
 	/* stmt_mcontext will be destroyed when function's main context is */
 
+	free_plpgsql_datums(&estate, func);
+
 	/*
 	 * Pop the error context stack
 	 */
@@ -1217,6 +1223,8 @@ plpgsql_exec_event_trigger(PLpgSQL_function *func, EventTriggerData *trigdata)
 	exec_eval_cleanup(&estate);
 	/* stmt_mcontext will be destroyed when function's main context is */
 
+	free_plpgsql_datums(&estate, func);
+
 	/*
 	 * Pop the error context stack
 	 */
@@ -1304,15 +1312,20 @@ copy_plpgsql_datums(PLpgSQL_execstate *estate,
 	char	   *ws_next;
 	int			i;
 
-	/* Allocate local datum-pointer array */
-	estate->datums = (PLpgSQL_datum **)
-		palloc(sizeof(PLpgSQL_datum *) * ndatums);
-
 	/*
+	 * Allocate local datum-pointer array, followed by space for the values.
+	 *
 	 * To reduce palloc overhead, we make a single palloc request for all the
 	 * space needed for locally-instantiated datums.
 	 */
-	workspace = palloc(func->copiable_size);
+	estate->datums = (PLpgSQL_datum **)
+		palloc(MAXALIGN(sizeof(PLpgSQL_datum *) * ndatums) + func->copiable_size);
+
+	/*
+	 * Space for values starts after the datum-pointer array, but we need to make
+	 * sure it's aligned properly.
+	 */
+	workspace = (char *) estate->datums + MAXALIGN(sizeof(PLpgSQL_datum *) * ndatums);
 	ws_next = workspace;
 
 	/* Fill datum-pointer array, copying datums into workspace as needed */
@@ -1362,6 +1375,22 @@ copy_plpgsql_datums(PLpgSQL_execstate *estate,
 	Assert(ws_next == workspace + func->copiable_size);
 }
 
+/*
+ * Free the local execution variables. We've allocated all of the space at once
+ * so we can simply free the main pointer.
+ */
+static void
+free_plpgsql_datums(PLpgSQL_execstate *estate,
+					PLpgSQL_function *func)
+{
+	if (estate->datums != NULL)
+	{
+		pfree(estate->datums);
+		estate->datums = NULL;
+	}
+
+}
+
 /*
  * If the variable has an armed "promise", compute the promised value
  * and assign it to the variable.
-- 
2.40.1