diff --git a/src/backend/executor/execUtils.c b/src/backend/executor/execUtils.c
index 4943339ebb..b74b0684b3 100644
--- a/src/backend/executor/execUtils.c
+++ b/src/backend/executor/execUtils.c
@@ -1348,10 +1348,25 @@ ExecGetExtraUpdatedCols(ResultRelInfo *relinfo, EState *estate)
 	return NULL;
 }
 
-/* Return columns being updated, including generated columns */
+/*
+ * Return columns being updated, including generated columns
+ *
+ * The bitmap is allocated in per-tuple memory context. It's up to the caller to
+ * copy it into a different context with the appropriate lifespan, if needed.
+ */
 Bitmapset *
 ExecGetAllUpdatedCols(ResultRelInfo *relinfo, EState *estate)
 {
-	return bms_union(ExecGetUpdatedCols(relinfo, estate),
-					 ExecGetExtraUpdatedCols(relinfo, estate));
+
+	Bitmapset	   *ret;
+	MemoryContext	oldcxt;
+
+	oldcxt = MemoryContextSwitchTo(GetPerTupleMemoryContext(estate));
+
+	ret = bms_union(ExecGetUpdatedCols(relinfo, estate),
+					ExecGetExtraUpdatedCols(relinfo, estate));
+
+	MemoryContextSwitchTo(oldcxt);
+
+	return ret;
 }