diff --git a/src/backend/access/common/tupdesc.c b/src/backend/access/common/tupdesc.c
index 9fec6e3386..4d22c03cab 100644
--- a/src/backend/access/common/tupdesc.c
+++ b/src/backend/access/common/tupdesc.c
@@ -56,18 +56,10 @@ ResourceOwnerForgetTupleDesc(ResourceOwner owner, TupleDesc tupdesc)
 	ResourceOwnerForget(owner, PointerGetDatum(tupdesc), &tupdesc_resowner_desc);
 }
 
-/*
- * populate_compact_attribute
- *		Fill in the corresponding CompactAttribute element from the
- *		Form_pg_attribute for the given attribute number.  This must be called
- *		whenever a change is made to a Form_pg_attribute in the TupleDesc.
- */
 void
-populate_compact_attribute(TupleDesc tupdesc, int attnum)
+populate_compact_attribute_internal(Form_pg_attribute src,
+									CompactAttribute *dst)
 {
-	Form_pg_attribute src = TupleDescAttr(tupdesc, attnum);
-	CompactAttribute *dst = &tupdesc->compact_attrs[attnum];
-
 	memset(dst, 0, sizeof(CompactAttribute));
 
 	dst->attcacheoff = -1;
@@ -101,6 +93,22 @@ populate_compact_attribute(TupleDesc tupdesc, int attnum)
 	}
 }
 
+/*
+ * populate_compact_attribute
+ *		Fill in the corresponding CompactAttribute element from the
+ *		Form_pg_attribute for the given attribute number.  This must be called
+ *		whenever a change is made to a Form_pg_attribute in the TupleDesc.
+ */
+void
+populate_compact_attribute(TupleDesc tupdesc, int attnum)
+{
+	Form_pg_attribute src = TupleDescAttr(tupdesc, attnum);
+	CompactAttribute *dst = &tupdesc->compact_attrs[attnum];
+
+	populate_compact_attribute_internal(src, dst);
+}
+
+
 /*
  * CreateTemplateTupleDesc
  *		This function allocates an empty tuple descriptor structure.
diff --git a/src/include/access/tupdesc.h b/src/include/access/tupdesc.h
index e61a4affa4..50b977a135 100644
--- a/src/include/access/tupdesc.h
+++ b/src/include/access/tupdesc.h
@@ -158,6 +158,9 @@ TupleDescAttr(TupleDesc tupdesc, int i)
 
 #undef TupleDescAttrAddress
 
+extern void populate_compact_attribute_internal(Form_pg_attribute src,
+												CompactAttribute *dst);
+
 /*
  * Accessor for the i'th CompactAttribute element of tupdesc.
  */
@@ -166,7 +169,8 @@ TupleDescCompactAttr(TupleDesc tupdesc, int i)
 {
 	CompactAttribute *cattr = &tupdesc->compact_attrs[i];
 #ifdef USE_ASSERT_CHECKING
-	CompactAttribute snapshot;
+	CompactAttribute tmp;
+	Form_pg_attribute attr = TupleDescAttr(tupdesc, i);
 
 	/*
 	 * In Assert enabled builds we verify that the CompactAttribute is
@@ -174,21 +178,13 @@ TupleDescCompactAttr(TupleDesc tupdesc, int i)
 	 * TABLE where code makes changes to the FormData_pg_attribute but forgets
 	 * to call populate_compact_attribute.
 	 */
+	populate_compact_attribute_internal(attr, &tmp);
 
-	/*
-	 * Take a snapshot of how the CompactAttribute is now before calling
-	 * populate_compact_attribute to make it up-to-date with the
-	 * FormData_pg_attribute.
-	 */
-	memcpy(&snapshot, cattr, sizeof(CompactAttribute));
-
-	populate_compact_attribute(tupdesc, i);
-
-	/* reset attcacheoff back to what it was */
-	cattr->attcacheoff = snapshot.attcacheoff;
+	/* make the attcacheoff match since it's been reset to -1 again */
+	tmp.attcacheoff = cattr->attcacheoff;
 
-	/* Ensure the snapshot matches the freshly populated CompactAttribute */
-	Assert(memcmp(&snapshot, cattr, sizeof(CompactAttribute)) == 0);
+	/* Check the freshly populated CompactAttribute matches the TupleDesc's */
+	Assert(memcmp(&tmp, cattr, sizeof(CompactAttribute)) == 0);
 #endif
 
 	return cattr;