Simplify pg_upgrade C comment about what is preserved.

diff --git a/contrib/pg_upgrade/pg_upgrade.c b/contrib/pg_upgrade/pg_upgrade.c
index dd50eb85ccc08751da1675db4b82ebd5976151ad..9a5ef0fd205f01f7fb684d9f9ec8b36fc64df6e1 100644 (file)
--- a/contrib/pg_upgrade/pg_upgrade.c
+++ b/contrib/pg_upgrade/pg_upgrade.c
@@ -15,22 +15,16 @@
  * oids are the same between old and new clusters.  This is important
  * because toast oids are stored as toast pointers in user tables.
  *
- * The only place where old/new relfilenode might not match is
- * pg_largeobject, pg_largeobject_metadata, and its indexes,
- * which can change their relfilenode values due to a cluster, reindex,
- * or vacuum full.  (We don't create those so have no control over their
- * new relfilenode values.)
- *
  * FYI, while pg_class.oid and pg_class.relfilenode are intially the same
- * in a cluster, but they can diverge due to cluster, reindex, or vacuum
- * full.  The new cluster will again have matching pg_class.relfilenode
- * and pg_class.oid values, but based on the old relfilenode value, so the
- * old/new oids might differ.
+ * in a cluster, but they can diverge due to CLUSTER, REINDEX, or VACUUM
+ * FULL.  The new cluster will have matching pg_class.oid and
+ * pg_class.relfilenode values and be based on the old oid value.  This can
+ * cause the old and new pg_class.relfilenode values to differ.
  *
- * We control all assignments of pg_type.oid because these oid are stored
+ * We control all assignments of pg_type.oid because these oids are stored
  * in user composite type values.
  *
- * We control all assignments of pg_enum.oid because these oid are stored
+ * We control all assignments of pg_enum.oid because these oids are stored
  * in user tables as enum values.
  */