pg_upgrade: Mention that we preserve database OIDs in a comment.

Oversight in commit aa01051418.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/4055696.1744134682%40sss.pgh.pa.us

diff --git a/src/bin/pg_upgrade/pg_upgrade.c b/src/bin/pg_upgrade/pg_upgrade.c
index 72b5a5fde5a0f1b2f96b9e83fb1c81d72b8d396b..d9db48dba0d25ce9a9876f194e83a42b2badad87 100644 (file)
--- a/src/bin/pg_upgrade/pg_upgrade.c
+++ b/src/bin/pg_upgrade/pg_upgrade.c
@@ -32,6 +32,9 @@
  *     We control all assignments of pg_authid.oid for historical reasons (the
  *     oids used to be stored in pg_largeobject_metadata, which is now copied via
  *     SQL commands), that might change at some point in the future.
+ *
+ *     We control all assignments of pg_database.oid because we want the directory
+ *     names to match between the old and new cluster.
  */