mdb_set_dupsort( txn, mdb->mi_dbis[i], mdb_dup_compare );
/* check for old dn2id format */
rc = mdb_cursor_open( txn, mdb->mi_dbis[i], &mc );
mdb_set_dupsort( txn, mdb->mi_dbis[i], mdb_dup_compare );
/* check for old dn2id format */
rc = mdb_cursor_open( txn, mdb->mi_dbis[i], &mc );