Patch to warn about oid/xid wraparound

Here is a patch that will warn you during VACUUM when you are within 75%
of oid/xid wraparound.

I will apply it if 7.2 has no solution to the wraparounds.

--
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 853-3000
  +  If your life is a hard drive,     |  830 Blythe Avenue
  +  Christ can be your backup.        |  Drexel Hill, Pennsylvania 19026
Index: src/backend/commands/vacuum.c
===================================================================
RCS file: /home/projects/pgsql/cvsroot/pgsql/src/backend/commands/vacuum.c,v
retrieving revision 1.195
diff -c -r1.195 vacuum.c
*** src/backend/commands/vacuum.c    2001/05/25 15:45:32    1.195
--- src/backend/commands/vacuum.c    2001/06/12 23:25:58
***************
*** 159,166 ****
  static bool enough_space(VacPage vacpage, Size len);
  static void init_rusage(VacRUsage *ru0);
  static char *show_rusage(VacRUsage *ru0);

-
  /*
   * Primary entry point for VACUUM and ANALYZE commands.
   */
--- 159,166 ----
  static bool enough_space(VacPage vacpage, Size len);
  static void init_rusage(VacRUsage *ru0);
  static char *show_rusage(VacRUsage *ru0);
+ static void check_limits(void);

  /*
   * Primary entry point for VACUUM and ANALYZE commands.
   */
***************
*** 236,241 ****
--- 236,242 ----

      /* clean up */
      vacuum_shutdown();
+     check_limits();
  }

  /*
***************
*** 2645,2648 ****
--- 2646,2672 ----
               (int) (ru1.tv.tv_usec - ru0->tv.tv_usec) / 10000);

      return result;
+ }
+
+ /*
+  *    check if we are near OID or XID wraparound
+  */
+ static void check_limits(void)
+ {
+     Oid nextOid;
+
+     /* If we are 75% to the limit, warn the user */
+     if (GetCurrentTransactionId() >
+         ~(TransactionId)0 - (~(TransactionId)0) / 4)
+         elog(NOTICE,"You are within 75%% of the limit for transaction ids.\n"
+             "Dumping your databases, running initdb, and reloading will reset\n"
+             "the transaction id counter.");
+
+     /* If we are 75% to the limit, warn the user */
+     GetNewObjectId(&nextOid);
+     if (nextOid > ~(Oid)0 - (~(Oid)0) / 4)
+         elog(NOTICE,"You are within 75%% of the limit for object ids.\n"
+             "If you are not using object ids as primary keys, dumping your\n"
+             "databases, running initdb, and reloading will reset\n"
+             "the oid counter.");
  }