Re: pg_upgrade if 'postgres' database is dropped

Robert Haas wrote:
> On Fri, Oct 28, 2011 at 10:16 AM, Bruce Momjian <bruce@momjian.us> wrote:
> > Robert Haas wrote:
> >> On Fri, Oct 28, 2011 at 10:07 AM, Bruce Momjian <bruce@momjian.us> wrote:
> >> > OK, then the simplest fix, once you modify pg_dumpall, would be to
> >> > modify pg_upgrade to remove reference to the postgres database in the
> >> > new cluster if it doesn't exist in the old one. ?That would allow
> >> > pg_upgrade to maintain a 1-1 matching of databases in the old and new
> >> > cluster --- it allows the change to be locallized without affecting much
> >> > code.
> >>
> >> That sounds just fine. ?+1.
> >
> > FYI, I don't want to modify pg_dumpall myself because I didn't want to
> > have pg_upgrade forcing a pg_dumpall change that applies to
> > non-binary-upgrade dumps. ?pg_dumpall is too important. ?I am fine if
> > someone else does it, though. ?:-)
>
> OK, done.

OK, the attached, applied patch removes the pg_upgrade dependency on the
'postgres' database existing in the new cluster.  However, vacuumdb,
used by pg_upgrade, still has this dependency:

        conn = connectDatabase("postgres", host, port, username,
        prompt_password, progname);

In fact, all the /scripts binaries use the postgres database, except for
createdb/dropdb, which has this heuristic:

    /*
     * Connect to the 'postgres' database by default, except have the
     * 'postgres' user use 'template1' so he can create the 'postgres'
     * database.
     */
    conn = connectDatabase(strcmp(dbname, "postgres") == 0 ? "template1" : "postgres",
                           host, port, username, prompt_password, progname);

This makes sense because you might be creating or dropping the postgres
database.  Do we want these to have smarter database selection code?

I will now work on code to allow the old cluster to optionally not have
a postgres database.

--
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + It's impossible for everything to be true. +
diff --git a/contrib/pg_upgrade/pg_upgrade.c b/contrib/pg_upgrade/pg_upgrade.c
new file mode 100644
index 273561e..12df463
*** a/contrib/pg_upgrade/pg_upgrade.c
--- b/contrib/pg_upgrade/pg_upgrade.c
*************** static void set_frozenxids(void);
*** 52,60 ****
  static void setup(char *argv0, bool live_check);
  static void cleanup(void);

- /* This is the database used by pg_dumpall to restore global tables */
- #define GLOBAL_DUMP_DB    "postgres"
-
  ClusterInfo old_cluster,
              new_cluster;
  OSInfo        os_info;
--- 52,57 ----
*************** prepare_new_databases(void)
*** 233,242 ****
      prep_status("Creating databases in the new cluster");

      /*
!      * Install support functions in the global-restore database to preserve
!      * pg_authid.oid.
       */
!     install_support_functions_in_new_db(GLOBAL_DUMP_DB);

      /*
       * We have to create the databases first so we can install support
--- 230,241 ----
      prep_status("Creating databases in the new cluster");

      /*
!      * Install support functions in the global-object restore database to
!      * preserve pg_authid.oid.  pg_dumpall uses 'template0' as its template
!      * database so objects we add into 'template1' are not propogated.  They
!      * are removed on pg_upgrade exit.
       */
!     install_support_functions_in_new_db("template1");

      /*
       * We have to create the databases first so we can install support
*************** create_new_objects(void)
*** 270,276 ****
          DbInfo       *new_db = &new_cluster.dbarr.dbs[dbnum];

          /* skip db we already installed */
!         if (strcmp(new_db->db_name, GLOBAL_DUMP_DB) != 0)
              install_support_functions_in_new_db(new_db->db_name);
      }
      check_ok();
--- 269,275 ----
          DbInfo       *new_db = &new_cluster.dbarr.dbs[dbnum];

          /* skip db we already installed */
!         if (strcmp(new_db->db_name, "template1") != 0)
              install_support_functions_in_new_db(new_db->db_name);
      }
      check_ok();