pg_upgrade: allow upgrades for new-only TOAST tables

Previously, when calculations on the need for toast tables changed,
pg_upgrade could not handle cases where the new cluster needed a TOAST
table and the old cluster did not.  (It already handled the opposite
case.)  This fixes the "OID mismatch" error typically generated in this
case.

Backpatch through 9.2

diff --git a/contrib/pg_upgrade/info.c b/contrib/pg_upgrade/info.c
index 6205c7457467cb14a83a0eda7148eafdeb865f4e..93ea2667bc80be3201202f3622c086ad7eb93ab9 100644 (file)
--- a/contrib/pg_upgrade/info.c
+++ b/contrib/pg_upgrade/info.c
@@ -38,21 +38,61 @@ gen_db_file_maps(DbInfo *old_db, DbInfo *new_db,
                 int *nmaps, const char *old_pgdata, const char *new_pgdata)
 {
    FileNameMap *maps;
-   int         relnum;
+   int         old_relnum, new_relnum;
    int         num_maps = 0;
 
    maps = (FileNameMap *) pg_malloc(sizeof(FileNameMap) *
                                     old_db->rel_arr.nrels);
 
-   for (relnum = 0; relnum < Min(old_db->rel_arr.nrels, new_db->rel_arr.nrels);
-        relnum++)
+   /*
+    * The old database shouldn't have more relations than the new one.
+    * We force the new cluster to have a TOAST table if the old table
+    * had one.
+    */
+   if (old_db->rel_arr.nrels > new_db->rel_arr.nrels)
+       pg_fatal("old and new databases \"%s\" have a mismatched number of relations\n",
+                old_db->db_name);
+
+   /* Drive the loop using new_relnum, which might be higher. */
+   for (old_relnum = new_relnum = 0; new_relnum < new_db->rel_arr.nrels;
+        new_relnum++)
    {
-       RelInfo    *old_rel = &old_db->rel_arr.rels[relnum];
-       RelInfo    *new_rel = &new_db->rel_arr.rels[relnum];
+       RelInfo    *old_rel;
+       RelInfo    *new_rel = &new_db->rel_arr.rels[new_relnum];
+
+       /*
+        * It is possible that the new cluster has a TOAST table for a table
+        * that didn't need one in the old cluster, e.g. 9.0 to 9.1 changed the
+        * NUMERIC length computation.  Therefore, if we have a TOAST table
+        * in the new cluster that doesn't match, skip over it and continue
+        * processing.  It is possible this TOAST table used an OID that was
+        * reserved in the old cluster, but we have no way of testing that,
+        * and we would have already gotten an error at the new cluster schema
+        * creation stage.  Fortunately, since we only restore the OID counter
+        * after schema restore, and restore in OID order via pg_dump, a
+        * conflict would only happen if the new TOAST table had a very low
+        * OID.  However, TOAST tables created long after initial table
+        * creation can have any OID, particularly after OID wraparound.
+        */
+       if (old_relnum == old_db->rel_arr.nrels)
+       {
+           if (strcmp(new_rel->nspname, "pg_toast") == 0)
+               continue;
+           else
+               pg_fatal("Extra non-TOAST relation found in database \"%s\": new OID %d\n",
+                        old_db->db_name, new_rel->reloid);
+       }
+
+       old_rel = &old_db->rel_arr.rels[old_relnum];
 
        if (old_rel->reloid != new_rel->reloid)
-           pg_fatal("Mismatch of relation OID in database \"%s\": old OID %d, new OID %d\n",
-                    old_db->db_name, old_rel->reloid, new_rel->reloid);
+       {
+           if (strcmp(new_rel->nspname, "pg_toast") == 0)
+               continue;
+           else
+               pg_fatal("Mismatch of relation OID in database \"%s\": old OID %d, new OID %d\n",
+                        old_db->db_name, old_rel->reloid, new_rel->reloid);
+       }
 
        /*
         * TOAST table names initially match the heap pg_class oid. In
@@ -76,14 +116,12 @@ gen_db_file_maps(DbInfo *old_db, DbInfo *new_db,
        create_rel_filename_map(old_pgdata, new_pgdata, old_db, new_db,
                                old_rel, new_rel, maps + num_maps);
        num_maps++;
+       old_relnum++;
    }
 
-   /*
-    * Do this check after the loop so hopefully we will produce a clearer
-    * error above
-    */
-   if (old_db->rel_arr.nrels != new_db->rel_arr.nrels)
-       pg_fatal("old and new databases \"%s\" have a different number of relations\n",
+   /* Did we fail to exhaust the old array? */
+   if (old_relnum != old_db->rel_arr.nrels)
+       pg_fatal("old and new databases \"%s\" have a mismatched number of relations\n",
                 old_db->db_name);
 
    *nmaps = num_maps;