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 6cc10c7b5a0f47876222d257846b04a9b14e605a..eec087fc486444fa0a4629d42912ecb3f282f673 100644 (file)
--- a/contrib/pg_upgrade/info.c
+++ b/contrib/pg_upgrade/info.c
@@ -37,21 +37,61 @@ 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_log(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_log(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_log(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_log(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
@@ -73,11 +113,12 @@ 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_log(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_log(PG_FATAL, "old and new databases \"%s\" have a mismatched number of relations\n",
                           old_db->db_name);
 
        *nmaps = num_maps;