Re: pg_upgrade and relkind filtering - Mailing list pgsql-hackers

On Sat, Dec 31, 2011 at 07:41:00PM -0500, Noah Misch wrote:
> On Mon, Dec 05, 2011 at 05:06:37PM -0500, Bruce Momjian wrote:
> > Pg_upgrade has the following check to make sure the cluster is safe for
> > upgrading:
> >
> >         res = executeQueryOrDie(conn,
> >                                 "SELECT n.nspname, c.relname, a.attname
> > "
> >                                 "FROM   pg_catalog.pg_class c, "
> >                                 "       pg_catalog.pg_namespace n, "
> >                                 "       pg_catalog.pg_attribute a "
> >                                 "WHERE  c.oid = a.attrelid AND "
> >                                 "       NOT a.attisdropped AND "
> >                                 "       a.atttypid IN ( "
> >           "         'pg_catalog.regproc'::pg_catalog.regtype, "
> >           "         'pg_catalog.regprocedure'::pg_catalog.regtype, "
> >           "         'pg_catalog.regoper'::pg_catalog.regtype, "
> >           "         'pg_catalog.regoperator'::pg_catalog.regtype, "
> >         /* regclass.oid is preserved, so 'regclass' is OK */
> >         /* regtype.oid is preserved, so 'regtype' is OK */
> >           "         'pg_catalog.regconfig'::pg_catalog.regtype, "
> >           "         'pg_catalog.regdictionary'::pg_catalog.regtype) AND
> > "
> >           "     c.relnamespace = n.oid AND "
> >           "     n.nspname != 'pg_catalog' AND "
> >           "     n.nspname != 'information_schema'");
> >
> > Based on a report from EnterpriseDB, I noticed that we check all
> > pg_class entries, while there are cases where this is unnecessary
> > because there is no data behind the entry, e.g. views.  Here are the
> > relkinds supported:
> >
> >     #define       RELKIND_RELATION        'r'       /* ordinary table */
> >     #define       RELKIND_INDEX           'i'       /* secondary index */
> >     #define       RELKIND_SEQUENCE        'S'       /* sequence object */
> >     #define       RELKIND_TOASTVALUE      't'       /* for out-of-line values */
> >     #define       RELKIND_VIEW            'v'       /* view */
> >     #define       RELKIND_COMPOSITE_TYPE  'c'       /* composite type */
> >     #define       RELKIND_FOREIGN_TABLE   'f'       /* foreign table */
> >     #define       RELKIND_UNCATALOGED     'u'       /* not yet cataloged */
> >
> > What types, other than views, can we skip in this query?
>
> RELKIND_UNCATALOGED should never appear on disk, and RELKIND_SEQUENCE and
> RELKIND_TOASTVALUE do not allow adding columns or changing column types.  We
> might as well keep validating them.  RELKIND_RELATION and RELKIND_INDEX have
> storage, so we must check those.
>
> The remaining three relkinds (RELKIND_VIEW, RELKIND_COMPOSITE_TYPE,
> RELKIND_FOREIGN_TABLE) have no storage, but all are usable as column types in
> other relations that do have storage.  You could skip them iff they're unused
> that way, per a check like find_composite_type_dependencies().

Good point.  I have applied the attached comment patch to document why
we check all relkinds for regtypes.  Thanks.

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

  + It's impossible for everything to be true. +