Re: [HACKERS] pg-dump bug (at 6.4)

I have investigated further the bug in pg_dump relating to inherited
check constraints.  This arises in src/bin/pg_dump/pg_dump.c in getTables(), where the query recovers all the
constraintsfor a table, whether or not
 
they are inherited:            1477        sprintf(query, "SELECT rcname, rcsrc from pg_relcheck "     1478
         "where rcrelid = '%s'::oid ",                1479                           tblinfo[i].oid);                 
 

In the following example, a constraint is inherited from the
table `individual':
  bray=> select oid, relname from pg_class         where oid in             (select rcrelid from pg_relcheck
 where rcname = 'is_named')       order by oid desc;    oid|relname     -----+----------  67552|staff
67436|outworker  67111|individual  (3 rows)
 

  bray=> select rcrelid, rcname, rcsrc from pg_relcheck         where rcname = 'is_named'         order by rcrelid
desc; rcrelid|rcname  |rcsrc
-------+--------+---------------------------------------------   67552|is_named|NOT ( surname IS NULL AND forenames IS
NULL)    67436|is_named|NOT ( surname IS NULL AND forenames IS NULL )    67111|is_named|NOT ( surname IS NULL AND
forenamesIS NULL )  (3 rows)
 


pg_dump writes all three constraints into its output, which causes the
table creation to fail on the inherited tables when the database is
restored.

We actually need to select a check constraint only if, for each constraint,
tblinfo[i].oid = min(rcrelid).  However, I cannot work out how
to write the query (not least because there is no min()
function for oids).

Can anyone take this further, please?

-- 
Oliver Elphick                                Oliver.Elphick@lfix.co.uk
Isle of Wight                              http://www.lfix.co.uk/oliver              PGP key from public servers; key
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