One other thing about this issue. A work around is that I can parse sql
statements myself to come up with the table names. Yes, it's a bit of
work, but not too bad. My question is whether or not column/table
combinations are guaranteed to return in the order that the table names
appear in a query. It seems like they're always returned this way. For
instance:
select * from projects join employees on projects.manager = employees.id;
projects.id would always appear in the return list before employees.id?
Omar Eljumaily wrote:
> This is with 8.1.8, but I don't see any mention of any bug fixes that
> cover this.
>
> I've run into this sort of obscure problem. I'm using libpq with a
> front end database api where I need to track column names and how
> they're returned in libpq queries. What's happening is that I start
> out with a set of table names when I open my database with a query:
>
> SELECT relfilenode, relname FROM pg_class WHERE relname !~
> '^(pg_|sql_)' AND relkind = 'r'
>
> But these don't agree with the oids when I subsequently fetch my rows
> and use the following:
>
> Oid o = PQftable(_res, i);
> std::string s1 = _con->_oidTableNames[o];
>
> _con->_oidTableNames is my own array that I've created with the above
> select query. The reason I need to get table names after queries is
> that queries often return with multiple cases of a single column name,
> but with different table names. I need to be able to decifer the
> table.column combination when people refer to a column in that way.
>
> My problem is that the Oids returned by PQftable sometimes do not
> return from the select query. For instance
>
> Oid returned from PQftable = 654989
> select relname from FROM pg_class WHERE relfilenode = 654989
> returns empty.
>
> The way I can solve this problem is by dumping and restoring the
> database. That's the only way I can fix it.
>
> I don't know how to reproduce the problem. Has anybody heard of
> this? I'm going to update to the latest version this weekened. Maybe
> that will fix it.
> Is there any other way to get table names from libpq queries without
> using the oid method I use above?
>
> One other thing I just remembered. The next time it happens I'm going
> to try a postgresql java driver with similar queries to see if the
> table.column combinations in ResultSet.getString() get messed up as
> well. That will tell me something. I suppose I can look and see how
> they get tablename information.
>
> Thanks
>
>
>
>
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