Re: Conditional JOINs ?

On 3/19/08, Erik Jones <erik(at)myemma(dot)com> wrote:
> >> Excuse me for bumping this up again, but I still don't understand how
> >> to use this approach to sequentially walk through all different child
> >> tables in one select, without having to JOIN these tables all the
> >> time
> >
> > Apparently a UNION all solved this problem -- sorry for the noise.
>
>
> If you have the child tables INHERITing from the parent, then a simple
>
> SELECT parent.* FROM parent;
>
> would be equivalent to manually spelling out a UNION ALL that
> explicitly lists all of the tables.

But this will only display the information that is common for all the
child tables -- if I also want to display all the information that is
specific for the child tables, as I understand it, I have to use a
UNION ALL and merge all the child tables together this way.

The EXPLAIN of this query:

Append (cost=0.00..2169.52 rows=34376 width=94)
-> Seq Scan ON child1 (cost=0.00..1824.71 rows=34371 width=94)
-> Seq Scan ON child2 (cost=0.00..1.05 rows=5 width=56)

Regards,

Leon Mergen