Re: EXPLAIN doesn't show sufficient info for wCTE cases

On Mon, Feb 28, 2011 at 11:44:06AM -0500, Robert Haas wrote:
> On Mon, Feb 28, 2011 at 11:39 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> > EXPLAIN currently shows ModifyTable nodes as just "Insert", "Update",
> > or "Delete", without any indication of the target table.  This was
> > more or less good enough when there could only be one such node per
> > query, but it's looking pretty inadequate to me as I play around
> > with data-modifying statements in WITH.
> >
> > The obvious thing to do is show the target table much as we do for
> > table scan nodes, eg "Update on my_table".  There is a deficiency
> > in that, which is that for inherited UPDATE/DELETE cases a single
> > ModifyTable node could have multiple target tables.  But after
> > reflecting on it a bit, I think it would be good enough to show
> > the parent table name.  The individual child plans will necessarily
> > include scans of the individual child tables, so you can figure
> > out which is which from that if you need to know.
> >
> > Alternatively we could list all the target tables in a new node
> > attribute, eg
> >
> >        Update (costs...)
> >                Target Tables: foo_parent, foo_child1, ...
> >
> > But in the majority of cases this seems like a waste of precious
> > vertical space.
> >
> > Thoughts?
>
> I think it's good to include the table name, for sure. I *think* I
> agree that it isn't necessary to include the child names.

Would this affect the use case of breaking up a too-long table into
partitions?

WITH f AS (
DELETE FROM ONLY foo
WHERE foo_ts >= '2011-01-01' AND foo_ts < '2011-02-01'
RETURNING *
)
INSERT INTO foo_201101
SELECT * FROM f;

Cheers,
David.
--
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