Re: Rule system goes weird with SELECT queries - Mailing list pgsql-hackers

Thanks for the reply.  I'll look into setting up CVS -- I've
just
been using the distributed 7.0.2 actually.

Moreover, the situation is even a bit more confused for me. 
When
I actually *execute* the 'insert into dummy', I get the
output
of only one select: the second one listed.  Is there
something
about executing a list I don't know about, or is this also
old news??

++ kevin



Tom Lane wrote:
> 
> "Kevin O'Gorman" <kogorman@pacbell.net> writes:
> > If I define two rules for the same action, each with
> > a single select command, I wind up with two selects as
> > expected, but they are both cross-product selects on the
> > two tables. This is unexpected.
> 
> Rangetable leakage, sounds like --- the two queries are sharing the same
> list of rangetable entries, and that's what the planner joins over.  Not
> sure if it's *good* that they share the same rtable list, or if that's a
> bug.  In any event, it's old news because current sources don't use the
> rtable list to control joining; now there is a separate join tree, which
> is definitely not shared.  I get
> 
> regression=# create rule rule4a as on insert to dummy do instead select * from
> d2;
> CREATE
> regression=# create rule rule4b as on insert to dummy do instead select * from
> d3;
> CREATE
> regression=# explain insert into dummy values(1);
> NOTICE:  QUERY PLAN:
> 
> Seq Scan on d2  (cost=0.00..20.00 rows=1000 width=4)
> 
> NOTICE:  QUERY PLAN:
> 
> Seq Scan on d3  (cost=0.00..20.00 rows=1000 width=4)
> 
> EXPLAIN
> 
> which looks fine.  Can't check your other example, since the grammar
> file hasn't been changed to allow it...
> 
> I'm not sure whether to recommend that you work from current CVS sources
> or not.  A couple weeks ago that's what I would have said, but Vadim is
> halfway through integrating WAL changes and I'm not sure how stable the
> tip really is.  You could try the tip, and if it blows up fall back to
> a dated retrieval from about 7-Oct.  Or you could investigate the way
> that the 7.0.* rewriter handles the rtable list for multiple queries,
> but that's probably not a real profitable use of your time.
> 
>                         regards, tom lane

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