On Tue, 2008-05-27 at 17:43 -0400, Tom Lane wrote:
> Simon Riggs <simon(at)2ndquadrant(dot)com> writes:
> > I have a complex query where making a small change to the SQL increases
> > run-time by > 1000 times.
> 
> > The first SQL statement is of the form
> 
> > A JOIN B ON (a.id = b.id) LEFT JOIN C ON (a.id = c.id) 
> 
> > and the second is like this
> 
> > A JOIN B ON (a.id = b.id) LEFT JOIN C ON (b.id = c.id)
> 
> > the only difference is the substitution of a -> b
> 
> Please provide an actual test case.

Getting closer, but still not able to produce a moveable test case.

Symptoms are

* using partitioning
* when none of the partitions are excluded
* when equivalence classes ought to be able to reconcile join 

Still working on it

-- 
 Simon Riggs           www.2ndQuadrant.com
 PostgreSQL Training, Services and Support

In response to

• Re: Outer joins and equivalence at 2008-05-27 21:43:12 from Tom Lane

Responses

• Re: Outer joins and equivalence at 2008-06-02 19:47:11 from Simon Riggs

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