Re: [GENERAL] Performance of full outer join in 8.3

On Wed, Apr 15, 2009 at 6:04 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Simon Riggs <simon@2ndQuadrant.com> writes:
>> I've always been scared to ask this question, in case the answer is No,
>> but: Do we have a set of regression tests for the optimizer anywhere?
>
> Nothing beyond what is in the standard tests.  While that's okay at
> catching wrong answers --- and we have memorialized a number of such
> issues in the tests --- the framework is not good for catching things
> that run slower than they ought.

We could add some regression tests that create a sample data set,
ANALYZE it, and then EXPLAIN various things.  The results should be
deterministic, but creating a reasonably comprehensive set of tests
might be a fair amount of work, and would likely add significantly to
the runtime of the tests.  Maybe it would need to be a separate suite
just for optimizer testing.

...Robert