Re: hist boundary duplicates bug in head and 8.3

On Tue, 2009-01-06 at 18:40 -0500, Tom Lane wrote:
> "Nathan Boley" <npboley@gmail.com> writes:
> >> I don't think this is a bug.
> 
> > hmmm... Well, I assumed it was a bug from a comment in analyze.
> 
> > From ( near ) line 2130 in analyze.c
> 
> >  * least 2 instances in the sample.  Also, we won't suppress values
> >  * that have a frequency of at least 1/K where K is the intended
> >  * number of histogram bins; such values might otherwise cause us to
> >  * emit duplicate histogram bin boundaries.
> 
> That's talking about a case where we have a choice whether to include a
> value in the MCV list or not.  Once the MCV list is maxed out, we can't
> do anything to avoid duplicates.

Surely the most important point in the OP was that ineqsel does not
correctly binary search in the presence of duplicates.

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