Re: More stable query plans via more predictable column statistics

Shulgin, Oleksandr wrote:

> Alright.  I'm attaching the latest version of this patch split in two
> parts: the first one is NULLs-related bugfix and the second is the
> "improvement" part, which applies on top of the first one.

I went over patch 0001 and it seems pretty reasonable.  It's missing
some comment updates -- at least the large comments that talk about Duj1
should be modified to indicate why the code is now subtracting the null
count.

Also, I can't quite figure out why the "else" now in line 2131
is now "else if track_cnt != 0".  What happens if track_cnt is zero?
The comment above the "if" block doesn't provide any guidance.