Re: Allow to collect statistics on virtual generated columns

On Wed, 1 Apr 2026 17:12:38 +0100
Dean Rasheed  wrote:

> On Tue, 31 Mar 2026 at 15:35, Yugo Nagata  wrote:
> >
> > Thank you for updating the patch. I am fine with that.
> >
> > One concern is that users might interpret "stored" as referring to
> > "stored generated columns", rather than including regular columns,
> 
> Yeah, possibly. I changed "stored" to "non-virtual", which should
> reduce the chances of that particular confusion.
> 
> > Also, the meaning of "automatically" might be a bit unclear, so we
> > could clarify it by adding "without defining extended statistics."
> >
> >       Defining extended statistics on a single stored
> >       column is not supported or necessary, because statistics are built
> >       automatically on such columns without defining extended statistics.
> 
> OK, pushed that way.

Thank you!

> 
> I also noticed that a few places in CreateStatistics() could use the
> variable "numcols" instead of "list_length(stmt->exprs)", so I changed
> that.
> 
> I decided to include the change to the error message discussed in [1],
> since there seemed to be a consensus there, except that I think it
> also needs to make it clear that it refers only to non-virtual
> columns.
> 
> In addition, there was another nearby error message which was no
> longer quite right for statistics on virtual generated columns, and I
> changed the order of checks, since that allowed the "if" statements to
> be simplified a bit.

I reviewed the commit, and it looks good to me.
Thanks again.

Regards,
Yugo Nagata


-- 
Yugo Nagata