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In-Reply-To: <20260327021807.3ae563de0a288086b98755fb@sraoss.co.jp>
From: Dean Rasheed <dean.a.rasheed@gmail.com>
Date: Thu, 26 Mar 2026 17:44:01 +0000
Message-ID: 
 <CAEZATCV5ZbGZzmqKPow9tsaVuE3vmTU4WwEq0wHrsM=QHBpUEQ@mail.gmail.com>
Subject: Re: Allow to collect statistics on virtual generated columns
To: Yugo Nagata <nagata@sraoss.co.jp>
Cc: Andres Freund <andres@anarazel.de>, pgsql-hackers@postgresql.org
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On Thu, 26 Mar 2026 at 17:18, Yugo Nagata <nagata@sraoss.co.jp> wrote:
>
> On Thu, 26 Mar 2026 16:00:38 +0000
> Dean Rasheed <dean.a.rasheed@gmail.com> wrote:
>
> > On Thu, 26 Mar 2026 at 15:09, Yugo Nagata <nagata@sraoss.co.jp> wrote:
> > >
> > > I've attached an updated patch including the documentation and tests.
> >
> > I think this is a much better approach.
> >
> > One thing that stands out in CreateStatistics() is that the check for
> > a less-than operator can be skipped if there is just a single virtual
> > generated column, for the same reason as for statistics on a single
> > expression. I.e., it should be possible to build statistics on a
> > single virtual generated column of any data type.
>
> I've attached a revised patch to skip the less-than operator check
> for a single virtual generated column.
>
> In fact, this change skips the check for any single column,
> not just virtual generated columns. However, using a non-virtual
> single column will result in an error elsewhere.

Makes sense. I think the comments could just be simplified to say
"Disallow data types without a less-than operator in multivariate
statistics", and add the word "multivariate" to the error message, as
in the expression case.

Regards,
Dean