Re: Removing Functionally Dependent GROUP BY Columns

From: Geoff Winkless <pgsqladmin(at)geoff(dot)dj>
To: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Removing Functionally Dependent GROUP BY Columns
Date: 2016-01-14 13:04:24
Message-ID: CAEzk6ffg=+cL_i_8fAPK3Y+a2UX65KZQv6Mx+SuaYTYAFeT0PA@mail.gmail.com
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On 14 January 2016 at 11:19, Julien Rouhaud <julien(dot)rouhaud(at)dalibo(dot)com> wrote:
> + /* don't try anything unless there's two Vars */
> + if (varlist == NULL || list_length(varlist) < 2)
> + continue;
>
> To be perfectly correct, the comment should say "at least two Vars".

Apologies for butting in and I appreciate I don't have any ownership
over this codebase or right to suggest any changes, but this just
caught my eye before I could hit "delete".

My mantra tends to be "why, not what" for inline comments; in this
case you can get the same information from the next line of code as
you get from the comment.

Perhaps something like

/* it's clearly impossible to remove duplicates if there are fewer
than two GROUPBY columns */

might be more helpful?

(also sorry if I've misunderstood what it _actually_ does, I just made
an assumption based on reading this thread!)

Geoff

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