Re: [patch] [doc] Minor variable related cleanup and rewording of plpgsql docs

I looked over the v2 patch. Parts of it seem like improvements but
other parts definitely don't. In particular, I thought you introduced
a great deal of confusion in 43.5.2 (Executing a Command with No Result).
The statement that you can write a non-result-returning SQL command as-is
is true in general, and ought not be confused with the question of whether
you can insert variable values into it. Also, starting with a spongy
definition of "utility command" and then contrasting with that does not
seem to me to add clarity.

I attach a v3 that I like better, although there's room to disagree
about that. I've always felt that the separation between 43.5.2 and
43.5.3 was rather artificial --- it's okay I guess for describing
how to handle command output, but we end up with considerable
duplication when it comes to describing how to insert values into a
command. It's tempting to try re-splitting it to separate optimizable
from non-optimizable statements; but maybe that'd just end with
different duplication.

regards, tom lane