From: Tom Lane <tgl@sss.pgh.pa.us>
To: Bruce Momjian <bruce@momjian.us>
cc: turon.david@seznam.cz, pgsql-bugs@lists.postgresql.org,
        Peter Eisentraut <peter.eisentraut@enterprisedb.com>
Subject: Re: BUG #16743: psql doesn't show whole expression in stored column
In-reply-to: <20201124155106.GE29448@momjian.us>
References: <16743-7b1bacc4af76e7ad@postgresql.org>
 <286182.1606232817@sss.pgh.pa.us> <20201124155106.GE29448@momjian.us>
Comments: In-reply-to Bruce Momjian <bruce@momjian.us>
	message dated "Tue, 24 Nov 2020 10:51:06 -0500"
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Date: Tue, 24 Nov 2020 11:25:51 -0500
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Bruce Momjian <bruce@momjian.us> writes:
> On Tue, Nov 24, 2020 at 10:46:57AM -0500, Tom Lane wrote:
>> Maybe we should decide that completeness is more important than keeping
>> the line to some arbitrary width.  But it's operating as designed.

> I think I am fine with the current behavior.

It's less great in the context of a GENERATED column.  As things stand,
the psql-side code wraps the truncated result into some more syntax:

            else if (generated[0] =3D=3D ATTRIBUTE_GENERATED_STORED)
                default_str =3D psprintf("generated always as (%s) stored"=
, PQgetvalue(res, i, attrdef_col));
            else
                /* (note: above we cut off the 'default' string at 128) */
                default_str =3D PQgetvalue(res, i, attrdef_col);

which seems distinctly more confusing than just truncating the result.
So maybe there's justification here for revisiting that ancient decision.

One could also imagine not appending ") stored" if the attrdef value
appears to have been truncated --- although encoding-conversion effects
would make it hard to tell that for sure.  Perhaps we'd be better off
to move the truncation logic to the psql side?

Another thing here, which is undeniably a bug, is that that psprintf
result is promptly leaked.

			regards, tom lane