Re: BUG #16743: psql doesn't show whole expression in stored column

On Tue, Nov 24, 2020 at 10:46:57AM -0500, Tom Lane wrote:
> PG Bug reporting form <noreply@postgresql.org> writes:
> > when generated column expression length is larger then some value - the rest
> > of expression is cut in \d[+] output:
> 
> Yeah, this is an intentional and very ancient behavior:
> 
>         appendPQExpBufferStr(&buf,
>                              ",\n  (SELECT substring(pg_catalog.pg_get_expr(d.adbin, d.adrelid, true) for 128)"
>                              "\n   FROM pg_catalog.pg_attrdef d"
> 
> 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.

If you run psql with -E, you can see the queries it generates:

    SELECT a.attname,
      pg_catalog.format_type(a.atttypid, a.atttypmod),
-->      (SELECT substring(pg_catalog.pg_get_expr(d.adbin, d.adrelid, true) for 128)
              ---------                                                  -------
       FROM pg_catalog.pg_attrdef d
       WHERE d.adrelid = a.attrelid AND d.adnum = a.attnum AND a.atthasdef),
      a.attnotnull,
      (SELECT c.collname FROM pg_catalog.pg_collation c, pg_catalog.pg_type t
       WHERE c.oid = a.attcollation AND t.oid = a.atttypid AND a.attcollation <> t.typcollation) AS attcollation,
      a.attidentity,
      a.attgenerated
    FROM pg_catalog.pg_attribute a
    WHERE a.attrelid = '16385' AND a.attnum > 0 AND NOT a.attisdropped
    ORDER BY a.attnum;

-- 
  Bruce Momjian  <bruce@momjian.us>        https://momjian.us
  EnterpriseDB                             https://enterprisedb.com

  The usefulness of a cup is in its emptiness, Bruce Lee