Re: COPY TO (FREEZE)?

On Sat, Oct 28, 2023 at 09:39:53PM -0400, Tom Lane wrote:
> Bruce Momjian <bruce@momjian.us> writes:
> > My apologies, wrong patch attached, right one attached now.
> 
> I think this one is fine as-is:
> 
>      /* Only single-byte delimiter strings are supported. */
>      if (strlen(opts_out->delim) != 1)
>          ereport(ERROR,
> -                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
> +                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
>                   errmsg("COPY delimiter must be a single one-byte character")));
>  
> While we have good implementation reasons for this restriction,
> there's nothing illogical about wanting the delimiter to be more
> general.  It's particularly silly, from an end-user's standpoint,
> that for example 'é' is an allowed delimiter in LATIN1 encoding
> but not when the server is using UTF8.  So I don't see how the
> distinction you presented justifies this change.

Agreed, my mistake.
 
> +    if (opts_out->freeze && !is_from)
> +        ereport(ERROR,
> +                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
> +                 errmsg("COPY freeze only available using COPY FROM")));
> 
> Not thrilled by the wording here.  I don't like the fact that the
> keyword FREEZE isn't capitalized, and I think you omitted too many
> words for intelligibility to be preserved.  Notably, all the adjacent
> examples use "must" or "must not", and this decides that that can be
> omitted.

I think it is modeled after:

    errmsg("COPY force null only available using COPY FROM")));

> I realize that you probably modeled the non-capitalization on nearby
> messages like "COPY delimiter", but there's a difference IMO:
> "delimiter" can be read as an English noun, but it's hard to read
> "freeze" as a noun.
> 
> How about, say,
> 
>     errmsg("COPY FREEZE must not be used in COPY TO")));
> 
> or perhaps that's redundant and we could write
> 
>     errmsg("FREEZE option must not be used in COPY TO")));

I now have:

    errmsg("COPY FREEZE mode only available using COPY FROM")));

Updated patch attached.

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

  Only you can decide what is important to you.