Re: refactor the CopyOneRowTo

On Fri, Jul 5, 2024 at 12:26 AM jian he <jian(dot)universality(at)gmail(dot)com> wrote:
>
> original CopyOneRowTo:
> https://git.postgresql.org/cgit/postgresql.git/tree/src/backend/commands/copyto.c#n922
> I change it to:
> -----------------------
> if (!cstate->opts.binary)
> {
> foreach_int(attnum, cstate->attnumlist)
> {
> Datum value = slot->tts_values[attnum - 1];
> bool isnull = slot->tts_isnull[attnum - 1];
>
> if (need_delim)
> CopySendChar(cstate, cstate->opts.delim[0]);
> need_delim = true;
>
> if (isnull)
> CopySendString(cstate, cstate->opts.null_print_client);
> else
> {
> string = OutputFunctionCall(&out_functions[attnum - 1],
> value);
> if (cstate->opts.csv_mode)
> CopyAttributeOutCSV(cstate, string,
> cstate->opts.force_quote_flags[attnum - 1]);
> else
> CopyAttributeOutText(cstate, string);
> }
> }
> }
> else
> {
> foreach_int(attnum, cstate->attnumlist)
> {
> Datum value = slot->tts_values[attnum - 1];
> bool isnull = slot->tts_isnull[attnum - 1];
> bytea *outputbytes;
>
> if (isnull)
> CopySendInt32(cstate, -1);
> else
> {
> outputbytes = SendFunctionCall(&out_functions[attnum - 1],
> value);
> CopySendInt32(cstate, VARSIZE(outputbytes) - VARHDRSZ);
> CopySendData(cstate, VARDATA(outputbytes),
> VARSIZE(outputbytes) - VARHDRSZ);
> }
> }
> }
>
>
> overall less "if else" logic,
> also copy format don't change during copy, we don't need to check
> binary or nor for each datum value.

I believe what you proposed is included in the patch 0002
attached in [1], but you use foreach_int, which I think is
an improvement.

[1] https://www.postgresql.org/message-id/20240724.173059.909782980111496972.kou%40clear-code.com

--
Regards
Junwang Zhao