Re: There doesn't seem to be any case where PQputCopyEnd() returns 0

On 2021/02/05 16:52, Kasahara Tatsuhito wrote:
> Hi,
> 
> The following is written in the comments of PQputCopyEnd().
> 
>   (snip)
>   * Returns 1 if successful, 0 if data could not be sent (only possible
>   * in nonblock mode), or -1 if an error occurs.
>   (snip)
> 
> The PQputCopyEnd() section of the manual (libpq.sgml) describes the following.
> 
>         The result is 1 if the termination message was sent; or in
>         nonblocking mode, this may only indicate that the termination
>         message was successfully queued.  (In nonblocking mode, to be
>         certain that the data has been sent, you should next wait for
>         write-ready and call <xref linkend="libpq-PQflush"/>, repeating until it
>         returns zero.)  Zero indicates that the function could not queue
>         the termination message because of full buffers; this will only
>         happen in nonblocking mode.  (In this case, wait for
>         write-ready and try the <xref linkend="libpq-PQputCopyEnd"/> call
>         again.)  If a hard error occurs, -1 is returned; you can use
>         <xref linkend="libpq-PQerrorMessage"/> to retrieve details.
> 
> 
> These says that 0 may be returned if a non-blocking mode is used, but
> there doesn't seem to be any case where 0 is returned in the code of
> PQputCopyEnd().

I found the past discussion [1] about this issue.

[1]
https://www.postgresql.org/message-id/CA+Tgmobjj+0modbnmjy7ezeBFOBo9d2mAVcSPkzLx4LtZmc==g@mail.gmail.com

Regards,

-- 
Fujii Masao
Advanced Computing Technology Center
Research and Development Headquarters
NTT DATA CORPORATION