RE: libpq debug log

Hi, 

> The basic idea being:
> 
> - Each line is a whole message.
> - The line begins with <<< for a message received and >>> for a message sent.
> - Strings in single quotes are those sent/received as a fixed number of bytes.
> - Strings in double quotes are those sent/received as a string.
> - 4-byte integers are printed unadorned.
> - 2-byte integers are prefixed by #.
> - I guess 1-byte integers would need some other prefix, maybe @ or ##.

I created v1 patch to improve PQtrace(); output log message in one line. 
Please find my attached patch.


Log output examples;

In current PQtrace log:

To backend> Msg Q
                   
 
To backend> "SELECT pg_catalog.set_config('search_path', '', false)"
To backend> Msg complete, length 60

I changed like this:

2019-04-04 02:39:51.488 UTC  > Query 59 "SELECT pg_catalog.set_config('search_path', '', false)" 

In current PQtrace log:

From backend> T
From backend (#4)> 35
From backend (#2)> 1
From backend> "set_config"
From backend (#4)> 0
From backend (#2)> 0
From backend (#4)> 25
From backend (#2)> 65535
From backend (#4)> -1
From backend (#2)> 0

I changed like this:

2019-04-04 02:39:51.489 UTC  < RowDescription 35 #1 "set_config" 0 #0 25 #65535 -1 #0


> I would like to add timestamp per line and when command processing function
> start/end.
> I think it is useful to know the application process start/end for diagnosis.
> So I will implement like this;
> 
> 2019-03-03 07:24:54.142 UTC   PQgetResult start
> 2019-03-03 07:24:54.143 UTC   < 'T' 35 1 "set_config" 0 #0 25 #65535 -1 #0
> 2019-03-03 07:24:54.144 UTC   PQgetResult end
I would like to add this in next patch if there are not any disagreement.

Regards,
Aya Iwata