[Monetdb-developers] MXQ: MapiClient -lxquery output mode

Martin Kersten Martin.Kersten at cwi.nl
Thu Aug 17 22:38:22 CEST 2006

Hi Fabian,

I support the request for consistency and verboseness.
The original reasons for the MAPI text exchange protocol
(which dates back to the early 80's ;-))
was to simplify analysis of responses received from a server
by any client tool. Including simple shell script filters.
That's the reason for #, [, and !ERROR, !FATAL, !WARNING
in all output lines.
To be consistent with this policy, xquery could have introduced
its own leader character(s) to analyse the result, and
which could be stripped (restyled) by any front-end easily.

Aside from the verbose information on the origin of an error
and context, I would not be pleased if an error message
appeared hidden at an arbitrary place in a 100MB XML output.
But, of course, the XQuery standardization committee may
have more wisdom or vision on how to deal with error responses.

regards, Martin
ps. Thanks in advance if you take the burden to approve them
by hand. Watch out for RSI !

Fabian Groffen wrote:
> Hi all,
> As you may have noticed by now, MapiClient has been changed to act
> differently for xquery than it used to before.  I reverted the original
> behaviour for greener XQuery pastures, but the change itself is not
> done without any doubts from my side.
> MapiClient used to report errors in xquery mode in a terse way; it just
> reported the error message, without the leading bang (!).  For all other
> languages, MapiClient is more verbose: it prints the query being
> executed, action taken and the error with leading bangs prefixed with
> "ERROR: ".  Niels made xquery behave as all the other languages for
> errors for the sake of consistency; a thing I wholeheartedly agree with.
> However, some considerable amount of tests in the XQuery testweb has to
> be reapproved if this change is put through, which was not done at the
> same time of Niels' change.
> So far for the history.  Since I'd like to have consistency (agreeing
> with Niels), I'd like to see MapiClient reporting errors for xquery in
> the verbose way like it does for all other languages.  However, why was
> this special mode enabled for xquery in the first place?
> My best guess is that because XQuery is non-interactive (through
> MapiClient) it makes no sense to print the query upon error, because the
> query already is in a file, and it can only contain one, unlike SQL,
> where it is nice to know *which* statement was being executed.
> Or did somebody just not like MapiClient's error output?
> I for one like the more terse error output in a way, and would be in
> favour of adding a flag to enable this error reporting.
> Here, I'd like to open up the discussion for who thinks that is
> necessary.  I go for removing the special error output for xquery and
> approving all tests in XQuery testweb that are affected by that change.
> With no (negative) response to this message, I will assume this change
> is ok with the XQuery people and "implement" this change somewhere next
> week.
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