Re: generic copy options

Tom Lane wrote:
> No, I don't think so.  Suppose I write
>
>     COPY ... (xml_header on)
>
> If HEADER isn't actually an option supported by XML format, what I will
> get here is an "unknown option" error, which conveys just about nothing
> --- is it really an unsupported combination, or did I just misspell the
> option name?
Well, I don't see why you would write that if the option is not documented.
Usually as a user, when I need to use a command, I look at the doc/man 
page and use the options that are indicated, I don't try to invent new 
options. That should prevent the kind of scenario you describe here:
>   If we go with the other way then I would expect
>
>     COPY ... (xml, header on)
>
> to draw a specific "HEADER is not supported in XML format" error.
> Of course, that will require some extra code to make it happen.
> So you could argue that format-specific option names are easier
> from the lazy programmer's viewpoint.  But I don't believe the
> argument that they're better from the user's viewpoint.
>   
Here you will force every format to use the same set of options and if 
someone introduces a new option, you will have to modify all other 
formats to make sure they throw an error telling the user that this 
option is not supported. I don't think this is a great design and that 
it will be easy to extend.

Emmanuel

-- 
Emmanuel Cecchet
Aster Data Systems
Web: http://www.asterdata.com