Re: machine-readable explain output v4 - Mailing list pgsql-hackers

Csaba Nagy wrote:
> On Wed, 2009-08-12 at 15:42 +0200, Andrew Dunstan wrote:
>   
>> Have you actually looked at a logfile with this in it? A simple 
>> stylesheet won't do at all. What you get is not an XML document but a 
>> text document with little bits of XML embedded in it. So you would need 
>> a program to parse that file and either turn it into a single legal XML 
>> document or pass each piece of XML individually to your XSLT processor. 
>> Bleah.
>>     
>
> I'm pretty sure you will never find a human readable format which is
> easily extracted from the logs by a program. But if you format the XML
> in a (very human unreadable) one-line-without-breaks format then it will
> be a lot easier extracted by a program and formatted at your will.
>   


That will just make things worse. And it will break if the XML includes 
any expression that contains a line break.

>   
>> And all this because you pose a false dichotomy between correctness and 
>> completeness on one hand and human readability on the other. I don't 
>> accept that at all. I think we can and should improve human readability 
>> without sacrificing anything on the correctness and completeness front. 
>> In fact, that also needs improving, and we can do them both at the same 
>> time.
>>     
>
> I really really doubt that. I would go here on the UNIX approach of
> piping the things through the right tools, each one doing a simple and
> good job for it's single and well defined purpose. So let the explain
> spit out a line of XML without much thought about formatting but
> focusing on completeness, making it easy for tools to get that line, and
> then let the tools do the formatting depending on what you want to do
> with the information. Each part will be simpler than you would put in a
> directly human readable XML (if that's possible at all) approach, which
> will anyway not cover all the uses and tastes.
>   


I think we're going to have to agree to disagree on this. I think you're 
going in precisely the wrong direction.

I repeat, I want to be able to have a log file that is both machine 
processable and not utterly unreadable by a human. And I do not accept 
at all that this is impossible. Nor do I accept I should need some extra 
processing tool to read the machine processable output without suffering 
brain damage. If we were to adopt your approach I bet you would find 
that nobody in their right mind would use the machine readable formats.

I sure wouldn't.


cheers

andrew