[Ex-plain] Existing Explain-- Servers

Alan Kent ajk at mds.rmit.edu.au
Thu Apr 4 12:50:36 CEST 2002

On Thu, Mar 28, 2002 at 11:36:03AM +0000, Mike Taylor wrote:
> I'm pretty sure someone on this list said they'd already put up an
> embryonic Explain-- server.  In fact, aren't there two?  I think Alan
> and Rob each have one.  Server details, please!

Mine is out of date. With the rapid change, I did not have the energy
to keep it up to date until things settled. I have just done this.

One comment on the v1.5 DTD as I do it.
I dislike 'authentication' being either #PCDATA or user/group/password.
This is generally bad DTD design. Worse, its an invalid DTD as the DTD
is ambiguous. Is <authentication></authentication> zero length PCDATA
or omitted user/group/password? SGML solved the problem by saying the
DTD is illegal (but tools are not required to spot the error).
I would suggest adding an <open> element or similar to wrap the PCDATA.

Actually, stronger opinion now. I have the 1.6 XML DTD and my parser
reports authentication as an error for the above reason.

Also, is there a standard public/system identifier for the DTD?

Back to my database details. I found a bug looking at this - I am
not reporting the XML record syntax. Also, I got the record count
wrong. But its a bit tricky to get right - while building the
database its empty. I only know the count when I am finished.
So I almost need to populate the database twice to get it right!
I guess I could just leave it out.

<?xml version="1.0"?> 
<!DOCTYPE explain SYSTEM "exp.dtd"> 
<explain authoritative="true"> 
<database numRecs="0">Zeerex</database> 
<description>Zeerex demo db</description> 
<index id="DatabaseName" search="true" scan="true" sort="true"> 
<title>Database Name</title> 
<map primary="true"> 
<attr type="1">1</attr> 
<index id="ExplainCategory" search="true" scan="true" sort="true"> 
<title>Explain category</title> 
<map primary="true"> 
<attr type="1">2</attr> 
<recordSyntax name="1.2.840.10003.5.101"> 
<elementSet name="F"><title>Full record details</title></elementSet> 
<elementSet name="B"><title>Brief record details</title></elementSet> 
<recordSyntax name="1.2.840.10003.5.105"> 
<elementSet name="F"><title>Full record details</title></elementSet> 
<elementSet name="B"><title>Brief record details</title></elementSet> 


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