size of XQuery developer community

[Ronald Bourret]

Martin Probst wrote:
> While there is certainly a potential performance benefit in processing
> fixed length records (relational) compared to arbitrary trees (XML),
> exploiting this benefit leads to the schema evolution problems that
> plague so many SQL users. I'm not sure whether the benefit is actually
> worth the hassle of near-impossible to change schemata, there are
> certainly many ares (e.g. document management) where the tradeoff
> favors XML.

Agreed. When I surveyed XML database vendors a few years ago about the 
kinds of applications their customers were building, schema evolution 
was one of the common use cases (the others being managing/querying 
documents, certain types of data integration, and semi-structured data).

What was interesting about all of these use cases was that they were 
places where people had tried to use relational databases and simply 
couldn't get them to work. Either the data simply didn't fit the 
relational model or the resulting code was too slow/unmanageable.

> For most document centric applications XML databases would be a huge
> win. What's holding them back is IMHO lack of awareness

Agreed again.

On the positive side, people now know that XML databases exist, 
understand what they are, and don't dismiss them out of hand. Five years 
ago, a significant portion of the XML cognescenti (much less the general 
public) didn't even know what an XML database was. Now, I see them 
mentioned in mainstream computer magazines.

On the other hand, I had hoped that the inclusion of an XML data type 
and XQuery in relational databases would cause an explosion in the use 
of XQuery and XML databases in general. If this has happened, it was a 
very quiet explosion.

One simple measure is the extent to which the major database vendors 
push XML as a selling point -- that is, how much their users care about 
XML. DB2 does push it fairly hard, but Oracle only gives it a mention 
and it barely shows up in SQL Server marketing. It's also significant 
that none of these databases has significantly upgraded their XML 
support in the past few years.


-- Ron