[xquery-talk] Re: The State of Native XML databases

Ilya Sterin sterini at gmail.com
Mon Aug 20 14:28:45 PDT 2007


> I agree there are use cases that don't split into many XML documents
> well, but one document is still a collection.

Yes, but that collection can be defined by a schema language.  I'm not
necessarily against collections, I'm against transactional isolation
on the collection level.  That just bugs me, that means that my
document has to be shred into pieces if I want ACID and scalability at
the same time.

> Some type of schema can of course be useful in different scenarios, but
> Ilya's suggestion that "ddl=xml schema" does not suit everyone.

Yeah, if you are not looking at XML as a persistence.  You wouldn't
work with a relational store without a DDL, be it SQL or any other way
to define your schema.  Yes, there are many use cases for using xml in
its semi-structured loose format, that's just not for persisting
application state per say, rather message snippets, configs, etc...
Again, you could also argue that MySQL was useful before InnoDB was

> Agreed - although it seems more pertinent to talk about the use cases
> solved rather than the implementation details. Node level locking is,
> after all, merely a means by which an engineer hopes to achieve better
> concurrency - which is the real use case.
> I have no reason to suggest that TigerLogic does not fulfill Ilya's use
> cases, nor that it shouldn't be considered along side other XML
> databases. I just object to his implications of a religious and blanket
> dismissal of other XML databases and other use cases.

I'm not dismissing any other XML databases, just like you can't
dismiss a file system with an embedded xquery engine as your database.
 I'm religious in the fact that I think before you can say that this
database can be used to persist application data with complex schemas,
you should really think about transactions, which most xml db vendors
do in a very rudimentary way.  Seems like eXist has a summer of code
challenge now to implement more granular transactions, though I'm not
sure where they are at this point.  Either way, I'd like to see some
use cases where other XML databases are being used to persist
transactional data in a highly concurrent environment and how well
they scale.


> John

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