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

[Jeff Dexter]

OK, I don't want to sounds like I'm always disagreeing, but I disagree :)

I'd be curious to hear from users on this, but in my experience the notion
of a "page" is too nebulous for most users. Granted, it's sub-document, but
what subset of the document does it represent. If there's a clear mapping
between a page and the nodes in the document, great, but I'd still argue
that node level granularity is about the most granular you can get, and
users understand what a node is (well, except for text node which still
seems to cause the odd confused look).

On a side note, while node level locks may be the most granular, some update
operations may require locking multiple nodes. For instance, if you replace
an element that has attributes and children, a lock of the element may imply
a lock of its attributes and descendants as well.

Jeff.

-----Original Message-----
From: talk-bounces at x-query.com [mailto:talk-bounces at x-query.com] On Behalf
Of John Snelson
Sent: Tuesday, August 21, 2007 7:23 AM
To: Ronald Bourret
Cc: talk at xquery.com
Subject: Re: [xquery-talk] Re: The State of Native XML databases

Ronald Bourret wrote:
> Does anybody know how many native XML databases actually support 
> node-level locking? My impression is that most support document-level 
> locking.

As I mentioned before, Berkeley DB XML has sub-document level locking in the
form of page level locking with user-configurable page size.

Talking about "node-level locking" is a bit of a red-herring - what you
should be interested in is sub-document granularity locking, which in itself
is only a means to achieve high concurrency in writes.

John
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