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

John Snelson john.snelson at oracle.com
Wed Aug 22 00:13:57 PDT 2007

It's not surprising that we disagree given our respective products. 
However it seems to me that you are mixing the marketing message with 
the technical details.

The user wants highly concurrent updates - the fact that node level 
locking can give them that does not mean that they are equivalent. Most 
users wouldn't want or need to know anything about locking.


Jeff Dexter wrote:
> 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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