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

Ronald Bourret rpbourret at rpbourret.com
Tue Aug 21 07:49:10 PDT 2007

Does anybody know how many native XML databases actually support 
node-level locking? My impression is that most support document-level 

-- Ron

Jeff Dexter wrote:

> To be fair, document level locking granularity affects more than the "one
> big document" use case, and it affects more than just throughput. XQuery
> updates can and do span multiple documents in a collection within a single
> update query and transaction, and if the best you have is document-level
> locking then you run the very real risk of colliding or deadlocking with the
> subset of documents another parallel update has chosen.
> True, node-level locking doesn't necessarily solve this problem, as updates
> can still contend for the same node subset, but it hopefully (drastically)
> mitigates the incidence of such contention. As you point out, less time
> waiting on locks means more throughput, but it can also mean the application
> spending less cycles figuring out what to do when it can't acquire those
> locks.

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