- From: TAN Kuan Hui <kuanhui@xemantics.com>
- Date: Thu, 2 Feb 2006 09:43:04 +0800
- To: "Jonathan Robie" <jonathan.robie@datadirect.com>, "Michael Rys" <mrys@microsoft.com>
- Cc: <www-ql@w3.org>
I presume the commutability constrains you are refering to is required by section 3.5 Compatibility of Update Primitives. Is this a really necessary constrain ? Is parallel update <<on the same node>> a must requirement ? While I could appreciate the value of unordered execution for query processing, I am not too sure if the same is warranted for updating. Furthermore, whether you have an ordered or unordered collection of update primitives, it actually has no impact on XQuery update semantics since snapshot imposes a post-query update. Right ? This statement remains true even if expression level snapshots are considered, correct ? Unless it is really justified, I would suggest to the WG to consider removing the "unorder-ness" constrain on update primitives; it can potentially remove a lot of complicated rules from the specs. ----- Original Message ----- From: "Jonathan Robie" <jonathan.robie@datadirect.com> To: "Michael Rys" <mrys@microsoft.com> Cc: "TAN Kuan Hui" <kuanhui@xemantics.com>; <www-ql@w3.org> Sent: Monday, January 30, 2006 11:03 PM Subject: Re: XQuery Update - unordered collection of update primitives > Looking at the spec, I see that we didn't really say that. We should put > a paragraph in the compatibility appendix to explain what Michael said > below. > > Jonathan > > Michael Rys wrote: > > >The updating integrity is guaranteed by the commutability constraints > >(only operations considered to be commutable are allowed). The reason > >you want an unordered collection is that you can perform your updates > >efficiently and potentially in parallel. > > > >Best regards > >Michael > > > > > > > >>-----Original Message----- > >>From: www-ql-request@w3.org [mailto:www-ql-request@w3.org] On > >>Behalf Of TAN Kuan Hui > >>Sent: Monday, January 30, 2006 5:07 AM > >>To: Jonathan Robie; www-ql@w3.org > >>Subject: XQuery Update - unordered collection of update primitives > >> > >> > >>Section 2.1, Extensions to the Processing Model, carries the following > >>definition. > >> > >>[Definition: A pending update list is an unordered collection > >>of update primitives, which represent node state changes that have not > >>yet been applied.] > >> > >>What is the significance of an <<unordered>> collection of > >>update primitives ? > >>How is updating integrity preserved with an unordered > >>collection of update > >>instructions ? I could not find an explicit description on > >>the above and > >>would appreciate clarifications. > >> > >>Thank you. > >> > >>Kuan Hui > >> > >> > >> > >> > >> > >> > >> > >> > > > -- > Read my Blog: http://blogs.datadirect.com/jonathan_robie/ > Learn XQuery: http://media.datadirect.com/download/docs/ddxquery/tutorial_query.html > Learn XQJ (the JDBC for XQuery): http://www.datadirect.com/developer/xquery/topics/xqj_tutorial/ > Get DataDirect XQuery: http://www.datadirect.com/products/xquery/ > > >
Received on Thursday, 2 February 2006 01:43:57 UTC