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Re: XQuery Update - unordered collection of update primitives

From: TAN Kuan Hui <kuanhui@xemantics.com>
Date: Thu, 2 Feb 2006 09:43:04 +0800
Message-ID: <001a01c6279a$2578abf0$6502a8c0@pinecone>
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
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
>
>
> -- 
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>
>
>
Received on Thursday, 2 February 2006 01:43:57 UTC

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