Re: [MonetDB-users] PF: warning: query will always return an error

On Thu, Jul 10, 2008 at 09:36:03AM +0200, Jens Teubner wrote:

On Wed, Jul 9, 2008 at 9:41 AM, Sjoerd Mullender wrote:

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empty-sequence() doesn't seem to be the right return type for fn:put(). Pathfinder decides the validity of updating expressions slightly different than the W3C specs (and, in my eyes, much more consistent).

The thing is, fn:put() is *not* an updating expression. It is defined in the same document by the same committee, but not in the same section as the updating expressions.

Hi Sjoerd,

I don't agree with this conclusion. fn:put() is defined in the same section (Section 2) as all the other update expressions. fn:put() has a side effect just as all the other update expressions.

Hi Jens, Whether fn:put() is an updating function or not, is left quite open by XQUF. I think it's not wrong to define it as a non-updating function, given its current implementation in MXQ, since the side effect of fn:put() is completely different than the other update expressions and the pathfinder document management functions, namely, it only stores a document in the file system, but does not make any change to the database.

There's an additional Section 3 that describes the underlying primitives that implement the ones from Section 2. But this is unrelated to the issue.

As of http://www.w3.org/TR/2006/WD-xqupdate-20060711/, XQUF has removed the definition "... this function adds implementation-defined updates to the Pending Update List." Maybe another indication that it doesn't have to be an updating function? Jennie

Jens

-- Jens Teubner, jens.teubner@gmail.com

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