[XQZone General] XQuery "grepping" idiom

[McBeath, Darin W. (ELS)]

Hi David.

Here is one possibility that you might try.

If the birthdays structure is stored as an XML document inside of CIS, you
could potentially use the xdmp:estimate function to boost performance ...
but, you could not use an attribute (date) since you will get an
'xdmp:unsearchable' error. 

So, if your XML was stored in CIS and it looked something like the
following:

  <birthdays>
   <born-date>1967-05-11</born-date>
   <born-date>1959-03-01</born-date>...
  </birthdays>

xdmp:estimate(cts:search(//born-date, cts:word-query("1967"))) would return
a non-zero value if 1967 occurred somewhere in one of the born-date fields.
I'm assuming that '-' was a word delimeter when the content was loaded.  

Hope this is helpful.

Darin.

-----Original Message-----
From: general-bounces at xqzone.marklogic.com
To: General XQZone Discussion
Sent: 10/7/2004 10:59 PM
Subject: [XQZone General] XQuery "grepping" idiom

Given the following XQuery search need, I'd like feedback on whether my
solution is optimal.

Assume an XML data structure like so:

define variable $bdays {
  <birthdays>
   <born date="1967-05-11"/>
   <born date="1959-03-01"/>  ...
  </birthdays>
}

Let's say @date is typed as xs:string.  I want to determine whether a
particular year is contained in the birthday data. I can't test for

  $year = $bdays/born/@date

because $year must match the entire @date string. Unfortunately I
can't do

  $year = substring-before($bdays/born/@date, '-')

because the first argument to substring-before() is not a string value.
So is the following the most elegant way to do the test?

  $year = ( for $string in $bdays/born/@date
            return substring-before($string, '-'))

Because the right side evaluates to the sequence ('1967', '1959') the
expression will be true when $year = one of those values.

Is there a more compact XQuery function to use here?

-- 
David Sewell, Editorial and Technical Manager
Electronic Imprint, The University of Virginia Press
PO Box 400318, Charlottesville, VA 22904-4318 USA
Courier: 310 Old Ivy Way, Suite 302, Charlottesville VA 22903
Email: dsewell at virginia.edu   Tel: +1 434 924 9973
Web: http://www.ei.virginia.edu/
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