Yes, if you try to generate multiple document URIs during
the same request from fn:current-dateTime they will all have
the same exact time values. Time is frozen during an XQuery
request.
I mix both time and randomness to create unique URIs, like
the following. This extracted code also has some handy time
normalization functions that may be generally useful.
xquery version '1.0-ml';
declare function local:dateTime-as-utc (
$date as xs:dateTime
) as xs:dateTime
{
fn:adjust-dateTime-to-timezone ($date, xs:dayTimeDuration ("PT0H"))
};
declare function local:current-as-utc (
) as xs:dateTime
{
local:dateTime-as-utc (fn:current-dateTime())
};
declare function local:unique-doc-uri (
$root as xs:string
) as xs:string
{
fn:concat ($root, xdmp:strftime ("-%Y-%m-%d-%H-%M-%S-",
local:current-as-utc()), (xdmp:random() mod 10000), ".xml")
};
for $i in (1 to 5)
return local:unique-doc-uri ("article")
=>
article-2013-05-29-21-05-30-4904.xml
article-2013-05-29-21-05-30-5570.xml
article-2013-05-29-21-05-30-111.xml
article-2013-05-29-21-05-30-7148.xml
article-2013-05-29-21-05-30-7944.xml
Zero-filling the fractional seconds value is left as an
exercise for the reader, if it matters.
On May 29, 2013, at 5:15 PM, John Snelson <[email protected]> wrote:
> I think the number underneath is consistent, but the serialization is
> changing according to the particular time. What about creating the
> timestamp like this?
>
> xs:string(
> (current-dateTime() - xs:dateTime("0001-01-01T00:00:00.0Z"))
> div xs:dayTimeDuration("PT0.000001S")
> )
>
> John
>
> On 29/05/13 17:07, Tim wrote:
>> Hi Folks,
>>
>> I am using fn:current-dateTime() to create a unique timestamp for
>> creating archive filenames, e.g.,
>>
>> *let **$dt*:= fn:/current-dateTime/() *cast as **xs:string*
>> *return */replace/(/substring/(*$dt*, 1, 22), "[:\-T\.]", "")
>>
>> To make it truly unique I need to include part of the fraction of a
>> second, but I noticed that fn:current-dateTime() does not always return
>> the same number of digits for fractions of a second. I have seen
>> results with a range anywhere from 2 to 6 digits. Is there a minimum
>> amount of digits that will be supplied in the fractions digits?
>>
>> Thank you!
>>
>> Tim Meagher
>
> --
> John Snelson, Lead Engineer http://twitter.com/jpcs
> MarkLogic Corporation http://www.marklogic.com
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---
Ron Hitchens {mailto:[email protected]} Ronsoft Technologies
+44 7879 358 212 (voice) http://www.ronsoft.com
+1 707 924 3878 (fax) Bit Twiddling At Its Finest
"No amount of belief establishes any fact." -Unknown
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