Glad it worked and you see proper speeds. Good use of map there as it cleanly
transforms to json. Lastly, for closure, have a glance at the options related
to frequency as you are now relying on some defaults. You should be able to
remove the order by in the floor statement, for instance.
Regards,
David
On April 12, 2014 10:37:52 AM EDT, Jakob Fix <[email protected]> wrote:
>Thanks David,
>
>I ended up separating time and date values into an attribute and
>element,
>respectively, as you suggested, with an element-range-index on the
>element's value. As I wanted to get this as JSON in the end, this is
>what
>I'm using right now (0.002 secs :-)):
>
>xdmp:to-json(
> for $date in cts:element-values(xs:QName("normalized-date"), ())
> order by $date descending
> return
> map:new((
> map:entry("date", $date),
> map:entry("count", cts:frequency($date))
> ))
>)
>
>cheers,
>Jakob.
>
>
>On Thu, Apr 10, 2014 at 11:26 PM, David Ennis <[email protected]>
>wrote:
>
>> I would personally use another element or even split the date and
>time
>> into two fields. Then you would use a range index on the date field
>of the
>> type date. Of course, you can also just store the date part as an
>> attribute of the current element and work off of an
>element-attribute-index
>> and wrk on the same solutions.
>>
>> to get your results (pseudocode)
>>
>> for $res in (for $date in
>> cts:element-values(xs:QName("yourdatefieldhere"), (set the frequency
>order
>> options here)
>> return
>>
><res><date>{$date}</date><count>{cts:frequencies($date)}</count></date>)
>> order by $res/count
>> return $res
>>
>> the result from element-values is from an index and is already a list
>of
>> distinct-values.
>>
>> Regards,
>> David
>>
>> On 10 April 2014 22:50, Jakob Fix <[email protected]> wrote:
>>
>>> Hello,
>>>
>>> How would one go about this one: I'm storing dateTime values for
>each
>>> document.
>>> I want to retrieve, efficiently, all unique dates (irrespective of
>the
>>> time part) and the number of items with that date.
>>>
>>> The naive implementation (because it takes about 1.5 seconds for not
>much
>>> data):
>>>
>>> let $c := collection("item")
>>> return
>>> for $d in distinct-values($c !
>>> xs:date(xs:dateTime(.//normalized-dateTime/text())))
>>> order by $d descending
>>> return concat($d, " - ",
>>> count($c//item[xs:date(xs:dateTime(.//normalized-dateTime)) = $d]))
>>>
>>> The profiler tells me that it's spending about 85% of the time in
>the
>>> predicate in the last line, so an index would probably speed up the
>lookups.
>>>
>>> I created an element range index for the normalized-dateTime
>element, of
>>> type dateTime. What I was hoping to be a bit less naive, turns out
>to be
>>> not feasible:
>>>
>>> for $d in distinct-values(collection("item")/item !
>>> xs:date(xs:dateTime(./normalized-dateTime/text())))
>>> order by $d descending
>>> return concat($d, " - ",
>>> count(
>>> cts:search(/item,
>>> cts:and-query((
>>> cts:collection-query("item")
>>> ,
>>> cts:element-range-query(xs:QName("normalized-dateTime"),
>"=",
>>> $d)
>>> ))
>>> )
>>> )
>>> )
>>>
>>> Now it complains that there is no element range index of type date
>for
>>> the normalized-dateTime element, which is correct...
>>>
>>> Would the recommendation be to add another element, normalized-date,
>that
>>> contained only the date part and work with that, or is there
>possibly
>>> another, even simpler solution?
>>>
>>> cheers,
>>> Jakob.
>>>
>>>
>>> _______________________________________________
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>>>
>>>
>>
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>
>
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