Query Performance Degrade With Sorting In Subquery

[Chirag Ratra]

Hi,

Facing a big performance degradation  while using sort query in subquery
If I run query without sorting the response of my query is around 200 ms
but when I use the order by query,  performance comes to be around 4-5
seconds.

Here is my query :

PREFIX text: <http://jena.apache.org/text#>
PREFIX skos: <http://www.w3.org/2004/02/skos/core#>
PREFIX skosxl: <http://www.w3.org/2008/05/skos-xl#>
PREFIX relations: <https://cxdata.bold.com/ontologies/myDomain#>

SELECT ?concept ?titleSkosxl ?title ?languageCode (GROUP_CONCAT(DISTINCT
?relatedTitle; separator=", ") AS ?relatedTitles) (GROUP_CONCAT(DISTINCT
?alternate; separator=", ") AS ?alternates)
WHERE
{
  (?titleSkosxl ?score) text:query ('cashier').

?concept skosxl:prefLabel ?titleSkosxl.
  ?titleSkosxl skosxl:literalForm ?title.
  ?titleSkosxl relations:usedInLocale ?controlledList.
  ?controlledList relations:languageMarketCode ?languageCode
FILTER(?languageCode = 'en-US').


#  get alternate title
OPTIONAL
  {
        Select ?alternate  {
        ?concept skosxl:altLabel ?alternateSkosxl.
        ?alternateSkosxl skosxl:literalForm ?alternate;
  relations:hasUserCount ?alternateUserCount.
        }
ORDER BY DESC (?alternateUserCount) LIMIT 10
}

#  get related titles
  OPTIONAL
  {
      Select ?relatedTitle
      {
            ?titleSkosxl relations:isRelatedTo ?relatedSkosxl.
            ?relatedSkosxl skosxl:literalForm ?relatedTitle;
            relations:hasUserCount ?relatedUserCount.
      }
ORDER BY DESC (?relatedUserCount) LIMIT 10
   }
}
GROUP BY ?concept ?titleSkosxl ?title ?languageCode ?alternateJobTitle
?notation
ORDER BY DESC(?jobtitleWeight) DESC(?score)
LIMIT 10

The sorting queries given causes huge performance degradation :
ORDER BY DESC (?alternateUserCount) AND ORDER BY DESC (?relatedUserCount)

How can this be improved, this sorting will be used in each and every query
in my application.

-- 








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