sparql - 这个 SPARQL 查询可以简化吗？

Question

目前我正在为 LDBC Benchmark 实现 SPARQL 查询.我想出了一个解决方案 bi-read-3询问。数据模式的相关部分如下:


查询说明:

Find the Tags that were used in Messages during the given month of the given year and the Tags that were used during the next month. For both months, compute the count of Messages that used each of the Tags.

我的解决方案( with some syntax highlight ):

PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
PREFIX sn: <http://www.ldbc.eu/ldbc_socialnet/1.0/data/>
PREFIX snvoc: <http://www.ldbc.eu/ldbc_socialnet/1.0/vocabulary/>
PREFIX sntag: <http://www.ldbc.eu/ldbc_socialnet/1.0/tag/>
PREFIX foaf: <http://xmlns.com/foaf/0.1/>
PREFIX dbpedia: <http://dbpedia.org/resource/>
PREFIX dbpedia-owl: <http://dbpedia.org/ontology/>


SELECT ?tagName (SUM(?countMonth1) as ?countMonth1) (SUM(?countMonth2) as ?countMonth2) (ABS( SUM(?countMonth1) - SUM(?countMonth2) ) as ?diff)
WHERE
{ 
  {
    SELECT ?tagName (COUNT(?message) as ?innerCountMonth1)
    WHERE {

      BIND ( 2010 as ?year1 ) .
      BIND ( 9 as ?month1 ) .

      {
        ?message rdf:type snvoc:Comment 
      } UNION {
        ?message rdf:type snvoc:Post 
      } .
      ?message snvoc:creationDate ?creationDate .
      FILTER ((year(?creationDate) = ?year1 && month(?creationDate) = ?month1) )

      ?message snvoc:hasTag ?tag .
      ?tag foaf:name ?tagName .

    }
    GROUP BY ?tagName
  } UNION {
    SELECT ?tagName (COUNT(?message) as ?innerCountMonth2)
    WHERE {

      BIND ( 2010 as ?year1 ) .
      BIND ( 9 as ?month1 ) .
      BIND ( ?year1 + FLOOR(?month1 / 12.0) as ?year2 ) .
      BIND ( IF (?month1 = 12, 1, ?month1 + 1) as ?month2 ) .
      {
        ?message rdf:type snvoc:Comment 
      } UNION {
        ?message rdf:type snvoc:Post 
      } .
      ?message snvoc:creationDate ?creationDate .
      FILTER (year(?creationDate) = ?year2 && month(?creationDate) = ?month2 ) 

      ?message snvoc:hasTag ?tag .
      ?tag foaf:name ?tagName .

    }
    GROUP BY  ?tagName
  }

  BIND ( COALESCE(?innerCountMonth1, 0) as ?countMonth1 )
  BIND ( COALESCE(?innerCountMonth2, 0) as ?countMonth2 )
}
GROUP BY ?tagName
ORDER BY DESC(?diff) ?tagName

我觉得有一个更简单的解决方案，但我想不通。

我的问题是:这个查询可以以更简单/更有效的方式实现吗？例如:没有嵌套查询或只是一种更快的方式。

我真的是 SPARQL 的新手，所以我会感谢每一个有用的评论或改进。

Answer 1

PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
PREFIX snvoc: <http://www.ldbc.eu/ldbc_socialnet/1.0/vocabulary/>
PREFIX foaf: <http://xmlns.com/foaf/0.1/>

SELECT
?tagName
(SUM(xsd:integer(?isFirst)) AS ?countMonth1)
(SUM(xsd:integer(?isSecond)) AS ?countMonth2)
(ABS(?countMonth1 - ?countMonth2) AS ?diff) 
WHERE
  {
  VALUES (?year1 ?month1) {(2010 9)}
  VALUES (?type) {(snvoc:Comment) (snvoc:Post)}
  ?message a ?type; snvoc:hasTag/foaf:name ?tagName; snvoc:creationDate ?creationDate .
  BIND (year(?creationDate) AS ?year) .
  BIND (month(?creationDate) AS ?month) .
  BIND (IF (?month1 = 12, ?year1 + 1, ?year1     ) AS ?year2) .
  BIND (IF (?month1 = 12,          1, ?month1 + 1) AS ?month2) .
  BIND (((?month1 = ?month) && (?year1 = ?year)) AS ?isFirst) .
  BIND (((?month2 = ?month) && (?year2 = ?year)) AS ?isSecond) .
  FILTER (?isFirst || ?isSecond)
  }
  GROUP BY ?tagName HAVING (bound(?tagName))

更新

看评论。