MarkLogic执行SPARQL查询返回错误结果的技术问询

问题背景 #

在MarkLogic查询控制台执行SPARQL查询时，涉及反向路径（^）与exists子句结合的场景下，出现不符合预期的错误结果，且结果存在高度不一致性。官方已确认这是MarkLogic的产品bug，影响版本包括MarkLogic 10及11.0.2。

初始测试场景 #

测试数据 #

场景：存在Folder对象包含File子对象，所有对象带有标签，每个Folder/File通过WritePermission关联拥有修改权限的Group。

prefix ex: <http://example.com/ns#>
prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#>

insert data {
  ex:ID0 rdfs:label "Root" .
  ex:ID0 rdf:type ex:Folder .
  ex:ID0 ex:WritePermission ex:GROUP1 . 
  ex:ID1 rdfs:label "File1" .
  ex:ID1 rdf:type ex:File .
  ex:ID1 ex:Parent ex:ID0 .
  ex:ID1 ex:WritePermission ex:GROUP2 . 
  ex:ID2 rdfs:label "File2" .
  ex:ID2 rdf:type ex:File .
  ex:ID2 ex:Parent ex:ID0 .
  ex:ID2 ex:WritePermission ex:GROUP2 . 
  ex:ID3 rdfs:label "File3" .
  ex:ID3 rdf:type ex:File .
  ex:ID3 ex:Parent ex:ID0 .
  ex:ID3 ex:WritePermission ex:GROUP2 .
  ex:GROUP1 rdf:type ex:Group .
  ex:GROUP1 rdfs:label "Admin" .
  ex:GROUP1 ex:Member ex:USER1 .
  ex:GROUP2 rdf:type ex:Group .
  ex:GROUP2 rdfs:label "Users" .
  ex:GROUP2 ex:Member ex:USER2 .
  ex:USER1 rdf:type ex:User .
  ex:USER1 rdfs:label "User1" .
  ex:USER2 rdf:type ex:User .
  ex:USER2 rdfs:label "User2" .
}

查询语句 #

该查询用于判断指定名称是否存在于父对象"Root"下，同时检查用户所属Group是否拥有父对象的写入权限：

prefix ex: <http://example.com/ns#>
prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#>

select ?nameConflict ?hasWritePermissionToParent
where { 
  bind(ex:ID0 as ?parent)
  bind("ZZZ" as ?nameToCheck)
  bind(ex:USER2 as ?userId)

  bind(exists { ?parent ^ex:Parent/rdfs:label ?nameToCheck } as ?nameConflict)
  bind(exists { ?userId ^ex:Member+/^ex:WritePermission ?parent } as ?hasWritePermissionToParent)
}

结果对比 #

• 预期结果：?nameConflict和?hasWritePermissionToParent均返回false
• 实际结果：两者均返回true

扩展测试场景（更新内容） #

新增ReadPermission三元组后，尝试select *的临时方案无效，结果仍存在高度不一致性。

测试数据 #

prefix ex: <http://example.com/ns#>
prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#>

insert data {
  ex:ID0 rdfs:label "Root" .
  ex:ID0 rdf:type ex:Folder .
  ex:ID0 ex:ReadPermission ex:GROUP1 .
  ex:ID0 ex:WritePermission ex:GROUP1 . 
  ex:ID1 rdfs:label "File1" .
  ex:ID1 rdf:type ex:File .
  ex:ID1 ex:Parent ex:ID0 .
  ex:ID1 ex:ReadPermission ex:GROUP2 .
  ex:ID1 ex:WritePermission ex:GROUP2 . 
  ex:ID2 rdfs:label "File2" .
  ex:ID2 rdf:type ex:File .
  ex:ID2 ex:Parent ex:ID0 .
  ex:ID2 ex:ReadPermission ex:GROUP2 .
  ex:ID2 ex:WritePermission ex:GROUP2 . 
  ex:ID3 rdfs:label "File3" .
  ex:ID3 rdf:type ex:File .
  ex:ID3 ex:Parent ex:ID0 .
  ex:ID3 ex:ReadPermission ex:GROUP2 .
  ex:ID3 ex:WritePermission ex:GROUP2 .
  ex:GROUP1 rdf:type ex:Group .
  ex:GROUP1 rdfs:label "Admin" .
  ex:GROUP1 ex:Member ex:USER1 .
  ex:GROUP2 rdf:type ex:Group .
  ex:GROUP2 rdfs:label "Users" .
  ex:GROUP2 ex:Member ex:USER2 .
  ex:USER1 rdf:type ex:User .
  ex:USER1 rdfs:label "User1" .
  ex:USER2 rdf:type ex:User .
  ex:USER2 rdfs:label "User2" .
}

查询语句 #

prefix ex: <http://example.com/ns#>
prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#>

select *
where { 
  bind(ex:ID0 as ?id)

  ex:USER1 ^ex:Member+ ?groups .

  bind(exists{?id ex:ReadPermission ?groups} as ?hasReadPermission)
  bind(exists{?id ex:Source/ex:ReadPermission ?groups ; ex:Destination/ex:ReadPermission ?groups .} as ?linkHasReadPermission)
}

预期结果 #

实际情况 #

部分组合初始看似符合预期，但遍历所有组合时总会出现错误结果，输出高度不一致。

临时解决方案建议 #

在官方修复bug前，可通过拆分路径表达式、避免复合反向路径直接嵌套在exists子句中的方式规避问题：

以初始查询为例，修改后的查询如下：

prefix ex: <http://example.com/ns#>
prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#>

select ?nameConflict ?hasWritePermissionToParent
where { 
  bind(ex:ID0 as ?parent)
  bind("ZZZ" as ?nameToCheck)
  bind(ex:USER2 as ?userId)

  # 拆分名称冲突检查逻辑
  bind(exists {
    ?file ex:Parent ?parent ;
          rdfs:label ?nameToCheck .
  } as ?nameConflict)

  # 先提取用户所属Group，再单独检查权限关联
  optional {
    ?userId ^ex:Member ?group .
    ?parent ex:WritePermission ?group .
  }
  bind(bound(?group) as ?hasWritePermissionToParent)
}

这种拆分方式可避开MarkLogic对复合反向路径的解析bug，得到符合预期的结果。

内容的提问来源于stack exchange，提问作者Vishal