关于nGQL中UNION使用遇到的问题

问答 问题
1
  • nebula 版本：3.3.0
  • 部署方式：分布式
  • 安装方式：RPM
  • 是否为线上版本：N
  • 硬件信息
    • 磁盘: SSD
    • CPU: 32 core 内存： 64G
  • 问题的具体描述
    我在SF10的模式测试LDBC SNB的IC4用例，里面涉及到UNION ALL的使用，UNION ALL左侧和右侧的语句都是可以正常获取数据，但是使用UNION ALL后会报错，具体如下：
    语句如下：
$a=GO 1 TO 2 STEPS FROM "27493" OVER person_knows_person YIELD dst(edge) AS dst; \
GO FROM $a.dst OVER person_isLocatedIn_place WHERE properties($$).type == "city" YIELD src(edge) AS src,properties($^).firstName AS personFirstName,properties($^).lastName AS personLastName,dst(edge) AS dst | \
 GO FROM $-.dst OVER place_isPartOf_place WHERE properties($$).name != "Papua_New_Guinea" AND properties($$).name != "Switzerland" YIELD $-.src AS src,$-.personFirstName AS personFirstName,$-.personLastName AS personLastName | \
GO FROM $-.src OVER comment_hasCreator_person,post_hasCreator_person REVERSELY YIELD id($$) AS messageID,$-.src AS personID,$-.personFirstName AS personFirstName,$-.personLastName AS personLastName | \
GO FROM $-.messageID OVER comment_isLocatedIn_place,post_isLocatedIn_place WHERE properties($$).type == "country" AND properties($$).name == "Switzerland" YIELD $-.messageID AS messageID,$-.personID AS personID,$-.personFirstName AS personFirstName,$-.personLastName AS personLastName | \
GROUP BY $-.personID,$-.personFirstName,$-.personLastName YIELD $-.personID AS personID,$-.personFirstName AS personFirstName,$-.personLastName AS personLastName,count(*) AS xCount,0 AS yCount \ 
UNION ALL \
 GO FROM $a.dst OVER person_isLocatedIn_place WHERE properties($$).type == "city" YIELD src(edge) AS src,properties($^).firstName AS personFirstName,properties($^).lastName AS personLastName,dst(edge) AS dst | \ 
GO FROM $-.dst OVER place_isPartOf_place WHERE properties($$).name != "Papua_New_Guinea" AND properties($$).name != "Switzerland" YIELD $-.src AS src,$-.personFirstName AS personFirstName,$-.personLastName AS personLastName | \ 
GO FROM $-.src OVER comment_hasCreator_person,post_hasCreator_person REVERSELY YIELD id($$) AS messageID,$-.src AS personID,$-.personFirstName AS personFirstName,$-.personLastName AS personLastName | \ 
GO FROM $-.messageID OVER comment_isLocatedIn_place,post_isLocatedIn_place WHERE properties($$).type == "country" AND properties($$).name == "Papua_New_Guinea" YIELD $-.messageID AS messageID,$-.personID AS personID,$-.personFirstName AS personFirstName,$-.personLastName AS personLastName | \ 
GROUP BY $-.personID,$-.personFirstName,$-.personLastName YIELD $-.personID AS personID,$-.personFirstName AS personFirstName,$-.personLastName AS personLastName,0 AS xCount,count(*) AS yCount | \ 
GROUP BY $-.personID,$-.personFirstName,$-.personLastName AS personLastName YIELD $-.personID AS personID,$-.personFirstName AS personFirstName,$-.personLastName AS personLastName,sum($-.xCount) AS xCount,sum($-.yCount) AS yCount,(sum($-.xCount)+sum($-.yCount)) AS count | \
 ORDER BY $-.personID asc,$-.count desc | LIMIT 20

但是，该语句执行时会报的错误内容如下：

-1009:SemanticError: number of columns to UNION/INTERSECT/MINUS must be same

我已经核对过了UNION ALL左侧和右侧最后一个YIELD语句后的colums应该时数量和类型都是能一一对应的，不知道为啥还会有这个错误？希望能够得到帮助。
PS：我发现UNION ALL等语句必须和GO联用，这点能否做一个优化？比如单个的YIELD columns UNION ALL YIELD columns 也能正常使用

2

抱歉打扰了，是我个人疏忽，这个问题可以参照管道通配符和UNION ALL的优先级文档中的内容，我在UNION ALL完了之后还做了一个GROUP BY，所以正常的解决办法应该时在UNION ALL的左侧和右侧语句外边加一个括号，再去做GROUP BY，具体如下：

$a=GO 1 TO 2 STEPS FROM "27493" OVER person_knows_person YIELD dst(edge) AS dst; \
(GO FROM $a.dst OVER person_isLocatedIn_place WHERE properties($$).type == "city" YIELD src(edge) AS src,properties($^).firstName AS personFirstName,properties($^).lastName AS personLastName,dst(edge) AS dst | \
 GO FROM $-.dst OVER place_isPartOf_place WHERE properties($$).name != "Papua_New_Guinea" AND properties($$).name != "Switzerland" YIELD $-.src AS src,$-.personFirstName AS personFirstName,$-.personLastName AS personLastName | \
GO FROM $-.src OVER comment_hasCreator_person,post_hasCreator_person REVERSELY YIELD id($$) AS messageID,$-.src AS personID,$-.personFirstName AS personFirstName,$-.personLastName AS personLastName | \
GO FROM $-.messageID OVER comment_isLocatedIn_place,post_isLocatedIn_place WHERE properties($$).type == "country" AND properties($$).name == "Switzerland" YIELD $-.messageID AS messageID,$-.personID AS personID,$-.personFirstName AS personFirstName,$-.personLastName AS personLastName | \
GROUP BY $-.personID,$-.personFirstName,$-.personLastName YIELD $-.personID AS personID,$-.personFirstName AS personFirstName,$-.personLastName AS personLastName,count(*) AS xCount,0 AS yCount \ 
UNION ALL \
 GO FROM $a.dst OVER person_isLocatedIn_place WHERE properties($$).type == "city" YIELD src(edge) AS src,properties($^).firstName AS personFirstName,properties($^).lastName AS personLastName,dst(edge) AS dst | \ 
GO FROM $-.dst OVER place_isPartOf_place WHERE properties($$).name != "Papua_New_Guinea" AND properties($$).name != "Switzerland" YIELD $-.src AS src,$-.personFirstName AS personFirstName,$-.personLastName AS personLastName | \ 
GO FROM $-.src OVER comment_hasCreator_person,post_hasCreator_person REVERSELY YIELD id($$) AS messageID,$-.src AS personID,$-.personFirstName AS personFirstName,$-.personLastName AS personLastName | \ 
GO FROM $-.messageID OVER comment_isLocatedIn_place,post_isLocatedIn_place WHERE properties($$).type == "country" AND properties($$).name == "Papua_New_Guinea" YIELD $-.messageID AS messageID,$-.personID AS personID,$-.personFirstName AS personFirstName,$-.personLastName AS personLastName | \ 
GROUP BY $-.personID,$-.personFirstName,$-.personLastName YIELD $-.personID AS personID,$-.personFirstName AS personFirstName,$-.personLastName AS personLastName,0 AS xCount,count(*) AS yCount) | \ 
GROUP BY $-.personID,$-.personFirstName,$-.personLastName AS personLastName YIELD $-.personID AS personID,$-.personFirstName AS personFirstName,$-.personLastName AS personLastName,sum($-.xCount) AS xCount,sum($-.yCount) AS yCount,(sum($-.xCount)+sum($-.yCount)) AS count | \
 ORDER BY $-.personID asc,$-.count desc | LIMIT 20
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