Sql 自联接因where子句而失败
我使用ApacheDrill在一个CSV文件中使用自引用联接对年初至今的数据进行求和。缩短的查询是Sql 自联接因where子句而失败,sql,csv,self-join,windows-subsystem-for-linux,apache-drill,Sql,Csv,Self Join,Windows Subsystem For Linux,Apache Drill,我使用ApacheDrill在一个CSV文件中使用自引用联接对年初至今的数据进行求和。缩短的查询是 select ... fields from table a ... a.PeriodAmount, sum(cast(b.PeriodAmount as dec(18,3))) as YTDAmount from dfs.`/home/foo/data/a.csv` a left join dfs.`/home/foo/data/a.csv` b on ... join-co
select
... fields from table a ...
a.PeriodAmount,
sum(cast(b.PeriodAmount as dec(18,3))) as YTDAmount
from dfs.`/home/foo/data/a.csv` a
left join dfs.`/home/foo/data/a.csv` b
on
... join-conditions ...
*** where a.Year = '2018' ***
group by
... group-conditions ...
order by
... order-conditions ...
;
查询在没有where子句的情况下工作。当where子句包含在同一数据集上时,我得到以下错误:
Error: UNSUPPORTED_OPERATION ERROR: This query cannot be planned possibly due to either a cartesian join or an inequality join
[Error Id: b62e6b63-eda7-4a52-8f95-2499a1f5c278 on foo:31010] (state=,code=0)
我可以通过删除where子句并执行子查询来避免此错误:
from (select * from dfs.`/home/foo/data/a.csv` where Year = '2017') a
from (select * from dfs.`/home/foo/data/a.csv` where Year = '2017') b
但我不确定这是正确的做法。这使得查询更容易出错,因为同一条件必须应用于多个子查询,而不是将其作为where子句应用于它自然所属的位置
是否可以重写此自联接以维护where子句
这是在Ubuntu16.04上使用win10上的WSL和apache drill版本。1.13
完成对钻孔查询的操作:
select
a.Dep_id,
a.Dep,
substr(a.Post_id, 1, 4) as Kap,
a.Post_id,
substr(a.Post_id, 5, 2) as Post,
a.Art_id,
a.Art,
a.V_id,
a.Reg,
a.Dep_V_id,
a.Dep_V,
concat(substr(a.Periode, 1, 4), '-', substr(a.Periode, 5, 2), '-15') as PeriodDate,
a.Period,
a.Year,
a.PeriodAmount,
sum(cast(b.PeriodAmount as dec(18,3))) as YTDAmount
from dfs.`/home/foo/data/a.csv` a
left join dfs.`/home/foo/data/a.csv` b
on
a.Dep_id = b.Dep_id
and a.Post_id = b.Post_id
and a.Post_id is not null
and a.Art_id = b.Art_id
and a.V_id = b.V_id
and a.Reg = b.Reg
and a.Dep_V_id = b.Dep_V_id
and a.Dep_id = b.Dep_id
and b.Period <= a.Period
and a.Year = b.Year
and a.Post_id = b.Post_id
and a.Art_id = b.Art_id
where a.Year in ('2018') and b.Year in (a.Year)
group by
a.Dep_id,
a.Dep,
a.Post_id,
a.Art_id,
a.Art,
a.V_id,
a.Reg,
a.Dep_V_id,
a.Dep_V,
a.Dep_id,
a.Period,
a.Year,
a.PeriodAmount
order by
a.Year,
a.Dep_id,
a.Post_id,
a.Art_id,
a.V_id,
a.Reg,
a.Dep_V_id,
a.Dep_id,
a.Period,
a.PeriodAmount
;
我还没有像这样查询csv文件,所以这更多的是一个尝试的建议 完成a和b的where子句来帮助编译器如何
WHERE a.Year = ‘2018’ AND b.Year = ‘2018’
或
问题是?@JoakimDanielson谢谢你。我试图详细说明这个问题。答对了!非常感谢。查询优化器似乎还没有按预期处理此场景。我应该在apache drill上提交一个问题吗?该查询也适用于a.年在'2017',2018'和b.年在a.年。我不确定这是否是一个错误,或者您是否必须这样定义查询。在postgres和ms sql中,在'2017',2018'中有a.年就足够了。我还没有在mysql上测试。@kometen最初的连接条件是什么&在哪里?你在说什么?如果您还没有将a.year强制为等于b.year的内容,但是这些添加的内容是可以的,那么您最初的查询就是错误的,本质上是交叉连接。
WHERE a.Year = ‘2018’ AND b.Year = a.Year