[jira] [Commented] (KYLIN-3634) when filter column has null value may cause incorrect query result

[ASF GitHub Bot (JIRA)]

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https://issues.apache.org/jira/browse/KYLIN-3634?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16653086#comment-16653086
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ASF GitHub Bot commented on KYLIN-3634:
---------------------------------------

coveralls commented on issue #292: KYLIN-3634 when filter column has null value 
may cause incorrect query result
URL: https://github.com/apache/kylin/pull/292#issuecomment-430513991
 
 
   ## Pull Request Test Coverage Report for [Build 
3773](https://coveralls.io/builds/19563938)
   
   * **0** of **6**   **(0.0%)**  changed or added relevant lines in **1** file 
are covered.
   * No unchanged relevant lines lost coverage.
   * Overall coverage increased (+**0.002%**) to **23.306%**
   
   ---
   
   |  Changes Missing Coverage | Covered Lines | Changed/Added Lines | % |
   | :-----|--------------|--------|---: |
   | 
[core-cube/src/main/java/org/apache/kylin/gridtable/GTUtil.java](https://coveralls.io/builds/19563938/source?filename=core-cube%2Fsrc%2Fmain%2Fjava%2Forg%2Fapache%2Fkylin%2Fgridtable%2FGTUtil.java#L300)
 | 0 | 6 | 0.0%
   <!-- | **Total:** | **0** | **6** | **0.0%** | -->
   
   
   |  Totals | [![Coverage 
Status](https://coveralls.io/builds/19563938/badge)](https://coveralls.io/builds/19563938)
 |
   | :-- | --: |
   | Change from base [Build 3768](https://coveralls.io/builds/19516792): |  
0.002% |
   | Covered Lines: | 16311 |
   | Relevant Lines: | 69986 |
   
   ---
   ##### 💛  - [Coveralls](https://coveralls.io)
   

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> when filter column has null value may cause incorrect query result
> ------------------------------------------------------------------
>
>                 Key: KYLIN-3634
>                 URL: https://issues.apache.org/jira/browse/KYLIN-3634
>             Project: Kylin
>          Issue Type: Bug
>          Components: Query Engine
>    Affects Versions: v2.0.0
>            Reporter: WangBo
>            Priority: Major
>         Attachments: 
> 0001-KYLIN-3634-when-filter-column-has-null-value-may-cau.patch
>
>
> h1. Question
> when a column has null value，and using it as a filter column when querying, 
> and the filter value is not exist in the table,this may cause incorrect result
> h1. An Example
> h2. Table A
> the table A has three rows,city column of one row has null value
>  
> ||day||...||city||price||
> |20180101| |null|10|
> |20180101| |beijing|20|
> |20180101| |shanghai|10|
> h2. Query SQL
> select day,sum(price) from a where city <> 'abc' group by day
> h2. Correct Result
> exclude the row contains null city value
> ||day||col||
> |20180101|30|
> h2. InCorrect Result
> resullt 0 rows
> this happens in our production environment,the kylin version is 2.0.0
> h1. Analysis process
> 1,city column dosen't have a value,so the CompareTupleFilter will turn into  
> ConstantTupleFilter(see GTUtil.java)
> 2,if dimensions in the sql dosen't match all the columns using in group 
> by,the  bytesComparator used in hbase aggregation map will only compare the 
> columns using in group by
> 3,when GTAggregateScanner constructs key of aggBufMap,the key may contains 
> null value,because the comparator of aggBufMap only compares group by 
> columns,so the tuple share same group by columns may also share the same keys 
> which contains null value;This may cause kylin server receives tuples 
> contains null value;
> 4,when the code which dynamically generated by calcilte deals tuples using 
> filter,it first judges whether the column is null.Because filter column in 
> the tuple contains null value,so it always return false, no tuples will 
> return.
> h1. Solution
> when the filter column value is a invalid means not in the table,turn the 
> CompareTupleFiter into IS_NOT_NULL filter,instead of ConstantTupleFilter.TURE
>  
> Now I have test the feature in our production environment ;
> test in “mvn test” had passed，but not test in sandbox
>  



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