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From "Sudheesh Katkam (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DRILL-4875) select over array of maps returns incorrect results
Date Tue, 06 Sep 2016 17:58:21 GMT

    [ https://issues.apache.org/jira/browse/DRILL-4875?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15468055#comment-15468055
] 

Sudheesh Katkam commented on DRILL-4875:
----------------------------------------

Simply put, based on the [documented model|http://drill.apache.org/docs/querying-complex-data-introduction/],
the initial query is _wrong_ for the intended usage. Drill should have failed nicely, instead
of returning any results.

> select over array of maps returns incorrect results
> ---------------------------------------------------
>
>                 Key: DRILL-4875
>                 URL: https://issues.apache.org/jira/browse/DRILL-4875
>             Project: Apache Drill
>          Issue Type: Bug
>          Components: Query Planning & Optimization
>    Affects Versions: 1.9.0
>         Environment: 4 node cluster CentOS
>            Reporter: Khurram Faraaz
>            Priority: Critical
>
> select over array of maps returns incorrect results
> Drill 1.9.0 git commit ID : 28d315bbb
> Data used in test
> {noformat}
> [test@centos-a ~]# cat arrayofmaps.json
> {"arr":[{"key":"a"},{"key":"b"},{"key":"c"},{"key":"d"}]}
> {noformat}
> Array elements are
> {noformat}
> 0: jdbc:drill:schema=dfs.tmp> select t.arr from `arrayofmaps.json` t;
> +----------------------------------------------------+
> |                        arr                         |
> +----------------------------------------------------+
> | [{"key":"a"},{"key":"b"},{"key":"c"},{"key":"d"}]  |
> +----------------------------------------------------+
> 1 row selected (0.289 seconds)
> {noformat}
> The below query should return 4 rows, each row containing one value a,b,c and d respectively
> However query just returns only one value, which is not correct.
> {noformat}
> 0: jdbc:drill:schema=dfs.tmp> select t.arr.key from `arrayofmaps.json` t where t.arr.key
is not null;
> +---------+
> | EXPR$0  |
> +---------+
> | a       |
> +---------+
> 1 row selected (0.33 seconds)
> {noformat}
> Explain plan for above failing query
> {noformat}
> 0: jdbc:drill:schema=dfs.tmp> explain plan for select t.arr.key from `arrayofmaps.json`
t where t.arr.key is not null;
> +------+------+
> | text | json |
> +------+------+
> | 00-00    Screen
> 00-01      Project(EXPR$0=[$0])
> 00-02        SelectionVectorRemover
> 00-03          Filter(condition=[IS NOT NULL($0)])
> 00-04            Project(ITEM=[ITEM($0, 'key')])
> 00-05              Scan(groupscan=[EasyGroupScan [selectionRoot=maprfs:/tmp/arrayofmaps.json,
numFiles=1, columns=[`arr`.`key`], files=[maprfs:///tmp/arrayofmaps.json]]])
> {noformat}



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