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https://issues.apache.org/jira/browse/DRILL-1889?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14278978#comment-14278978
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Jinfeng Ni commented on DRILL-1889:
-----------------------------------
Expression in some sense is similar to regular columns. When expression (i.e.
C1 + C2 + 10) is not associated with an alias, the project will have (C1 + C2
+ 10) --> f1, column "f1" could be viewed as a regular column, and does not
require prefix. If use put an alias, then, f1 will be replaced by the alias.
Therefore, in terms of prefixing, the expressions would behavior similar as a
regular table column. That's why the code did not differentiate them.
> when 'select *' is used along with an order by on length of a column, Drill
> is adding the computed length to the list of columns
> --------------------------------------------------------------------------------------------------------------------------------
>
> Key: DRILL-1889
> URL: https://issues.apache.org/jira/browse/DRILL-1889
> Project: Apache Drill
> Issue Type: Bug
> Components: Query Planning & Optimization
> Reporter: Rahul Challapalli
> Assignee: Jinfeng Ni
> Priority: Critical
> Fix For: 0.9.0
>
> Attachments:
> 0001-DRILL-1889-Fix-star-column-prefix-and-subsume-logic-.patch.2
>
>
> git.commit.id.abbrev=9dfa4a1
> Dataset :
> {code}
> {
> "col1":1,
> "col2":"a"
> }
> {
> "col1":2,
> "col2":"b"
> }
> {
> "col1":2,
> "col2":"abc"
> }
> {code}
> Query :
> {code}
> select * from `b.json` order by length(col2);
> +------------+------------+------------+
> | col1 | col2 | EXPR$1 |
> +------------+------------+------------+
> | 1 | a | 1 |
> | 2 | b | 1 |
> | 2 | abc | 3 |
> +------------+------------+------------+
> {code}
> Drill adds the length column. (EXPR$1) Not sure if this is intended behavior
> since postgres does not do this
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