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Posted to issues@tajo.apache.org by "Jihoon Son (JIRA)" <ji...@apache.org> on 2014/02/01 12:18:08 UTC
[jira] [Commented] (TAJO-573) Allow the same column in a schema
[ https://issues.apache.org/jira/browse/TAJO-573?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13888536#comment-13888536 ]
Jihoon Son commented on TAJO-573:
---------------------------------
I have thought about this issue, and want to discuss with other people.
Do we really need to support multiple columns of the same name in a schema?
I think that the above example query is hardly used in real applications, because users generally don't want to get the duplicated data.
> Allow the same column in a schema
> ---------------------------------
>
> Key: TAJO-573
> URL: https://issues.apache.org/jira/browse/TAJO-573
> Project: Tajo
> Issue Type: Improvement
> Components: catalog
> Reporter: Jihoon Son
> Fix For: 0.8-incubating
>
>
> Recently, I have been working on TAJO-554, and I found that we should allow two or more same columns in a schema to handle the asterisk properly.
> My try in TAJO-554 is rewriting asterisks with their relations' schemas. So, the resulting schema can contain multiple same columns. Here is an example.
> {noformat}
> postgres=# select n_name, n_nationkey+10, *, n_regionkey from nation;
> n_name | ?column? | n_nationkey | n_name | n_regionkey | n_comment | n_regionkey
> ---------------------------+----------+-------------+---------------------------+-------------+--------------------------------------------------------------------------------------------------------------------+-------------
> ALGERIA | 10 | 0 | ALGERIA | 0 | haggle. carefully final deposits detect slyly agai | 0
> ARGENTINA | 11 | 1 | ARGENTINA | 1 | al foxes promise slyly according to the regular accounts. bold requests alon | 1
> {noformat}
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