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https://issues.apache.org/jira/browse/TAJO-1403?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14374976#comment-14374976
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ASF GitHub Bot commented on TAJO-1403:
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Github user jihoonson commented on the pull request:
https://github.com/apache/tajo/pull/434#issuecomment-84623003
@dongjoon-hyun, thanks for your nice work.
In overall, the patch looks good, but I want to check my understanding.
If the ```WHERE``` clause involves only a subset of partition columns, it
seems that every partition directory which are not specified in the ```where```
clause will be read.
Please correct me if I misunderstand something.
> Improve 'Simple Query' with only partition columns and constant values
> ----------------------------------------------------------------------
>
> Key: TAJO-1403
> URL: https://issues.apache.org/jira/browse/TAJO-1403
> Project: Tajo
> Issue Type: Improvement
> Reporter: Dongjoon Hyun
> Assignee: Dongjoon Hyun
> Fix For: 0.11.0
>
> Attachments: TAJO-1403.patch
>
>
> Tajo shows a very fast response for a simple query (
> https://cwiki.apache.org/confluence/display/TAJO/Simple+Query+and+Forwarded+Query)
> like the followings.
> {code:sql}
> select * from t1 limit 10;
> {code}
> However, in many cases, tables have partitions.
> {code:sql}
> create external table t1(id int) using csv with ('csvfile.delimiter'='|')
> partition by column(dt text) location '/data';
> select * from t1 where dt='2015-03-15' limit 10;
> {code}
> If all predicates in WHERE consist of partition columns and 'EQUAL'
> predicates with constant values, I think Tajo can handle these cases very
> fast.
> This kind of queries is very popular for DevOps users and simple ETL apps.
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