[TAJO-1403] Improve 'Simple Query' with only partition columns and constant values

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.11.0
• Assignee: Dongjoon Hyun
• Reporter: Dongjoon Hyun
• Created: 15/Mar/15 03:18
• Updated: 26/Mar/15 05:05
• Resolved: 23/Mar/15 06:06

Description

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.

select * from t1 limit 10;

However, in many cases, tables have partitions.

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;

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.