Zhong Yanghong created KYLIN-3490:
-------------------------------------
Summary: For some single column related queries, don't need to
query cuboids, only dictionaries are enough
Key: KYLIN-3490
URL: https://issues.apache.org/jira/browse/KYLIN-3490
Project: Kylin
Issue Type: Improvement
Reporter: Zhong Yanghong
A common use case for BI tools is as follows:
# Firstly, extract all of the values of a dimension column
# Then, select part of the values as filter condition.
Previously query for the first step requires to hit all of the segments' cuboid
data, which may not be efficient, especially when the segments occupy many
regions.
To use dictionary rather than cuboid data to answer this kind of queries, will
reduce the cost of many rpcs to hbase.
Sample queries are as follows:
{code}
select A
from T
group by A
{code}
{code}
select distinct A
from T
{code}
{code}
select max(A)
from T
{code}
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