[jira] [Created] (KYLIN-1921) Support Grouping Funtions

["Yerui Sun (JIRA)" <ji...@apache.org>]

Yerui Sun created KYLIN-1921:
--------------------------------

             Summary: Support Grouping Funtions
                 Key: KYLIN-1921
                 URL: https://issues.apache.org/jira/browse/KYLIN-1921
             Project: Kylin
          Issue Type: New Feature
          Components: Query Engine
    Affects Versions: v1.5.4
            Reporter: Yerui Sun
            Assignee: Yerui Sun


Usually we used 'group by dim1, dim2' to fetch the metrics with every value of dims, and we also want the summary metrics with the dim2 rolled up.
This case could be resolved by union two query, like:
{code}
select dim1, dim2 metric from table group by dim1, dim2
union all
select dim1, 'ALL', metric from table group by dim1
{code}

Now with the expression cube/rollup/grouping sets in calcite, we can make the query sql more simple and more clearly:
{code}
select dim1, case(grouping(dim2) when 1 then 'ALL' else dim2 end) 
from table
group by grouping sets((dim1, dim2), (dim1))
{code}



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