Qifan Chen created TRAFODION-1677:
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Summary: Implement the ROLLUP and CUBE SQL functions in Trafodion
Key: TRAFODION-1677
URL: https://issues.apache.org/jira/browse/TRAFODION-1677
Project: Apache Trafodion
Issue Type: Bug
Components: sql-general
Reporter: Qifan Chen
I am currently working the high level design for 2nd part of the OLAP function
RollUp and Cube. The 1st part (the identification of missing OLAP window
functions in Trafodion and their implementation) is done.
For RollUp and Cube, I believe the key is to handle many more # of aggregates
properly. Note that that number is n for RollUp and 2^n for Cube, where n is
the # of grouping columns. Parallel computation of these aggregates is the key.
One way to achieve such is to extend the Hash Group By operators so that it can
do multiple aggregates in a single operator. The requires the following:
1. random partition the data fed into the aggregate operator
2. force the multiple-level group by
3. pack multiple pairs of groupping and aggregate expressions (both in compiler
and in executor, and in MapValueIds, GroupByPartialRoot, and
GroupByPartialLeaf).
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