Matthias Boehm created SYSTEMML-2007:
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Summary: New order with multiple order-by columns
Key: SYSTEMML-2007
URL: https://issues.apache.org/jira/browse/SYSTEMML-2007
Project: SystemML
Issue Type: Task
Reporter: Matthias Boehm
There are multiple use cases, where users have to emulate an order with
multiple order-by columns as follows (which works due to stable sort):
{code}
X = order(target=X, by=3, ...)
X = order(target=X, by=2, ...)
X = order(target=X, by=1, ...)
{code}
This causes unnecessary overhead by sorting the dataset in the number of
order-by columns. Hence, this task aims to support an order function that
allows both scalar and matrix {{by}} parameters.
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