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From "Matthias Boehm (JIRA)" <>
Subject [jira] [Created] (SYSTEMML-2031) Perftest: Unnecessary compression of incompressible blocks
Date Thu, 30 Nov 2017 03:34:00 GMT
Matthias Boehm created SYSTEMML-2031:

             Summary: Perftest: Unnecessary compression of incompressible blocks
                 Key: SYSTEMML-2031
             Project: SystemML
          Issue Type: Bug
            Reporter: Matthias Boehm

By default, we apply compression for data sets that are known to exceed aggregate memory if
all operations of the given script that touch the respective input are supported over compressed

On the perftest 800GB dense scenario, this leads to a slight slowdown and increase in the
matrix size due to incompressible data, where each block is represented as follows:
--col groups sizes (OLE,RLE,DDC1,DDC2,UC): 0,0,0,0,1000
--compression ratio: 0.999475777837746

We should investigate the set of incompressible columns as well as final representation and
simply return the uncompressed block in such such scenarios.

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