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Jeremy Hanna edited comment on CASSANDRA-2855 at 7/28/11 10:16 PM:
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Added a configuration property cassandra.skip.empty.results which defaults to
false. We can't skip just complete empty rows because there is no way to tell
if the complete row is empty based on a result from a slice predicate.
was (Author: jeromatron):
Added a configuration property cassandra.skip.empty.results which defaults
to false. We can't skip just complete empty rows because there is no way to
tell if the complete row is empty based on a result that is a slice predicate.
> Skip rows with empty columns when slicing entire row
> ----------------------------------------------------
>
> Key: CASSANDRA-2855
> URL: https://issues.apache.org/jira/browse/CASSANDRA-2855
> Project: Cassandra
> Issue Type: Improvement
> Components: API
> Reporter: Jeremy Hanna
> Assignee: Jeremy Hanna
> Priority: Minor
> Labels: hadoop
> Fix For: 0.7.9, 0.8.3
>
> Attachments: 2855-v2.txt, 2855-v3.txt
>
>
> We have been finding that range ghosts appear in results from Hadoop via Pig.
> This could also happen if rows don't have data for the slice predicate that
> is given. This leads to having to do a painful amount of defensive checking
> on the Pig side, especially in the case of range ghosts.
> We would like to add an option to skip rows that have no column values in it.
> That functionality existed before in core Cassandra but was removed because
> of the performance penalty of that checking. However with Hadoop support in
> the RecordReader, that is batch oriented anyway, so individual row reading
> performance isn't as much of an issue. Also we would make it an optional
> config parameter for each job anyway, so people wouldn't have to incur that
> penalty if they are confident that there won't be those empty rows or they
> don't care.
> It could be parameter cassandra.skip.empty.rows and be true/false.
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