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https://issues.apache.org/jira/browse/HIVE-3552?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Namit Jain updated HIVE-3552:
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Summary: HIVE-3552 performant manner for performing cubes/rollups/grouping
sets for a high number of grouping set keys (was: performant manner for
performing cubes and rollups in case of less aggregation)
> HIVE-3552 performant manner for performing cubes/rollups/grouping sets for a
> high number of grouping set keys
> -------------------------------------------------------------------------------------------------------------
>
> Key: HIVE-3552
> URL: https://issues.apache.org/jira/browse/HIVE-3552
> Project: Hive
> Issue Type: New Feature
> Components: Query Processor
> Reporter: Namit Jain
> Assignee: Namit Jain
>
> This is a follow up for HIVE-3433.
> Had a offline discussion with Sambavi - she pointed out a scenario where the
> implementation in HIVE-3433 will not scale. Assume that the user is performing
> a cube on many columns, say '8' columns. So, each row would generate 256 rows
> for the hash table, which may kill the current group by implementation.
> A better implementation would be to add an additional stage - in the first
> stage perform the group by assuming there was no cube. Ad another stage, where
> you would perform the cube. The assumption is that the group by would have
> decreased the output data significantly.
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