[ https://issues.apache.org/jira/browse/HIVE-23365?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Stamatis Zampetakis reassigned HIVE-23365: ------------------------------------------ Assignee: Stamatis Zampetakis > Put RS deduplication optimization under cost based decision > ----------------------------------------------------------- > > Key: HIVE-23365 > URL: https://issues.apache.org/jira/browse/HIVE-23365 > Project: Hive > Issue Type: Improvement > Components: Physical Optimizer > Reporter: Jesus Camacho Rodriguez > Assignee: Stamatis Zampetakis > Priority: Major > > Currently, RS deduplication is always executed whenever it is semantically > correct. However, it could be beneficial to leave both RS operators in the > plan, e.g., if the NDV of the second RS is very low. Thus, we would like this > decision to be cost-based. We could use a simple heuristic that would work > fine for most of the cases without introducing regressions for existing > cases, e.g., if NDV for partition column is less than estimated parallelism > in the second RS, do not execute deduplication. -- This message was sent by Atlassian Jira (v8.3.4#803005)