[jira] [Created] (CALCITE-2077) Use druid scan query instead of the select query.

["Nishant Bangarwa (JIRA)" <ji...@apache.org>]

Nishant Bangarwa created CALCITE-2077:
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             Summary: Use druid scan query instead of the select query.
                 Key: CALCITE-2077
                 URL: https://issues.apache.org/jira/browse/CALCITE-2077
             Project: Calcite
          Issue Type: Improvement
            Reporter: Nishant Bangarwa
            Assignee: Nishant Bangarwa


The biggest difference between select query and scan query is that, scan query doesn't retain all rows in memory before rows can be returned to client.
Select query on very large segments will cause memory pressure on druid historicals if too many rows required by select query whereas Scan query doesn't have this issue.
Scan query can also return all rows without issuing another pagination query, which is extremely useful when query against historical or realtime node directly.




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