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https://issues.apache.org/jira/browse/HIVE-20278?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16570713#comment-16570713
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Ashutosh Chauhan commented on HIVE-20278:
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+1
What will it take to have RecordReaders other than Scan to return rows in
order. No reason to overhead in that case either. Can you please create a
follow-up for that.
> Druid Scan Query avoid copying from List -> Map -> List
> -------------------------------------------------------
>
> Key: HIVE-20278
> URL: https://issues.apache.org/jira/browse/HIVE-20278
> Project: Hive
> Issue Type: Improvement
> Reporter: Nishant Bangarwa
> Assignee: Nishant Bangarwa
> Priority: Major
> Labels: PERFORMANCE
> Attachments: HIVE-20278.patch
>
>
> DruidScanQueryRecordReader gets a compacted List<Object> from druid. It then
> converts that list into a Map<String,Object> as DruidWritable where key is
> the column name.
> At the second stage DruidSerde takes this DruidWritable and creates a List
> out out of the map again. We can avoid the map creation part by reading the
> list sent by druid directly in the DruidSerde.deserialize() method.
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