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From "Ashutosh Chauhan (JIRA)" <>
Subject [jira] [Commented] (HIVE-20278) Druid Scan Query avoid copying from List -> Map -> List
Date Mon, 06 Aug 2018 20:08:00 GMT


Ashutosh Chauhan commented on HIVE-20278:

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:
>             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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