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https://issues.apache.org/jira/browse/DRILL-3209?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14940185#comment-14940185
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Venki Korukanti commented on DRILL-3209:
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Can you attach the profiles of queries that ran slowly using native scan and
their corresponding hive scan?
> [Umbrella] Plan reads of Hive tables as native Drill reads when a native
> reader for the underlying table format exists
> ----------------------------------------------------------------------------------------------------------------------
>
> Key: DRILL-3209
> URL: https://issues.apache.org/jira/browse/DRILL-3209
> Project: Apache Drill
> Issue Type: Improvement
> Components: Query Planning & Optimization, Storage - Hive
> Reporter: Jason Altekruse
> Assignee: Chun Chang
> Fix For: 1.2.0
>
>
> All reads against Hive are currently done through the Hive Serde interface.
> While this provides the most flexibility, the API is not optimized for
> maximum performance while reading the data into Drill's native data
> structures. For Parquet and Text file backed tables, we can plan these reads
> as Drill native reads. Currently reads of these file types provide untyped
> data. While parquet has metadata in the file we currently do not make use of
> the type information while planning. For text files we read all of the files
> as lists of varchars. In both of these cases, casts will need to be injected
> to provide the same datatypes provided by the reads through the SerDe
> interface.
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