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https://issues.apache.org/jira/browse/HIVE-3585?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13713370#comment-13713370
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Yin Huai commented on HIVE-3585:
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I am concerned about the performance of Trevni. Please correct me if my
explanation is not accurate.
First, seems we store a column by multiple compression blocks and the size of a
block is around 64 KiB. When the reader reads data from a stored table, we read
a compression block at a time. Because the reader is row-oriented, in the worst
case, the reader needs to seek to another column after reading every single
compression block. As pointed out in AVRO-1208, the performance degradation is
significant.
Second, since we read a compression unit at a time, when the size of a
compression unit is smaller than the size of buffer used in the
BufferedInputStream inside BlockReader, we may not be able to efficiently read
data. We will just use a portion of data fetched by BufferedInputStream and the
rest of data cannot be used. I have experience that the performance of Trevni
on HDFS without short circuit is not good. I think this issue may be the
reason. But I have not dug very deep.
> Integrate Trevni as another columnar oriented file format
> ---------------------------------------------------------
>
> Key: HIVE-3585
> URL: https://issues.apache.org/jira/browse/HIVE-3585
> Project: Hive
> Issue Type: Improvement
> Components: Serializers/Deserializers
> Affects Versions: 0.10.0
> Reporter: alex gemini
> Assignee: Mark Wagner
> Priority: Minor
> Attachments: futurama_episodes.avro, HIVE-3585.1.patch.txt
>
>
> add new avro module trevni as another columnar format.New columnar format
> need a columnar SerDe,seems fastutil is a good choice.the shark project use
> fastutil library as columnar serde library but it seems too large (almost
> 15m) for just a few primitive array collection.
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