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https://issues.apache.org/jira/browse/ARROW-14429?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17433829#comment-17433829
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David Li commented on ARROW-14429:
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[~lingkai2] does the Datasets reader perform better?
Also see the [pull request|https://github.com/apache/arrow/pull/11535]; while
the API is less convenient, the generator-based reader may be the fastest for
you.
> [C++] RecordBatchFileReader performance really bad in S3
> --------------------------------------------------------
>
> Key: ARROW-14429
> URL: https://issues.apache.org/jira/browse/ARROW-14429
> Project: Apache Arrow
> Issue Type: Bug
> Components: C++
> Affects Versions: 5.0.0
> Reporter: Lingkai Kong
> Assignee: David Li
> Priority: Major
> Labels: pull-request-available
> Fix For: 7.0.0
>
> Time Spent: 0.5h
> Remaining Estimate: 0h
>
> We are using RecordBatchFileWriter to write Arrow type directly to S3 using
> the S3FileSystem, then using RecordBatchFileReader to read from S3. The write
> is pretty efficient, write a 50MB finishes within 0.2s. But reading that file
> is taking 30s, which is definitely too long. Then I did several tests:
> # I tried to use S3FileSystem to read the file into bytes, it's only taking
> 1s. which somehow makes me believe it's an issue with RecordBatchFileReader
> # Half the size (around 25MB), with
> [RecordBatchFileReader|https://arrow.apache.org/docs/python/generated/pyarrow.RecordBatchFileReader.html]
> took 17s, without
> [RecordBatchFileReader|https://arrow.apache.org/docs/python/generated/pyarrow.RecordBatchFileReader.html]
> took 0.28s
> # Double the size (around 100MB), with
> [RecordBatchFileReader|https://arrow.apache.org/docs/python/generated/pyarrow.RecordBatchFileReader.html]
> took 61s, without
> [RecordBatchFileReader|https://arrow.apache.org/docs/python/generated/pyarrow.RecordBatchFileReader.html]
> took 2.3s
> # I tried to get all bytes using S3FileSystem first, then create a reader
> from the bytes. Then read all context from the reader, it's only taking 0.1s.
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