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https://issues.apache.org/jira/browse/PARQUET-2122?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17534123#comment-17534123
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Micah Kornfield commented on PARQUET-2122:
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I believe the answer is the Bloom filter implementation isn't adaptive, so it 
simply preallocates all the bytes necessary.  It would certainly be a nice 
option to have more adaptive data structures that can scale down for smaller 
files but is probably a decent amount of work to build consensus around this.

> Adding Bloom filter to small Parquet file bloats in size X1700
> --------------------------------------------------------------
>
>                 Key: PARQUET-2122
>                 URL: https://issues.apache.org/jira/browse/PARQUET-2122
>             Project: Parquet
>          Issue Type: Bug
>          Components: parquet-cli, parquet-mr
>    Affects Versions: 1.13.0
>            Reporter: Ze'ev Maor
>            Priority: Critical
>         Attachments: data.csv, data_index_bloom.parquet
>
>
> Converting a small, 14 rows/1 string column csv file to Parquet without bloom 
> filter yields a 600B file, adding '.withBloomFilterEnabled(true)' to 
> ParquetWriter then yields a 1049197B file.
> It isn't clear what the extra space is used by.
> Attached csv and bloated Parquet files.



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