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https://issues.apache.org/jira/browse/PARQUET-2222?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17693874#comment-17693874
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Xuwei Fu commented on PARQUET-2222:
-----------------------------------
ok, I got it. Previously I found `RLE` format requires a length here:
```
{{rle-bit-packed-hybrid: <length> <encoded-data>}}
{{length := length of the <encoded-data> in bytes stored as 4 bytes little
endian (unsigned int32)}}
{{encoded-data := <run>*}}
{{```}}
So I thought it already has `length` in encoded data, but actually, in data
page v2's rep-levels and def-levels, length is not included?
> [Format] RLE encoding spec incorrect for v2 data pages
> ------------------------------------------------------
>
> Key: PARQUET-2222
> URL: https://issues.apache.org/jira/browse/PARQUET-2222
> Project: Parquet
> Issue Type: Bug
> Components: parquet-format
> Reporter: Antoine Pitrou
> Priority: Critical
> Fix For: format-2.10.0
>
>
> The spec
> (https://github.com/apache/parquet-format/blob/master/Encodings.md#run-length-encoding--bit-packing-hybrid-rle--3)
> has this:
> {code}
> rle-bit-packed-hybrid: <length> <encoded-data>
> length := length of the <encoded-data> in bytes stored as 4 bytes little
> endian (unsigned int32)
> {code}
> But the length is actually prepended only in v1 data pages, not in v2 data
> pages.
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