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Pass Decompressed Size to Parquet Codec::decompress #2956

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tustvold opened this issue Oct 27, 2022 · 1 comment · Fixed by #2959
Closed

Pass Decompressed Size to Parquet Codec::decompress #2956

tustvold opened this issue Oct 27, 2022 · 1 comment · Fixed by #2959
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enhancement Any new improvement worthy of a entry in the changelog good first issue Good for newcomers help wanted parquet Changes to the parquet crate

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@tustvold
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Is your feature request related to a problem or challenge? Please describe what you are trying to do.

We know the size of the decompressed data, as this information is provided in the page header. We can potentially avoid unnecessary reallocations by passing this down to the codecs.

Describe the solution you'd like

Add an optional uncompressed_size: Option<usize> to Codec::decompress

Describe alternatives you've considered

Additional context
@tustvold tustvold added the enhancement Any new improvement worthy of a entry in the changelog label Oct 27, 2022
@tustvold tustvold mentioned this issue Oct 27, 2022
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@marioloko
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Then, I guess that the internal behavior of the decompress methods should be something like:

let uncompressed_size = uncompressed_size
    .unwrap_or_else(|| estimate_max_size(compressed_size));

marioloko pushed a commit to marioloko/arrow-rs that referenced this issue Oct 27, 2022
Pass decompressed size to parquet Codec::decompress (apache#2956)
0ffec74 
Added optional argument uncompressed_size to Coded::decompress to do a better
estimation of the required uncompress size.

* snappy: Probably no much improvement as `decompress_len` is already accurate.
* gzip: No improvement. Ignores the size hint.
* brotli: Probably no much improvement. The buffer size will be equal to the uncompressed_size size.
* lz4: No improvement. As the buffer is located at the stack there are no extra allocations. Then it probably is better to keep it working as it is.
* zstd: No improvement. Ignores the size hint.
* lz4_raw: Improvement. The estimation method over-estimates, so knowin the uncompressed size reduces allocations.
@marioloko marioloko mentioned this issue Oct 27, 2022
Merged
tustvold pushed a commit that referenced this issue Oct 29, 2022
@marioloko
Pass decompressed size to parquet Codec::decompress (#2956) (#2959)
344c552 
* Pass decompressed size to parquet Codec::decompress (#2956)

Added optional argument uncompressed_size to Coded::decompress to do a better
estimation of the required uncompress size.

* snappy: Probably no much improvement as `decompress_len` is already accurate.
* gzip: No improvement. Ignores the size hint.
* brotli: Probably no much improvement. The buffer size will be equal to the uncompressed_size size.
* lz4: No improvement. As the buffer is located at the stack there are no extra allocations. Then it probably is better to keep it working as it is.
* zstd: No improvement. Ignores the size hint.
* lz4_raw: Improvement. The estimation method over-estimates, so knowin the uncompressed size reduces allocations.

* Do not include header size in uncompressed_size.

A page may contain header, uncompressed size includes the header size. The `decompress` method expects to receive the `uncompress_size` for the compress block, that is without the page headers.

Co-authored-by: Adrián Gallego Castellanos <[email protected]>
@alamb alamb added the parquet Changes to the parquet crate label Dec 1, 2022
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Pass decompressed size to parquet Codec::decompress (#2956) marioloko/arrow-rs
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@alamb @tustvold @marioloko