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This means that within a column chunk, if there are <= 65535 unique entries, we can use dictionary based compression to potentially save space. However, if there are > 65535 unique entries we can't use dictionary compression, potentially leading to larger file sizes.
Some users have shared that using libcudf instead of the traditional Java Parquet implementation has resulted in file sizes >5x larger in some scenarios (due to not being able to use dictionary encoding), which can pose a storage challenge at scale.
The text was updated successfully, but these errors were encountered:
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Currently, the parquet writer has a 16 bit maximum dictionary size.
cudf/cpp/src/io/parquet/parquet_gpu.hpp
Lines 48 to 50 in da74744
This means that within a column chunk, if there are <= 65535 unique entries, we can use dictionary based compression to potentially save space. However, if there are > 65535 unique entries we can't use dictionary compression, potentially leading to larger file sizes.
The Apache Parquet format specification indicates support for a 32 bit maximum width, and this is available in the official Java implementation of Parquet.
Some users have shared that using libcudf instead of the traditional Java Parquet implementation has resulted in file sizes >5x larger in some scenarios (due to not being able to use dictionary encoding), which can pose a storage challenge at scale.
The text was updated successfully, but these errors were encountered: