prtkgaur opened a new pull request, #557: URL: https://github.com/apache/parquet-format/pull/557
Add the encoding specification for ALP (encoding value 10) to Encodings.md. ALP compresses FLOAT and DOUBLE columns by converting values to integers via decimal scaling, then applying Frame of Reference encoding and bit-packing. Values that cannot be losslessly round-tripped are stored as exceptions. The spec covers: - Page layout: 7-byte header, offset array, compressed vectors - Vector format: AlpInfo, ForInfo, packed values, exception data - Encoding math: two-step multiplication for cross-language consistency - Parameter selection, exception detection, and decoding steps Based on the paper "ALP: Adaptive Lossless floating-Point Compression" (Afroozeh and Boncz, SIGMOD 2024). Wire format matches the C++ Arrow and Java parquet-java implementations. <!-- Thanks for opening a pull request! If you're new to Parquet-Format, information on how to contribute can be found here: https://parquet.apache.org/docs/contribution-guidelines/contributing Please open a GitHub issue for this pull request: https://github.com/apache/parquet-format/issues/new/choose and format pull request title as below: GH-${GITHUB_ISSUE_ID}: ${SUMMARY} or simply use the title below if it is a minor issue: MINOR: ${SUMMARY} --> ### Rationale for this change ### What changes are included in this PR? ### Do these changes have PoC implementations? <!-- Please uncomment the line below and replace ${GITHUB_ISSUE_ID} with the actual Github issue id. --> <!-- Closes #${GITHUB_ISSUE_ID} --> -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
