richardstartin opened a new pull request #7655: URL: https://github.com/apache/pinot/pull/7655
## Description All other chunk compression formats can already report their decompressed lengths in O(1) time, but this is missing from the LZ4 specification. The LZ4 library has a compressed mode to add the size as a prefix, but this is incompatible with the compression mode currently in use, which requires the introduction of a new compression mode. Moreover, this new compression mode cannot be relied upon for buffer sizing when reading v1, v2, or v3 of the forward index chunk format. This PR paves the way to introduce a new chunk format where all chunks are self-describing and reader buffers can be sized from compression metadata. Systems which choose LZ4 compression will be automatically upgraded to LZ4_WITH_LENGTH iff using a new chunk format about to be introduced (but the v3 writer is unaffected). Users of the v3 chunk format can configure LZ4_WITH_LENGTH if they want to, but since it can't be relied on by the reader, this doesn't offer any benefits. ## Upgrade Notes Does this PR prevent a zero down-time upgrade? (Assume upgrade order: Controller, Broker, Server, Minion) * [ ] Yes (Please label as **<code>backward-incompat</code>**, and complete the section below on Release Notes) Does this PR fix a zero-downtime upgrade introduced earlier? * [ ] Yes (Please label this as **<code>backward-incompat</code>**, and complete the section below on Release Notes) Does this PR otherwise need attention when creating release notes? Things to consider: - New configuration options - Deprecation of configurations - Signature changes to public methods/interfaces - New plugins added or old plugins removed * [ ] Yes (Please label this PR as **<code>release-notes</code>** and complete the section on Release Notes) ## Release Notes <!-- If you have tagged this as either backward-incompat or release-notes, you MUST add text here that you would like to see appear in release notes of the next release. --> <!-- If you have a series of commits adding or enabling a feature, then add this section only in final commit that marks the feature completed. Refer to earlier release notes to see examples of text. --> ## Documentation <!-- If you have introduced a new feature or configuration, please add it to the documentation as well. See https://docs.pinot.apache.org/developers/developers-and-contributors/update-document --> -- 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]
