[GitHub] [incubator-pinot] siddharthteotia commented on pull request #6876: Support ZSTD compression codec for raw index

[GitBox <gi...@apache.org>]

siddharthteotia commented on pull request #6876:
URL: https://github.com/apache/incubator-pinot/pull/6876#issuecomment-832251598


   > Nit: You may want to note that if someone upgrades and then enables ZSTD for new segments, and for some reason has to roll back their deployment, the segments will not be readable.
   > One way of avoiding this will be to introduce a config to enable the feature, but that could be an overkill. It should be enough to note in the release notes that this is the case for the next release (so, basically mark it for release notes)
   
   Table level config is there. I mean it was already there. Just reused the same in FieldConfig (the new model). 
   Yes, let's label it for release notes and also call the upgrade aspect in PR description. 
   
   @GSharayu let's also mention that just like other table level changes (column renaming, type changing, column dropping, index dropping) which are currently not allowed, changing the compression codec on an existing noDictionary column from snappy to zstd or vice-versa will not happy since we currently don't have a mechanism for doing this in-place in the segment file. Newly pushed segments will pick up the new codec and since the codec type is written into the file header, we will be able to read both old and new segments


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