* [HUDI-2763] Metadata table records - support for key deduplication and virtual keys
- The backing log format for the metadata table is HFile, a KeyValue type.
Since the key field in the metadata record payload is a duplicate of the
Key in the Cell, the redundant key field in the record can be emptied
to save on the cost.
- HoodieHFileWriter and HoodieHFileDataBlock will now serialize records
with the key field emptied by default. HFile writer tries to find if
the record has metadata payload schema field 'key' and if so it does
the key trimming from the record payload.
- HoodieHFileReader when reading the serialized records back from disk,
it materializes the missing keyFields if any. HFile reader tries to
find if the record has metadata payload schema fiels 'key' and if so
it does the key materialization in the record payload.
- Tests have been added to verify the default virtual keys and key
deduplication support for the metadata table records.
Co-authored-by: Vinoth Chandar <vinoth@apache.org>
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