[HUDI-2763] Metadata table records - support for key deduplication and virtual keys #4447
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…d 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 level relies on the callers to tell about the key field in the schema. - HoodieHFileReader when reading the serialized records back from disk, it materializes the missing keyFields if any. It relies on the callers to tell about the key field in the record schema. - WriteHandles and all its derived classes rely on the table properties for the key field when constructing the file and log readers. This way base file creation, append and merging all work seamlessly irrespective of data or metadata table. - Tests have been added to verify the default virtual keys and key deduplication support for the metadata table records.
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We have decided to go with #4449 approach instead this PR approach. |
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What is the purpose of the pull request
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 level relies on the
callers to tell about the key field in the schema.
HoodieHFileReader when reading the serialized records back from disk,
it materializes the missing keyFields if any. It relies on the callers
to tell about the key field in the record schema.
WriteHandles and all its derived classes rely on the table properties
for the key field when constructing the file and log readers. This way
base file creation, append and merging all work seamlessly irrespective
of data or metadata table.
NOTE: There is a simplified version of this PR at #4449
where the HFile reader and writer would do key deduplication and key materialization only if
the record has the metadata payload schema field 'key' (the hardcoded version).
Verify this pull request
Tests have been added to verify the default virtual keys and key
deduplication support for the metadata table records.
Manually verified the serialized records on the disk are trimmed
off the key field
Committer checklist
Has a corresponding JIRA in PR title & commit
Commit message is descriptive of the change
CI is green
Necessary doc changes done or have another open PR
For large changes, please consider breaking it into sub-tasks under an umbrella JIRA.