Column and File Metadata RFC#62
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Add RFC 0062 proposing generic per-column and file-level metadata (opaque map<string,[u8]>) for Iceberg field IDs, Arrow field-metadata round-trip, and file-level sidecar metadata. Co-Authored-By: Claude <noreply@anthropic.com> Signed-off-by: mprammer <martin@spiraldb.com>
robert3005
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Jul 6, 2026
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I think this rfc needs some editing. Overall I think we could go with this option but I thought it's simpler (while not easier) to go with alternative 1. There's a bit of duplication but only places interested in the metadata have to read it.
The solution described in this rfc is the alternative I considered to plain file level metadata but concluded it's complicated without an overwhelming benefit
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Proposes RFC 0062: Column and File Metadata — generic, user-defined metadata at two granularities:
DTypenode but held out of the in-memoryDType, soEq/Hashand every compute/scan/chunk path are unaffected.Both are an opaque
map<string, [u8]>. The change is additive with no file-format version bump, and it unblocks three independent needs: Iceberg field IDs / schema evolution, lossless ArrowFieldmetadata round-trip, and file-level sidecar metadata.iceberg.idrides as a convention, modeled on ORC.Opening as a draft for discussion. The design is grounded against the current
dtype.fbs,footer.fbs, and the Arrow bridge; open questions (in-memory carrier shape, file-level segment granularity, Arrow non-UTF-8 export, reserved namespaces) are called out in the RFC.🤖 Generated with Claude Code