Add variant type support to ParquetTypeVisitor #14588
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Implement variant(GroupType) method in ParquetTypeVisitor and all subclasses to enable proper handling of Parquet variant logical types during schema conversion and manipulation operations.
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cc @aihuaxu |
aihuaxu
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Nov 16, 2025
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Minor comments. Otherwise looks good.
| return visitList(group, visitor); | ||
| } else if (LogicalTypeAnnotation.mapType().equals(annotation)) { | ||
| return visitMap(group, visitor); | ||
| } else if (LogicalTypeAnnotation.variantType((byte) 1).equals(annotation)) { |
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nit: use Variant.VARIANT_SPEC_VERSION instead of hardcoded 1.
| primitive(29, "v", PrimitiveTypeName.INT32, Repetition.REQUIRED)), | ||
| variant(30, "variant_col_1", Repetition.OPTIONAL), | ||
| variant(null, "variant_col_2", Repetition.REQUIRED), | ||
| list(31, "list_col_6", Repetition.OPTIONAL, variant(32, "v", Repetition.OPTIONAL)), |
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Can we also add a test with a variant in map?
| private Type variant(Integer id, String name, Repetition repetition) { | ||
| GroupBuilder<GroupType> builder = | ||
| org.apache.parquet.schema.Types.buildGroup(repetition) | ||
| .as(org.apache.parquet.schema.LogicalTypeAnnotation.variantType((byte) 1)) |
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Same here. Use Variant.VARIANT_SPEC_VERSION instead of 1.
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Summary
Adds variant type support to
ParquetTypeVisitorand all its subclasses to enable proper handling of Parquet variant logical types during schema operations.Background
This issue surfaced when using
ParquetUtil.footerMetrics(), which callsconvertAndPrune()on the Parquet schema.TestVariantMetricsuseswriteParquet()and callsParquetMetrics.metrics()directly, which bypasses the schema conversion path and didn't expose this gap. Without thevariant()method implementations, variant fields were being skipped during schema conversion, which then caused an NPE inTypeWithSchemaVisitorwhen it tried to process the variant field that was missing from the converted schema.Changes
variant(GroupType)method toParquetTypeVisitorbase classvariant()in allParquetTypeVisitorsubclasses:MessageTypeToType- converts Parquet variant to IcebergVariantTypeApplyNameMapping- applies name mappings to variant fieldsParquetSchemaUtil.HasIds- checks for field IDs in variant typesRemoveIds- removes IDs from variant schemastestVariantTypeConversion()inTestParquetSchemaUtilTesting
New test validates schema conversion from Parquet variant logical type to Iceberg
VariantType.