Fix errors and inconsistencies in Variant format documentation#574
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iemejia wants to merge 1 commit into
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Fix errors and inconsistencies in Variant format documentation#574iemejia wants to merge 1 commit into
iemejia wants to merge 1 commit into
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VariantEncoding.md:
- Fix BINARY -> BYTE_ARRAY (BINARY is not a Parquet physical type)
- Add note on decimal little-endian vs big-endian difference
- Fix decimal implied-precision formula for val <= 0
- Label undocumented reserved bits in metadata/object/array headers
- Make sorted_strings description consistent across three definitions
- Use INT(N, true) notation consistent with LogicalTypes.md
- Hyphenate compound adjectives ("3 byte" -> "3-byte", etc.)
VariantShredding.md:
- Fix Python syntax error: iterating dict yields keys only;
add .items() for (name, field) unpacking
- Replace BINARY with BYTE_ARRAY
- Fix comma -> colon inside JSON-like literal in table cell
- Remove trailing space inside backticks in table header
- Use INT(N, true) notation consistent with LogicalTypes.md
alamb
reviewed
Jun 3, 2026
| `sorted_strings` is a 1-bit value indicating whether dictionary strings are sorted and unique. | ||
| `offset_size_minus_one` is a 2-bit value providing the number of bytes per dictionary size and offset field. | ||
| The actual number of bytes, `offset_size`, is `offset_size_minus_one + 1`. | ||
| Bit 5 (marked `R`) is reserved; it must be set to 0 by writers and ignored by readers. |
Contributor
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THis "must be set to 0 by writers" seems to me to change the spec. Previously it was not specified. I think we should leave it as unspecified -- it would be nice to clarify it should be ignored by readers
Suggested change
| Bit 5 (marked `R`) is reserved; it must be set to 0 by writers and ignored by readers. | |
| Bit 5 (marked `R`) is reserved; it must be ignored by readers. |
| The actual number of bytes is computed as `field_offset_size_minus_one + 1` and `field_id_size_minus_one + 1`. | ||
| `is_large` is a 1-bit value that indicates how many bytes are used to encode the number of elements. | ||
| If `is_large` is `0`, 1 byte is used, and if `is_large` is `1`, 4 bytes are used. | ||
| Bit 5 (marked `R`) is reserved; it must be set to 0 by writers and ignored by readers. |
Contributor
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same comment as above -- I don't think we should mandate setting to 0
| The actual number of bytes is computed as `field_offset_size_minus_one + 1`. | ||
| `is_large` is a 1-bit value that indicates how many bytes are used to encode the number of elements. | ||
| If `is_large` is `0`, 1 byte is used, and if `is_large` is `1`, 4 bytes are used. | ||
| Bits 5-3 (marked `RRR`) are reserved; they must be set to 0 by writers and ignored by readers. |
| | Float | float | `14` | FLOAT | IEEE little-endian | | ||
| | Binary | binary | `15` | BINARY | 4 byte little-endian size, followed by bytes | | ||
| | String | string | `16` | STRING | 4 byte little-endian size, followed by UTF-8 encoded bytes | | ||
| | Binary | binary | `15` | BYTE_ARRAY | 4-byte little-endian size, followed by bytes | |
Contributor
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Double checked against https://parquet.apache.org/docs/file-format/types/
| | boolean | BOOLEAN | | | ||
| | int8 | INT32 | INT(8, signed=true) | | ||
| | int16 | INT32 | INT(16, signed=true) | | ||
| | int8 | INT32 | INT(8, true) | |
Contributor
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I found the signed=true easier to understand to be honest, but this is technically accurate too
| object_fields = { | ||
| name: construct_variant(metadata, field.value, field.typed_value) | ||
| for (name, field) in typed_value | ||
| for (name, field) in typed_value.items() |
Contributor
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Why this change? Does the original not work? Did you test that this still works after the proposed change?
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Summary
Fix bugs, terminology errors, and inconsistencies in the Variant format specification documents.
Changes
VariantEncoding.md
sorted_stringsdescription consistent across three definitionsINT(N, true)notation consistent with LogicalTypes.mdVariantShredding.md
.items()for (name, field) unpackingINT(N, true)notation consistent with LogicalTypes.mdValidation
No semantic/behavioral changes to the format specification. All fixes are documentation-only.
Split from #572 for easier review.