rdblue commented on code in PR #17918: URL: https://github.com/apache/iceberg/pull/17918#discussion_r4222002713
########## format/spec.md: ########## @@ -322,6 +325,36 @@ For `geography` types, an additional parameter A specifies an algorithm for inte * `andoyer`: Thomas, Paul D. Mathematical models for navigation systems. US Naval Oceanographic Office, 1965. * `karney`: [Karney, Charles FF. "Algorithms for geodesics." Journal of Geodesy 87 (2013): 43-55](https://link.springer.com/content/pdf/10.1007/s00190-012-0578-z.pdf), and [GeographicLib](https://geographiclib.sourceforge.io/) +#### File Type + +A **`file`** represents a range of bytes that may be stored inline as a value or a reference to an external file. The `file` type and its value semantics are defined by the `FILE` logical type in the [Parquet project](https://github.com/apache/parquet-format/blob/master/LogicalTypes.md#file). + +A `file` value has a fixed set of sub-fields. The sub-fields are implicit: they are not represented in the Iceberg schema and cannot be added, removed, reordered, or promoted. Their names, types, and field-ID offsets are: + +| Sub-field | ID offset | Type | +|----------------|-----------|----------| +| `uri` | +1 | `string` | +| `offset` | +2 | `long` | +| `size` | +3 | `long` | +| `content_type` | +4 | `string` | +| `checksum` | +5 | `string` | +| `inline` | +6 | `binary` | + +Adding a `file` field reserves the root field's ID plus six consecutive IDs for its sub-fields, assigned by the offsets above. Writers must advance `last-column-id` past all seven IDs and must not assign these IDs to any other field. Review Comment: I think this is a good point. To fix it, we should not specify how to change things, we should specify what is valid. > A `file` field uses its field ID and the next six consecutive IDs for its sub-fields. Adding a `file` field must advance `last-column-id` to account for all 7 IDs. (_Second sentence here is probably optional_) -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
