rdblue commented on code in PR #585: URL: https://github.com/apache/parquet-format/pull/585#discussion_r3399122146
########## LogicalTypes.md: ########## @@ -635,7 +635,76 @@ The type has two type parameters: The sort order used for `GEOGRAPHY` is undefined. When writing data, no min/max statistics should be saved for this type and if such non-compliant statistics -are found during reading, they must be ignored. +are found during reading, they must be ignored. + +### FILE + +`FILE` annotates a group that represents a reference to an external file, along with +the minimum metadata required to read it. It is intended for use cases such as +storing file inventories, manifests, and unstructured data references (e.g., images +or audio files stored in object storage). + +The annotated group must contain the following fields, identified by name. Field IDs +may also be used for projection: + +| Field | Type | Required | +|----------|--------|----------| +| `path` | STRING | Yes | +| `size` | INT64 | No | +| `offset` | INT64 | No | +| `etag` | STRING | No | + +#### Fields + +##### path + +An opaque path string to the referenced file (e.g., `s3://bucket/file.jpg`). No special +encoding (e.g., URI encoding) is applied. This is the only required field. + +##### size + +The length of the content in bytes. Must be zero or a positive integer if provided. +A value of 0 indicates an empty file. If not provided, the length of the referenced +content is unknown and the entirety of the content can be read. + +##### offset + +A byte offset indicating the start of a content slice within the referenced file. +If not provided, readers must treat the value as 0. +If provided and non-zero, readers must seek to this offset and read `size` bytes to retrieve the referenced data. +If `offset` is provided, `size` must also be provided. + +##### etag + +An eTag value provided by the storage system (e.g., from S3 or Azure Blob Storage). +Can be used to detect whether the referenced file has been updated. If the reference +points to a byte range within a file, the eTag applies to the entire file. Review Comment: What should writers do when there is no etag provided by the system, like in a local FS? What about systems that have checksums but don't call them etags? -- 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]
