nastra commented on code in PR #14234: URL: https://github.com/apache/iceberg/pull/14234#discussion_r3137147718
########## format/spec.md: ########## @@ -707,6 +714,119 @@ For `geography` only, xmin (X value of `lower_bounds`) may be greater than xmax When calculating upper and lower bounds for `geometry` and `geography`, null or NaN values in a coordinate dimension are skipped; for example, POINT (1 NaN) contributes a value to X but no values to Y, Z, or M dimension bounds. If a dimension has only null or NaN values, that dimension is omitted from the bounding box. If either the X or Y dimension is missing then the bounding box itself is not produced. +##### Content Stats + +Iceberg v4 introduces content stats which represent stats in a `struct<struct<...>>`. The statistics for fields are tracked inside a nested struct of value counts and bounds (described in the next section). Each field-level statistics struct is a field of the `content_stats` struct, which holds all statistics for table fields. + +###### ID assignment for stats fields + +ID assignment follows a deterministic transform that maps from the **table ID space** to the **metadata ID space**. For a given field ID from the **table ID space** each nested stats struct gets an ID assigned from the **metadata ID space**. +The offset defined in the [field stats types section](#field-stats-types) is added to the stats ID of the enclosing stats struct to calculate IDs for each individual field stats type. + +**Data columns (normal table field ids)** + +Let `table_field_id` be the column's id in the table schema. Allocate a contiguous block of **200** ids per column (`num_supported_stats_per_column = 200`). The stats struct for that column starts at: Review Comment: I'd like to keep table_field_id as I feel this is slightly more descriptive. Also I feel like reading "number of supported stats per column" from that variable name feels better than having the `max` in the name -- 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]
