mapleFU commented on code in PR #469: URL: https://github.com/apache/parquet-format/pull/469#discussion_r1827536763
########## LogicalTypes.md: ########## @@ -709,13 +709,18 @@ to values. `MAP` must annotate a 3-level structure: * The outer-most level must be a group annotated with `MAP` that contains a single field named `key_value`. The repetition of this level must be either - `optional` or `required` and determines whether the list is nullable. + `optional` or `required` and determines whether the map is nullable. * The middle level, named `key_value`, must be a repeated group with a `key` - field for map keys and, optionally, a `value` field for map values. + field for map keys and, optionally, a `value` field for map values. It must + not contain any other values. * The `key` field encodes the map's key type. This field must have - repetition `required` and must always be present. + repetition `required` and must always be present. I must be placed at the 0th Review Comment: I must be -> It must be? ########## LogicalTypes.md: ########## @@ -709,13 +709,18 @@ to values. `MAP` must annotate a 3-level structure: * The outer-most level must be a group annotated with `MAP` that contains a single field named `key_value`. The repetition of this level must be either - `optional` or `required` and determines whether the list is nullable. + `optional` or `required` and determines whether the map is nullable. * The middle level, named `key_value`, must be a repeated group with a `key` - field for map keys and, optionally, a `value` field for map values. + field for map keys and, optionally, a `value` field for map values. It must + not contain any other values. * The `key` field encodes the map's key type. This field must have - repetition `required` and must always be present. + repetition `required` and must always be present. I must be placed at the 0th + position of the `key_value` group. It is suggested to use a primitive as the + type. * The `value` field encodes the map's value type and repetition. This field can - be `required`, `optional`, or omitted. + be `required`, `optional`, or omitted. It must be placed at the 1st position + of the `key_value` group if present. In case of not present, the map can be + either represented with all null values or as a set of keys. Review Comment: I just realized that the value can be emitted 🤔 When would a case be like that? ########## LogicalTypes.md: ########## @@ -741,18 +746,19 @@ keys. It is required that the repeated group of key-value pairs is named `key_value` and that its fields are named `key` and `value`. However, these names may not be used in existing data and should not be enforced as errors when reading. +(`key` and `value` can be identified by their position in case of misnaming.) Some existing data incorrectly used `MAP_KEY_VALUE` in place of `MAP`. For backward-compatibility, a group annotated with `MAP_KEY_VALUE` that is not contained by a `MAP`-annotated group should be handled as a `MAP`-annotated -group. +group. `MAP_KEY_VALUE` may be used for the `kay_value` group. Review Comment: ```suggestion group. `MAP_KEY_VALUE` may be used for the `key_value` group. ``` ? -- 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]
