wgtmac commented on code in PR #240:
URL: https://github.com/apache/parquet-format/pull/240#discussion_r1768761788
##########
src/main/thrift/parquet.thrift:
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@@ -373,6 +467,98 @@ struct JsonType {
struct BsonType {
}
+/**
+ * Physical type and encoding for the geometry type.
+ */
+enum GeometryEncoding {
+ /**
+ * Allowed for physical type: BYTE_ARRAY.
+ *
+ * Well-known binary (WKB) representations of geometries.
+ *
+ * To be clear, we follow the same rule of WKB and coordinate axis order from
+ * GeoParquet [1][2]. It is the ISO WKB supporting XY, XYZ, XYM, XYZM and the
+ * standard geometry types (Point, LineString, Polygon, MultiPoint,
+ * MultiLineString, MultiPolygon, and GeometryCollection).
+ *
+ * This is the preferred encoding for maximum portability. It also supports
+ * GeometryStatistics to be set in the column chunk and page index.
+ *
+ * [1]
https://github.com/opengeospatial/geoparquet/blob/v1.1.0/format-specs/geoparquet.md?plain=1#L92
+ * [2]
https://github.com/opengeospatial/geoparquet/blob/v1.1.0/format-specs/geoparquet.md?plain=1#L155
+ */
+ WKB = 0;
+}
+
+/**
+ * Geometry logical type annotation (added in 2.11.0)
+ */
+struct GeometryType {
+ /**
+ * Physical type and encoding for the geometry type.
+ * Please refer to the definition of GeometryEncoding for more detail.
+ */
+ 1: required GeometryEncoding encoding;
+ /**
+ * Edges of geometry type.
+ * Please refer to the definition of Edges for more detail.
+ */
+ 2: required Edges edges;
+ /**
+ * Coordinate Reference System, i.e. mapping of how coordinates refer to
+ * precise locations on earth. Writers are not required to set this field.
+ * Once crs is set, crs_encoding field below MUST be set together.
+ * For example, "OGC:CRS84" can be set in the form of PROJJSON as below:
+ * {
+ * "$schema": "https://proj.org/schemas/v0.5/projjson.schema.json";,
+ * "type": "GeographicCRS",
+ * "name": "WGS 84 longitude-latitude",
+ * "datum": {
+ * "type": "GeodeticReferenceFrame",
+ * "name": "World Geodetic System 1984",
+ * "ellipsoid": {
+ * "name": "WGS 84",
+ * "semi_major_axis": 6378137,
+ * "inverse_flattening": 298.257223563
+ * }
+ * },
+ * "coordinate_system": {
+ * "subtype": "ellipsoidal",
+ * "axis": [
+ * {
+ * "name": "Geodetic longitude",
+ * "abbreviation": "Lon",
+ * "direction": "east",
+ * "unit": "degree"
+ * },
+ * {
+ * "name": "Geodetic latitude",
+ * "abbreviation": "Lat",
+ * "direction": "north",
+ * "unit": "degree"
+ * }
+ * ]
+ * },
+ * "id": {
+ * "authority": "OGC",
+ * "code": "CRS84"
+ * }
+ * }
+ */
+ 3: optional string crs;
+ /**
+ * Encoding used in the above crs field. It MUST be set if crs field is set.
+ * Currently the only allowed value is "PROJJSON".
+ */
+ 4: optional string crs_encoding;
+ /**
+ * Additional informative metadata.
+ * GeoParquet could offload its column metadata in a JSON-encoded UTF-8
string:
+ *
https://github.com/opengeospatial/geoparquet/blob/v1.1.0/format-specs/geoparquet.md?plain=1#L46
Review Comment:
The original intention to use a `string` field is to store metadata from
GeoParquet which is currently a json string:
https://github.com/opengeospatial/geoparquet/blob/main/examples/example_metadata.json
and it might be easier for GeoParquet to serialize and deserialize it. I will
switch to `optional list<KeyValue> key_value_metadata` since there is no
objection.
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