wgtmac commented on code in PR #240:
URL: https://github.com/apache/parquet-format/pull/240#discussion_r1722617837
##########
src/main/thrift/parquet.thrift:
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@@ -373,6 +462,56 @@ 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. It supports 2D or
+ * 3D geometries of the standard geometry types (Point, LineString, Polygon,
+ * MultiPoint, MultiLineString, MultiPolygon, and GeometryCollection). This
+ * is the preferred option for maximum portability.
+ *
+ * This encoding enables GeometryStatistics to be set in the column chunk
+ * and page index.
+ */
+ WKB = 0;
+
+ // TODO: add native encoding from GeoParquet/GeoArrow
+}
+
+/**
+ * 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 polygon.
+ */
+ 2: required Edges edges;
+ /**
+ * Coordinate Reference System, i.e. mapping of how coordinates refer to
+ * precise locations on earth.
+ */
+ 3: optional string crs;
+ /**
+ * Encoding used in the above crs field.
+ * Currently the only allowed value is "PROJJSON".
+ */
+ 4: optional string crs_encoding;
+ /**
+ * Additional informative metadata.
+ * It can be used by GeoParquet to offload some of the column metadata.
+ */
+ 5: optional binary metadata;
Review Comment:
I found an issue with the type of this `metadata` field during PoC:
https://github.com/apache/arrow/pull/43196#discussion_r1720791233
If we make it a `binary` type, the writer impl is free to write whatever it
likes, be it a JSON string (like what GeoParquet does) or binary-serialized
metadata (e.g. in ProtoBuf or Base64). However, the reader impl is painful
because it cannot assume whether it is a JSON string or something else.
Should we change it to `string` type and observe the practice of GeoParquet
spec, at least saying it is a valid JSON string?
@paleolimbot @jiayuasu @zhangfengcdt @jorisvandenbossche
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