paleolimbot commented on code in PR #240:
URL: https://github.com/apache/parquet-format/pull/240#discussion_r1732011662
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src/main/thrift/parquet.thrift:
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@@ -237,6 +237,98 @@ struct SizeStatistics {
3: optional list<i64> definition_level_histogram;
}
+/**
+ * Interpretation for edges of GEOMETRY logical type, i.e. whether the edge
+ * between points represent a straight cartesian line or the shortest line on
+ * the sphere. It applies to all non-point geometry objects.
+ */
+enum Edges {
+ PLANAR = 0;
+ SPHERICAL = 1;
+}
+
+/**
+ * A custom binary-encoded polygon or multi-polygon to represent a covering of
+ * geometries. For example, it may be a bounding box or an envelope of
geometries
+ * when a bounding box cannot be built (e.g. a geometry has spherical edges,
or if
+ * an edge of geographic coordinates crosses the antimeridian). In addition,
it can
+ * also be used to provide vendor-agnostic coverings like S2 or H3 grids.
+ */
+struct Covering {
+ /**
+ * A type of covering. Currently accepted values: "WKB".
+ */
+ 1: required string kind;
+ /**
+ * A payload specific to kind. Below are the supported values:
+ * - WKB: well-known binary of a POLYGON or MULTI-POLYGON that completely
+ * covers the contents. This will be interpreted according to the same CRS
+ * and edges defined by the logical type.
+ */
+ 2: required binary value;
+}
+
+/**
+ * Bounding box of geometries in the representation of min/max value pair of
+ * coordinates from each axis. Values of Z and M are omitted for 2D geometries.
+ * Filter pushdown on geometries are only safe for planar spatial predicate
+ * but it is recommended that the writer always generates bounding box
statistics,
+ * regardless of whether the geometries are planar or spherical.
Review Comment:
I think the motivation for reccomending that statistics are added is to make
one less geospatial concept that Parquet implementations have to bake in to
their implementation (which would otherwise not care about geospatial details).
That said, if I were writing spherical geometires to Parquet today I would
personally reccomend not writing them (since it would be a waste of time, as
they cannot be used by readers safely).
Maybe some language inbetween might be that "writers CAN include bounding
box statistics for geometries with spherical or planar edges; however, they are
only meaningful for filter pushdown for geometires with planar edges".
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