Add a native Box2D type for bounding boxes

[jiayuasu]

Tracking issue for adding a native Box2D bounding-box type to Sedona. Each child issue corresponds to one PR.

Background

Sedona has no first-class bounding-box value type. ST_Envelope returns a polygon Geometry, and users reconstruct bboxes via ST_MinX / ST_MaxX / ST_MinY / ST_MaxY. This is awkward for common operations — bbox-from-geometry, dataset extent, GeoParquet covering columns, partition pruning.

Sister project apache/sedona-db has an internal BoundingBox (rust/sedona-geometry/src/bounding_box.rs) but doesn't expose it as a SQL type. PostGIS has box2d / box3d. GeoParquet 1.1 standardizes a struct<xmin, ymin, xmax, ymax> bbox covering column, which Sedona already reads/writes as a raw struct (GeoParquetMetaData.scala, GeoParquetSpatialFilter.scala).

Plan

Add Box2D as a native value type. Phase 1 covers the Spark/JVM side, Python and Flink mirrors, and GeoParquet writer integration. Box3D and geography bboxes are out of scope and tracked as follow-ups.

Type

Box2DUDT is a struct-backed UDT with sqlType = struct<xmin: double, ymin: double, xmax: double, ymax: double> (all non-nullable). Struct-backed (not binary-backed) so values round-trip natively to Parquet and align zero-copy with GeoParquet 1.1 bbox covering columns.

Field names match the GeoParquet 1.1 spec and sedona-db's GeoParquet writer.

A Box2D value is always a valid finite bbox. Absence of a bbox (e.g. ST_Box2D of an empty geometry, ST_Extent over zero rows) is represented by SQL NULL at the column level, not by an in-band sentinel. This matches PostGIS behavior (where Box2D(POINT EMPTY) returns NULL) and leaves xmin > xmax reserved for a future antimeridian-wraparound semantics on geography bboxes (cf. sedona-db's WraparoundInterval, S2's S2LatLngRect).

Split Box2D / Box3D rather than a unified type with optional Z. Reasons:

1. GeoParquet 1.1 covering columns are 2D-only. A dedicated Box2D matches the spec bit-for-bit.
2. Storage: 32 bytes/row vs. ~56 bytes for a unified type with nullable Z. Material cost on ST_Extent shuffles.
3. Static dispatch for dimension-specific functions (ST_Area(box2d) vs ST_Volume(box3d)).
4. PostGIS familiarity.

Box3D is deferred until a concrete need (point clouds, BIM, voxel data) lands.

SQL surface (Phase 1)

Function	Signature
ST_Box2D(geom)	Geometry → Box2D (NULL for empty geom)
ST_MakeBox2D(point, point)	(Point, Point) → Box2D
ST_Extent(geom)	aggregate Geometry → Box2D (NULL over zero rows)
ST_XMin / ST_XMax / ST_YMin / ST_YMax(box2d)	Box2D → Double (overload existing accessors)
CAST(box2d AS geometry)	Box2D → Polygon
ST_AsText(box2d)	Box2D → 'BOX(x1 y1, x2 y2)'

ST_Envelope keeps returning a polygon Geometry (no break). ST_Envelope_Aggr is left untouched.

Sub-issues

Foundation

• [GH-2877] Add Box2D type and Box2DUDT #2878 — Box2D value class + Box2DUDT (struct-backed) + UDT registration + Python Box2DType

SQL surface

• Implement ST_Box2D(geom) scalar function #2881 — ST_Box2D(geom) scalar
• Overload ST_XMin/XMax/YMin/YMax for Box2D #2882 — ST_XMin / XMax / YMin / YMax(box2d) accessor overloads
• Implement ST_MakeBox2D(p1, p2) scalar constructor #2883 — ST_MakeBox2D(p1, p2) scalar constructor
• Implement ST_Extent aggregate (returns Box2D) #2884 — ST_Extent(geom) aggregate
• Add CAST(box2d AS geometry) and ST_AsText(box2d) #2885 — CAST(box2d AS geometry) and ST_AsText(box2d)

Storage

• Emit Box2D columns as GeoParquet 1.1 bbox covering columns #2886 — Emit Box2D columns as GeoParquet 1.1 bbox covering columns (Float32 + conservative rounding)

Cross-language bindings

• Python bindings for Box2D scalar functions and ST_Extent #2887 — Python bindings for the Phase 1 surface
• Flink bindings for Box2D scalar functions and ST_Extent #2888 — Flink bindings for the Phase 1 surface

Out of scope (future phases)

• ST_Expand(box, dx, dy)
• Box predicates (ST_BoxIntersects, ST_BoxContains)
• Implicit geometry → box2d cast
• Box3D, ST_3DExtent, ST_3DMakeBox, ST_ZMin/ZMax
• ST_Box2dFromGeoHash, ST_EstimatedExtent
• Reader-side auto-materialization of GeoParquet bbox covering columns as Box2D
• Geography bboxes (likely path: reuse Box2D with antimeridian-wraparound semantics on the X axis, encoded via xmin > xmax)

Coordination with sedona-db

sedona-db's GeoParquet writer uses xmin/ymin/xmax/ymax (Float32), but its st_analyze_agg returns minx/miny/maxx/maxy (Float64). Worth aligning on the Parquet-spec naming as part of this work.