feat(geography): explicit GEOMETRY <-> GEOGRAPHY casts#175
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estebanzimanyi wants to merge 9 commits into
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feat(geography): explicit GEOMETRY <-> GEOGRAPHY casts#175estebanzimanyi wants to merge 9 commits into
estebanzimanyi wants to merge 9 commits into
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Adds doc/geography-boundary.md as the canonical write-up of how MobilityDuck represents geodetic geography values across the MEOS<->DuckDB columnar boundary. Covers: - The closed-algebra property in MEOS and why it doesn't survive the columnar boundary without a dedicated LogicalType. - The GEOGRAPHY LogicalType registration: a BLOB alias carrying MEOS-WKB with the geodetic flag preserved in the type tag, with no dependence on a DuckDB upstream change or on a third-party duckdb-geography extension. - The I/O surface (ST_GeogFromText, ST_AsText, ST_AsBinary, ST_GeogFromBinary), all thin shims over existing MEOS exports. - The operation surface (length, area, eIntersects, etc.) — every call delegates to a MEOS function that takes geodetic input and returns the correct type; DuckDB never sees a non-geodetic representation of a geodetic value during a computation. - The complete inter-type cast matrix (GEOMETRY / GEOGRAPHY / TGEOGPOINT / TGEOMPOINT), mirroring the MobilityDB-on-Postgres surface. - TemporalParquet round-trip preservation via the footer JSON's base_type / geodetic / srid fields. - Pitfalls a binding implementation must avoid (using ST_GeomFromText to construct a GEOGRAPHY value, reusing DuckDB Spatial Cartesian functions on a GEOGRAPHY blob, stripping the geodetic flag in Parquet output, etc.). - Current state of the implementation and the bounded pending work (~430 LoC, single PR) to register the LogicalType, the I/O UDFs, the casts, and the tests. README updated with a single-paragraph pointer in the parity-gaps neighbourhood so adopters land here when looking for geography semantics on the DuckDB side.
…yDB#168 design) Foundation for the DuckDB GEOGRAPHY boundary documented in MobilityDB#168. Registers the LogicalType alias (BLOB carrying MEOS-WKB with the geodetic flag preserved in the type tag) so DuckDB columns can be declared as `GEOGRAPHY`. Files: - src/include/geo/geography.hpp — GeographyType struct declaration (LogicalType getter + RegisterType entry point), mirroring the shape of StboxType / TgeogpointType. - src/geo/geography.cpp — implementation: BLOB with SetAlias ("GEOGRAPHY") and loader.RegisterType("GEOGRAPHY", GEOGRAPHY()). - src/mobilityduck_extension.cpp — Load() wires GeographyType::RegisterType after StboxType. - CMakeLists.txt — adds src/geo/geography.cpp to EXTENSION_SOURCES. - test/sql/geography.test — CREATE TABLE / INSERT NULL / SELECT round-trip sanity test verifying the alias is registered. Follow-up PRs build on this: - I/O UDFs: ST_GeogFromText, ST_AsText, ST_AsBinary, ST_GeogFromBinary (~150 LoC) - Casts: GEOMETRY <-> GEOGRAPHY, GEOGRAPHY <-> TGEOGPOINT (~80 LoC) - Operations: length / area / eIntersects / nearestApproachDistance on GEOGRAPHY columns dispatching to MEOS geog_* functions - Tests: round-trip, cast-matrix, numeric checks against MEOS-on-Postgres ground truth (~200 LoC) Total target surface (from MobilityDB#168): ~430 LoC across the four follow-ups. Each follow-up is independently mergeable on top of this skeleton. Stacks on MobilityDB#168 (geography boundary design doc).
… PR MobilityDB#161) Cherry-picked from open PR MobilityDB#161 so this PR's CI compiles against the vcpkg-installed MEOS, which exposes 'meosType' (pre-consolidation) not 'MeosType'. When MobilityDB#161 reaches main, this commit collapses to a no-op on rebase.
…MobilityDB#136) Cherry-picked from open PR MobilityDB#136 so this PR's amd64 Linux test phase goes green before MobilityDB#136 lands. When MobilityDB#136 reaches main, this rebase collapses to a no-op.
…en PR MobilityDB#140) Cherry-picked from open PR MobilityDB#140 so this PR's osx_amd64 / osx_arm64 / wasm builds compile. On macOS LP64 and Wasm/emscripten, int64 (long) and int64_t (long long) are the same width but distinct types; clang rejects passing bigint_to_set where Set *(*)(int64_t) is expected. The cast is a no-op on Linux. When MobilityDB#140 reaches main, this rebase collapses to a no-op.
The first geography.cpp landing had a 'reference to Interval is ambiguous' arm64 build error because the duckdb header chain pulled in duckdb::Interval before meos.h's extern "C" block scoped MEOS's Interval to global linkage. Reorder includes to put meos_wrapper_simple.hpp first, mirroring the existing static-type pattern in stbox.cpp / tgeogpoint.cpp.
…e_ptr<FunctionData> in Copy()
GCC + DuckDB 1.4.4's unique_ptr does not implicitly convert
derived->base, so 'return r;' in BinsBindData::Copy() fails to compile:
error: could not convert 'r' from 'unique_ptr<duckdb::{anonymous}::BinsBindData,...>'
to 'unique_ptr<duckdb::FunctionData,...>'
Use duckdb's unique_ptr_cast helper (from duckdb/common/helper.hpp) to
do the conversion explicitly, matching the canonical pattern used by
DuckDB core (e.g. table_scan.hpp's TableScanBindData::Copy()). No
behaviour change; the move is exactly what the implicit conversion
would have done if the compiler accepted it.
…romBinary Four I/O UDFs over the GEOGRAPHY LogicalType, each a thin shim over a MEOS export: - ST_GeogFromText(VARCHAR) -> GEOGRAPHY via geog_in - ST_AsText(GEOGRAPHY) -> VARCHAR via geo_as_ewkt - ST_AsBinary(GEOGRAPHY) -> BLOB via geo_as_ewkb - ST_GeogFromBinary(BLOB) -> GEOGRAPHY via geo_from_ewkb The BLOB payload of a GEOGRAPHY value is the raw GSERIALIZED struct (varlena VARSIZE bytes), which preserves the geodetic flag in the type tag across the DuckDB columnar boundary; standard EWKB does not carry the flag, so ST_GeogFromBinary re-sets it explicitly via MEOS_FLAGS_SET_GEODETIC. test/sql/geography.test covers EWKT round-trip + EWKB round-trip on POINT and LINESTRING. Step 1 of the ~430-LoC GEOGRAPHY follow-up roadmap. Casts (GEOMETRY <-> GEOGRAPHY, GEOGRAPHY <-> TGEOGPOINT) and operations (length / area / eIntersects / nearestApproachDistance) land in follow-up PRs. See doc/geography-boundary.md.
Two cast functions, both reusing the same GSERIALIZED with the geodetic
flag toggled:
- GEOMETRY -> GEOGRAPHY: lift via GeometryToGSerialized, set the
geodetic flag on the resulting GSERIALIZED, store as GEOGRAPHY BLOB.
- GEOGRAPHY -> GEOMETRY: deserialize the GEOGRAPHY BLOB, clear the
geodetic flag, emit sgl GEOMETRY via GSerializedToGeometry.
DuckDB-Spatial GEOMETRY has no SRID slot, so a round-trip via GEOMETRY
drops the SRID prefix; an EWKT / EWKB round-trip preserves SRID. The
EWKT and EWKB paths are already tested in test/sql/geography.test.
The existing TGEOGPOINT(GEOMETRY, …) constructors transparently accept
GEOGRAPHY arguments via the new implicit cast — no extra overloads
needed for the temporal geographic family.
Step 2 of the GEOGRAPHY follow-up roadmap. Operations (length / area /
eIntersects / nearestApproachDistance) and the full test matrix land in
steps 3 and 4.
test/sql/geography.test: 9 assertions pass locally.
This was referenced May 20, 2026
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Summary
Two cast functions for the
GEOGRAPHYLogicalType (registered in #169), each reusing the sameGSERIALIZEDwith the geodetic flag toggled:GEOMETRY -> GEOGRAPHYGeometryToGSerializedlifts the sgl GEOMETRY to aGSERIALIZED; the geodetic flag is set explicitly viaMEOS_FLAGS_SET_GEODETIC(gs->gflags, true).GEOGRAPHY -> GEOMETRYGSERIALIZED; the geodetic flag is cleared;GSerializedToGeometryemits sgl GEOMETRY.SRID handling
DuckDB-Spatial GEOMETRY has no SRID slot, so a round-trip via GEOMETRY drops the SRID prefix. The EWKT / EWKB round-trip (covered by step 1's
ST_AsTextandST_AsBinary) preserves SRID.TGEOGPOINT(GEOGRAPHY, …) is transparent
The existing
TGEOGPOINT(GEOMETRY, …)constructor overloads transparently accept GEOGRAPHY arguments via the new implicit cast — no extra explicit overloads are needed.Step in the GEOGRAPHY roadmap
This is step 2 of 4 in
doc/geography-boundary.md:ST_Length/ST_Area/eIntersects/nearestApproachDistanceoverGEOGRAPHY— ~50 LoCTests
test/sql/geography.testnow covers:POINTandLINESTRINGPOINTGEOMETRY -> GEOGRAPHYexplicit castGEOGRAPHY -> GEOMETRY -> GEOGRAPHYround-trip (SRID dropped, value preserved)Local: 9 assertions pass.
Depends on
GEOGRAPHYLogicalTypeST_AsText/ST_GeogFromTextused to drive the test)