Supported PostGIS Function: STNumPoints for Geospatial datatypes (#4510)

[Gopalverma062]

Implement STNumPoints GeoSpatial SQL Function

Implemented the STNumPoints GeoSpatial TSQL function that was previously unsupported in Babelfish.

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What's Changed

Function Implementation

• Added sys.STNumPoints(geog sys.GEOGRAPHY) function in geography.sql
• Delegates to sys.STNumPoints_geography_helper() for valid, non-empty instances
• Function is marked as IMMUTABLE STRICT PARALLEL SAFE for optimal performance

Error Handling

• Returns exception for invalid geography instances
• Returns 0 for empty geography instances
• Returns actual point count for valid instances

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Function Behavior

Input	Output
Valid geography instance	Integer count of points
Empty geography instance	0
Invalid geography instance	Exception

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Examples

Point

DECLARE @point geography;
SET @point = geography::STPointFromText('POINT(-122.34900 47.65100)', 4326);
SELECT @point.STNumPoints() AS NumPoints;
-- Output: 1

LineString

DECLARE @line geography;
SET @line = geography::STGeomFromText('LINESTRING(-122.360 47.656, -122.343 47.656, -122.310 47.690)', 4326);
SELECT @line.STNumPoints() AS NumPoints;
-- Output: 3

Polygon

DECLARE @polygon geography;
SET @polygon = geography::STGeomFromText('POLYGON((-122.358 47.653, -122.348 47.649, -122.348 47.658, -122.358 47.658, -122.358 47.653))', 4326);
SELECT @polygon.STNumPoints() AS NumPoints;
-- Output: 5

Empty Instance

DECLARE @empty geography;
SET @empty = geography::STGeomFromText('POINT EMPTY', 4326);
SELECT @empty.STNumPoints() AS NumPoints;
-- Output: 0

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Issues Resolved

Task: BABEL-6329

Signed-off by: Gopal verma gopalgv@amazon.com

Authored by: Gopal verma gopalgv@amazon.com

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Test Coverage

• Use case based
• Boundary conditions
• Arbitrary inputs
• Negative test cases

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Checklist

• Commits are signed per the DCO using --signoff
• Contribution is under Apache 2.0 and PostgreSQL licenses

By submitting this pull request, I confirm that my contribution is under the terms of the Apache 2.0 and PostgreSQL licenses, and grant any person obtaining a copy of the contribution permission to relicense all or a portion of my contribution to the PostgreSQL License solely to contribute all or a portion of my contribution to the PostgreSQL open source project.