How would you perform a radius search to find nearby addresses?

• A. Use a general search by textual matching and then filter results by distance manually.
• B. Use a geospatial index (e.g., PostGIS) with latitude/longitude; perform distance calculations within a defined radius; optimize with bounding-box filters.
• C. Compute distance by approximate coordinates for all records without an index.
• D. Limit the search to postal codes only and ignore coordinates.

Answer: (B)

Radius search relies on having coordinates stored for each address and using a geospatial index to query within a distance from a point. By placing addresses in a spatial index (like PostGIS with a geography or geometry column), you can run a radius query that first narrows candidates with a bounding-box filter and then computes exact distances to confirm which addresses lie inside the defined radius. Using latitude/longitude enables accurate distance calculations over the earth’s surface, and the index makes this fast and scalable rather than scanning every record. Textual searches with manual distance checks are slow and unscalable, computing distance for all records without an index is impractical, and limiting to postal codes ignores coordinates and can miss nearby addresses across code boundaries.