‹ back to GIS Glossary

Spatial Query

Definition

A spatial query retrieves or relates data based on spatial relationships—intersection, containment, proximity, distance, and topology. Spatial databases implement predicates like ST_Intersects, ST_Within, ST_Touches, buffers, and nearest-neighbor searches using indexes (R-tree, GiST). Correct spatial queries depend on coordinate reference systems, geometry validity, and precision models to avoid ambiguous outcomes.

Application

Analysts find parcels within floodplains, customers within drive-time bands, utilities crossing construction sites, or crimes near schools. Developers power location-based features in apps: ‘what’s near me’, geofencing, and routing constraints. Auditors and regulators run compliance checks by spatial joins at scale.

FAQ

How do coordinate systems affect spatial query results?

Distance and area thresholds must use appropriate projected units; performing distance queries in degrees can return nonsensical results near the poles.

What is the role of geometry validity before querying?

Self-intersections, ring orientation errors, or slivers cause unpredictable predicates. Run validity checks and fix geometries to ensure reliable joins.

How can you speed up massive many-to-many spatial joins?

Use spatial indexes on both tables, tile data into manageable partitions, and pre-filter with bounding boxes before precise predicates.

What precautions help when buffering features for selection?

Choose buffer units consistent with the CRS, dissolve where appropriate, and be mindful that buffering polygons with holes may create unexpected shapes without careful rules.