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“What is a port?” · “Why is my code erroring?”
A PostGIS table stores geometry as a column type, not a file on disk, so many analysts can query and edit the same features at once.
PostGIS: Geometry in the Database
A PostGIS table stores geometry as a column type, not a file on disk, so many analysts can query and edit the same features at once.
Querying Geometry with ST_ Functions
PostGIS adds ST_ functions to ordinary SQL, so a SELECT can measure, inspect, reproject, and build geometry the same way it already filters rows.
Spatial Joins with ST_Intersects and ST_DWithin
A spatial join matches rows from two tables by where their geometries sit relative to each other, not by a shared ID column, and PostGIS supplies the predicates that do the matching.
GiST Indexes and Fast Spatial Queries
A GiST index lets PostGIS discard geometries whose bounding boxes cannot possibly match before it ever tests the real shapes, turning a spatial join from a full scan into a handful of checks.
A Full Spatial Analysis in SQL
One query buffers every park by 500 meters, joins that buffer to census blocks, and sums population to answer what share of a city lives within walking distance of one, all without leaving the database.