supabase-vector-tile

Use MapLibre's addProtocol to visualize large PostGIS tables, by calling a custom function using the Supabase JS client.

Steps

Use the Overture CLI to download places for a bounding box.

pip install overturemaps
overturemaps download --bbox=103.570233,1.125077,104.115855,1.490957 -f geojson --type=place -o places.geojson

Use ogr2ogr:

You can install GDAL via homebrew brew install gdal or follow the download instructions.

PG_USE_COPY=true ogr2ogr -f pgdump places.sql places.geojson

Enable PostGIS in your Supabase project:

CREATE EXTENSION IF NOT EXISTS "postgis" WITH SCHEMA "extensions";

Import this as the places table in a Supabase database:

psql -h aws-0-us-west-1.pooler.supabase.com -p 5432 -d postgres -U postgres.project-ref < places.sql

Enable Row level security and enable public read access:

ALTER TABLE "public"."places" ENABLE ROW LEVEL SECURITY;

CREATE POLICY "Enable read access for all users" ON "public"."places" FOR SELECT USING (true);

Create a new Postgres Function called mvt by running the SQL in function.sql.

Modify that pl/pgsql function to include only the data you need to visualize, and consider NULLing some columns at low zooms to make tiles smaller.

Edit index.html with your Supabase URL and anonymous key.

You will also need an index on your places table:

CREATE INDEX webmercator ON public.places USING gist (st_transform(wkb_geometry, 3857))