openmaptiles/layers/waterway/merge_waterway.sql

45 wiersze
2.1 KiB
SQL

-- We merge the waterways by name like the highways
-- This helps to drop not important rivers (since they do not have a name)
-- and also makes it possible to filter out too short rivers
-- etldoc: osm_waterway_linestring -> osm_important_waterway_linestring
CREATE TABLE IF NOT EXISTS osm_important_waterway_linestring AS (
SELECT
(ST_Dump(geometry)).geom AS geometry,
name
FROM (
SELECT
ST_LineMerge(ST_Union(geometry)) AS geometry,
name
FROM osm_waterway_linestring
WHERE name <> '' AND waterway = 'river'
GROUP BY name
) AS waterway_union
);
CREATE INDEX IF NOT EXISTS osm_important_waterway_linestring_geometry_idx ON osm_important_waterway_linestring USING gist(geometry);
-- etldoc: osm_important_waterway_linestring -> osm_important_waterway_linestring_gen1
CREATE TABLE IF NOT EXISTS osm_important_waterway_linestring_gen1 AS (
SELECT ST_Simplify(geometry, 60) AS geometry, name
FROM osm_important_waterway_linestring
WHERE ST_Length(geometry) > 1000
);
CREATE INDEX IF NOT EXISTS osm_important_waterway_linestring_gen1_geometry_idx ON osm_important_waterway_linestring_gen1 USING gist(geometry);
-- etldoc: osm_important_waterway_linestring_gen1 -> osm_important_waterway_linestring_gen2
CREATE TABLE IF NOT EXISTS osm_important_waterway_linestring_gen2 AS (
SELECT ST_Simplify(geometry, 100) AS geometry, name
FROM osm_important_waterway_linestring_gen1
WHERE ST_Length(geometry) > 4000
);
CREATE INDEX IF NOT EXISTS osm_important_waterway_linestring_gen2_geometry_idx ON osm_important_waterway_linestring_gen2 USING gist(geometry);
-- etldoc: osm_important_waterway_linestring_gen2 -> osm_important_waterway_linestring_gen3
CREATE TABLE IF NOT EXISTS osm_important_waterway_linestring_gen3 AS (
SELECT ST_Simplify(geometry, 200) AS geometry, name
FROM osm_important_waterway_linestring_gen2
WHERE ST_Length(geometry) > 8000
);
CREATE INDEX IF NOT EXISTS osm_important_waterway_linestring_gen3_geometry_idx ON osm_important_waterway_linestring_gen3 USING gist(geometry);