68 lines
2.7 KiB
PL/PgSQL
68 lines
2.7 KiB
PL/PgSQL
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-- We merge the waterways by name like the highways
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-- This helps to drop not important rivers (since they do not have a name)
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-- and also makes it possible to filter out too short rivers
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-- etldoc: osm_waterway_linestring -> osm_important_waterway_linestring
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CREATE MATERIALIZED VIEW osm_important_waterway_linestring AS (
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SELECT
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(ST_Dump(geometry)).geom AS geometry,
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name
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FROM (
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SELECT
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ST_LineMerge(ST_Union(geometry)) AS geometry,
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name
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FROM osm_waterway_linestring
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WHERE name <> '' AND waterway = 'river'
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GROUP BY name
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) AS waterway_union
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);
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CREATE INDEX IF NOT EXISTS osm_important_waterway_linestring_geometry_idx ON osm_important_waterway_linestring USING gist(geometry);
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-- etldoc: osm_important_waterway_linestring -> osm_important_waterway_linestring_gen1
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CREATE MATERIALIZED VIEW osm_important_waterway_linestring_gen1 AS (
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SELECT ST_Simplify(geometry, 60) AS geometry, name
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FROM osm_important_waterway_linestring
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WHERE ST_Length(geometry) > 1000
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);
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CREATE INDEX IF NOT EXISTS osm_important_waterway_linestring_gen1_geometry_idx ON osm_important_waterway_linestring_gen1 USING gist(geometry);
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-- etldoc: osm_important_waterway_linestring_gen1 -> osm_important_waterway_linestring_gen2
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CREATE MATERIALIZED VIEW osm_important_waterway_linestring_gen2 AS (
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SELECT ST_Simplify(geometry, 100) AS geometry, name
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FROM osm_important_waterway_linestring_gen1
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WHERE ST_Length(geometry) > 4000
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);
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CREATE INDEX IF NOT EXISTS osm_important_waterway_linestring_gen2_geometry_idx ON osm_important_waterway_linestring_gen2 USING gist(geometry);
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-- etldoc: osm_important_waterway_linestring_gen2 -> osm_important_waterway_linestring_gen3
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CREATE MATERIALIZED VIEW osm_important_waterway_linestring_gen3 AS (
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SELECT ST_Simplify(geometry, 200) AS geometry, name
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FROM osm_important_waterway_linestring_gen2
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WHERE ST_Length(geometry) > 8000
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);
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CREATE INDEX IF NOT EXISTS osm_important_waterway_linestring_gen3_geometry_idx ON osm_important_waterway_linestring_gen3 USING gist(geometry);
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--- Triggers
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CREATE OR REPLACE FUNCTION refresh_osm_important_waterway_linestring() RETURNS trigger AS
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$BODY$
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BEGIN
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REFRESH MATERIALIZED VIEW osm_important_waterway_linestring;
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REFRESH MATERIALIZED VIEW osm_important_waterway_linestring_gen1;
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REFRESH MATERIALIZED VIEW osm_important_waterway_linestring_gen2;
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REFRESH MATERIALIZED VIEW osm_important_waterway_linestring_gen3;
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RETURN null;
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END;
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$BODY$
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language plpgsql;
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CREATE TRIGGER trigger_refresh_osm_important_waterway_linestring
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AFTER INSERT OR UPDATE OR DELETE ON osm_waterway_linestring
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FOR EACH STATEMENT
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EXECUTE PROCEDURE refresh_osm_important_waterway_linestring();
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