Nominatim/lib-sql/functions/ranking.sql

-- SPDX-License-Identifier: GPL-2.0-only
--
-- This file is part of Nominatim. (https://nominatim.org)
--
-- Copyright (C) 2022 by the Nominatim developer community.
-- For a full list of authors see the git log.

-- Functions related to search and address ranks

-- Return an approximate search radius according to the search rank.
CREATE OR REPLACE FUNCTION reverse_place_diameter(rank_search SMALLINT)
  RETURNS FLOAT
  AS $$
BEGIN
  IF rank_search <= 4 THEN
    RETURN 5.0;
  ELSIF rank_search <= 8 THEN
    RETURN 1.8;
  ELSIF rank_search <= 12 THEN
    RETURN 0.6;
  ELSIF rank_search <= 17 THEN
    RETURN 0.16;
  ELSIF rank_search <= 18 THEN
    RETURN 0.08;
  ELSIF rank_search <= 19 THEN
    RETURN 0.04;
  END IF;

  RETURN 0.02;
END;
$$
LANGUAGE plpgsql IMMUTABLE;


-- Return an approximate update radius according to the search rank.
CREATE OR REPLACE FUNCTION update_place_diameter(rank_search SMALLINT)
  RETURNS FLOAT
  AS $$
BEGIN
  -- postcodes
  IF rank_search = 11 or rank_search = 5 THEN
    RETURN 0.05;
  -- anything higher than city is effectively ignored (polygon required)
  ELSIF rank_search < 16 THEN
    RETURN 0;
  ELSIF rank_search < 18 THEN
    RETURN 0.1;
  ELSIF rank_search < 20 THEN
    RETURN 0.05;
  ELSIF rank_search = 21 THEN
    RETURN 0.001;
  ELSIF rank_search < 24 THEN
    RETURN 0.02;
  ELSIF rank_search < 26 THEN
    RETURN 0.002;
  ELSIF rank_search < 28 THEN
    RETURN 0.001;
  END IF;

  RETURN 0;
END;
$$
LANGUAGE plpgsql IMMUTABLE;

-- Compute a base address rank from the extent of the given geometry.
--
-- This is all simple guess work. We don't need particularly good estimates
-- here. This just avoids to have very high ranked address parts in features
-- that span very large areas (or vice versa).
CREATE OR REPLACE FUNCTION geometry_to_rank(search_rank SMALLINT, geometry GEOMETRY, country_code TEXT)
  RETURNS SMALLINT
  AS $$
DECLARE
  area FLOAT;
BEGIN
  IF ST_GeometryType(geometry) in ('ST_Polygon','ST_MultiPolygon') THEN
      area := ST_Area(geometry);
  ELSIF ST_GeometryType(geometry) in ('ST_LineString','ST_MultiLineString') THEN
      area := (ST_Length(geometry)^2) * 0.1;
  ELSE
    RETURN search_rank;
  END IF;

  -- adjust for the fact that countries come in different sizes
  IF country_code IN ('ca', 'au', 'ru') THEN
    area := area / 5;
  ELSIF country_code IN ('br', 'kz', 'cn', 'us', 'ne', 'gb', 'za', 'sa', 'id', 'eh', 'ml', 'tm') THEN
    area := area / 3;
  ELSIF country_code IN ('bo', 'ar', 'sd', 'mn', 'in', 'et', 'cd', 'mz', 'ly', 'cl', 'zm') THEN
    area := area / 2;
  END IF;

  IF area > 1 THEN
    RETURN 7;
  ELSIF area > 0.1 THEN
    RETURN 9;
  ELSIF area > 0.01 THEN
    RETURN 13;
  ELSIF area > 0.001 THEN
    RETURN 17;
  ELSIF area > 0.0001 THEN
    RETURN 19;
  ELSIF area > 0.000005 THEN
    RETURN 21;
  END IF;

   RETURN 23;
END;
$$
LANGUAGE plpgsql IMMUTABLE;


-- Guess a ranking for postcodes from country and postcode format.
CREATE OR REPLACE FUNCTION get_postcode_rank(country_code VARCHAR(2), postcode TEXT,
                                             OUT rank_search SMALLINT,
                                             OUT rank_address SMALLINT)
AS $$
DECLARE
  part TEXT;
BEGIN
    rank_search := 30;
    rank_address := 30;
    postcode := upper(postcode);

    IF country_code = 'gb' THEN
        IF postcode ~ '^([A-Z][A-Z]?[0-9][0-9A-Z]? [0-9][A-Z][A-Z])$' THEN
            rank_search := 25;
            rank_address := 5;
        ELSEIF postcode ~ '^([A-Z][A-Z]?[0-9][0-9A-Z]? [0-9])$' THEN
            rank_search := 23;
            rank_address := 5;
        ELSEIF postcode ~ '^([A-Z][A-Z]?[0-9][0-9A-Z])$' THEN
            rank_search := 21;
            rank_address := 5;
        END IF;

    ELSEIF country_code = 'sg' THEN
        IF postcode ~ '^([0-9]{6})$' THEN
            rank_search := 25;
            rank_address := 11;
        END IF;

    ELSEIF country_code = 'de' THEN
        IF postcode ~ '^([0-9]{5})$' THEN
            rank_search := 21;
            rank_address := 11;
        END IF;

    ELSE
        -- Guess at the postcode format and coverage (!)
        IF postcode ~ '^[A-Z0-9]{1,5}$' THEN -- Probably too short to be very local
            rank_search := 21;
            rank_address := 11;
        ELSE
            -- Does it look splitable into and area and local code?
            part := substring(postcode from '^([- :A-Z0-9]+)([- :][A-Z0-9]+)$');

            IF part IS NOT NULL THEN
                rank_search := 25;
                rank_address := 11;
            ELSEIF postcode ~ '^[- :A-Z0-9]{6,}$' THEN
                rank_search := 21;
                rank_address := 11;
            END IF;
        END IF;
    END IF;

END;
$$
LANGUAGE plpgsql IMMUTABLE;


-- Get standard search and address rank for an object.
--
-- \param country        Two-letter country code where the object is in.
-- \param extended_type  OSM type (N, W, R) or area type (A).
-- \param place_class    Class (or tag key) of object.
-- \param place_type     Type (or tag value) of object.
-- \param admin_level    Value of admin_level tag.
-- \param is_major       If true, boost search rank by one.
-- \param postcode       Value of addr:postcode tag.
-- \param[out] search_rank   Computed search rank.
-- \param[out] address_rank  Computed address rank.
--
CREATE OR REPLACE FUNCTION compute_place_rank(country VARCHAR(2),
                                              extended_type VARCHAR(1),
                                              place_class TEXT, place_type TEXT,
                                              admin_level SMALLINT,
                                              is_major BOOLEAN,
                                              postcode TEXT,
                                              OUT search_rank SMALLINT,
                                              OUT address_rank SMALLINT)
AS $$
DECLARE
  classtype TEXT;
BEGIN
  IF place_class in ('place','boundary')
     and place_type in ('postcode','postal_code')
  THEN
    SELECT * INTO search_rank, address_rank
      FROM get_postcode_rank(country, postcode);
  ELSEIF extended_type = 'N' AND place_class = 'highway' THEN
    search_rank = 30;
    address_rank = 30;
  ELSEIF place_class = 'landuse' AND extended_type != 'A' THEN
    search_rank = 30;
    address_rank = 30;
  ELSE
    IF place_class = 'boundary' and place_type = 'administrative' THEN
      classtype = place_type || admin_level::TEXT;
    ELSE
      classtype = place_type;
    END IF;

    SELECT l.rank_search, l.rank_address INTO search_rank, address_rank
      FROM address_levels l
     WHERE (l.country_code = country or l.country_code is NULL)
           AND l.class = place_class AND (l.type = classtype or l.type is NULL)
     ORDER BY l.country_code, l.class, l.type LIMIT 1;

    IF search_rank is NULL OR address_rank is NULL THEN
      search_rank := 30;
      address_rank := 30;
    END IF;

    -- some postcorrections
    IF place_class = 'waterway' AND extended_type = 'R' THEN
        -- Slightly promote waterway relations so that they are processed
        -- before their members.
        search_rank := search_rank - 1;
    END IF;

    IF is_major THEN
      search_rank := search_rank - 1;
    END IF;
  END IF;
END;
$$
LANGUAGE plpgsql IMMUTABLE;

CREATE OR REPLACE FUNCTION get_addr_tag_rank(key TEXT, country TEXT,
                                             OUT from_rank SMALLINT,
                                             OUT to_rank SMALLINT,
                                             OUT extent FLOAT)
  AS $$
DECLARE
  ranks RECORD;
BEGIN
  from_rank := null;

  FOR ranks IN
    SELECT * FROM
      (SELECT l.rank_search, l.rank_address FROM address_levels l
        WHERE (l.country_code = country or l.country_code is NULL)
               AND l.class = 'place' AND l.type = key
        ORDER BY l.country_code LIMIT 1) r
      WHERE rank_address > 0
  LOOP
    extent := reverse_place_diameter(ranks.rank_search);

    IF ranks.rank_address <= 4 THEN
        from_rank := 4;
        to_rank := 4;
    ELSEIF ranks.rank_address <= 9 THEN
        from_rank := 5;
        to_rank := 9;
    ELSEIF ranks.rank_address <= 12 THEN
        from_rank := 10;
        to_rank := 12;
    ELSEIF ranks.rank_address <= 16 THEN
        from_rank := 13;
        to_rank := 16;
    ELSEIF ranks.rank_address <= 21 THEN
        from_rank := 17;
        to_rank := 21;
    ELSEIF ranks.rank_address <= 24 THEN
        from_rank := 22;
        to_rank := 24;
    ELSE
        from_rank := 25;
        to_rank := 25;
    END IF;
  END LOOP;
END;
$$
LANGUAGE plpgsql IMMUTABLE;