Add support for node processing in second stage

flex-config/README.md

@@ -17,6 +17,8 @@ following order (from easiest to understand to the more complex ones):
 
 After that you can dive into more advanced topics:
 
+* [public-transport.lua](public-transport.lua) -- Use multi-stage processing
+  to bring tags from public transport relations to member nodes and ways
 * [route-relations.lua](route-relations.lua) -- Use multi-stage processing
   to bring tags from relations to member ways
 * [unitable.lua](unitable.lua) -- Put all OSM data into a single table

flex-config/public-transport.lua

@@ -0,0 +1,224 @@
+-- This config example file is released into the Public Domain.
+
+-- This file shows how to use multi-stage processing to bring tags from
+-- public transport relations into member nodes and ways. This allows
+-- advanced processing of public transport networks including stops.
+
+-- Nodes tagged as public transport stops are imported into the 'stops' table,
+-- if they are part of a public transport relation. Ways tagged as highway or
+-- railway or imported into the 'lines' table. The public transport routes
+-- themselves will be in the 'routes' table, but without any geometry. As a
+-- "bonus" public transport stop area relations will be imported into the
+-- 'stop_areas' table.
+--
+-- For the 'stops' and 'lines' table two-stage processing is used. The
+-- 'rel_refs' text column will contain a list of all ref tags found in parent
+-- relations with type=route and route=public_transport. The 'rel_ids' column
+-- will be an integer array containing the relation ids. These could be used,
+-- for instance, to look up other relation tags from the 'routes' table.
+
+local tables = {}
+
+tables.stops = osm2pgsql.define_node_table('stops', {
+    { column = 'tags',     type = 'jsonb' },
+    { column = 'rel_refs', type = 'text' }, -- for the refs from the relations
+    { column = 'rel_ids',  sql_type = 'int8[]' }, -- array with integers (for relation IDs)
+    { column = 'geom',     type = 'point', not_null = true },
+})
+
+tables.lines = osm2pgsql.define_way_table('lines', {
+    { column = 'tags',     type = 'jsonb' },
+    { column = 'rel_refs', type = 'text' }, -- for the refs from the relations
+    { column = 'rel_ids',  sql_type = 'int8[]' }, -- array with integers (for relation IDs)
+    { column = 'geom',     type = 'linestring', not_null = true },
+})
+
+-- Tables don't have to have a geometry column
+tables.routes = osm2pgsql.define_relation_table('routes', {
+    { column = 'ref',  type = 'text' },
+    { column = 'type', type = 'text' },
+    { column = 'from', type = 'text' },
+    { column = 'to',   type = 'text' },
+    { column = 'tags', type = 'jsonb' },
+})
+
+-- Stop areas contain everything belonging to a specific public transport
+-- stop. We model them here by adding a center point as geometry plus the
+-- radius of a circle that contains everything in that stop.
+tables.stop_areas = osm2pgsql.define_relation_table('stop_areas', {
+    { column = 'tags',   type = 'jsonb' },
+    { column = 'radius', type = 'real', not_null = true },
+    { column = 'geom',   type = 'point', not_null = true },
+})
+
+-- This will be used to store information about relations queryable by member
+-- node/way id. These are table of tables. The outer table is indexed by the
+-- node/way id, the inner table indexed by the relation id. This way even if
+-- the information about a relation is added twice, it will be in there only
+-- once. It is always good to write your osm2pgsql Lua code in an idempotent
+-- way, i.e. it can be called any number of times and will lead to the same
+-- result.
+local n2r = {}
+local w2r = {}
+
+local function clean_tags(tags)
+    tags.odbl = nil
+    tags.created_by = nil
+    tags.source = nil
+    tags['source:ref'] = nil
+
+    return next(tags) == nil
+end
+
+local function unique_array(array)
+    local result = {}
+
+    local last = nil
+    for _, v in ipairs(array) do
+        if v ~= last then
+            result[#result + 1] = v
+            last = v
+        end
+    end
+
+    return result
+end
+
+local separator = '·' -- use middle dot as separator character
+
+local function add_rel_data(row, d)
+    if not d then
+        return
+    end
+
+    local refs = {}
+    local ids = {}
+    for rel_id, rel_ref in pairs(d) do
+        refs[#refs + 1] = rel_ref
+        ids[#ids + 1] = rel_id
+    end
+    table.sort(refs)
+    table.sort(ids)
+
+    row.rel_refs = table.concat(unique_array(refs), separator)
+    row.rel_ids = '{' .. table.concat(unique_array(ids), ',') .. '}'
+end
+
+function osm2pgsql.process_node(object)
+    -- We are only interested in public transport stops here, and they are
+    -- only available in the second stage.
+    if osm2pgsql.stage ~= 2 then
+        return
+    end
+
+    local row = {
+        tags = object.tags,
+        geom = object:as_point()
+    }
+
+    -- If there is any data from parent relations, add it in
+    add_rel_data(row, n2r[object.id])
+
+    tables.stops:insert(row)
+end
+
+function osm2pgsql.process_way(object)
+    -- We are only interested in highways and railways
+    if not object.tags.highway and not object.tags.railway then
+        return
+    end
+
+    clean_tags(object.tags)
+
+    -- Data we will store in the 'lines' table always has the tags from
+    -- the way
+    local row = {
+        tags = object.tags,
+        geom = object:as_linestring()
+    }
+
+    -- If there is any data from parent relations, add it in
+    add_rel_data(row, w2r[object.id])
+
+    tables.lines:insert(row)
+end
+
+local pt = {
+    bus = true,
+    light_rail = true,
+    subway = true,
+    tram = true,
+    trolleybus = true,
+}
+
+-- We are only interested in certain route relations with a ref tag
+local function wanted_relation(tags)
+    return tags.type == 'route' and pt[tags.route] and tags.ref
+end
+
+-- This function is called for every added, modified, or deleted relation.
+-- Its only job is to return the ids of all member nodes/ways of the specified
+-- relation we want to see in stage 2 again. It MUST NOT store any information
+-- about the relation!
+function osm2pgsql.select_relation_members(relation)
+    -- Only interested in public transport relations with refs
+    if wanted_relation(relation.tags) then
+        local node_ids = {}
+        local way_ids = {}
+
+        for _, member in ipairs(relation.members) do
+            if member.type == 'n' and member.role == 'stop' then
+                node_ids[#node_ids + 1] = member.ref
+            elseif member.type == 'w' and member.role == '' then
+                way_ids[#way_ids + 1] = member.ref
+            end
+        end
+
+        return {
+            nodes = node_ids,
+            ways = way_ids,
+        }
+    end
+end
+
+-- The process_relation() function should store all information about relation
+-- members that might be needed in stage 2.
+function osm2pgsql.process_relation(object)
+    if object.tags.type == 'public_transport' and object.tags.public_transport == 'stop_area' then
+        local x1, y1, x2, y2 = object:as_geometrycollection():transform(3857):get_bbox()
+        local radius = math.sqrt((x2-x1)*(x2-x1) + (y2-y1)*(y2-y1))
+        tables.stop_areas:insert({
+            tags = object.tags,
+            geom = object:as_geometrycollection():centroid(),
+            radius = radius,
+        })
+        return
+    end
+
+    if wanted_relation(object.tags) then
+        tables.routes:insert({
+            type = object.tags.route,
+            ref = object.tags.ref,
+            from = object.tags.from,
+            to = object.tags.to,
+            tags = object.tags,
+        })
+
+        -- Go through all the members and store relation ids and refs so they
+        -- can be found by the member node/way id.
+        for _, member in ipairs(object.members) do
+            if member.type == 'n' then
+                if not n2r[member.ref] then
+                    n2r[member.ref] = {}
+                end
+                n2r[member.ref][object.id] = object.tags.ref
+            elseif member.type == 'w' then
+                if not w2r[member.ref] then
+                    w2r[member.ref] = {}
+                end
+                w2r[member.ref][object.id] = object.tags.ref
+            end
+        end
+    end
+end
+

src/init.lua

@@ -46,6 +46,16 @@ function osm2pgsql.define_area_table(_name, _columns, _options)
     return _define_table_impl('area', _name, _columns, _options)
 end
 
+function osm2pgsql.node_member_ids(relation)
+    local ids = {}
+    for _, member in ipairs(relation.members) do
+        if member.type == 'n' then
+            ids[#ids + 1] = member.ref
+        end
+    end
+    return ids
+end
+
 function osm2pgsql.way_member_ids(relation)
     local ids = {}
     for _, member in ipairs(relation.members) do

src/middle-pgsql.cpp

@@ -691,7 +691,10 @@ INSERT INTO osm2pgsql_changed_relations
         m_db_connection.exec(build_sql(*m_options, query));
     }
 
-    load_id_list(m_db_connection, "osm2pgsql_changed_ways", parent_ways);
+    if (parent_ways) {
+        load_id_list(m_db_connection, "osm2pgsql_changed_ways", parent_ways);
+    }
+
     load_id_list(m_db_connection, "osm2pgsql_changed_relations",
                  parent_relations);
 
@@ -700,9 +703,17 @@ INSERT INTO osm2pgsql_changed_relations
     timer.stop();
 
     log_debug("Found {} new/changed nodes in input.", changed_nodes.size());
-    log_debug("  Found in {} their {} parent ways and {} parent relations.",
-              std::chrono::duration_cast<std::chrono::seconds>(timer.elapsed()),
-              parent_ways->size(), parent_relations->size());
+
+    auto const elapsed_sec =
+        std::chrono::duration_cast<std::chrono::seconds>(timer.elapsed());
+
+    if (parent_ways) {
+        log_debug("  Found in {} their {} parent ways and {} parent relations.",
+                  elapsed_sec, parent_ways->size(), parent_relations->size());
+    } else {
+        log_debug("  Found in {} their {} parent relations.", elapsed_sec,
+                  parent_relations->size());
+    }
 }
 
 void middle_pgsql_t::get_way_parents(idlist_t const &changed_ways,
@@ -771,6 +782,21 @@ void middle_pgsql_t::way_set(osmium::Way const &way)
 
 namespace {
 
+/**
+ * Build node in buffer from database results.
+ */
+void build_node(osmid_t id, pg_result_t const &res, int res_num, int offset,
+                osmium::memory::Buffer *buffer, bool with_attributes)
+{
+    osmium::builder::NodeBuilder builder{*buffer};
+    builder.set_id(id);
+
+    if (with_attributes) {
+        set_attributes_on_builder(&builder, res, res_num, offset);
+    }
+    pgsql_parse_json_tags(res.get_value(res_num, offset + 1), buffer, &builder);
+}
+
 /**
  * Build way in buffer from database results.
  */
@@ -789,6 +815,24 @@ void build_way(osmid_t id, pg_result_t const &res, int res_num, int offset,
 
 } // anonymous namespace
 
+bool middle_query_pgsql_t::node_get(osmid_t id,
+                                    osmium::memory::Buffer *buffer) const
+{
+    assert(buffer);
+
+    auto const res = m_db_connection.exec_prepared("get_node", id);
+
+    if (res.num_tuples() != 1) {
+        return false;
+    }
+
+    build_node(id, res, 0, 0, buffer, m_store_options.with_attributes);
+
+    buffer->commit();
+
+    return true;
+}
+
 bool middle_query_pgsql_t::way_get(osmid_t id,
                                    osmium::memory::Buffer *buffer) const
 {

src/middle-pgsql.hpp

@@ -59,6 +59,8 @@ class middle_query_pgsql_t : public middle_query_t
 
     size_t nodes_get_list(osmium::WayNodeList *nodes) const override;
 
+    bool node_get(osmid_t id, osmium::memory::Buffer *buffer) const override;
+
     bool way_get(osmid_t id, osmium::memory::Buffer *buffer) const override;
 
     size_t rel_members_get(osmium::Relation const &rel,

src/middle-ram.cpp

@@ -278,6 +278,16 @@ std::size_t middle_ram_t::nodes_get_list(osmium::WayNodeList *nodes) const
     return count;
 }
 
+bool middle_ram_t::node_get(osmid_t id, osmium::memory::Buffer *buffer) const
+{
+    assert(buffer);
+
+    if (m_store_options.nodes) {
+        return get_object(osmium::item_type::node, id, buffer);
+    }
+    return false;
+}
+
 bool middle_ram_t::way_get(osmid_t id, osmium::memory::Buffer *buffer) const
 {
     assert(buffer);

src/middle-ram.hpp

@@ -68,6 +68,8 @@ class middle_ram_t : public middle_t, public middle_query_t
 
     std::size_t nodes_get_list(osmium::WayNodeList *nodes) const override;
 
+    bool node_get(osmid_t id, osmium::memory::Buffer *buffer) const override;
+
     bool way_get(osmid_t id, osmium::memory::Buffer *buffer) const override;
 
     size_t rel_members_get(osmium::Relation const &rel,