Add 'natural=volcanal' into mountain_peak layer

1. Add new field "class" into mountain_peak layer,
   which is original value of "natural" tag
2. Reformat layer.sql

layers/mountain_peak/layer.sql

@@ -2,29 +2,52 @@
 -- etldoc: layer_mountain_peak[shape=record fillcolor=lightpink,
 -- etldoc:     style="rounded,filled", label="layer_mountain_peak | <z7_> z7+" ] ;
 
-CREATE OR REPLACE FUNCTION layer_mountain_peak(bbox geometry, zoom_level integer, pixel_width numeric)
-RETURNS TABLE(osm_id bigint, geometry geometry, name text, name_en text, name_de text, tags hstore, ele int, ele_ft int, "rank" int) AS $$
+CREATE OR REPLACE FUNCTION layer_mountain_peak(
+    bbox geometry, 
+    zoom_level integer, 
+    pixel_width numeric)
+  RETURNS TABLE(
+    osm_id bigint,
+    geometry geometry, 
+    name text, 
+    name_en text, 
+    name_de text, 
+    class text, 
+    tags hstore,
+    ele int, 
+    ele_ft int, 
+    "rank" int) AS 
+$$
    -- etldoc: osm_peak_point -> layer_mountain_peak:z7_
-   SELECT osm_id, geometry, name, name_en, name_de, tags, ele::int, ele_ft::int, rank::int
-   FROM (
-     SELECT osm_id, geometry, name,
-     COALESCE(NULLIF(name_en, ''), name) AS name_en,
-     COALESCE(NULLIF(name_de, ''), name, name_en) AS name_de,
-     tags,
-     substring(ele from E'^(-?\\d+)(\\D|$)')::int AS ele,
-     round(substring(ele from E'^(-?\\d+)(\\D|$)')::int*3.2808399)::int AS ele_ft,
-       row_number() OVER (
-           PARTITION BY LabelGrid(geometry, 100 * pixel_width)
-           ORDER BY (
-             substring(ele from E'^(-?\\d+)(\\D|$)')::int +
-             (CASE WHEN NULLIF(wikipedia, '') is not null THEN 10000 ELSE 0 END) +
-             (CASE WHEN NULLIF(name, '') is not null THEN 10000 ELSE 0 END)
-           ) DESC
-       )::int AS "rank"
-     FROM osm_peak_point
-     WHERE geometry && bbox AND ele is not null AND ele ~ E'^-?\\d+'
-   ) AS ranked_peaks
-   WHERE zoom_level >= 7 AND (rank <= 5 OR zoom_level >= 14)
-   ORDER BY "rank" ASC;
+  SELECT 
+    osm_id, 
+    geometry, 
+    name, 
+    name_en, 
+    name_de, 
+    tags -> 'natural' AS class, 
+    tags,
+    ele::int, 
+    ele_ft::int, 
+    rank::int FROM (
+      SELECT osm_id, geometry, name,
+      COALESCE(NULLIF(name_en, ''), name) AS name_en,
+      COALESCE(NULLIF(name_de, ''), name, name_en) AS name_de,
+      tags,
+      substring(ele from E'^(-?\\d+)(\\D|$)')::int AS ele,
+      round(substring(ele from E'^(-?\\d+)(\\D|$)')::int*3.2808399)::int AS ele_ft,
+      row_number() OVER (
+          PARTITION BY LabelGrid(geometry, 100 * pixel_width)
+          ORDER BY (
+            substring(ele from E'^(-?\\d+)(\\D|$)')::int +
+            (CASE WHEN NULLIF(wikipedia, '') is not null THEN 10000 ELSE 0 END) +
+            (CASE WHEN NULLIF(name, '') is not null THEN 10000 ELSE 0 END)
+          ) DESC
+      )::int AS "rank"
+      FROM osm_peak_point
+      WHERE geometry && bbox AND ele is not null AND ele ~ E'^-?\\d+'
+    ) AS ranked_peaks
+  WHERE zoom_level >= 7 AND (rank <= 5 OR zoom_level >= 14)
+  ORDER BY "rank" ASC;
 
 $$ LANGUAGE SQL IMMUTABLE;