Add international airports at z8-9 (#1187)

Closes #1082

This PR moves the aerodrome/aerodrome_type consolidation (via template) into the lower-level `osm_aerodrome_label_point` table, and creates a partial index on class `international` for airports with an `iata` code.  The presence of an `iata` code is more significant than an `icao` code which exists at many smaller, general aviation airport.  Therefore, `international` + `iata` should be a sufficient filter.

Zoom 8 international airports in the NYC area (blue dots):
![image](https://user-images.githubusercontent.com/3254090/130335311-10b7aa35-d2f9-42cc-a054-878048012040.png)

Zoom 10 in the same area:
![image](https://user-images.githubusercontent.com/3254090/130335327-3989cfba-80ca-46dd-a157-45b375f84a8d.png)

layers/aerodrome_label/aerodrome_label.sql

@@ -19,6 +19,28 @@ CREATE OR REPLACE FUNCTION layer_aerodrome_label(bbox geometry,
             )
 AS
 $$
+SELECT
+    -- etldoc: osm_aerodrome_label_point -> layer_aerodrome_label:z8
+    -- etldoc: osm_aerodrome_label_point -> layer_aerodrome_label:z9
+    ABS(osm_id) AS id, -- mvt feature IDs can't be negative
+    geometry,
+    name,
+    COALESCE(NULLIF(name_en, ''), name) AS name_en,
+    COALESCE(NULLIF(name_de, ''), name, name_en) AS name_de,
+    tags,
+    aerodrome_type AS class,
+    NULLIF(iata, '') AS iata,
+    NULLIF(icao, '') AS icao,
+    substring(ele FROM E'^(-?\\d+)(\\D|$)')::int AS ele,
+    round(substring(ele FROM E'^(-?\\d+)(\\D|$)')::int * 3.2808399)::int AS ele_ft
+FROM osm_aerodrome_label_point
+WHERE geometry && bbox
+  AND aerodrome_type = 'international'
+  AND iata <> ''
+  AND zoom_level BETWEEN 8 AND 9
+
+UNION ALL
+
 SELECT
     -- etldoc: osm_aerodrome_label_point -> layer_aerodrome_label:z10_
     ABS(osm_id) AS id, -- mvt feature IDs can't be negative
@@ -27,10 +49,7 @@ SELECT
     COALESCE(NULLIF(name_en, ''), name) AS name_en,
     COALESCE(NULLIF(name_de, ''), name, name_en) AS name_de,
     tags,
-    CASE
-        %%FIELD_MAPPING: class %%
-        ELSE 'other'
-        END AS class,
+    aerodrome_type AS class,
     NULLIF(iata, '') AS iata,
     NULLIF(icao, '') AS icao,
     substring(ele FROM E'^(-?\\d+)(\\D|$)')::int AS ele,

layers/aerodrome_label/update_aerodrome_label_point.sql

@@ -2,6 +2,18 @@ DROP TRIGGER IF EXISTS trigger_flag ON osm_aerodrome_label_point;
 DROP TRIGGER IF EXISTS trigger_store ON osm_aerodrome_label_point;
 DROP TRIGGER IF EXISTS trigger_refresh ON aerodrome_label.updates;
 
+-- Partial index for zoom 8/9 queries
+CREATE INDEX IF NOT EXISTS osm_aerodrome_label_point_type_partial_idx
+    ON osm_aerodrome_label_point USING gist (geometry)
+    WHERE aerodrome_type = 'international'
+      AND iata <> '';
+
+UPDATE osm_aerodrome_label_point SET aerodrome_type=(
+   CASE
+        %%FIELD_MAPPING: class %%
+        ELSE 'other' END
+);
+
 CREATE SCHEMA IF NOT EXISTS aerodrome_label;
 
 CREATE TABLE IF NOT EXISTS aerodrome_label.osm_ids