put postcodes in extra table on import

lib-lua/themes/nominatim/init.lua

@@ -65,7 +65,19 @@ local table_definitions = {
             { column = 'geometry', type = 'geometry', projection = 'WGS84', not_null = true }
         },
         indexes = {}
-    }
+    },
+    place_postcode = {
+        ids = { type = 'any', id_column = 'osm_id', type_column = 'osm_type' },
+        columns = {
+            { column = 'postcode', type = 'text', not_null = true },
+            { column = 'country_code', type = 'text' },
+            { column = 'centroid', type = 'point', projection = 'WGS84', not_null = true },
+            { column = 'geometry', type = 'geometry', projection = 'WGS84' }
+        },
+        indexes = {
+            { column = 'postcode', method = 'btree' }
+        }
+     }
 }
 
 local insert_row = {}
@@ -113,6 +125,7 @@ local PlaceTransform = {}
 
 -- Special transform meanings which are interpreted elsewhere
 PlaceTransform.fallback = 'fallback'
+PlaceTransform.postcode_area = 'postcode_area'
 PlaceTransform.delete = 'delete'
 PlaceTransform.extra = 'extra'
 
@@ -419,11 +432,25 @@ function Place:write_place(k, v, mfunc)
     return 0
 end
 
-function Place:write_row(k, v)
+
+function Place:geometry_is_valid()
     if self.geometry == nil then
         self.geometry = self.geom_func(self.object)
+
+        if self.geometry == nil or self.geometry:is_null() then
+            self.geometry = false
+            return false
+        end
+
+        return true
     end
-    if self.geometry == nil or self.geometry:is_null() then
+
+    return self.geometry ~= false
+end
+
+
+function Place:write_row(k, v)
+    if not self:geometry_is_valid() then
         return 0
     end
 
@@ -675,9 +702,6 @@ function module.process_tags(o)
     if o.address.country ~= nil and #o.address.country ~= 2 then
         o.address['country'] = nil
     end
-    if POSTCODE_FALLBACK and fallback == nil and o.address.postcode ~= nil then
-        fallback = {'place', 'postcode', PlaceTransform.always}
-    end
 
     if o.address.interpolation ~= nil then
         o:write_place('place', 'houses', PlaceTransform.always)
@@ -685,20 +709,41 @@ function module.process_tags(o)
     end
 
     -- collect main keys
+    local postcode_collect = false
     for k, v in pairs(o.intags) do
         local ktable = MAIN_KEYS[k]
         if ktable then
             local ktype = ktable[v] or ktable[1]
             if type(ktype) == 'function' then
                 o:write_place(k, v, ktype)
+            elseif ktype == 'postcode_area' then
+                postcode_collect = true
+                if o.object.type == 'relation'
+                        and o.address.postcode ~= nil
+                        and o:geometry_is_valid() then
+                    insert_row.place_postcode{
+                        postcode = o.address.postcode,
+                        centroid = o.geometry:centroid(),
+                        geometry = o.geometry
+                    }
+                end
             elseif ktype == 'fallback' and o.has_name then
                 fallback = {k, v, PlaceTransform.named}
             end
         end
     end
 
-    if fallback ~= nil and o.num_entries == 0 then
-        o:write_place(fallback[1], fallback[2], fallback[3])
+    if o.num_entries == 0 then
+        if fallback ~= nil then
+            o:write_place(fallback[1], fallback[2], fallback[3])
+        elseif POSTCODE_FALLBACK and not postcode_collect
+                and o.address.postcode ~= nil
+                and o:geometry_is_valid() then
+            insert_row.place_postcode{
+                postcode = o.address.postcode,
+                centroid = o.geometry:centroid()
+            }
+        end
     end
 end
 

lib-lua/themes/nominatim/presets.lua

@@ -118,7 +118,7 @@ module.MAIN_TAGS.all_boundaries = {
                 place = 'delete',
                 land_area = 'delete',
                 protected_area = 'fallback',
-                postal_code = 'always'},
+                postal_code = 'postcode_area'},
     landuse = 'fallback',
     place = 'always'
 }