From ea7c16fbaf60fd400a943006b3a55fce174a9c0e Mon Sep 17 00:00:00 2001
From: Paul Norman <penorman@mac.com>
Date: Mon, 21 Dec 2015 23:59:26 -0800
Subject: [PATCH] Convert some simple functions from plpgsql to sql

SQL is a faster language to call, and these are very simple functions.
---
 scripts-available/CDB_LatLng.sql | 12 ++++--------
 scripts-available/CDB_XYZ.sql    | 21 +++------------------
 2 files changed, 7 insertions(+), 26 deletions(-)

diff --git a/scripts-available/CDB_LatLng.sql b/scripts-available/CDB_LatLng.sql
index d1304c3..7f08f61 100644
--- a/scripts-available/CDB_LatLng.sql
+++ b/scripts-available/CDB_LatLng.sql
@@ -8,16 +8,12 @@
 --
 
 CREATE OR REPLACE FUNCTION CDB_LatLng (lat NUMERIC, lng NUMERIC) RETURNS geometry as $$ 
-BEGIN 
     -- this function is silly
-    RETURN ST_SetSRID(ST_MakePoint(lng,lat),4326); 
-END; 
-$$ language plpgsql IMMUTABLE;
+    SELECT ST_SetSRID(ST_MakePoint(lng,lat),4326);
+$$ language SQL IMMUTABLE;
 
 CREATE OR REPLACE FUNCTION CDB_LatLng (lat FLOAT8, lng FLOAT8) RETURNS geometry as $$ 
-BEGIN 
     -- this function is silly
-    RETURN ST_SetSRID(ST_MakePoint(lng,lat),4326); 
-END; 
-$$ language plpgsql IMMUTABLE;
+    SELECT ST_SetSRID(ST_MakePoint(lng,lat),4326);
+$$ language SQL IMMUTABLE;
 
diff --git a/scripts-available/CDB_XYZ.sql b/scripts-available/CDB_XYZ.sql
index 92e7dae..fa38171 100644
--- a/scripts-available/CDB_XYZ.sql
+++ b/scripts-available/CDB_XYZ.sql
@@ -5,24 +5,9 @@
 CREATE OR REPLACE FUNCTION CDB_XYZ_Resolution(z INTEGER)
 RETURNS FLOAT8
 AS $$
-DECLARE
-  earth_circumference FLOAT8;
-  tile_size INTEGER;
-  full_resolution FLOAT8;
-BEGIN
-
-  -- Earth equatorial circumference in meters (according to wikipedia)
-  earth_circumference := 40075017;
-
-  -- Size of each tile in pixels (1:1 aspect ratio)
-  tile_size := 256;
-
-  full_resolution := earth_circumference/tile_size;
-
-  RETURN full_resolution / (power(2,z));
-
-END
-$$ LANGUAGE 'plpgsql' IMMUTABLE STRICT;
+  -- circumference divided by 256 is z0 resolution, then divide by 2^z
+  SELECT 40075017 / 256 / power(2, z);
+$$ LANGUAGE SQL IMMUTABLE STRICT;
 -- }
 
 -- {