A function to create a PostGIS geometry out of a Google Tile X/Y/Z definition

v_get_tile.plsql

-- Function: v_get_tile(integer, integer, integer)

-- DROP FUNCTION v_get_tile(integer, integer, integer);

CREATE OR REPLACE FUNCTION v_get_tile(x integer, y integer, z integer)
  RETURNS geometry AS
$BODY$
DECLARE
  origin_shift CONSTANT FLOAT := 20037508.342789244;
  initial_resolution CONSTANT FLOAT := 156543.03392804062;
  res float;
  minx float; 
  miny float; 
  maxx float; 
  maxy float;
BEGIN
  res  := initial_resolution / (power(2,z));

  minx := (x*256)*res  - origin_shift;
  miny := -((y*256)*res  - origin_shift);
  maxx := ((x+1)*256)*res  - origin_shift;
  maxy := -(((y+1)*256)*res  - origin_shift);  
  

RETURN (ST_GeomFromText('POLYGON(('||minx||' '||maxy||','||maxx||' '||maxy||','||maxx||' '||miny||','||minx||' '||miny||','||minx||' '||maxy||'))',900913));END;
$BODY$
  LANGUAGE 'plpgsql' IMMUTABLE STRICT
  COST 100;
ALTER FUNCTION v_get_tile(integer, integer, integer) OWNER TO postgres;

this will be very useful for our vector tile server!

True. Didnt realize you where doing all the coding for this. We should include this functions in all CartoDB

we are doing it on the client side and asking for the geometry inside the bbox

By the way, here is a method to generate all tiles for a specific zoom

SELECT ST_Transform(v_get_tile(x,y,2),3857) as the_geom_webmercator from(
select distinct * from generate_series(0,3) as x, generate_series(0,3) as y) as l