ST_ZMax() does not exist in PostGIS

Question

I'm trying to follow this example on Mapbox blog, about using 3D shapes in PostGIS.

The database-query is this:

DROP TABLE tilemill_buildings;
CREATE TABLE tilemill_buildings
AS SELECT
ogc_fid,
CAST(size_sqm AS INT) as size_sqm,
CAST(ROUND(CAST(ST_ZMax(wkb_geometry)/2 AS NUMERIC),0) AS INT) AS z_xlarge,
CAST(ROUND(CAST(ST_ZMax(wkb_geometry)/2.5 AS NUMERIC),0) AS INT) AS z_large,
CAST(ROUND(CAST(ST_ZMax(wkb_geometry)/3 AS NUMERIC),0) AS INT) AS z_med,
CAST(ROUND(CAST(ST_ZMax(wkb_geometry)/4 AS NUMERIC),0) AS INT) AS z_small,
wkb_geometry AS wkb_geometry
FROM building_3d
ORDER BY
ST_YMax(Box3D(wkb_geometry)) DESC;

...but I get this error:

ERROR:  function st_zmax(bytea) does not exist
LINE 5: CAST(ROUND(CAST(ST_ZMax(wkb_geometry)/2 AS NUMERIC),0) AS IN...
                        ^
HINT:  No function matches the given name and argument types. You might need to add explicit type casts.

I have tried to re-install PostGIS twice. I have run the CREATE EXTENSION postgis; command.

Why am I getting this error, and how to fix it?

Answer 1

Reason is that your wkb_geometry is "well known binary" in bytea type of column, it should be geometry type. You can convert it to geometry using ST_GeomFromWKB(bytea) see this , if you dont want add new column then replace ST_ZMax(wkb_geometry) with ST_ZMax(ST_GeomFromWKB(wkb_geometry))