Returns a geography representing the geohash cell. It will return null
on error (invalid input).
SELECT `carto-un`.carto.GEOHASH_BOUNDARY('ezrqcjzgdr3');
-- POLYGON((-1.00000128149986 41.9999988377094, -0.999999940395355 41.9999988377094, ...
SELECT `carto-un-eu`.carto.GEOHASH_BOUNDARY('ezrqcjzgdr3');
-- POLYGON((-1.00000128149986 41.9999988377094, -0.999999940395355 41.9999988377094, ...
SELECT `carto-os`.carto.GEOHASH_BOUNDARY('ezrqcjzgdr3');
-- POLYGON((-1.00000128149986 41.9999988377094, -0.999999940395355 41.9999988377094, ...
SELECT carto.GEOHASH_BOUNDARY('ezrqcjzgdr3');
-- POLYGON((-1.00000128149986 41.9999988377094, -0.999999940395355 41.9999988377094, ...