PostGIS geometry as binary

geom2bin.sql

CREATE OR REPLACE FUNCTION geom2bin (geometry)
RETURNS text AS $$
SELECT reverse(string_agg(
CASE WHEN i > 0 AND mod(i, 8) = 0 THEN ' ' ELSE '' END ||
CASE 
WHEN chr = '0' THEN '0000'
WHEN chr = '1' THEN '0001'
WHEN chr = '2' THEN '0010'
WHEN chr = '3' THEN '0011'
WHEN chr = '4' THEN '0100'
WHEN chr = '5' THEN '0101'
WHEN chr = '6' THEN '0110'
WHEN chr = '7' THEN '0111'
WHEN chr = '8' THEN '1000'
WHEN chr = '9' THEN '1001'
WHEN chr = 'a' THEN '1010'
WHEN chr = 'b' THEN '1011'
WHEN chr = 'c' THEN '1100'
WHEN chr = 'd' THEN '1101'
WHEN chr = 'e' THEN '1110'
WHEN chr = 'f' THEN '1111'
END
, '')) FROM
(SELECT row_number() OVER() AS i, chr FROM 
  (SELECT lower(
    regexp_split_to_table(
      reverse(encode(
        ST_AsBinary($1, 'XDR'),
      'hex')), 
    '')) chr) ssq
) sq
$$ LANGUAGE sql;