COPY statement REAL vs VARCHAR precision issue

Hello all,

I'm using a COPY statement to load data into a PostGIS. The issue I am
facing is that if I define fields with the REAL type, the COPY will only
preserve 4 decimals which is not sufficient for my application.

Here is the commands I'm running and a sample of the results :

CREATE TABLE sites (
id VARCHAR(9) PRIMARY KEY,
name VARCHAR(128),
type VARCHAR(1),
agency VARCHAR(128),
status INTEGER,
napsDesignated BOOLEAN,
address VARCHAR(128),
city VARCHAR(128),
network VARCHAR(128),
timeZone REAL,
lat REAL,
lon REAL,
elevation REAL
);

COPY sites (
id,
name,
type,
agency,
status,
napsDesignated,
address,
city,
network,
timeZone,
lat,
lon,
elevation
) FROM
'/data/sites.csv'
WITH DELIMITER '|' CSV HEADER;

-- Then I use some PostGIS functions to convert the lat/lon into a geometry
-- The issue is independent of the GIS processing.

SELECT lat, lon FROM sites LIMIT 4;
-- lat | lon
-- ---------+----------
-- 47.5681 | -52.7022
-- 47.56 | -52.7114
-- 49.3208 | -57.3972
-- 48.9495 | -57.9454
-- (4 rows)

-- If I define the fields as being VARCHAR instead of REAL, I get all
-- the decimals :

CREATE TABLE sites (
id VARCHAR(9) PRIMARY KEY,
name VARCHAR(128),
type VARCHAR(1),
agency VARCHAR(128),
status INTEGER,
napsDesignated BOOLEAN,
address VARCHAR(128),
city VARCHAR(128),
network VARCHAR(128),
timeZone REAL,
lat VARCHAR(32),
lon VARCHAR(32),
elevation REAL
);

COPY sites (
id,
name,
type,
agency,
status,
napsDesignated,
address,
city,
network,
timeZone,
lat,
lon,
elevation
) FROM
'/data/sites.csv'
WITH DELIMITER '|' CSV HEADER;

SELECT lat, lon FROM sites LIMIT 4;
lat | lon
------------------+-------------------
47.5680555555556 | -52.7022222222222
47.56 | -52.7113888888889
49.3208333333333 | -57.3972222222222
48.949479 | -57.945387
(4 rows)

-- When I convert the lat/lon to GEOMETRY, the function takes a string as
input. Therefore, the precision depends on how the REAL are converted to
strings. :

UPDATE sites SET
position = GeomFromEWKT('SRID=4326;POINT(' || lon || ' ' || lat ||' ' ||
elevation || ')');

-- Are the values stored with all the possible precision of a REAL or are they
stored as displayed?

-- Is it because of the behaviour of the COPY statement?

Thank you for your help!

Samuel