Hey Fernando,
If you need to store binary data in a table you should use bytea data type.
Than, in case of libpq:
If you want to transmit binary data from client to server in text format you
must prepare (escape) it for including into you SQL command (e.g., INSERT).
If you can transmit the data from client to server in binary format you don't
need escape you binary data, but you must tell libpq (or the library you use)
that you transmission will be in a binary format.
What library do you use to work with PostgreSQL ?
--
// Dmitriy.