error inserting big files in DB.

Hi, Folks.

I've a problem so i can use some help.
I've trying to put a 5 MB file in my database, but i got an error.
Anyone knows if "lo_import" or "lo" (type of bytea) has a limit of
data transferred in one operation?
Some people tell me that i can't transferr more than 1 MB a time to
Postgresql, so i need to
divide my file in many small pices, than upload they one at time, and
finally, use some workaround in DB to restore my original file. Is
this correct?
Below is a piece of code that i use:

$conteudo=addslashes(fread(fopen($arq, "r"), filesize($arq)));
$sql="insert into arquivos (nome, tipo, tamanho, dados) values
('$arq_name', '$arq_type', '$arq_size', lo_import('" .
addslashes($arq) . "'));";

I would be pleased if anyone could help me.
Thanx in advance.