declare
name bpchar;
data1 bytea;
sqlstr varchar;
tname bpchar;
begin
name = 'test';
data1 = 'sfblsdgkbsdflgbsdfjgsdfgsdg'::bytea;
tname = 'test1';
sqlstr = 'insert into ' || tname
	    || ' values ('''
	    || name 
            || ''', '''
	    || data1
	    || '''::bytea);'; 

execute sqlstr;

ERROR:  оператор не существует: text || bytea
HINT:  No operator matches the given name and argument type(s). You may need to add explicit type casts.
CONTEXT:  SQL-команда: "SELECT  'insert into ' ||  $1  || ' values (''' ||  $2  || ''', ''' ||  $3  || '''::bytea);'"
PL/pgSQL function "test" line 10 at assignment