INSERT INTO "ayz"."table2_sync" ("field1", "OIDF") 
VALUES('str1\\015\\012str2\\015\\012str3', Взять_OID);

INSERT INTO pg_largeobject (loid, pageno, data) 
VALUES (Полученный_OID,  0 , 'oid1\\015\\012oid2\\015\\012oid3');

CREATE OR REPLACE FUNCTION create_lo(_data bytea) RETURNS OID AS $$
DECLARE _new_lo OID;
        _handle INT;
        _tmp INT;
BEGIN
        _new_lo  := lo_creat( 2  <<  16 );
        _handle  := lo_open(_new_lo,  2  <<  16 );
        _tmp     := lowrite( _handle, _data);
        _tmp     := lo_close( _handle);
        return _new_lo;
END
$$ LANGUAGE 'plpgsql';

-- вставка
INSERT INTO  INSERT INTO "ayz"."table2_sync" ("field1", "OIDF") 
VALUES('str1\\015\\012str2\\015\\012str3', create_lo('oid1\\015\\012oid2\\015\\012oid3'::bytea));