How to get updated order data

Hi!

Orders are in table

         create table order (
           dokumnr int primary key,
           packno char(10)
           );
        insert into order dokumnr values (123);

One user sets pack number using

     update order set packno='Pack1' where dokumnr=123

3 seconds later other user retrieves pack number using

     select packno from order where dokumnr=123

However, other user gets null value, not Pack1 as expected. After some 
time later, correct value Pack1 is returned.

How to get updated data from other user immediately?
3 seconds is long time, it is expected that select suld retrieve update 
data.

There are lot of transactions running concurrently. Maybe update command 
is not written to database if second user retrieves it.

How to flush orders table so that current results are returned for 
second user select ?

Using

PostgreSQL 13.2, compiled by Visual C++ build 1914, 64-bit

and psqlODBC driver.

Andrus.