I should have said that SELECT * FROM order_item o JOIN product p USING(product_id)
(without the "STREAM" keyword) is a time-varying relation. You can execute it at 10am, and it terminates, and again at 10.10am and get different results. The difference is due to differences in both product and order_item. If you want to join based on when the order was placed, you must have a column that records the order time. Beyond that, I'm not sure of the details - you may be able to use AS OF, there may be a system-maintained column that records when product was last updated. Julian On Fri, Mar 20, 2020 at 12:01 AM Viliam Durina <vil...@hazelcast.com> wrote: > > On Thu, 19 Mar 2020 at 21:04, Julian Hyde <jh...@apache.org> wrote: > > Suppose you execute that query at 10am and get a particular result. ... you > > execute again at 10.10am. > > > > I execute that query at 10am and expect it to run continuously. My > understanding is that a query with `EMIT STREAM` will run continuously. > Does it just fetch results and finish? > > Now, if you have particular time-sensitive join semantics - such as wanting > > to join the order_item to the product table as if was at the time the order > > was placed - you will need to express that explicitly in the join condition. > > > > How would such a query look? Could you write it? There's no time column in > either relation. > > Regards, > Viliam > > -- > This message contains confidential information and is intended only for the > individuals named. If you are not the named addressee you should not > disseminate, distribute or copy this e-mail. Please notify the sender > immediately by e-mail if you have received this e-mail by mistake and > delete this e-mail from your system. E-mail transmission cannot be > guaranteed to be secure or error-free as information could be intercepted, > corrupted, lost, destroyed, arrive late or incomplete, or contain viruses. > The sender therefore does not accept liability for any errors or omissions > in the contents of this message, which arise as a result of e-mail > transmission. If verification is required, please request a hard-copy > version. -Hazelcast
