Hi, Correct me if I am wrong James, but I think your original question was how do you create a Table out of a changelog (a stream with a change flag). Unfortunately I think it is not possible right now. This definitely is high on our priority list for the near future. There were first approaches[1] to implement that before, but we must clarify all aspects of such operation first.
Best, Dawid [1] https://github.com/apache/flink/pull/6787 On 19/12/2019 04:05, Kurt Young wrote: > Hi James, > > If I understand correctly, you can use `TableEnvironment#sqlQuery` to > achieve > what you want. You can pass the whole sql statement in and get a > `Table` back > from the method. I believe this is the table you want which is > semantically > equivalent with the stream you mentioned. > > For example, you can further operate on the `Table` with other sql > operations, > like `GROUP BY cnt` on the returned table. You can think of it in this > way that > Flink would attach another aggregation operator to the original plan, > and this > operator can consume the retraction stream which the original sql > statement > produced and start to generate correct results. > > Best, > Kurt > > > On Thu, Dec 19, 2019 at 1:25 AM James Baker <j.ba...@outlook.com > <mailto:j.ba...@outlook.com>> wrote: > > Hi! > I've been looking at Flink for the last few days and have very > much appreciated the concept of Dynamic Tables, it solves a lot of > my needs and handles a lot of the complex state tracking that is > otherwise painful. I have a question about the composability of > the system which the docs don't answer. > > The docs use the example of 'SELECT user, COUNT(url) as cnt FROM > clicks GROUP BY user', where clicks is a stream coming in of user > and the url they've clicked. > > From such a Table, I can then get a retract stream written into an > external system, perhaps outputting (true, User1, 1), ..., (true, > User1, 2) indicating that User1's clicked on something. > > Is there an idiomatic way to convert a retract stream into a > semantically equivalent table? > > Thanks, > James >
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