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From Shailendra Mishra <>
Subject Re: How to use S4 to implement Join operator
Date Wed, 03 Oct 2012 14:43:46 GMT
I am assuming you are planning on doing windowed joins - all you need
to do is keep save the window state and on each insert to the state
data strucuture check if the window has expired. If the window does
expire then compute the join and output it. Now this logic works only
for tumbling windows for sliding windows you have to work harder,
however the logic is kinda similar. - Shailendra

On Wed, Oct 3, 2012 at 1:24 AM, 杨定裕 <> wrote:
> I have read the paper of S4: Distributed Stream Computing Platform.
> There is a example of Joining: Click-through rate. Two data tables RawServe
> and RawClick are joined according 'serve' column.
> The data with same serve in two tables are sent to the same PE. The data are
> streaming to the PE and joined.
>  I have a question :
> While there are new tuples sent to the PE, PE has no previous data and
> previous data in the PE are discarded after streaming processing.
> As I know,the data is not stored in the PE.
> So how can I join the data in the PE?

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