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I am trying to group events by User and return them in batches (per user). For example, if 3 users each sent 5 events, I would like 3 batches of 5 events to be output from esper.

Using the following EPL, I am able to validate that 3 data windows are created and that each window has 5 events in it.

select * from EVT.std:groupwin(User).win:time_batch(2).std:size()

However, when I remove std:size() it returns all 15 events in one batch. As I understand it, this is due to how the std:groupwin grouped-window view gets evaluated by the std:merge view.

How can I output the batched events from each data window without them all being merged together?

beterthanlife
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1 Answers1

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I think you would like to receive multiple calls to the listener instead of a single call? A single call is generally more efficient so that is the default. I think you want to use "for". The link is http://esper.codehaus.org/esper-5.1.0/doc/reference/en-US/html_single/index.html#epl-grouped-delivery

user3613754
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  • That is exactly what I was looking for. Not sure how I missed "for" given how many times Ive been over that doc! For others, the statement which worked for us is: select * from EVT.std:groupwin(User).win:time_accum(2) for grouped_delivery(User) – beterthanlife Jan 26 '15 at 09:57