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From Nirmalya Sengupta <sengupta.nirma...@gmail.com>
Subject Re: Interpretation of Trigger and Eviction on a window
Date Sat, 28 Nov 2015 02:14:34 GMT
Hello Fabian,

>From your reply to this thread:
' it is correct that the evictor is called BEFORE the window function is
applied because this is required to support certain types of sliding
windows. '

This is clear to me now. However, my point was about the way it is
described in the User-guide. The guide says this:
' *After the trigger fires, and before the function (e.g., sum, count) is
applied to the window contents, an optional Evictor removes some elements
from the beginning of the window before the remaining elements are passed
on to the function* '

As I read it again, I see where the problem lies. It says some elements are
removed before the **rest** are passed to the function. This is not what
happens, I think. Evictor removes elements and the function *sees this set
of removed elements, not the remaining elements*. Remaining elements remain
in the window and are perhaps picked up by the Evictor next time.

Carrying on from your elaboration, I think guide's statement can be better
rearranged as:

' *After the trigger fires, the function (e.g., sum, count) is applied to
the entire contents of the window. However, an optionally
provided Evictor, removes some elements from the beginning of the window,
according to the criteria of eviction. The function is then applied to this
set of __removed__ elements. '*

Let me know if I am way off the mark here.

-- Nirmalya

-- 
Software Technologist
http://www.linkedin.com/in/nirmalyasengupta
"If you have built castles in the air, your work need not be lost. That is
where they should be.
Now put the foundation under them."

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