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I'm having trouble comprehending the output of the createWindowJoinEngine function in the context of special windows (window=0:0), as shown in the following diagram. Could you please provide a detailed explanation?

enter image description here

Eva Gao
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1 Answers1

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In the diagram, “(1)” and “(2)” represent the first and second records in the left table; “(a)” and “(b)” represent the first and second records in the right table.

When the parameter window of createWindowJoinEngine is set to 0:0, the windows over the right table are determined by the current timestamp in the left table and its previous timestamp. The diagram below shows how the windows of the right table (left-closed and right-open) are created:

enter image description here

The calculation of the windows is triggered by the arrival of the next record after the window ends.

Here's the setp-by-step explanationof the calculation process:

The first window of the right table contains only record “(a)”. The second window of the right table has no data. The calculations for the first two windows are both triggered by the arrival of the next record “(b)” from the third window.

The third window contains records “(b)” and “(c)”. Its calculation is triggered by the arrival of the next record “(d)” from the fourth window.

The process continues for the subsequent windows.

JaneYe
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