THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
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Based on Calcite-4865[3], we can already use Session Window TVF syntax as described in FLIP-145. However, in Calcite, a Table Function contains PARTITION BY
or ORDER BY
will be converted into a PTF (Polymorphic Table function). PTF has some key features that need to be set as follows. (copied from Calcite documentation[4])
- ROW semantics or SET semantics
- Row semantics means that the result of the table function depends on a row-by-row basis.
- Set semantics means that the outcome of the function depends on how the data is partitioned.
2. Whether the table function can generate a result row even if the input table is empty
- If the table function can generate a result row on empty input, the table is said to be “keep when empty”.
- The alternative is called “prune when empty”, meaning that the result would be pruned out if the input table is empty.
3. Whether the input table supports pass-through columns or not
- Pass-through columns is a mechanism enabling the table function to copy every column of an input row into columns of an output row.
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