mjsax commented on a change in pull request #11114:
URL: https://github.com/apache/kafka/pull/11114#discussion_r675707618
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File path: docs/streams/upgrade-guide.html
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@@ -135,25 +135,30 @@ <h3><a id="streams_api_changes_300"
href="#streams_api_changes_300">Streams API
We removed the default implementation of
<code>RocksDBConfigSetter#close()</code>.
</p>
<p>
- We dropped the default 24 hours grace period for windowed operations
such as Window or Session aggregates, or stream-stream joins.
- This period determines how long after a window ends any out-of-order
records will still be processed.
- Records coming in after the grace period has elapsed will be dropped
from those windows.
- With a long grace period, though Kafka Streams can handle out-of-order
data up to that amount of time, it will also incur a high and confusing latency
for users,
- e.g. suppression operators with the default won't emit results up for
24 hours, while in practice out-of-order data usually has a much smaller
time-skewness.
- Instead of abstracting this config from users with a long default
value, we introduced new constructs such as
<code>TimeWindows#ofSizeAndGrace</code> to let callers always set it upon
constructing the windows;
- the other setters such as <code>TimeWindows#grace</code> are
deprecated and will be removed in the future.
+ We dropped the default 24 hours grace period for windowed operations
such as Window or Session aggregates, or
+ stream-stream joins. This period determines how long after a window
ends any out-of-order records will still
+ be processed. Records coming in after the grace period has elapsed are
considered late and will be dropped.
+ But in operators such as suppression, a large grace period has the
drawback of incurring an equally large
+ output latency. The current API made it all too easy to miss the grace
period config completely, leading you
+ to wonder why your application seems to produce no output -- it
actually is, but not for 24 hours.
+ <p>
+ To prevent accidentally or unknowingly falling back to the default
24hr grace period, we deprecated all of the
+ existing static constructors for the <code>indows</code> classes (such
as <code>TimeWindows#of</code>). These
+ are replaced by new static constructors of two flavors:
<code>#ofSizeAndGrace</code> and <code>#ofSizeWithNoGrace</code>
+ (these are for the <code>TimeWindows</code> class; analogous APIs
exist for the <code>JoinWindows</code>,
Review comment:
For JoinWindows and left/outer join, we also enable the spurious result
fix (as pointed out in the next paragraph -- might be good to call out here,
too, by referring to the next paragraph).
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