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https://issues.apache.org/jira/browse/KAFKA-10494?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Andy Coates updated KAFKA-10494:
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Fix Version/s: 2.7.0
> Streams: enableSendingOldValues should not call parent if node is itself
> materialized
> -------------------------------------------------------------------------------------
>
> Key: KAFKA-10494
> URL: https://issues.apache.org/jira/browse/KAFKA-10494
> Project: Kafka
> Issue Type: Improvement
> Components: streams
> Reporter: Andy Coates
> Assignee: Andy Coates
> Priority: Blocker
> Fix For: 2.7.0
>
>
> Calling `enableSendingOldValues` on many nodes, e.g. `KTableFilter`, is
> unnecessarily calling `enableSendingOldValues` on the parent, even when the
> processor itself is materialized. This can force the parent table to be
> materialized unnecessarily.
> For example:
> {code:java}
> StreamsBuilder builder = new StreamsBuilder();builder
> .table("t1", Consumed.of(...))
> .filter(predicate, Materialized.as("t2"))
> .<downStreamOps>
> {code}
> If `downStreamOps` result in a call to `enableSendingOldValues` on the table
> returned by the `filter` call, i.e. `t2`, then it will result in `t1` being
> materialized unnecessarily.
> This ticket was raised off the back of [comments in a
> PR|#discussion_r490152263]] while working on KAFKA-10077.
> A good test that highlights this would be to add this to `KTableFilterTest`:
> {code:java}
> @Test
> public void
> shouldEnableSendOldValuesIfSourceTableNotMaterializedButFinalTableIsEvenIfNotForcedToMaterialize()
> {
> final StreamsBuilder builder = new StreamsBuilder();
> final String topic1 = "topic1";
> final KTableImpl<String, Integer, Integer> table1 =
> (KTableImpl<String, Integer, Integer>) builder.table(topic1, consumed);
> final KTableImpl<String, Integer, Integer> table2 =
> (KTableImpl<String, Integer, Integer>) table1.filter(predicate,
> Materialized.as("store2"));
> table2.enableSendingOldValues(false);
> doTestSendingOldValue(builder, table1, table2, topic1);
> }
> {code}
> Though this problem is not restricted to the filter call. Other processor
> suppliers suffer from the same issue.
> In addition, once [https://github.com/apache/kafka/pull/9156] is merged, if
> you call {{enableSendingOldValues}} without forcing materialization on a
> table that is itself materialized, but who's upstream is not. In such a
> situation, the table will _not_ enable sending old values, but should.
>
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