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Posted to commits@kafka.apache.org by mj...@apache.org on 2018/12/06 19:15:16 UTC
[kafka-site] branch asf-site updated: Porting PR 5996
This is an automated email from the ASF dual-hosted git repository.
mjsax pushed a commit to branch asf-site
in repository https://gitbox.apache.org/repos/asf/kafka-site.git
The following commit(s) were added to refs/heads/asf-site by this push:
new 92483fc Porting PR 5996
92483fc is described below
commit 92483fc3a740b1a122444685cc80e4d002f9f4e2
Author: Matthias J. Sax <ma...@confluent.io>
AuthorDate: Thu Dec 6 11:14:21 2018 -0800
Porting PR 5996
---
21/streams/developer-guide/dsl-api.html | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/21/streams/developer-guide/dsl-api.html b/21/streams/developer-guide/dsl-api.html
index 4b91eaa..04e7659 100644
--- a/21/streams/developer-guide/dsl-api.html
+++ b/21/streams/developer-guide/dsl-api.html
@@ -194,6 +194,7 @@
<p>
GlobalKTable provides the ability to look up <em>current</em> values of data records by keys. This table-lookup functionality is available through <code class="interpreted-text">join operations</code>.
+ Note that a GlobalKTable has <strong>no</strong> notion of time in contrast to a KTable.
</p>
<p>Benefits of global tables:</p>
@@ -2635,7 +2636,7 @@
<a class="reference internal" href="#streams_concepts_globalktable"><span class="std std-ref">GlobalKTable</span></a> (entire changelog stream) upon receiving a new record from the
KStream (record stream). An example use case would be “star queries” or “star joins”, where you would enrich a stream
of user activities (KStream) with the latest user profile information (GlobalKTable) and further context information
- (further GlobalKTables).</p>
+ (further GlobalKTables). However, because GlobalKTables have no notion of time, a KStream-GlobalKTable join is not a temporal join, and there is no event-time synchronization between updates to a GlobalKTable and processing of KStream records.</p>
<p>At a high-level, KStream-GlobalKTable joins are very similar to
<a class="reference internal" href="#streams-developer-guide-dsl-joins-kstream-ktable"><span class="std std-ref">KStream-KTable joins</span></a>. However, global tables provide you
with much more flexibility at the <a class="reference internal" href="#streams_concepts_globalktable"><span class="std std-ref">some expense</span></a> when compared to partitioned
@@ -2783,9 +2784,9 @@
</tr>
</tbody>
</table>
- <p><strong>Semantics of stream-table joins:</strong>
- The join semantics are identical to <a class="reference internal" href="#streams-developer-guide-dsl-joins-kstream-ktable"><span class="std std-ref">KStream-KTable joins</span></a>.
- The only difference is that, for KStream-GlobalKTable joins, the left input record is first “mapped” with
+ <p><strong>Semantics of stream-global-table joins:</strong>
+ The join semantics are different to <a class="reference internal" href="#streams-developer-guide-dsl-joins-kstream-ktable"><span class="std std-ref">KStream-KTable joins</span> because it's not a temopral join.</a>.
+ Another difference is that, for KStream-GlobalKTable joins, the left input record is first “mapped” with
a user-supplied <code class="docutils literal"><span class="pre">KeyValueMapper</span></code> into the table’s keyspace prior to the table lookup.</p>
</div>
</div>