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MINOR: document timestamped state stores (#8920) 

Reviewers: Matthias J. Sax <matthias@confluent.io>
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Jim Galasyn 2020-07-06 18:09:24 -07:00 committed by Matthias J. Sax
parent 5bea1a423b
commit 76f490e785
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docs/streams/developer-guide/processor-api.html
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@ -49,6 +49,7 @@
<li><a class="reference internal" href="#defining-and-creating-a-state-store" id="id4">Defining and creating a State Store</a></li>
<li><a class="reference internal" href="#fault-tolerant-state-stores" id="id5">Fault-tolerant State Stores</a></li>
<li><a class="reference internal" href="#enable-or-disable-fault-tolerance-of-state-stores-store-changelogs" id="id6">Enable or Disable Fault Tolerance of State Stores (Store Changelogs)</a></li>
<li><a class="reference internal" href="#timestamped-state-stores" id="id11">Timestamped State Stores</a></li>
<li><a class="reference internal" href="#implementing-custom-state-stores" id="id7">Implementing Custom State Stores</a></li>
</ul>
</li>
@ -229,6 +230,10 @@
<a class="reference internal" href="config-streams.html#streams-developer-guide-rocksdb-config"><span class="std std-ref">RocksDB configuration</span></a>.</li>
<li>Available <a class="reference external" href="/{{version}}/javadoc/org/apache/kafka/streams/state/Stores.html#persistentKeyValueStore-java.lang.String-">store variants</a>:
time window key-value store, session window key-value store.</li>
<li>Use <a class="reference external" href="/{{version}}/javadoc/org/apache/kafka/streams/state/Stores.html#persistentTimestampedKeyValueStore-java.lang.String-">persistentTimestampedKeyValueStore</a>
when you need a persistent key-(value/timestamp) store that supports put/get/delete and range queries.</li>
<li>Use <a class="reference external" href="/{{version}}/javadoc/org/apache/kafka/streams/state/Stores.html#persistentTimestampedWindowStore-java.lang.String-java.time.Duration-java.time.Duration-boolean-">persistentTimestampedWindowStore</a>
when you need a persistent windowedKey-(value/timestamp) store.</li>
</ul>
<div class="highlight-java"><div class="highlight"><pre><span></span><span class="c1">// Creating a persistent key-value store:</span>
<span class="c1">// here, we create a `KeyValueStore&lt;String, Long&gt;` named &quot;persistent-counts&quot;.</span>
@ -260,6 +265,10 @@
in-between app instance restarts.</li>
<li>Available <a class="reference external" href="/{{version}}/javadoc/org/apache/kafka/streams/state/Stores.html#inMemoryKeyValueStore-java.lang.String-">store variants</a>:
time window key-value store, session window key-value store.</li>
<li>Use <a class="reference external" href="/{{version}}/javadoc/org/apache/kafka/streams/state/TimestampedKeyValueStore.html">TimestampedKeyValueStore</a>
when you need a key-(value/timestamp) store that supports put/get/delete and range queries.</li>
<li>Use <a class="reference external" href="/{{version}}/javadoc/org/apache/kafka/streams/state/TimestampedWindowStore.html">TimestampedWindowStore</a>
when you need to store windowedKey-(value/timestamp) pairs.</li>
</ul>
<div class="highlight-java"><div class="highlight"><pre><span></span><span class="c1">// Creating an in-memory key-value store:</span>
<span class="c1">// here, we create a `KeyValueStore&lt;String, Long&gt;` named &quot;inmemory-counts&quot;.</span>
@ -343,6 +352,25 @@
</pre></div>
</div>
</div>
<div class="section" id="timestamped-state-stores">
<span id="streams-developer-guide-state-store-timestamps"></span><h3><a class="toc-backref" href="#id11">Timestamped State Stores</a><a class="headerlink" href="#timestamped-state-stores" title="Permalink to this headline"></a></h3>
<p>KTables always store timestamps by default.
A timestamped state store improves stream processing semantics and enables
handling out-of-order data in source KTables, detecting out-of-order joins and aggregations,
and getting the timestamp of the latest update in an Interactive Query.</p>
<p>You can query timestamped state stores both with and without a timestamp.</p>
<b>Upgrade note:</b> All users upgrade with a single rolling bounce per instance.
<ul class="first simple">
<li>For Processor API users, nothing changes in existing applications, and you
have the option of using the timestamped stores.</li>
<li>For DSL operators, store data is upgraded lazily in the background.</li>
<li>No upgrade happens if you provide a custom XxxBytesStoreSupplier, but you can opt-in
by implementing the <a class="reference external" href="/{{version}}/javadoc/org/apache/kafka/streams/state/TimestampedBytesStore.html">TimestampedBytesStore</a>
interface. In this case, the old format is retained, and Streams uses a proxy store
that removes/adds timestamps on read/write.</li>
</ul>
</p>
</div>
<div class="section" id="implementing-custom-state-stores">
<span id="streams-developer-guide-state-store-custom"></span><h3><a class="toc-backref" href="#id7">Implementing Custom State Stores</a><a class="headerlink" href="#implementing-custom-state-stores" title="Permalink to this headline"></a></h3>
<p>You can use the <a class="reference internal" href="#streams-developer-guide-state-store-defining"><span class="std std-ref">built-in state store types</span></a> or implement your own.