Github user tdas commented on a diff in the pull request:
https://github.com/apache/spark/pull/17246#discussion_r106722579
--- Diff: docs/structured-streaming-kafka-integration.md ---
@@ -373,11 +375,204 @@ The following configurations are optional:
</tr>
</table>
+## Producing Data to Kafka
+
+### Writing Streaming Queries to Kafka
+
+<div class="codetabs">
+<div data-lang="scala" markdown="1">
+{% highlight scala %}
+
+// Write key-value data from a DataFrame to a specific Kafka topic
specified in an option
+val s1 = df1
+ .selectExpr("CAST(key AS STRING)", "CAST(value AS STRING)")
+ .writeStream
+ .format("kafka")
+ .option("kafka.bootstrap.servers", "host1:port1,host2:port2")
+ .option("topic", "topic1")
+ .start()
+
+// Write key-value data from a DataFrame to Kafka using a topic specified
in the data
+val s2 = df2
+ .selectExpr("topic", "CAST(key AS STRING)", "CAST(value AS STRING)")
+ .writeStream
+ .format("kafka")
+ .option("kafka.bootstrap.servers", "host1:port1,host2:port2")
+ .start()
+
+{% endhighlight %}
+</div>
+<div data-lang="java" markdown="1">
+{% highlight java %}
+
+// Write key-value data from a DataFrame to a specific Kafka topic
specified in an option
+StreamingQuery s1 = df1
+ .selectExpr("CAST(key AS STRING)", "CAST(value AS STRING)")
+ .writeStream()
+ .format("kafka")
+ .option("kafka.bootstrap.servers", "host1:port1,host2:port2")
+ .option("topic", "topic1")
+ .start()
+
+// Write key-value data from a DataFrame to Kafka using a topic specified
in the data
+StreamingQuery s2 = df1
+ .selectExpr("topic", "CAST(key AS STRING)", "CAST(value AS STRING)")
+ .writeStream()
+ .format("kafka")
+ .option("kafka.bootstrap.servers", "host1:port1,host2:port2")
+ .start()
+
+{% endhighlight %}
+</div>
+<div data-lang="python" markdown="1">
+{% highlight python %}
+
+# Write key-value data from a DataFrame to a specific Kafka topic
specified in an option
+s1 = df1 \
+ .selectExpr("CAST(key AS STRING)", "CAST(value AS STRING)") \
+ .writeStream \
+ .format("kafka") \
+ .option("kafka.bootstrap.servers", "host1:port1,host2:port2") \
+ .option("topic", "topic1") \
+ .start()
+
+# Write key-value data from a DataFrame to Kafka using a topic specified
in the data
+s2 = df2 \
+ .selectExpr("topic", "CAST(key AS STRING)", "CAST(value AS STRING)") \
+ .writeStream \
+ .format("kafka") \
+ .option("kafka.bootstrap.servers", "host1:port1,host2:port2") \
+ .start()
+
+{% endhighlight %}
+</div>
+</div>
+
+### Writing Batch Queries to Kafka
+
+<div class="codetabs">
+<div data-lang="scala" markdown="1">
+{% highlight scala %}
+
+// Write key-value data from a DataFrame to a specific Kafka topic
specified in an option
+df1.selectExpr("CAST(key AS STRING)", "CAST(value AS STRING)")
+ .write
+ .format("kafka")
+ .option("kafka.bootstrap.servers", "host1:port1,host2:port2")
+ .option("topic", "topic1")
+ .save()
+
+// Write key-value data from a DataFrame to Kafka using a topic specified
in the data
+df2.selectExpr("topic", "CAST(key AS STRING)", "CAST(value AS STRING)")
+ .write
+ .format("kafka")
+ .option("kafka.bootstrap.servers", "host1:port1,host2:port2")
+ .save()
+
+{% endhighlight %}
+</div>
+<div data-lang="java" markdown="1">
+{% highlight java %}
+
+// Write key-value data from a DataFrame to a specific Kafka topic
specified in an option
+df1.selectExpr("CAST(key AS STRING)", "CAST(value AS STRING)")
+ .write()
+ .format("kafka")
+ .option("kafka.bootstrap.servers", "host1:port1,host2:port2")
+ .option("topic", "topic1")
+ .save()
+
+// Write key-value data from a DataFrame to Kafka using a topic specified
in the data
+df1.selectExpr("topic", "CAST(key AS STRING)", "CAST(value AS STRING)")
+ .write()
+ .format("kafka")
+ .option("kafka.bootstrap.servers", "host1:port1,host2:port2")
+ .save()
+
+{% endhighlight %}
+</div>
+<div data-lang="python" markdown="1">
+{% highlight python %}
+
+# Write key-value data from a DataFrame to a specific Kafka topic
specified in an option
+df1.selectExpr("CAST(key AS STRING)", "CAST(value AS STRING)") \
+ .write \
+ .format("kafka") \
+ .option("kafka.bootstrap.servers", "host1:port1,host2:port2") \
+ .option("topic", "topic1") \
+ .save()
+
+# Write key-value data from a DataFrame to Kafka using a topic specified
in the data
+df2.selectExpr("topic", "CAST(key AS STRING)", "CAST(value AS STRING)") \
+ .write \
+ .format("kafka") \
+ .option("kafka.bootstrap.servers", "host1:port1,host2:port2") \
+ .save()
+
+{% endhighlight %}
+</div>
+</div>
+
+Each row being written to Kafka has the following schema:
--- End diff --
I think its better to put this section of necessary and optional columns
before the examples, right after "Producing Data to Kafka". The sink options
can stay here after the examples.
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