gaborgsomogyi commented on a change in pull request #23791:
[SPARK-20597][SQL][SS][WIP] KafkaSourceProvider falls back on path as synonym
for topic
URL: https://github.com/apache/spark/pull/23791#discussion_r260285023
##########
File path: docs/structured-streaming-kafka-integration.md
##########
@@ -499,20 +522,28 @@ StreamingQuery ds = df
.option("topic", "topic1")
.start();
-// Write key-value data from a DataFrame to Kafka using a topic specified in
the data
+// Write key-value data from a DataFrame to Kafka using the topic specified in
the data
StreamingQuery ds = df
.selectExpr("topic", "CAST(key AS STRING)", "CAST(value AS STRING)")
.writeStream()
.format("kafka")
.option("kafka.bootstrap.servers", "host1:port1,host2:port2")
.start();
+// Write key-value data from a DataFrame to Kafka using the topic specified in
the path option
+StreamingQuery ds = df
+ .selectExpr("CAST(key AS STRING)", "CAST(value AS STRING)")
Review comment:
With the latest change don't fully understand the direction. Now half of the
doc uses `selectExpr` and the other part `select`. Still questioning the need,
what is the benefit? If the `selectExpr` executed and properly formed not more
unstable than the simple `select` in the doc right?
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