I am working on confluent-4.1.1 with ksql cli. Can I create stream for nested avro data format in this version as i tried with version-5 and it was working fine but no useful link found where mentioned about nested avro schema in confluent-4.1.1
I tried to create stream -
create stream new_order with(kafka_topic='transition',value_format='avro');
Got error -
Could not fetch the AVRO schema from schema registry. Cannot find correct type for avro type: transition.Value
Nested Avro support for KSQL was added in version 5.0 of Confluent Platform
Related
The difference between vanilla apache Avro and Avro with confluent schema registry is that when using apache avro , we send schema+message in kafka topic whereas in confluent schema registry , we send schemaID+message in kafka topic ? So here , schema registry helps in performance improvement via schema look up in registry. Is there any other benefit of using confluent schema registry ? Also , does apache avro supports compatabilty rules of schema evolution like schema registry ?
Note: There are other implementations of a "Schema Registry" that can use used with Kafka.
Here are a list of reasons
Clients can discover schemas without interacting with Kafka. For example, Apache Hive / Presto / Spark can download schemas from the Registry to perform analytics.
The registry is centrally responsible for compatibility checks rather than pushing each client to operate that on their own (to answer your second question)
The same applies to any serialization format, as well, not only Avro
Can we use schema registry for json messages and json schemas? Or is it like we have to use avro serialization for value serialization of messages.
Confluent schema registry also support JSON schema and Protobuf with the release of Confluent Platform 5.5. It has been announced in this blog.
How to auto-save Avro schema in Confluent Schema Registry from Apache NiFi flow?
That's basically the question.
I am not finding the way of automatically storing the Avro schema of the record in the Confluent Schema Registry from a NiFi flow. It is possible to flexibly read and populate message with the reference to the schema in the Confluent Schema-Registry, but there should be a way of auto-creating one in the registry instead of demanding Confluent Schema-Registry to be initialized upfront before NiFi flow starts.
Update
Here is my current Flow:
I'm reading from a Postgres table using QueryDatabaseTableRecord processor (version 1.10) and publishing [new] records to a Kafka topic using PublishKafkaRecord_2_0 (version 1.10.0).
I want to publish to Kafka in Avro format storing (and passing around) the Avro schema in the Confluent Schema Registry (that works well in other places of my NiFi setup).
For that, I am using AvroRecordSetWriter in the "Record Writer" property on the QueryDatabaseTableRecord processor with the following properties:
PublishKafkaRecord processor is configured to read Avro schema from the input message (using the Confluent schema registry, the schema is not embedded into each FlowFile) and uses same AvroRecordSetWriter as QueryDatabaseTableRecord processor to write to Kafka.
That's basically it.
Trying to replace the first AvroRecordSetWriter with one that embeds the schema with the hope that the second AvroRecordSetWriter could auto generate schema in the Confluent Schema Registry on publish, since I don't want to bloat each message with my embedded Avro schema.
Update
I've tried to follow the advice from the comment as follows
With that I was trying to make first access to the Confluent Schema Registry the last step in the chain. Unfortunately, my attempts were unsuccessful. The only option that worked was my initial described in this question that required a schema in the registry upfront/in advance to work.
Both other cases that I tried ended up with the exception:
org.apache.nifi.schema.access.SchemaNotFoundException: Cannot write Confluent Schema Registry Reference because the Schema Identifier is not known
Please note, that I cannot use "Inherit Schema from record" in the last writer's schema access, since I'm getting an invalid combination and the NiFi config validation doesn't pass such combination through.
I have a Kafka topic where the values are MessagePack-encoded.
Is there any way to sink the records from this topic into MongoDB using the MongoDB Kafka connector, or must the record values simply be stored as JSON?
You will need to find or create your own Kafka Connect Converter, then add that package to each Connect worker's classpath, followed by setting it as your key/value converter setting, from which the existing Mongo Sink Connector can deserialize the messages into a Struct and Schema form, and handle correctly.
JSON was never a requirement. Avro and Protobuf should work as well
I can run example by following Start Streaming with Kafka and Spring Cloud, but unfortunately it doesn't use confluent schema registry. I read the confluent schema registry part of Spring Cloud Stream reference guide, but it didn't work with my confluent 3.0.0 and the guide doesn't mention how to produce Avro message using confluent schema registry. So, can anyone guide me how to achieve it? Thanks!
The Spring Cloud Stream is not yet compatible with Confluent Schema Registry. See discussion in this thread https://github.com/spring-cloud/spring-cloud-stream/issues/850