Preferred leader is a broker that was leader when topic was created. It is preferred because when partitions are first created, the leaders are balanced between brokers. Otherwise, any of the in-sync replicas (ISR) will be elected leader, as long as unclean.leader.election=false (by default)

As of Kafka 2.3, the kafka-topics.sh command can take --bootstrap-server localhost:9092 as an argument. You could also use the (now deprecated) option of --zookeeper localhost:2181.

date is a logical type

Kafka Connect Sink is used to export data from Kafka to external databases and Kafka Connect Source is used to import from external databases into Kafka.

Point-to-point (request-response) style will couple client to the server.

When you create a new topic, partitions replicas are spreads across racks to maintain availability. Hence, the Rack A, which currently does not hold the topic partition, will be selected for the last replica

Kafka partitions are made of segments (usually each segment is 1GB), and each segment has two corresponding indexes (offset index and time index)

Since Confluent 5.4.0, Avro 1.9.1 is used. Since default value was added to enum complex type , the schema resolution changed from:

(<1.9.1) if both are enums:** if the writer's symbol is not present in the reader's enum, then an error is signalled. **(>=1.9.1) if both are enums:

if the writer's symbol is not present in the reader's enum and the reader has a default value, then that value is used, otherwise an error is signalled.

GlobalKTables have their datasets replicated on each Kafka Streams instance and therefore no repartitioning is required

metadata is stored in and built from the KSQL command topic. Each KSQL server has its own in-memory version of the metastore.