is there any option that the job should truncate all cassandra table before inserting the new records ?
Which Cassandra connector are you referring to?
There are several and questions for the datastax one should probably be asked over at GitHub - datastax/kafka-sink: Apache Kafka® sink for transferring events/messages from Kafka topics to Apache Cassandra®, DataStax Astra and DataStax Enterprise (DSE).
But no, I don’t think providing this option on any sink connector is a safe operation since it would require knowing if the table had already been truncated or not