Just wondering Mukesh - the reason you want this feature is because your value payload is not small (tens of kb). Don't know if that is the right usage of kafka. It might be worthwhile to store the avro files in a filesystem (regular, cluster fs, hdfs or even hbase) and the value in your kafka message can be the reference or uri for the avro file.
That way you make the best use of each system's features and strengths. Kafka does have api to get metadata - the topics, partitions and primary for partition etc. If we consider a key-value pair as a "record" than what you are looking for is to get a part of the record (ie key only) and not the whole record - so i would still consider that a data query/api.
