From the documentation [below] I understand PCAP files that are stored in HDFS sequenceFile has the structure of timestamp as the key and a value of the raw data. However, there are files that ONLY contains keys with no value. If no value is captured; why would we need the key? When would this be useful?
A key which is the byte representation of a 64-bit unsigned long representing a time-unit since the unix epoch
A value which is the raw packet data without header (either global pcap header or packet header)