Compaction refers to a maintenance process in Cassandra , in which, the SSTables are reorganized for data optimization of data structure son the disk. The compaction process is useful during interactive with memtable. There are two type sof compaction in Cassandra:
Minor compaction: started automatically when a new sstable is created. Here, Cassandra condenses all the equally sized sstables into one.
Major compaction : is triggered manually using nodetool. Compacts all sstables of a ColumnFamily into one.