Cassandra Commit Log is an append only log that is used to track the mutations made to Column Families and provide durability for those mutations. Every mutation is appended to a Commit Log first before applied to an in memory write-back cache called Memtable. If a Memtable is not flushed to disk to create a SSTable then the mutations stored in it can be lost if Cassandra suddenly shutdowns or crashes. At startup, Cassandra replays the Commit Log to recover the data that was not stored to dis...| Key Concepts
Memtables store the current mutations applied to Column families. They function as a write back cache and provide faster write performance and faster read performance for recently written data. Mutations are organized in sorted order using skip list data structure in the Memtable. Each Column family is associated with its own Memtable. In this blog, on-heap based Memtable type is described. | Key Concepts