Coordinator node The request initially goes to a coordinator node. Coordinator node is a node in the Cassandra cluster, which will act as a proxy for that request for the client. If all the replica nodes are alive based on the consistency level that user set with this request, Then the request will be propagated to the replica nodes, Otherwise, an unavailable exception will be thrown from the coordinator node. Replica nodes The remaining read steps are same in all replica nodes, For a single row request, it will use a QueryFilter class to pick the data from the Memtable and SStales that we are looking for. If Row cache is enabled, it will look into the memory to get that row. The row will contain an entire row, which will be trimmed based on the need of the request. For a row cache hit, the replica node will respond back immediately to the coordinator node, else the SSTable will be searched. SSTable Choosing algorithms If a ro