Configuring memtable thresholds
Configuring memtable thresholds can improve write performance.
The database flushes memtables to disk, creating SSTables when the commit log space threshold or the memtable cleanup threshold has been exceeded. Configure the commit log space threshold per node in the cassandra.yaml. How you tune memtable thresholds depends on your data and write load. Increase memtable thresholds under either of these conditions:
The write load includes a high volume of updates on a smaller set of data.
A steady stream of continuous writes occurs. This action leads to more efficient compaction.
Allocating memory for memtables reduces the memory available for caching and other internal database structures, so tune carefully and in small increments.