Calculating partition size
Determining how much data your Cassandra partitions can hold.
For efficient operation, partitions must be sized within certain limits. Two measures of partition size are the number of values in a partition and the partition size on disk. The maximum number of columns per row is two billion. Sizing the disk space is more complex, and involves the number of rows and the number of columns, primary key columns and static columns in each table. Each application will have different efficiency parameters, but a good rule of thumb is to keep the maximum number of values below 100,000 items and the disk size under 100MB.