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The following page has been changed by EricEvans: http://wiki.apache.org/cassandra/MemtableThresholds New page: = Memtable Thresholds = When performing write operations, Cassandra stores values to column-family specific, in-memory data structures, called Memtables. Memtables are flused to disk whenever a threshold is exceeded, so it's important to have these thresholds configured properly configured to keep Memtable size in check, and memory usage in general with limits. == MemtableSizeInMB == == MemtableObjectCountInMillions == == Using Jconsole To Optimize Thresholds == Cassandra's column-family mbeans have a number of attributes that can prove invaluable in determining optimal thresholds. Once way to access this instrumentation is using Jconsole, a graphical monitoring and management application that ships with your JDK. Launching Jconsole with no arguments will display the "New Connection" dialog box. If you are running Jconsole on the same machine that Cassandra is running on, then you can connect using the PID, otherwise you will need to connect remotely (the default startup scripts for Cassandra cause the VM to listen on port 8080). [connect.png] Once connected, select the ''MBeans'' tab, expand the ''org.apache.cassandra.db'' section, and finally one of your column families. The interesting attributes here are: * ''!MemtableColumnsCount:'' * ''!MemtableDataSize:'' * ''!MemtableSwitchCount:'' [attributes.png] [operations.png]
