Virtual tables, introduced in Apache Cassandra™ 4.0, allow you to expose metrics and properties of the node with the same interface as ordinary tables. This allows for a much easier way to observe the state and the health of the cluster without leaving the CQL protocol.
In this scenario you will learn:
- how to look at virtual tables and their contents
- what you cannot do with virtual tables
- what to expect if you change node settings
Note: wait until you see the message "Cassandra has started" in the terminal before proceeding.
First, verify that Cassandra is properly installed on this machine and is running as a system service. To do so, you can ask your operating system's daemon manager:
systemctl status cassandra --no-pager
Look for a green circle and
Active (running) in the output.
Even better, you can use
nodetool, Cassandra's utility for node administration:
The output should show that the current node (which forms a cluster by itself) is in a status "UN" (meaning Up and Normal).
Make sure Cassandra is completely started before proceeding.
Please run the following to initialize the other terminals of this scenario:
echo Initializing terminal 2
echo Initializing terminal 3
You will use
cqlsh several times during this exercise. So let us open a
cqlsh console and keep it running on the second terminal: