question

Hi, querying system.local is usually very fast, but indeed we cannot guarantee that such a query will always be fast.

While Erick is right when he says that this is a good way to check the availability of one node, this is definitely NOT the right thing to do to check the availability of the cluster as a whole.

As a matter fo fact, we are right now rethinking Spring Boot's health check mechanism, see JAVA-2472. The idea is to replace that check by a token ring inspection. This would give us a much more accurate picture of the cluster health, and has the advantage of not requiring executing any query.

This enhanced health check should be released soon.

In the meanwhile:

there's no way to tell Spring via configuration to not include it

Actually there is: add this line to your application.properties:

management.health.cassandra.enabled=false

@vkayanala_42513 Querying the system.local table is a good way to do an end-to-end check on the availability of a node:

• confirms that the services are operational
• node is listening for requests from clients
• confirms reads are working for a specific node because the table is local to each node

It is also very performant because there is only ever 1 partition in the table (partition key local). And for what it's worth, one of its authors @alexandre.dutra is one of the leading engineers for drivers and tools here at DataStax.

If the check is slow, it might indicate a problem with read latency on the node (it's busy serving lots of requests) or the network between your app servers(s) and the cluster is slow so check for those. Cheers!