apache/cassandra · error · IllegalArgumentException

Unknown metric name:

Error message

Unknown metric name: 

What it means

RuntimeException from NodeProbe.getSaiMetricValue's switch when the metric name is not one of the recognized SAI metric names (QueryLatency, PostFilteringReadLatency, DiskUsedBytes, etc.). This is a guard over user-supplied metric names for nodetool SAI metric lookups.

Solutions

1. Use one of the supported SAI metric names (see nodetool help / StorageAttachedIndexMetrics)
2. Check spelling and case of the metric argument
3. Extend the switch if a newly added SAI metric must be exposed

When it happens

Trigger: Thrown at src/java/org/apache/cassandra/tools/NodeProbe.java:2078 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/57053ef1b5ced719. Report an issue: GitHub.

Appendix: source

Thrown at src/java/org/apache/cassandra/tools/NodeProbe.java:2078

    private Object getSaiMetricValue(String metricName, ObjectName oName) throws IOException
    {
        switch (metricName)
        {
            case "QueryLatency":
                return JMX.newMBeanProxy(mbeanServerConn, oName, CassandraMetricsRegistry.JmxTimerMBean.class);
            case "PostFilteringReadLatency":
            case "SSTableIndexesHit":
            case "IndexSegmentsHit":
            case "RowsFiltered":
                return JMX.newMBeanProxy(mbeanServerConn, oName, CassandraMetricsRegistry.JmxHistogramMBean.class);
            case "DiskUsedBytes":
            case "TotalIndexCount":
            case "TotalQueryableIndexCount":
                return JMX.newMBeanProxy(mbeanServerConn, oName, CassandraMetricsRegistry.JmxGaugeMBean.class).getValue();
            case "TotalQueryTimeouts":
                return JMX.newMBeanProxy(mbeanServerConn, oName, CassandraMetricsRegistry.JmxCounterMBean.class).getCount();
            default:
                throw new IllegalArgumentException("Unknown metric name: " + metricName);
        }
    }

    private String getSaiMetricScope(String metricName)
    {
        switch (metricName)
        {
            case "QueryLatency":
            case "SSTableIndexesHit":
            case "IndexSegmentsHit":
            case "RowsFiltered":
                return TableQueryMetrics.PerQueryMetrics.PER_QUERY_METRICS_TYPE;
            case "PostFilteringReadLatency":
            case "TotalQueryTimeouts":
                return TableQueryMetrics.TABLE_QUERY_METRIC_TYPE;
            case "DiskUsedBytes":
                return IndexGroupMetrics.INDEX_GROUP_METRICS_TYPE;
            case "TotalIndexCount":

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