While we want a number of virtual tables to display data in a way thats great and intuitive like in nodetool. There is also much for being able to expose the metrics we have for tooling via CQL instead of JMX. This is more for the tooling and adhoc advanced users who know exactly what they are looking for.
Initial idea is to expose data via ((keyspace, table), metric) with a column for each metric value. Could also use a Map or UDT instead of the column based that can be a bit more specific to each metric type. To that end there can be a metric_type column and then a UDT for each metric type filled in, or a single value with more of a Map<Text, Text> style. I am purposing the column type though as with ALLOW FILTERING it does allow more extensive query capabilities.
- Use reflection to grab all the metrics from TableMetrics (see:
CASSANDRA-7622impl). This is easiest and least abrasive towards new metric implementors... but its reflection and a kinda a bad idea.
- Add a hook in TableMetrics to register with this virtual table when registering
- Pull from the CassandraMetrics registery (either reporter or iterate through metrics query on read of virtual table)