Memory (Off-Heap)
The Memory (Off-Heap) metrics groups contain metrics regarding Cassandra’s off-heap memory usage. There are two metrics groups: one for overall metrics and one for column-family-level metrics. The metrics available are:
- Memtable
- AllMemtables
- Compression metadata
- Index summary
- Bloom filter
Memtable
The total amount of data stored in the memtable that resides off-heap, including column related overhead and partitions overwritten.
You can also get this metric through the Monitoring API with the query param metrics=n::offheapsizememtable for overall metrics and the query param cf::{keyspace}::{table}::offHeapSizeMemtable for column-family-level metrics.
AllMemtables
The total amount of data stored in the memtables, including secondary indexes and pending flush memtables, that resides off-heap.
You can also get this metric through the Monitoring API with the query param metrics=n::offheapsizeallmemtables for overall metrics and the query param cf::{keyspace}::{table}::offHeapSizeAllMemtables for column-family-level metrics.
Compression metadata
The off-heap memory used by compression metadata.
You can also get this metric through the Monitoring API with the query param metrics=n::offheapusedcompressionmetadata for overall metrics and the query param metrics=cf::{keyspace}::{table}::offHeapUsedCompressionMetadata for column-family-level metrics.
Index summary
The off-heap memory used by the index summary.
You can also get this metric through the Monitoring API with the query param metrics=n::offheapusedindexsummary for overall metrics and the query param metrics=cf::{keyspace}::{table}::offHeapUsedIndexSummary for column-family-level metrics.
Bloom filter
The off-heap memory used by the bloom filter.
You can also get this metric through the Monitoring API with the query param metrics=n::offheapusedbloomfilter for overall metrics and the query param metrics=cf::{keyspace}::{table}::offHeapUsedBloomFilter for column-family-level metrics.
