Collecting histogram diagnostics

DSE histogram table data
Histogram	Details table	Summary table	Keyspace details	Keyspace summary	Global details	Global summary
cell_count	Y	Y	N	N	N	N
partition_size	Y	Y	N	N	N	N
range_latency	Y	Y	Y	N	Y	N
read_latency	Y	Y	Y	N	Y	N
sstables_per_read	Y	Y	Y	N	N	N
write_latency	Y	Y	Y	N	N	N

These tables show similar information to the data obtained by the nodetool tablehistograms utility. The major difference is that the nodetool histograms output is recent data, while the diagnostic tables contain lifetime data. The data in the diagnostic histogram tables is cumulative since the DSE server was started. In contrast, the nodetool tablehistograms shows the values for the past fifteen minutes.

To collect table histogram data for DataStax Enterprise (DSE), use the DSE Performance Service:

Edit the dse.yaml file.

In the dse.yaml file, set the enabled option for histogram_data_options to true.

# Column Family Histogram data tables options
histogram_data_options:
  enabled: true
  refresh_rate_ms: 10000
  retention_count: 3

Optional: To control how often the statistics are refreshed, increase or decrease the refresh_rate_ms option in dse.yaml.

The refresh_rate_ms specifies the length of the sampling period, which is the frequency that this data is updated.

Collecting histogram diagnostics

Was this helpful?

Give Feedback