Collecting database summary diagnostics

You can enable collecting database summary diagnostics using the DataStax Enterprise Performance Service.

These database summary diagnostic tables collect statistics at a database level:

node_table_snapshot: Per node lifetime table metrics broken down by keyspace and table.
table_snapshot: Cluster-wide lifetime table metrics broken down by keyspace and table (aggregates node_table_snapshot from each node in the cluster).
keyspace_snapshot: Cluster-wide lifetime table metrics, aggregated at the keyspace level (rolls up the data in table_snapshot).

Where is the dse.yaml file?

The location of the dse.yaml file depends on the type of installation:

Installation Type Location

Installation Type	Location
Package installations + Installer-Services installations	`/etc/dse/dse.yaml`
Tarball installations + Installer-No Services installations	`<installation_location>/resources/dse/conf/dse.yaml`

Package installations + Installer-Services installations

/etc/dse/dse.yaml

Tarball installations + Installer-No Services installations

<installation_location>/resources/dse/conf/dse.yaml

Examples

These example commands make temporary changes only. Changes made with performance object subcommands do not persist between restarts and are useful only for short-term diagnostics.

See Collecting database summary diagnostics.

To enable the collection of database-level statistics data:

dsetool perf clustersummary enable

To disable the collection of database-level statistics data:

dsetool perf clustersummary disable

See Collecting slow queries.

To keep slow queries in-memory only:

dsetool perf cqlslowlog skip_writing_to_db

To set the number of slow queries to keep in-memory:

dsetool perf cqlslowlog set_num_slowest_queries 5

To write slow queries to the database:

dsetool perf cqlslowlog write_to_db

To disable collecting information on slow queries:

dsetool perf cqlslowlog disable

To change the threshold to collect information on 5% of the slowest queries:

dsetool perf cqlslowlog 95.0

To enable collecting information to identify slow search queries:

dsetool perf solrslowlog enable

To change the threshold value (in milliseconds) at which a sub-query is slow enough to be reported:

dsetool perf solrslowlog 200

Procedure

To permanently enable the collection of database-level statistics data:

Edit the dse.yaml file.

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

# Database summary stats options
db_summary_stats_options:
    enabled: true
    refresh_rate_ms: 10000

Optional: To control how often the statistics are refreshed, increase or decrease the refresh_rate_ms parameter.

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

Example

To temporarily enable the collection of database-level statistics data:

dsetool perf clustersummary enable

To temporarily disable the collection of database-level statistics data:

dsetool perf clustersummary disable