Collecting database summary diagnostics

Steps to enable collecting database summary diagnostics using the DataStax Enterprise Performance Service.

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).

Examples

These example commands make temporarily 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:

  1. Edit the dse.yaml file.

    dse.yaml

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

    Package installations
    Installer-Services installations

    		 /etc/dse/dse.yaml

    Tarball installations
    Installer-No Services installations

    		 installation_location/resources/dse/conf/dse.yaml
  2. 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
  3. (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