Specifying DSE database and graph settings

How to set DSE database and graph settings for a graph.

• Check all non-default values of configuration settings.

  schema.config().describe()

  graph.tx_groups.default.write_consistency: ALL
  graph.tx_groups.default.read_consistency: QUORUM

  Note: Default settings are not displayed with this call.
• Check the values of a specific setting.

  schema.config().option('graph.tx_groups.default.write_consistency').get()

  ALL

• Set the value of a configuration setting.

  schema.config().option('graph.tx_groups.default.write_consistency').set('ALL')

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• To retrieve all traversal sources that have been set, use the get() command with the traversal source type option:

  schema.config().option('graph.traversal_sources.*.type').get()

  REAL_TIME

• Set the maximum time to wait for a traversal to evaluate:

  schema.config().option("graph.traversal_sources.g.evaluation_timeout").set('PT2H')

  Tip: The timeout values can also be entered in seconds or minutes, as appropriate, using set('1500 ms'), for example.

  Important: Setting a timeout value greater than 1095 days (maximum integer) can exceed the limit of a graph session. Starting a new session and setting the timeout to a lower value can recover access to a hung session. This caution is applicable for all timeouts: evaluation_timeout, system_evaluation_timeout, analytic_evaluation_timeout, and realtime_evaluation_timeout

  PT2H

  Note: The dse.yaml file has settings realtime_evaluation_timeout_in_seconds and analytic_evaluation_timeout_in_minutes that determine the timeout value used depending on whether the query is an OLTP or OLAP query, respectively. The command shown above using evaluation_timeoutwill override any system level setting for the traversal source g specified. The hierarchy for OLTP traversals is, in order of override: graph.traversal_sources.g.evaluation_timeout > realtime_evaluation_timeout_in_seconds > system_evaluation_timeout_in_seconds. The hierarchy for OLAP traversal timeout overrides is similar to OLTP: graph.traversal_sources.a.evaluation_timeout > analytic_evaluation_timeout_in_minutes > system_evaluation_timeout_in_seconds.

• Settings can also be set while creating a new graph. For instance, replication for graph inherits DSE database defaults, so the replication factor is set to 1 and the class is SimpleStrategy. As with the DSE database, the replication factor for graph should be set before adding data.

  system.graph('gizmo').
      replication("{'class' : 'NetworkTopologyStrategy', 'dc1' : 3 }").
      ifNotExists().create()

• Graph also creates a keyspace for storing graph variables in DSE tables. This keyspace holds essential information, so the replication factor should be set to something higher than one replica to ensure no loss.

  gremlin>  system.graph('gizmo').    
      replication("{'class' : 'NetworkTopologyStrategy', 'dc1' : 3 }").
      systemReplication("{'class' : 'NetworkTopologyStrategy', 'dc1' : 3 }").
      ifNotExists().create()

• Additional schema settings can be configured at graph creation.

  system.graph('food2').
    replication("{'class' : 'SimpleStrategy', 'replication_factor' : 1 }").
    systemReplication("{'class' : 'SimpleStrategy', 'replication_factor' : 1 }").
    option("graph.schema_mode").set("Development").
    option("graph.allow_scan").set("false").
    option("graph.default_property_key_cardinality").set("multiple").
    option("graph.tx_groups.*.write_consistency").set("ALL").
    create()

  More information can be found in the Schema API reference.

• The allow_scan option can be set at either a single graph level or as shown here, for all actions within a transaction made on a single node. This setting can be useful if a quorum cannot be mustered for writing the option change to the system table.

  graph.tx().config().option("allow_scan", true).open()

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