DSE Graph configuration

DSG stores cluster-wide options for DSE Graph in dse.yaml under the graph: and gremlin-server: keys. Most of the options that are common to modify have been discussed in the sections below. Of particular note, the Graph sandbox is configured in the Gremlin Server options of the dse.yaml file. This feature is enabled by default and provides protection from malicious attacks within the JVM.

To modify dse.yaml settings, modify the file on each node in the cluster and restart each node. Settings in the dse.yaml are node system level in scope. The dse.yaml files can also be modified using OpsCenter.

The remote.yaml file is the primary configuration file for DSG Gremlin console connections to the Gremlin Server. Most options are self-explanatory. In particular, be aware that if you are using analytic OLAP queries with DSG, changes are required in this file.

The replication factor (RF) for a graph can affect the performance of reads and writes in DSG. Just as for the DSE database, these factors control the number of replicas of data that the distributed graph database will store across multiple nodes.

One keyspaces are created for each graph. The replication factor is set when a graph is created.

Consistency level in DSG is controlled with graph traversal options and used for read and write operations on a traversal basis. Gremlin queries execute CQL commands to insert, read, and update graph data via traversals, and so the DSE database consistency level settings can affect the execution of graph operations. The consistency level for reads or writes are set per graph with the with('consistency', <cl_level>)used for both reads and writes.

The DSE Graph sandbox, configured in the dse.yaml file under the gremlin-server: key, is enabled by default. This security feature prevents malicious code execution in the JVM that could harm a DSE instance. Sandbox rules are defined to both blacklist (disallow execution) and whitelist (allow execution) packages, superclasses and types. For Java/Groovy code entered in the Gremlin console, only the specified allowed operations will execute. The default sandbox rules may be overridden in the dse.yaml file. The sandbox rules are applied in the following order:

Any types not specified in the whitelist are blocked by default. If an item is blacklisted, it cannot be placed in the whitelist unless it is removed from the blacklist; otherwise, an error occurs and the item is blocked.

An example of possible whitelisted and blacklisted items in the gremlin_server section of the dse.yaml file:

The Fluent API restricts the allowable operations to secure execution, but uses the sandbox to enable lambda functions.

DSE can authenticate or authorize access by users, secure the stored data with encryption, or secure Gremlin console with SSL, based on Graph vertex labels or graphs, as applicable.

DSE Graph security is managed by DSE security. As noted in this topic, you can modify the Graph Sandbox by customizing the gremlin-server: key of the dse.yaml file.

To configure the DSE Graph Gremlin console connection to the Gremlin Server, customize the remote.yaml file for your environment.

DSE Graph also supports auditing using DSE auditing; for details, refer to Setting up database auditing.

Lambda restriction is enabled by default to block arbitrary code execution in Gremlin traversals. Most applications should not require user-defined lambda functions. If lambda functions are required, disable lambda restrictions using the TraversalSource option to change the restrict_lambda (default: true) value.

Use the dev traversal source while you are experimenting in early DSG use and design. It allows you to query without creating any indexing, a distinct advantage for exploring your data and data model.

Use the with() traversal options to finetune the performance of graph queries. At various stages of using DSG, different options are more or less useful. For instance, similar to CQL, an option to allow-filtering can be useful early in design, but harmful when large datasets are inserted into the database. Familiarize yourself with the capabilities of the options available.

Timeout settings can cause failure of DSG in a variety of ways, both client-side and server-side. On the client-side, commands from the Gremlin console can time out before reaching the Gremlin server. Issuing the command :remote config timeout none in the Gremlin console allows the default maximum timeout of 3 minutes to be overridden with no time limit. Any request typed into the Gremlin console is sent to the Gremlin Server, and the console waits for a response before it aborts the request and returns control to the user. If the timeout is changed to none, the request will never timeout. This can be useful if the time to send a request to the server and get a return is taking longer than the default timeout, for complex traversals or large datasets.

On the server-side, the cluster-wide timeout settings, realtime_evaluation_timeout_in_seconds (default: 30 seconds) or analytic_evaluation_timeout_in_minutes(default: 1008 minutes), are the maximum time to wait for a traversal to evaluate for OLTP or OLAP traversals, respectively. These settings are found in the dse.yaml file. If the timeout behavior for traversal evaluation needs to be overridden for a particular graph, evaluation_timeout can be set on a graph-by-graph basis, to override either the OLTP or OLAP traversal evaluation timeout. If complex traversals are timing out during execution, changing an appropriate timeout setting should fix the error.

An additional server-side setting that can be adjusted in the dse.yaml file is schema_agreement_timeout_in_ms (30 seconds), the maximum time to wait for schema versions to agree across a cluster when making schema changes. If a large schema is submitted to a cluster, especially with indexes defined, this setting may need adjustment before data is submitted to the graph.

Finally, in the dse.yaml file, system_evaluation_timeout_in_seconds (default: 180 seconds) is defined as the maximum time to wait for a graph system request to evaluate. Creating or dropping a graph is a system request affected by this setting, which does not interact with the other timeout options.

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