Dgraph flags

Dgraph flags modify the Dgraph's configuration and behavior.

Important: Dgraph flags are intended for use by Oracle Support only. They are included in this document for completeness.

You can set Dgraph flags by adding them to the DGRAPH_ADDITIONAL_ARG property in bdd.conf in $BDD_HOME/BDD_manager/conf directory, then using the bdd-admin publish-config script to update the cluster configuration. Any flag included in this list will be set each time the Dgraph starts. For more information, see publish-config.

Note: Some of the Dgraph flags have the same names as HDFS Agent flags. These must have the same settings as their HDFS Agent counterparts.
Flag Description
? Prints the help message and exits. The help message includes usage information for each Dgraph flag.
-v Enables verbose mode. The Dgraph will print information about each request it receives to either its stdout/stderr file (dgraph.out) or the file set by the --out flag.
--backlog-timeout Specifies the maximum number of seconds that a query is allowed to spend waiting in the processing queue before the Dgraph responds with a timeout message.

The default is 0 seconds.

--bulk_load_port Sets the port on which the Dgraph listens for bulk load ingest requests. This must be the same as the port specified for the HDFS Agent --bulk_load_port flag.

This flag maps to the DGRAPH_BULKLOAD_PORT property in bdd.conf.

--cluster_identity Specifies the cluster identity of the Dgraph running on this node. The syntax is: 
protocol:hostname:dgraph_port:dgraph_bulk_load_port:agent_port

This must be the same as the cluster identity specified for the HDFS Agent --custer_identity flag.

--cmem Specify the maximum memory usage (in MB) for the Dgraph cache. For more information, see Tips for setting the Dgraph cache size.

This flag maps to the DGRAPH_CACHE property in bdd.conf.

--export_port Specifies the port on which the Dgraph listens for requests from the HDFS Agent.

This should be the same as the number specified for the HDFS Agent --export_port flag. It should be different from the numbers specified for both the --port and --bulk_load_port flags.

This flag maps to the AGENT_EXPORT_PORT property in bdd.conf.

--help Prints the help message and exits. The help message includes usage information for each Dgraph flag.
--host Specifies the name of the Dgraph's host server.

This flag maps to the DGRAPH_SERVERS property in bdd.conf.

--log Specifies the path to the Dgraph request log file. The default file used is dgraph.reqlog.
--log-level Specifies the log level for the Dgraph log subsystems. For information on setting this flag, see Setting the Dgraph log levels.

This flag maps to the DGRAPH_LOG_LEVEL property in bdd.conf.

--memory-limit Specifies the maximum amount of memory (in MB) the Dgraph is allowed to use for processing.

If you do not use this flag, the memory limit is by default set to 80% of the machine's available RAM.

If you specify a limit in MB for this flag, this number is used as the memory consumption limit, for the Dgraph, instead of 80% of the machine's available RAM.

If you specify 0 for this flag, this overrides the default of 80% and means there is no limit on the amount of memory the Dgraph can use for processing.

For a summary of how Dgraph allocates and utilizes memory, see Memory consumption by the Dgraph.

--mount_hdfs Specifies that the Dgraph should mount HDFS in a CDH or HDP environment. The target HDFS is specified by <hdfs config> which is the Hadoop HDFS configuration file (usually named hdfs-site.xml) and <core config> which is the Hadoop core configuration file (usually named core-site.xml).
--mount-maprfs Specifies that the Dgraph should mount MapR-FS. <cluster> specifies the name of MapR cluster, while <path> is the index path on MapR-FS.
--mppPort Specifies the port on this machine used for the Distributed Dgraph connection.

This flag maps to the DGRAPH_MPP_PORT property in bdd.conf.

--net-timeout Specifies the maximum amount of time (in seconds) the Dgraph waits for the client to download data from queries across the network. The default value is 30 seconds.
--out Specifies a file to which the Dgraph's stdout/stderr will be remapped. If this flag is omitted, the Dgraph uses its default stdout/stderr file, dgraph.out.

This file must be different from the one specified by the HDFS Agent's --out flag.

This flag maps to the DGRAPH_OUT_FILE property in bdd.conf.

--pidfile Specifies the file the Dgraph's process ID (PID) will be written to. The default filename is dgraph.pid.
--port Specifies the port used by the Dgraph's host server.

This flag maps to the DGRAPH_WS_PORT property in bdd.conf.

--search_char_limit Specifies the maximum number of characters that a text search term can contain. The default value is 132.
--search_max Specifies the maximum number of terms that a text search query can contain. The default value is 10.
--snip_cutoff Specifies the maximum number of words in an attribute that the Dgraph will evaluate to identify a snippet. If a match is not found within the specified number of words, the Dgraph won't return a snippet, even if a match occurs later in the attribute value.

The default value is 500.

--snip_disable Globally disables snippeting.
--sslcafile
Note: This flag is not used in Oracle Big Data Discovery.
Specifies the path to the SSL Certificate Authority file that the Dgraph will use to authenticate SSL communications with other components.
--sslcertfile
Note: This flag is not used in Oracle Big Data Discovery.
Specifies the path of the SSL certificate file that the Dgraph will present to clients for SSL communications.
--stat-brel
Note: This flag is deprecated and not used in Oracle Big Data Discovery.
Creates dynamic record attributes that indicate the relevance rank assigned to full-text search result records.
--syslog Directs all output to syslog.
--threads Specifies the number of threads the Dgraph will use to process queries and execute internal maintenance tasks. The value you provide must be a positive integer (2 or greater). The default is 2 threads.

The recommended number of threads for machines running only the Dgraph is the number of CPU cores the machine has. For machines co-hosting the Dgraph with other Big Data Discovery components, the recommended number of threads is the number of CPU cores the machine has minus two.

This flag maps to the DGRAPH_THREADS property in bdd.conf.

--version Prints version information and then exits. The version information includes the Oracle Big Data Discovery version number and the internal Dgraph identifier.
--wildcard_max Specifies the maximum number of terms that can match a wildcard term in a wildcard query that contains punctuation, such as ab*c.def*. The default is 100.
--zookeeper Specifies a comma-separated list of ZooKeeper servers. The syntax for each ZooKeeper server is: 
<hostname>:<port>

This must be the same as the value specified for the HDFS Agent --zookeeper flag.

--zookeeper_auth Obtains the ZooKeeper authentication password from standard in. Note the following about this flag:
  • The "ZooKeeper authentication password" corresponds to individual node-level access using ACL described here (Dgraph uses the digest scheme): https://zookeeper.apache.org/doc/r3.1.2/zookeeperProgrammers.html#sc_ZooKeeperAccessControl

    It has nothing to do with Kerberos or the ability of the Dgraph to establish a session with ZooKeeper.

  • It is imperative that all Dgraphs, Dgraph Gateway, and Dgraph HDFS Agent are using the same "Zookeeper authentication password" because they will not be able to access needed information created by other components if they are using different passwords. If the Dgraph cannot access information in ZooKeeper due to a wrong password, it is a fatal error.
--zookeeper_index Specifies the index of the Dgraph cluster in the ZooKeeper ensemble. ZooKeeper uses this value to identify the Dgraph cluster. This must be the same as the value specified for the HDFS Agent --zookeeper_index flag.

This flag maps to the ZOOKEEPER_INDEX property in bdd.conf.