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Server Configuration

This page discusses configuring the Stardog server. Configuring a Stardog database is discussed in detail in the Database Configuration section.

Page Contents
  1. Configuring Temporary (“Scratch”) Space
  2. stardog.properties
    1. Example
  3. Updatable Properties
  4. Configuration Options
    1. Query Answering
    2. Connection Configuration
    3. Backups
    4. Memory
    5. Geospatial
    6. Cluster
    7. Security
    8. SSL
    9. LDAP
    10. Kerberos
    11. Logging
      1. Access Logging
      2. Audit Logging
      3. Slow Query Logging
    12. Monitoring
    13. Exports
    14. HTTP Configuration
    15. Optimizer Configuration

Configuring Temporary (“Scratch”) Space

Stardog uses the value of the JVM argument java.io.tmpdir to write temporary files for many different operations. If you want to configure temp space to use a particular disk volume or partition, use the java.io.tmpdir JVM argument on Stardog startup.

Undesirable behavior will occur if this part of the filesystem runs out of (or even is low on) free disk space. Stardog will delete temporary files when they’re no longer needed. Still, Stardog admins should configure their monitoring systems to make sure that free disk space is always available, both on java.io.tmpdir and on the disk volume that hosts STARDOG_HOME. When using the Stardog HA Cluster, this is also true of Zookeeper’s access to free disk space.

stardog.properties

The main configuration file for Stardog is the stardog.properties file, which is a Java properties file. This file contains configuration properties to configure Stardog’s global behavior. The stardog.properties file should be placed into the $STARDOG_HOME directory to take effect.

To specify another location for the stardog.properties file, you can set the STARDOG_PROPERTIES environment variable.

Example

An example stardog.properties file is provided in our Stardog examples Github repository.

Updatable Properties

For most server properties to take effect in a running Stardog Server, it is necessary to restart it. However, certain properties (e.g. some of the LDAP properties) are updatable and can be mutated without a restart using the property set admin command, which updates a property (on all Stardog servers in a cluster) and saves the change to the stardog.properties file. Use the property get command to see a list of all set server properties (updatable and otherwise).

Configuration Options

The properties described in this section control the global behavior of the Stardog Server.

You’ll observe each server property has a field “Overridable”. Overridable, in this context, means you can set this option at the database level, overriding the value set for the server. This isn’t relevant for most properties, but can be useful for setting query-related properties, for example. See the Database Configuration section for details on setting and configuring database options.

Query Answering

Properties to configure queries at the server level:

query.all.graphs

Default
false
Description
If a SPARQL query does not use FROM or FROM NAMED keywords, this option will define what data it is evaluated against; if true, it will run over the default graph and the union of all named graphs; if false (the default), it will run only over the default graph.
Overridable
true

query.timeout

Default
5m
Description
Sets the upper bound for query execution time. This value is inherited by all databases unless explicitly overridden by a database-specific timeout value in database options. The following unit suffixes are available: "ms" for milliseconds, "s" for seconds, "m" for minutes, and "h" for hours.
Overridable
true

query.update.timeout

Default
10h
Description
Sets the upper bound for SPARQL Update query execution time. This value is inherited by all databases unless explicitly overridden by a database-specific timeout value in database options. The following unit suffixes are available: "ms" for milliseconds, "s" for seconds, "m" for minutes, and "h" for hours.
Overridable
true

query.timeout.override.enabled

Default
true
Description
When enabled, users are able to override the default timeout value. When disabled, queries must respect the value set in query.timeout.
Overridable
false

Connection Configuration

database.connection.timeout

Default
10m
Description
The amount of time a connection to the database can be open, but inactive, before being automatically closed to reclaim the resources. The timeout values specified in the property file should be a positive integer followed by either letter 'h' (for hours), letter 'm' (for minutes), letter 's' (for seconds), or letters 'ms' (for milliseconds). Example intervals: 1h for 1 hour, 5m for 5 minutes, 90s for 90 seconds, 500ms for 500 milliseconds.

NOTE: setting a short timeout can have adverse results, especially if updates are being performed without commit changes to the server. This can close the connection prematurely while using it.
Overridable
true

Backups

Server properties for backing up the Stardog server and databases.

backup.dir

Default
$STARDOG_HOME/.backup
Description
The top level directory which is to be used by Stardog for storing backups. By default, this is the .backup directory in your $STARDOG_HOME, but you can use this property to specify a different location for backups. Within this directory, backups are stored by database, and for each database, in date-versioned directories.
Overridable
false

backup.location

Default
Description
This property can be set if you need to specify a backup location outside of $STARDOG_HOME (e.g. a network mount). A default S3 or GCP backup location can also be specified here. See the sections Backup to S3 and Backup to GCP for more info.
Overridable
false

backup.keep.last.number.backups

Default
4
Description
Controls how many server backups will be retained by Stardog. See the Server Backup & Restore section for more details.
Overridable
false

backup.autorestore.dbnames

Default
Description
A regular expression that matches the names of the databases to automatically restore on startup, eg: .* for every database. See Automatic Restore for more information.
Overridable
false

backup.autorestore.onfailure

Default
false
Description
A boolean value that determines if all databases which failed to load should be automatically restored from a backup location. See Automatic Restore for more information.
Overridable
false

Memory

Server properties to configure memory in Stardog.

memory.management

Default
NATIVE
Description
To disable custom memory management and have Stardog run all queries on heap, you can set this property to JVM. Please consult the memory management section of the docs to learn more about how Stardog manages memory and to see if modifying this property is right for you.
Overridable
false

memory.mode

Default
default
Description
Stardog defines three standard memory consumption modes to allow users to configure how memory should be distributed based on the usage scenario - read_optimized, write_optimized, bulk_load. Please consult the memory management section of the docs to learn more about these options.
Overridable
false

memory.managed.block.size

Default
32K
Description
Size of blocks allocated by the memory management subsystem. Smaller blocks may improve memory utilization but increase overhead.
Overridable
false

memory.managed.allocate.immediately

Default
true
Description
Immediately allocate the maximum number of memory blocks on server start.
Overridable
false

spilling.dir

Default
$STARDOG_HOME/.spilling
Description
When Stardog cannot handle an operation (e.g. a query) in memory, it spills data to disk. This property determines the directory these operations will spill data to. By default, data will be spilled to the .spilling directory inside $STARDOG_HOME. It may make sense to set this to another disk to minimize disk contention.
Overridable
false

spilling.max.file.length

Default
10G
Description
When Stardog cannot handle an operation in memory, it spills data to disk. This property controls the maximum size of a single file Stardog will spill data to. A query can spill to multiple files and each are bound by the value set here. NOTE: this will only take effect if the server property, memory.management, is also enabled, which Stardog does by default.
Overridable
false

query.memory.limit.hard

Default
9223372036854775807B
Description
Configuration option for determining the memory limit used by query. Value should be provided in bytes as seen in the default value. This value overrides lower database configurations.
Overridable
false

query.memory.exceeds.strategy.hard

Default
SPILL_TO_DISK
Description
Configuration option for determining strategy for the query behaviour once query memory limit reached. Specifying FINISH_QUERY_EXECUTION will override database configurations. Query memory limit is determined by the server configuration option query.memory.limit.
Overridable
false

Geospatial

Server properties to modify Stardog’s geospatial support.

spatial.use.jts

Default
false
Description
Enable support for JTS in the geospatial module.
Overridable
false

Cluster

Server properties for Stardog Cluster.

pack.enabled

Default
false
Description
Flag to enable the cluster. Without this flag set, the rest of the cluster properties have no effect.
Overridable
false

pack.node.address

Default
InetAddress.getLocalhost().getAddress()
Description
The local address of the node. The default value of this property is InetAddress.getLocalhost().getAddress(), which should work for many deployments. However, if you’re using an atypical network topology and the default value is not correct, you can provide a value for this property. If provided, it should be unique for each Stardog node.
Overridable
false

pack.zookeeper.address

Default
Description
A ZooKeeper connection string where cluster stores its state.
Overridable
false

pack.zookeeper.auth

Default
admin:admin
Description
When starting Stardog instances for the cluster, unlike single server mode, you need to provide the credentials of a superuser. The superuser will be used for securing the data stored in ZooKeeper and for intra-cluster communication. Each node should be started with the same superuser credentials. By default, Stardog comes with a superuser admin that has password "admin" (these are the default credentials used by the server start CLI command). For a secure installation of Stardog cluster, you should change these credentials by specifying this property and restarting the cluster with new credentials.
Overridable
false

pack.connection.timeout

Default
The default value is the default connection timeout for ZooKeeper.
Description
Specifies the max time that Stardog waits to establish a connection to ZooKeeper. See Connection/Session Timeouts for more information.
Overridable
false

pack.session.timeout

Default
The default value is the default session timeout for ZooKeeper.
Description
Specifies the max time that Stardog nodes wait to establish a session with the Zookeeper cluster. See Connection/Session Timeouts for more information.
Overridable
false

Security

Properties used to configure Security in Stardog:

password.length.min

Default
4
Description
Sets the password policy for the minimum length of user passwords.
Overridable
false

password.length.max

Default
1024
Description
Sets the password policy for the maximum length of user passwords.
Overridable
false

password.regex

Default
[\w@#$%!&]+
Description
Sets the password policy of accepted chars in user passwords, via a Java regular expression.
Overridable
false

password.store.sha1

Default
true
Description
Sets whether to store SHA1-hashed credentials, required for MySQL Native Authentication
Overridable
false

security.named.graphs

Default
false
Description
Sets named graph security globally.
Overridable
true

security.disable.password

Default
false
Description
Sets whether username/password authentication is disabled. Default value changes to `true` in conjunction with Kerberos.
Overridable
true

SSL

Properties used to configure Stardog to use SSL:

javax.net.ssl.keyStorePassword

Default
Description
The password for the keystore.
Overridable
false

javax.net.ssl.keyStore

Default
Description
If this is not specified, $STARDOG_home/keystore is checked. After that, the standard JVM locations within $JAVA_HOME are checked. Example: /path/to/the/keystore
Overridable
false

javax.net.ssl.keyStoreType

Default
jks
Description
If the keystore is of a different type than the default (jks), you can specify its type. Example: pkcs12
Overridable
false

LDAP

LDAP and the server properties required for LDAP configuration are described at length in its dedicated chapter.


Kerberos

Kerberos and the server properties required for Kerberos configuration are described at length in its dedicated chapter.


Logging

This section contains configuration properties for logging in Stardog. See the section on Server Logging for further information on configuring logging.

Access Logging

The server properties used for Access Logging are listed below:

logging.access.enabled

Default
false
Description
Access log is disabled by default and should be enabled explicitly by setting this to true.
Overridable
false

logging.access.type

Default
binary
Description
The type of access log. There are two allowed values: text and binary. Both are based on Protobuf. In text logs, entries are serialized as key-value pairs in plain text, and log entries are delimited by the ASCII Start of Text and ASCII End of Text bytes. In binary logs, entries are written as size-delimited protobuf binary messages.
Overridable
false

logging.access.file

Default
${STARDOG_HOME}/access.log
Description
File name for the access log. By default, the access log is saved as a file named access.log inside the ${STARDOG_HOME} directory. Optionally, an absolute path can be provided to save the file in a different directory.
Overridable
false

logging.access.rotation.type

Default
Description
It is possible to define a file rotation strategy so that access log entries will be split into multiple files. One possibility is to define a limit on file size and start a new file when the size limit is reached. Specify size as the value for this option. Alternately, log files can be rotated at fixed time intervals by specifying a value of time.
Overridable
false

logging.access.rotation.limit

Default
Description
If you've set logging.access.rotation.type=size, you can specify the size limit in bytes to determine the rotation frequency of the access log. Example: 1000000. The file that exceeds the limit will be renamed with a unique suffix, and all the subsequent entries will be added to the newly created file.
Overridable
false

logging.access.rotation.interval

Default
Description
If you've set logging.access.rotation.type=time, you can specify the log to be rotated at fixed time intervals. The interval value should be a positive integer followed by either letter 'd' (for days) or letter 'h' (for hours). Examples intervals are 7d for weekly logs, 1d for daily logs, 12h for two log files per day, and 1h for hourly logs. The file that exceeds the interval will be renamed with a unique suffix, and all the subsequent entries will be added to the newly created file.
Overridable
false

logging.access.rotation.compress

Default
false
Description
When rotation is enabled, setting this options to true will cause rotated log files to be compressed with gzip.
Overridable
false

logging.access.rotation.file.count

Default
-1
Description
The maximum number of rotated files to keep. When the number of rotated files exceeds this limit, the oldest rotated file will be deleted. Setting this option to -1 means the limit is undefined, and all rotated files will be kept indefinitely. If the option is set to 0, then no rotated files will be kept. Once the log file reaches the rotation limit, it will be deleted, and a fresh log file will be created.
Overridable
false

Audit Logging

The server properties used for Audit Logging are listed below:

logging.audit.enabled

Default
false
Description
Audit log is disabled by default and should be enabled explicitly by setting this to true.
Overridable
false

logging.audit.type

Default
binary
Description
The type of audit log. There are two allowed values: text and binary. Both are based on Protobuf. In text logs, entries are serialized as key-value pairs in plain text and log entries are delimited by the ASCII Start of Text and ASCII End of Text bytes. In binary logs, entries are written as size delimited protobuf binary messages.
Overridable
false

logging.audit.file

Default
${STARDOG_HOME}/audit.log
Description
File name for the audit log. By default, audit log is saved as a file named audit.log inside the ${STARDOG_HOME} directory. Optionally an absolute path can be provided to save the file in a different directory.
Overridable
false

logging.audit.rotation.type

Default
Description
It is possible to define a file rotation strategy so that audit log entries will be split into multiple files. One possibility is to define a limit on file size and start a new file when the size limit is reached. Specify size as the value for this option. Alternately, log files can be rotated at fixed time intervals by specifying a value of time.
Overridable
false

logging.audit.rotation.limit

Default
Description
If you've set logging.audit.rotation.type=size, you can specify the size limit in bytes to determine the rotation frequency of the audit log. Example: 1000000. The file that exceeds the limit will be renamed with a unique suffix, and all the subsequent entries will be added to the newly created file.
Overridable
false

logging.audit.rotation.interval

Default
Description
If you've set logging.audit.rotation.type=time, you can specify the log to be rotated at fixed time intervals. The interval value should be a positive integer followed by either letter 'd' (for days) or letter 'h' (for hours). Examples intervals are 7d for weekly logs, 1d for daily logs, 12h for two log files per day, and 1h for hourly logs. The file that exceeds the interval will be renamed with a unique suffix, and all the subsequent entries will be added to the newly created file.
Overridable
false

logging.audit.rotation.compress

Default
false
Description
When rotation is enabled, setting this options to true will cause rotated log files to be compressed with gzip.
Overridable
false

logging.audit.rotation.file.count

Default
-1
Description
The maximum number of rotated files to keep. When the number of rotated files exceeds this limit, the oldest rotated file will be deleted. Setting this option to -1 means the limit is undefined, and all rotated files will be kept indefinitely. If the option is set to 0, then no rotated files will be kept. Once the log file reaches the rotation limit, it will be deleted, and a fresh log file will be created.
Overridable
false

Slow Query Logging

The server properties used for Slow Query Logging are listed below:

logging.slow_query.enabled

Default
false
Description
Slow query logging is disabled by default and should be enabled explicitly by setting this to true.
Overridable
false

logging.slow_query.time

Default
1m
Description
To define what counts as a "slow" query, set this property to a time duration value (positive integer plus h, m, s, or ms for hours, minutes, seconds, or milliseconds respectively).
Overridable
false

logging.slow_query.type

Default
text
Description
Log type. Unlike access or audit logs, slow query log has a default type for formatting the slow query events, which is intended to be human-readable. If no log type is specified, this default type (text) will be used. This default format is not suitable for machine-processing and is meant only for developers to read. For a machine-processable format, the type of the slow query log can be set to binary, similar to access and audit logs.
Overridable
false

logging.slow_query.rotation.type

Default
Description
It is possible to define a file rotation strategy so that slow query log entries will be split into multiple files. One possibility is to define a limit on file size and start a new file when the size limit is reached. Specify size as the value for this option. Alternately, log files can be rotated at fixed time intervals by specifying a value of time.
Overridable
false

logging.slow_query.rotation.limit

Default
Description
If you've set logging.slow_query.rotation.type=size, you can specify the size limit in bytes to determine the rotation frequency of the slow query log. Example: 1000000. The file that exceeds the limit will be renamed with a unique suffix, and all the subsequent entries will be added to the newly created file.
Overridable
false

logging.slow_query.rotation.interval

Default
Description
If you've set logging.slow_query.rotation.type=time, you can specify the log to be rotated at fixed time intervals. The interval value should be a positive integer followed by either letter 'd' (for days) or letter 'h' (for hours). Examples intervals are 7d for weekly logs, 1d for daily logs, 12h for two log files per day, and 1h for hourly logs. The file that exceeds the interval will be renamed with a unique suffix, and all the subsequent entries will be added to the newly created file.
Overridable
false

logging.slow_query.rotation.compress

Default
false
Description
When rotation is enabled, setting this options to true will cause rotated log files to be compressed with gzip.
Overridable
false

logging.slow_query.rotation.file.count

Default
-1
Description
The maximum number of rotated files to keep. When the number of rotated files exceeds this limit, the oldest rotated file will be deleted. Setting this option to -1 means the limit is undefined, and all rotated files will be kept indefinitely. If the option is set to 0, then no rotated files will be kept. Once the log file reaches the rotation limit, it will be deleted, and a fresh log file will be created.
Overridable
false

Monitoring

Properties used to configure Server Monitoring:

metrics.reporter

Default
Description
Enables JMX monitoring by setting this property to a value of jmx.
Overridable
false

metrics.jmx.remote.access

Default
false
Description
When set to true, Stardog will bind an RMI server for remote access on port 5833 to connect to the JMX server remotely. To change the port, modify the metrics.jmx.port server property.
Overridable
false

metrics.jmx.port

Default
5833
Description
The port Stardog will expose for a JMX server to connect to remotely.
Overridable
false

Exports

export.dir

Default
$STARDOG_HOME/.exports
Description
The top-level directory for storing files which are exported by the server. The default value is .exports in your $STARDOG_HOME directory.
Overridable
false

HTTP Configuration

http.max.connection

Default
200
Description
The maximum number of simultaneous http connections.
Overridable
false

http.max.get.query.length

Default
2000
Description
The length in characters of the longest query that can be sent over HTTP GET to the Stardog server. This is to avoid URL overflow in some web servers. When the query is longer than this threshold, Stardog will automatically switch over to using HTTP POST.
Overridable
false

http.max.request.parameters

Default
2000
Description
Any value smaller than Java's Integer.MAX_VALUE may be provided. Useful if you have lots of named graphs and are at risk of exceeding the default value.
Overridable
false

cors.allowed.origins

Default
Description
By default, CORS is enabled on Stardog's HTTP server. (It can be disabled when starting the server via the CLI by including the --no-cors flag.) In order for any cross-origin requests to be acknowledged, their Origin header value must be included in this list. Example: http://stardog.com, http://example.org
Overridable
false

Optimizer Configuration

optimizer.join.order.robustness

Default
true
Description
When enabled, the query plan optimizer will consider alternative join orders in the presence of SPARQL-based services and select a *robust* query plan. See this section for more details. The behaviour can also be disabled on a per-query basis using the optimizer.join.order.topk query hint.
Overridable
false