5.7. Dynamic settings

This section describes how to change your Neo4j configuration while Neo4j is running, and which settings can be changed.

This section contains the following:

5.7.1. Introduction

Neo4j Enterprise Edition supports changing some configuration settings at runtime, without restarting the service.

Changes to the configuration at runtime are not persisted. To avoid losing changes when restarting Neo4j make sure to update neo4j.conf as well.

5.7.2. Discover dynamic settings

Use the procedure dbms.listConfig() to discover which configuration values can be dynamically updated, or consult Section 5.7.4, “Dynamic settings reference”.

Example 5.8. Discover dynamic settings
CALL dbms.listConfig()
YIELD name, dynamic
WHERE dynamic
RETURN name
ORDER BY name
LIMIT 4;
+----------------------------------------------+
| name                                         |
+----------------------------------------------+
| "dbms.checkpoint.iops.limit"                 |
| "dbms.logs.query.allocation_logging_enabled" |
| "dbms.logs.query.enabled"                    |
| "dbms.logs.query.page_logging_enabled"       |
+----------------------------------------------+
4 rows

5.7.3. Update dynamic settings

An administrator is able to change some configuration settings at runtime, without restarting the service.

Syntax:

CALL dbms.setConfigValue(*setting*, value)

Returns:

Nothing on success.

Exceptions:

Unknown or invalid setting name.

The setting is not dynamic and can not be changed at runtime.

Invalid setting value.

The following example shows how to dynamically enable query logging.

Example 5.9. Set a config value
CALL dbms.setConfigValue('dbms.logs.query.enabled', 'info')

If an invalid value is passed, the procedure will show a message to that effect.

Example 5.10. Try to set invalid config value
CALL dbms.setConfigValue('dbms.logs.query.enabled', 'yes')
Failed to invoke procedure `dbms.setConfigValue`: Caused by: org.neo4j.graphdb.config.InvalidSettingException: Bad value 'yes' for setting 'dbms.logs.query.enabled': 'yes' not one of [OFF, INFO, VERBOSE]

To reset a config value to its default, pass an empty string as the value argument.

Example 5.11. Reset a config value to default
CALL dbms.setConfigValue('dbms.logs.query.enabled', '')

5.7.4. Dynamic settings reference

Table 5.5. Dynamic settings reference
Name Description

dbms.allow_single_automatic_upgrade

Whether to allow a system graph upgrade to happen automatically in single instance mode (dbms.mode=SINGLE).

dbms.allow_upgrade

Whether to allow a store upgrade in case the current version of the database starts against an older version of the store.

dbms.checkpoint.iops.limit

Limit the number of IOs the background checkpoint process will consume per second.

dbms.logs.debug.level

Debug log level threshold.

dbms.logs.query.allocation_logging_enabled

Log allocated bytes for the executed queries being logged.

dbms.logs.query.early_raw_logging_enabled

Log query text and parameters without obfuscating passwords.

dbms.logs.query.enabled

Log executed queries.

dbms.logs.query.page_logging_enabled

Log page hits and page faults for the executed queries being logged.

dbms.logs.query.parameter_full_entities

Log complete parameter entities including id, labels or relationship type, and properties.

dbms.logs.query.parameter_logging_enabled

Log parameters for the executed queries being logged.

dbms.logs.query.rotation.keep_number

Maximum number of history files for the query log.

dbms.logs.query.rotation.size

The file size in bytes at which the query log will auto-rotate.

dbms.logs.query.runtime_logging_enabled

Logs which runtime that was used to run the query.

dbms.logs.query.threshold

If the execution of query takes more time than this threshold, the query is logged once completed - provided query logging is set to INFO.

dbms.logs.query.time_logging_enabled

Log detailed time information for the executed queries being logged.

dbms.memory.transaction.datababase_max_size

Limit the amount of memory that all transaction in one database can consume, in bytes (or kilobytes with the 'k' suffix, megabytes with 'm' and gigabytes with 'g').

dbms.memory.transaction.global_max_size

Limit the amount of memory that all of the running transactions can consume, in bytes (or kilobytes with the 'k' suffix, megabytes with 'm' and gigabytes with 'g').

dbms.memory.transaction.max_size

Limit the amount of memory that a single transaction can consume, in bytes (or kilobytes with the 'k' suffix, megabytes with 'm' and gigabytes with 'g').

dbms.track_query_allocation

Enables or disables tracking of how many bytes are allocated by the execution of a query.

dbms.track_query_cpu_time

Enables or disables tracking of how much time a query spends actively executing on the CPU.

dbms.transaction.concurrent.maximum

The maximum number of concurrently running transactions.

dbms.transaction.sampling.percentage

Transaction sampling percentage.

dbms.transaction.timeout

The maximum time interval of a transaction within which it should be completed.

dbms.transaction.tracing.level

Transaction creation tracing level.

dbms.tx_log.preallocate

Specify if Neo4j should try to preallocate logical log file in advance.

dbms.tx_log.rotation.retention_policy

Make Neo4j keep the logical transaction logs for being able to backup the database.

dbms.tx_log.rotation.size

Specifies at which file size the logical log will auto-rotate.

dbms.upgrade_max_processors

Max number of processors used when upgrading the store.

fabric.routing.servers

A comma-separated list of Fabric instances that form a routing group.