The neo4j.conf file
The neo4j.conf file is the main source of configuration settings in Neo4j and includes the mappings of configuration setting keys to values. The location of the neo4j.conf file in the different configurations of Neo4j is listed in Default file locations.
Most of the configuration settings in the neo4j.conf file apply directly to Neo4j itself, but there are also other settings related to the Java Runtime (the JVM) on which Neo4j runs.
For more information, see the JVM specific configuration settings.
Many of the configuration settings are also used by neo4j
launcher scripts.
neo4j.conf
conventions
The syntax in the neo4j.conf
file follows the following conventions:
-
The equals sign (
=
) maps configuration setting keys to configuration values. -
Lines that start with the number sign (
#
) are handled as comments. -
Trailing comments are not supported.
-
Empty lines are ignored.
-
Configuring a setting in neo4j.conf overwrites any default values. If you want to amend the default values with custom ones, you must explicitly list the default values along with the new ones.
-
The configuration settings are not ordered.
-
The configuration settings have strict validation enabled by default. It prevents Neo4j from starting if the neo4j.conf file contains typos, incorrect information, or duplicates (except for
server.jvm.additional
). If you set more than one value forserver.jvm.additional
, each setting value adds another custom JVM argument to thejava
launcher.To disable the strict validation, set
server.config.strict_validation.enabled=false
. -
By default, the character encoding is assumed to be ISO 8859-1. From Neo4j 4.8 onwards, this can be overridden by setting the environment variable
NEO4J_CONFIG_FILE_CHARSET
to, for example,utf8
.
Configuration settings
General synopsis
Neo4j configuration settings have the following general synopsis:
<prefix>.<scope>.<component>….<component>.<name>
- Prefix
-
Prefixes are reserved for denoting two special cases (most settings do not have a prefix):
-
initial
— Settings that are only used during the initialization but are ignored thereafter. For example,initial.server.mode_constraint
,initial.dbms.default_database
, etc. -
internal
— The prefix replaces the termsunsupported
andexperimental
used in previous versions. This namespace is dedicated to features that are used internally and may change without notice.
-
- Scope
-
All configuration settings fall into one of the following scopes that behave differently:
-
db
settings can be varied between each database but must be consistent across all configuration files in a cluster/DBMS. -
dbms
settings must be consistent across all configuration files in a cluster/DBMS. -
server
settings apply only to the specific server and can be varied between configuration files across a cluster/DBMS. -
browser
settings apply only to Neo4j Browser. -
client
settings apply only to the client.In Neo4j 5, the
fabric
scope is no longer available. All configuration settings identified by thefabric
namespace in theneo4j.conf
file are moved into thesystem
database. The Cypher surface is extended to support the Fabric configuration.For more information, see Composite databases.
-
- Component
-
Component namespaces are used to group settings that affect similar systems.
- Name
-
The name of the setting. It may contain a common verb and unit patterns, such as
size
,enabled
, etc. Words are separated by an underscore.
For a complete reference of Neo4j configuration settings, see Configuration settings. |
JVM-specific configuration settings
A Java virtual machine (JVM) is a virtual machine that enables a computer to run Java programs and programs written in other languages that are also compiled in Java bytecode. The Java heap is where the objects of a Java program live. Depending on the JVM implementation, the JVM heap size often determines how and for how long time the virtual machine performs garbage collection.
Setting | Description |
---|---|
Sets the initial heap size for the JVM. By default, the JVM heap size is calculated based on the available system resources. |
|
Sets the maximum size of the heap for the JVM. By default, the maximum JVM heap size is calculated based on the available system resources. |
|
Sets additional options for the JVM. The options are set as a string and can vary depending on JVM implementation. |
If you want to have good control of the system behavior, it is recommended to set the heap size parameters to the same value to avoid unwanted full garbage collection pauses. |
List currently active settings
You can use SHOW SETTINGS
to list the currently active configuration settings and their values.
SHOW SETTINGS
YIELD name, value
WHERE name STARTS WITH 'server.default'
RETURN name, value
ORDER BY name
LIMIT 3;
+---------------------------------------------------+ | name | value | +---------------------------------------------------+ | "server.default_advertised_address" | "localhost" | | "server.default_listen_address" | "localhost" | +---------------------------------------------------+
For information about dynamic settings, see Update dynamic settings and Configuration settings reference. |