Graph Service configuration¶

NebulaGraph provides two initial configuration files for the Graph Service, nebula-graphd.conf.default and nebula-graphd.conf.production. Users can use them in different scenarios conveniently. The default file path is /usr/local/nebula/etc/.

Caution

It is not recommended to modify the value of local_config to false. If modified, the NebulaGraph service will first read the cached configurations, which may cause configuration inconsistencies between clusters and cause unknown risks.
It is not recommended to modify the configurations that are not introduced in this topic, unless you are familiar with the source code and fully understand the function of configurations.

How to use the configuration files¶

To use the initial configuration file, choose one of the above two files and delete the suffix .default or .production from the initial configuration file for the Meta Service to apply the configurations defined in it.

About parameter values¶

If a parameter is not set in the configuration file, NebulaGraph uses the default value. Not all parameters are predefined. And the predefined parameters in the two initial configuration files are different. This topic uses the parameters in nebula-metad.conf.default.

Caution

Some parameter values in the configuration file can be dynamically modified during runtime. We label these parameters as Yes that supports runtime dynamic modification in this article. When the local_config value is set to true, the dynamically modified configuration is not persisted, and the configuration will be restored to the initial configuration after the service is restarted. For more information, see Modify configurations.

For all parameters and their current values, see Configurations.

Basics configurations¶

Name	Predefined value	Description	Whether supports runtime dynamic modifications
`daemonize`	`true`	When set to `true`, the process is a daemon process.	No
`pid_file`	`pids/nebula-graphd.pid`	The file that records the process ID.	No
`enable_optimizer`	`true`	When set to `true`, the optimizer is enabled.	No
`timezone_name`	-	Specifies the NebulaGraph time zone. This parameter is not predefined in the initial configuration files. The system default value is `UTC+00:00:00`. For the format of the parameter value, see Specifying the Time Zone with TZ. For example, `--timezone_name=UTC+08:00` represents the GMT+8 time zone.	No
`default_charset`	`utf8`	Specifies the default charset when creating a new graph space.	No
`default_collate`	`utf8_bin`	Specifies the default collate when creating a new graph space.	No
`local_config`	`true`	When set to `true`, the process gets configurations from the configuration files.	No

Note

While inserting property values of time types, NebulaGraph transforms time types (except TIMESTAMP) to the corresponding UTC according to the time zone specified by timezone_name. The time-type values returned by nGQL queries are all UTC time.
timezone_name is only used to transform the data stored in NebulaGraph. Other time-related data of the NebulaGraph processes still uses the default time zone of the host, such as the log printing time.

Logging configurations¶

Name	Predefined value	Description	Whether supports runtime dynamic modifications
`log_dir`	`logs`	The directory that stores the Graph service log. It is recommended to put logs on a different hard disk from the data.	No
`minloglevel`	`0`	Specifies the minimum level of the log. That is, log messages at or above this level. Optional values are `0` (INFO), `1` (WARNING), `2` (ERROR), `3` (FATAL). It is recommended to set it to `0` during debugging and `1` in a production environment. If it is set to `4`, NebulaGraph will not print any logs.	Yes
`v`	`0`	Specifies the detailed level of VLOG. That is, log all VLOG messages less or equal to the level. Optional values are `0`, `1`, `2`, `3`, `4`, `5`. The VLOG macro provided by glog allows users to define their own numeric logging levels and control verbose messages that are logged with the parameter `v`. For details, see Verbose Logging.	Yes
`logbufsecs`	`0`	Specifies the maximum time to buffer the logs. If there is a timeout, it will output the buffered log to the log file. `0` means real-time output. This configuration is measured in seconds.	No
`redirect_stdout`	`true`	When set to `true`, the process redirects the`stdout` and `stderr` to separate output files.	No
`stdout_log_file`	`graphd-stdout.log`	Specifies the filename for the `stdout` log.	No
`stderr_log_file`	`graphd-stderr.log`	Specifies the filename for the `stderr` log.	No
`stderrthreshold`	`3`	Specifies the `minloglevel` to be copied to the `stderr` log.	No
`timestamp_in_logfile_name`	`true`	Specifies if the log file name contains a timestamp. `true` indicates yes, `false` indicates no.	No

Query configurations¶

Name	Predefined value	Description	Whether supports runtime dynamic modifications
`accept_partial_success`	`false`	When set to `false`, the process treats partial success as an error. This configuration only applies to read-only requests. Write requests always treat partial success as an error. A partial success query will prompt `Got partial result`.	Yes
`session_reclaim_interval_secs`	`60`	Specifies the interval that the Session information is sent to the Meta service. This configuration is measured in seconds.	Yes
`max_allowed_query_size`	`4194304`	Specifies the maximum length of queries. Unit: bytes. The default value is `4194304`, namely 4MB.	Yes

Networking configurations¶

Name	Predefined value	Description	Whether supports runtime dynamic modifications
`meta_server_addrs`	`127.0.0.1:9559`	Specifies the IPs (or hostnames) and ports of all Meta Services. Multiple addresses are separated with commas.	No
`local_ip`	`127.0.0.1`	Specifies the local IP (or hostname) for the Graph Service. The local IP address is used to identify the nebula-graphd process. If it is a distributed cluster or requires remote access, modify it to the corresponding address.	No
`listen_netdev`	`any`	Specifies the listening network device.	No
`port`	`9669`	Specifies RPC daemon listening port of the Graph service.	No
`reuse_port`	`false`	When set to `false`, the `SO_REUSEPORT` is closed.	No
`listen_backlog`	`1024`	Specifies the maximum length of the connection queue for socket monitoring. This configuration must be modified together with the `net.core.somaxconn`.	No
`client_idle_timeout_secs`	`28800`	Specifies the time to expire an idle connection. The value ranges from 1 to 604800. The default is 8 hours. This configuration is measured in seconds.	No
`session_idle_timeout_secs`	`28800`	Specifies the time to expire an idle session. The value ranges from 1 to 604800. The default is 8 hours. This configuration is measured in seconds.	No
`num_accept_threads`	`1`	Specifies the number of threads that accept incoming connections.	No
`num_netio_threads`	`0`	Specifies the number of networking IO threads. `0` is the number of CPU cores.	No
`num_max_connections`	`0`	Max active connections for all networking threads. 0 means no limit. Max connections for each networking thread = num_max_connections / num_netio_threads	No
`num_worker_threads`	`0`	Specifies the number of threads that execute queries. `0` is the number of CPU cores.	No
`ws_ip`	`0.0.0.0`	Specifies the IP address for the HTTP service.	No
`ws_http_port`	`19669`	Specifies the port for the HTTP service.	No
`heartbeat_interval_secs`	`10`	Specifies the default heartbeat interval. Make sure the `heartbeat_interval_secs` values for all services are the same, otherwise NebulaGraph CANNOT work normally. This configuration is measured in seconds.	Yes
`storage_client_timeout_ms`	-	Specifies the RPC connection timeout threshold between the Graph Service and the Storage Service. This parameter is not predefined in the initial configuration files. You can manually set it if you need it. The system default value is `60000` ms.	No
`slow_query_threshold_us`	`200000`	When the execution time of a query exceeds the value, the query is called a slow query. Unit: Microsecond. Note: Even if the execution time of DML statements exceeds this value, they will not be recorded as slow queries.	No
`ws_meta_http_port`	`19559`	Specifies the Meta service listening port used by the HTTP protocol. It must be consistent with the `ws_http_port` in the Meta service configuration file.	No

Caution

It is recommended to use a real IP when using IP address. Otherwise, 127.0.0.1/0.0.0.0 cannot be parsed correctly in some cases.

Authorization configurations¶

Name	Predefined value	Description	Whether supports runtime dynamic modifications
`enable_authorize`	`false`	When set to `false`, the system authentication is not enabled. For more information, see Authentication.	No
`auth_type`	`password`	Specifies the login method. Available values are `password`, `ldap`, and `cloud`.	No

Memory configurations¶

Name	Predefined value	Description	Whether supports runtime dynamic modifications
`system_memory_high_watermark_ratio`	`0.8`	Specifies the trigger threshold of the high-level memory alarm mechanism. If the system memory usage is higher than this value, an alarm mechanism will be triggered, and NebulaGraph will stop querying. This parameter is not predefined in the initial configuration files.	Yes

Metrics configurations¶

Name	Predefined value	Description	Whether supports runtime dynamic modifications
`enable_space_level_metrics`	`false`	Enable or disable space-level metrics. Such metric names contain the name of the graph space that it monitors, for example, `query_latency_us{space=basketballplayer}.avg.3600`. You can view the supported metrics with the `curl` command. For more information, see Query NebulaGraph metrics.	No

Session configurations¶

Name	Predefined value	Description	Whether supports runtime dynamic modifications
`max_sessions_per_ip_per_user`	`300`	The maximum number of active sessions that can be created from a single IP adddress for a single user.	No

Experimental configurations¶

Note

The switch of the experimental feature is only available in the Community Edition.

Name	Predefined value	Description	Whether supports runtime dynamic modifications
`enable_experimental_feature`	`false`	Specifies the experimental feature. Optional values are `true` and `false`.	No
`enable_data_balance`	`true`	Whether to enable the BALANCE DATA feature. Only works when `enable_experimental_feature` is `true`.	No

Memory tracker configurations¶

Name	Predefined value	Description	Whether supports runtime dynamic modifications
`memory_tracker_limit_ratio`	`0.8`	The value of this parameter can be set to `(0, 1]`, `2`, and `3`. Caution: When setting this parameter, ensure that the value of `system_memory_high_watermark_ratio` is not set to `1`, otherwise the value of this parameter will not take effect. `(0, 1]`: The percentage of available memory. Formula: `Percentage of available memory = Available memory / (Total memory - Reserved memory)`. When an ongoing query results in memory usage exceeding the configured limit, the query fails and subsequently the memory is released. Note: For the hybrid deployment of a cluster with cloud-based and on-premises nodes, the value of `memory_tracker_limit_ratio` should be set to a lower value. For example, when the graphd is expected to occupy only 50% of memory, the value can be set to less than `0.5`. `2`: Dynamic Self Adaptive mode. MemoryTracker dynamically adjusts the available memory based on the system's current available memory. Note: This feature is experimental. As memory usage cannot be monitored in real time in dynamic adaptive mode, an OOM error may still occur to handle large memory allocations. `3`: Disable MemoryTracker. MemoryTracker only logs memory usage and does not interfere with executions even if the limit is exceeded.	Yes
`memory_tracker_untracked_reserved_memory_mb`	`50`	The reserved memory that is not tracked by the memory tracker. Unit: MB.	Yes
`memory_tracker_detail_log`	`false`	Whether to enable the memory tracker log. When the value is `true`, the memory tracker log is generated.	Yes
`memory_tracker_detail_log_interval_ms`	`60000`	The time interval for generating the memory tracker log. Unit: Millisecond. `memory_tracker_detail_log` is `true` when this parameter takes effect.	Yes
`memory_purge_enabled`	`true`	Whether to enable the memory purge feature. When the value is `true`, the memory purge feature is enabled.	Yes
`memory_purge_interval_seconds`	`10`	The time interval for the memory purge feature to purge memory. Unit: Second. This parameter only takes effect if `memory_purge_enabled` is set to true.	Yes

performance optimization configurations¶

Name	Predefined value	Description	Whether supports runtime dynamic modifications
`max_job_size`	`1`	The maximum number of concurrent jobs, i.e., the maximum number of threads used in the phase of query execution where concurrent execution is possible. It is recommended to be half of the physical CPU cores.	Yes
`min_batch_size`	`8192`	The minimum batch size for processing the dataset. Takes effect only when `max_job_size` is greater than 1.	Yes
`optimize_appendvertices`	`false`	When enabled, the `MATCH` statement is executed without filtering dangling edges.	Yes
`path_batch_size`	`10000`	The number of paths constructed per thread.	Yes

Last update: April 7, 2024