Resource Management
If database resource usage is not controlled, concurrent tasks easily preempt resources. As a result, the OS will be overloaded and cannot respond to user tasks; or even crash and cannot provide any services to users. The GaussDB(DWS) workload management function balances the database workload based on available resources to avoid database overloading.
space_once_adjust_num
Parameter description: In the space control and space statistics functions, specifies the threshold of the number of files processed each time during slow building and fine-grained calibration. This parameter is supported by version 8.1.3 or later clusters.
Type: SIGHUP
Value range: an integer ranging from 1 to INT_MAX
- The value 0 indicates that the slow build and fine-grained calibration functions are disabled.
Default value: 300

The file quantity threshold affects database resources. You are advised to set the threshold to a proper value.
max_active_statements
Parameter description: Specifies the maximum global concurrency. This parameter applies to one CN.
The database administrator changes the value of this parameter based on system resources (for example, CPU, I/O, and memory resources) so that the system fully supports the concurrency tasks and avoids too many concurrency tasks resulting in system crash.
Type: SIGHUP
Value range: an integer ranging from –1 to INT_MAX. The values –1 and 0 indicate that the number of concurrent requests is not limited.
Default value: 60
cgroup_name
Parameter description: Specifies the name of the Cgroup in use. It can be used to change the priorities of jobs in the queue of a Cgroup.
If you set cgroup_name and then session_respool, the Cgroups associated with session_respool take effect. If you reverse the order, Cgroups associated with cgroup_name take effect.
If the Workload Cgroup level is specified during the cgroup_name change, the database does not check the Cgroup level. The level ranges from 1 to 10.
Type: USERSET
You are not advised to set cgroup_name and session_respool at the same time.
Value range: a string
Default value: DefaultClass:Medium

DefaultClass:Medium indicates the Medium Cgroup belonging to the Timeshare Cgroup under the DefaultClass Cgroup.
enable_cgroup_switch
Parameter description: Specifies whether the database automatically switches to the TopWD group when executing statements by group type.
Type: USERSET
Value range: Boolean
- on: The database automatically switches to the TopWD group when executing statements by group type.
- off: The database does not automatically switch to the TopWD group when executing statements by group type.
Default value: off
memory_tracking_mode
Parameter description: Specifies the memory information recording mode.
Type: USERSET
Value range:
- none: Memory statistics is not collected.
- normal: Only memory statistics is collected in real time and no file is generated.
- executor: The statistics file is generated, containing the context information about all allocated memory used by the execution layer.
- fullexec: The generated file includes the information about all memory contexts requested by the execution layer.
Default value: none
memory_detail_tracking
Parameter description: Specifies the sequence number of the memory background information distributed in the needed thread and plannodeid of the query where the current thread is located.
Type: USERSET
Value range: a string
Default value: empty

It is recommended that you retain the default value for this parameter.
enable_resource_track
Parameter description: Specifies whether the real-time resource monitoring function is enabled. This parameter must be applied on both CNs and DNs.
Type: SIGHUP
Value range: Boolean
- on indicates the resource monitoring function is enabled.
- off indicates the resource monitoring function is disabled.
Default value: on
enable_resource_record
Parameter description: Specifies whether resource monitoring records are archived. When this parameter is enabled, records that have been executed are archived to the corresponding INFO views (GS_WLM_SESSION_INFO and GS_WLM_OPERATOR_INFO). This parameter must be applied on both CNs and DNs.
Type: SIGHUP
Value range: Boolean
- on indicates that the resource monitoring records are archived.
- off indicates that the resource monitoring records are not archived.
Default value: on

The default value of this parameter is on for a new cluster. In upgrade scenarios, the default value of this parameter is the same as that of the source version.
enable_track_record_subsql
Parameter description: Specifies whether to enable the function of recording and archiving sub-statements. When this function is enabled, sub-statements in stored procedures and anonymous blocks are recorded and archived to the corresponding INFO table (GS_WLM_SESSION_INFO). This parameter is a session-level parameter. It can be configured and take effect in the session connected to the CN and affects only the statements in the session. It can also be configured on both the CN and DN and take effect globally.
Type: USERSET
Value range: Boolean
- on indicates that the sub-statement resource monitoring records are archived.
- off indicates that the sub-statement resource monitoring records are not archived.
Default value: off
enable_user_metric_persistent
Parameter description: Specifies whether the user historical resource monitoring dumping function is enabled. When this function is enabled, data in the PG_TOTAL_USER_RESOURCE_INFO view is periodically sampled and saved to the GS_WLM_USER_RESOURCE_HISTORY system catalog, and data in the GS_RESPOOL_RESOURCE_INFO view is periodically sampled and saved to the GS_RESPOOL_RESOURCE_HISTORY system catalog.
Type: SIGHUP
Value range: Boolean
- on indicates that the user historical resource monitoring dumping function is enabled.
- off indicates that the user historical resource monitoring dumping function is disabled.
Default value: on
user_metric_retention_time
Parameter description: Specifies the retention time of the user historical resource monitoring data.
Type: SIGHUP
Value range: an integer ranging from 0 to 3650. The unit is day.
- If this parameter is set to 0, user historical resource monitoring data is permanently stored.
- If the value is greater than 0, user historical resource monitoring data is stored for the specified number of days.
Default value: 7
resource_track_level
Parameter description: Specifies the resource monitoring level of the current session. This parameter is valid only when enable_resource_track is set to on.
Type: USERSET
Value range: enumerated values
- none: Resources are not monitored.
- query: Enables query-level resource monitoring. If this function is enabled, the plan information (similar to the output information of EXPLAIN) of SQL statements will be recorded in top SQL statements.
- perf: Enables the perf-level resource monitoring. If this function is enabled, the plan information (similar to the output information of EXPLAIN ANALYZE) that contains the actual execution time and the number of execution rows will be recorded in the top SQL.
- operator: enables the operator-level resource monitoring. If this function is enabled, not only the information including the actual execution time and number of execution rows is recorded in the top SQL statement, but also the operator-level execution information is updated to the top SQL statement.
Default value: query
resource_track_cost
Parameter description: Specifies the minimum execution cost for resource monitoring on statements in the current session. This parameter is valid only when enable_resource_track is set to on.
Type: USERSET
Value range: an integer ranging from –1 to INT_MAX
- –1 indicates that resource monitoring is disabled.
- A value greater than or equal to 0 indicates that statements whose execution cost exceeds this value will be monitored.
Default value: 0

The default value of this parameter is 0 for a new cluster. In upgrade scenarios, the default value of this parameter is the same as that of the source version.
resource_track_duration
Parameter description: Specifies the minimum statement execution time that determines whether information about jobs of a statement recorded in the real-time view (see Table 1) will be dumped to a historical view after the statement is executed. Job information will be dumped from the real-time view (with the suffix statistics) to a historical view (with the suffix history) if the statement execution time is no less than this value. This parameter is valid only when enable_resource_track is set to on.
Type: USERSET
Value range: an integer ranging from 0 to INT_MAX. The unit is second (s).
- 0 indicates that information about all statements recorded in the real-time resource monitoring view (see Table 1) will be archived into historical views.
- When the value is greater than 0, the system archives historical information if the total execution and queuing time of statements in the real-time resource monitoring view (Table 1) goes over the parameter value.
Default value: 60s
disable_memory_protect
Parameter description: Stops memory protection. To query system views when system memory is insufficient, set this parameter to on to stop memory protection. This parameter is used only to diagnose and debug the system when system memory is insufficient. Set it to off in other scenarios.
Type: USERSET
Value range: Boolean
- on indicates that memory protection stops.
- off indicates that memory is protected.
Default value: off
query_band
Parameter description: Specifies the job type of the current session.
Type: USERSET
Value range: a string
Default value: empty
bbox_dump_count
Parameter description: Specifies the maximum number of core files that are generated by GaussDB(DWS) and can be stored in the path specified by bbox_dump_path. If the number of core files exceeds this value, old core files will be deleted. This parameter is valid only if enable_bbox_dump is set to on.
Type: USERSET
Value range: an integer ranging from 1 to 20
Default value: 8

When core files are generated during concurrent SQL statement execution, the number of files may be larger than the value of bbox_dump_count.
io_limits
Parameter description: This parameter has been discarded in version 8.1.2 and is reserved for compatibility with earlier versions. This parameter is invalid in the current version.
Type: USERSET
Value range: an integer ranging from 0 to 1073741823
Default value: 0
io_priority
Parameter description: This parameter has been discarded in version 8.1.2 and is reserved for compatibility with earlier versions. This parameter is invalid in the current version.
Type: USERSET
Value range: enumerated values
- None
- Low
- Medium
- High
Default value: None
session_respool
Parameter description: Specifies the resource pool associated with the current session.
Type: USERSET
If you set cgroup_name and then session_respool, the Cgroups associated with session_respool take effect. If you reverse the order, Cgroups associated with cgroup_name take effect.
If the Workload Cgroup level is specified during the cgroup_name change, the database does not check the Cgroup level. The level ranges from 1 to 10.
You are not advised to set cgroup_name and session_respool at the same time.
Value range: a string. This parameter can be set to the resource pool configured through create resource pool.
Default value: invalid_pool
enable_transaction_parctl
Parameter description: whether to control transaction block statements and stored procedure statements.
Type: USERSET
Value range: Boolean
- on: Transaction block statements and stored procedure statements are controlled.
- off: Transaction block statements and stored procedure statements are not controlled.
Default value: on
session_history_memory
Parameter description: Specifies the memory size of a historical query view.
Type: SIGHUP
Value range: an integer ranging from 10240 to 50% of max_process_memory. The unit is KB.
Default value: 100 MB
topsql_retention_time
Parameter description: Specifies the retention period of historical Top SQL data in the gs_wlm_session_info and gs_wlm_operator_info tables.
Type: SIGHUP
Value range: an integer ranging from 0 to 3650. The unit is day.
- If it is set to 0, the data is stored permanently.
- If the value is greater than 0, the data is stored for the specified number of days.
Default value: 30

- Before setting this GUC parameter to enable the data retention function, delete data from the gs_wlm_session_info and gs_wlm_operator_info tables.
- The default value of this parameter is 30 for a new cluster. In upgrade scenarios, the default value of this parameter is the same as that of the source version.
transaction_pending_time
Parameter description: maximum queuing time of transaction block statements and stored procedure statements if enable_transaction_parctl is set to on.
Type: USERSET
Value range: an integer ranging from –1 to INT_MAX. The unit is second (s).
- –1 or 0: No queuing timeout is specified for transaction block statements and stored procedure statements. The statements can be executed when resources are available.
- Value greater than 0: If transaction block statements and stored procedure statements have been queued for a time longer than the specified value, they are forcibly executed regardless of the current resource situation.
Default value: 0

This parameter is valid only for internal statements of stored procedures and transaction blocks. That is, this parameter takes effect only for the statements whose enqueue value (for details, see PG_SESSION_WLMSTAT) is Transaction or StoredProc.
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