Workload Management

use_workload_manager

Parameter description: Specifies whether to enable the resource management function. This parameter must be set to a same value on CNs and DNs.

Parameter type: Boolean.

Unit: none

Value range:

• on: The resource management function is enabled.
• off: The resource management function is disabled.

Default value: on

Setting method: This is a SUSET parameter. Set it based on instructions provided in Table 1.

Setting suggestion: Retain the default value.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

• If method 2 in Table 1 is used to change the parameter value, the new value takes effect only for the threads that are started after the change. In addition, the new value does not take effect for new jobs that are executed by backend threads and reused threads. You can make the new value take effect for these threads by using kill session or restarting the node.
• After the value of use_workload_manager changes from off to on, statistics about storage resources when use_workload_manager was off are not collected. To collect statistics about such resources, run the following SQL statement:

  1	SELECT gs_wlm_readjust_user_space(0);

enable_control_group

Parameter description: Specifies whether to enable the Cgroup function. This parameter must be set to a same value on CNs and DNs.

Parameter type: Boolean.

Unit: none

Value range:

• on: The Cgroups function is enabled.
• off: The Cgroups function is disabled.

Default value: on

Setting method: This is a SIGHUP parameter. Set it based on the corresponding setting method in Table 1. When you change the parameter value using method 2 listed in the table, the new value takes effect only for the thread that is started after the change.

Setting suggestion: The modification does not take effect for backend threads and new jobs that are reused by threads. If you want such threads to identify parameter changes in real time, kill sessions or restart nodes.

Risks and impacts of improper settings: If this parameter and the resource management function (use_workload_manager) are enabled at the same time, the user resource management function takes effect, deteriorating the performance of jobs executed by users.

enable_cgroup_switch

Parameter description: Specifies whether a statement is automatically switched to the TopWD group when the statement is executed by control group type.

Parameter type: Boolean.

Unit: none

Value range:

• on: A statement is automatically switched to the TopWD group when the statement is executed by control group type.
• off: A statement is not automatically switched to the TopWD group when the statement is executed by control group type.

Default value: off

Setting method: This is a USERSET parameter. Set it based on instructions provided in Table 1.

Setting suggestion: Retain the default value.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

This parameter is valid only when enable_control_group is set to on.

cgroup_name

Parameter description: Specifies the name of the Cgroup in use and changes the priority of items in the queue of the Cgroup.

If you set cgroup_name and then session_respool, the Cgroup associated with session_respool takes effect. If you reverse the order, the Cgroup associated with cgroup_name takes 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.

Parameter type: string.

Unit: none

Value range: name of an existing Cgroup.

Default value: "DefaultClass:Medium"

Setting method: This is a USERSET parameter. Set it based on instructions provided in Table 1.

Setting suggestion: Do not use both cgroup_name and session_respool.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

DefaultClass:Medium indicates the Medium Cgroup that belongs to the Timeshare Cgroup under the DefaultClass Cgroup.

enable_backend_control

Parameter description: Specifies whether the database permanent thread is bound to the DefaultBackend Cgroup. This parameter must be set to a same value on CNs and DNs.

Parameter type: Boolean.

Unit: none

Value range:

• on: Permanent threads are bound to the DefaultBackend Cgroup.
• off: Permanent threads are not bound to the DefaultBackend Cgroup.

Default value: on

Setting method: This is a POSTMASTER parameter. Set it based on instructions provided in Table 1.

Setting suggestion: Retain the default value.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

This parameter is valid only when enable_control_group is set to on.

enable_vacuum_control

Parameter description: Specifies whether autovacuum worker in the database permanent thread is bound to the Vacuum Cgroup. This parameter must be set to a same value on CNs and DNs.

Parameter type: Boolean.

Unit: none

Value range:

• on: The autovacuum worker thread is bound to the Vacuum Cgroup.
• off: The autovacuum worker thread is not bound to the Vacuum Cgroup.

Default value: on

Setting method: This is a POSTMASTER parameter. Set it based on instructions provided in Table 1.

Setting suggestion: Retain the default value.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

This parameter is valid only when enable_control_group is set to on.

enable_perm_space

Parameter description: Specifies whether to enable the perm space function. This parameter must be set to a same value on CNs and DNs.

Parameter type: Boolean.

Unit: none

Value range:

• on: The perm space management is enabled.
• off: The perm space management is disabled.

Default value: on

Setting method: This is a POSTMASTER parameter. Set it based on instructions provided in Table 1.

Setting suggestion: Retain the default value.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

enable_verify_active_statements

Parameter description: Specifies whether to enable the background calibration during static self-adaptive workload balancing. This parameter must be used on CNs.

Parameter type: Boolean.

Unit: none

Value range:

• on: The backend calibration is enabled.
• off: The backend calibration is disabled.

Default value: on

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: Retain the default value.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

parctl_min_cost

Parameter description: Specifies the execution cost threshold of a statement. If the execution cost of a statement exceeds the specified value, the statement is subject to the concurrent limit of a resource pool.

Parameter type: integer.

Unit: none

Value range: –1 to 2147483647

• If the value is –1 or the cost of executing a statement is less than 10, the statement is not subject to the concurrency limit of the resource pool.
• If the value is greater than or equal to 0, enable_dynamic_workload is set to off, and the cost of executing a statement exceeds the value and is greater than or equal to 10, the statement is subject to the concurrency limit of the resource pool.

Default value: 100000

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: Retain the default value.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

cpu_collect_timer

Parameter description: Specifies how frequently CPU data is collected during statement execution on database nodes.

Parameter type: integer.

Unit: second

Value range: 1 to 2147483647

Default value: 30

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1. The value cannot contain a unit.

Setting suggestion: A database administrator should set a proper collection frequency based on system resources (for example, CPU, I/O, and memory resources). A too small value will affect the execution efficiency and a too large value will reduce the accuracy of exception handling.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

memory_tracking_mode

Parameter description: Specifies the memory information recording mode.

Parameter type: enumerated type.

Unit: none

Value range:

• none: Memory statistics are not collected.
• peak: Memory statistics on the peak value of the query level are collected. The value is recorded in the database log and can also be output by using explain analyze.
• normal: Memory statistics are collected in real time but no file is generated.
• executor: A statistics file is generated, containing the context information of all allocated memory used on the execution layer.
• fullexec: A statistics file is generated, containing the information about all memory contexts requested by the execution layer.

Default value: none

Setting method: This is a USERSET parameter. Set it based on instructions provided in Table 1.

Setting suggestion: Retain the default value.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

memory_detail_tracking

Parameter description: Specifies the memory context allocation priority of a thread and the plannodeid of the query for which the current thread is running. This parameter is used only in the debug version.

Parameter type: string.

Unit: none

Value range: a string.

Default value: ""

Setting method: This is a USERSET parameter. Set it based on instructions provided in Table 1.

Setting suggestion: Retain the default value. You are not allowed to set this parameter.

Risks and impacts of improper settings: none

enable_resource_track

Parameter description: Specifies whether to enable the real-time resource monitoring function. This parameter must be set to a same value on CNs and DNs.

Parameter type: Boolean.

Unit: none

Value range:

• on: The resource monitoring is enabled.
• off: The resource monitoring is disabled.

Default value: on

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: Retain the default value.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

enable_resource_record

Parameter description: Specifies whether resource monitoring records are archived. If this parameter is set to on, records in the history views (GS_WLM_SESSION_HISTORY and GS_WLM_OPERATOR_HISTORY) are archived to the corresponding info views (GS_WLM_SESSION_INFO and GS_WLM_OPERATOR_INFO) at an interval of 3 minutes. After being archived, the records are deleted from the history views. This parameter must be set to a same value on CNs and DNs.

Parameter type: Boolean.

Unit: none

Value range:

• on: The resource monitoring records are archived.
• off: The resource monitoring records are not archived.

Default value: off

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: Retain the default value.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

enable_logical_io_statistics

Parameter description: Specifies whether to enable the logical I/O statistics function during resource monitoring. If this function is enabled, the read_kbytes, write_kbytes, read_counts, write_counts, read_speed, and write_speed fields in the PG_TOTAL_USER_RESOURCE_INFO view will collect statistics on the byte count, number of times, and speed of logical read and write. Fields related to logical read and write in the system catalogs GS_WLM_USER_RESOURCE_HISTORY and GS_WLM_INSTANCE_HISTORY will collect statistics on the logical read and write of related users and instances.

Parameter type: Boolean.

Unit: none

Value range:

• on: The logical I/O statistics function is enabled.
• off: The logical I/O statistics function is disabled.

Default value: on

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: Retain the default value.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

enable_user_metric_persistent

Parameter description: Specifies whether to dump the historical monitoring data of user resources. If 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. For details, see "System Catalogs and System Views > System Views > GS_WLM_USER_RESOURCE_HISTORY" in Developer Guide.

Parameter type: Boolean.

Unit: none

Value range:

• on: The historical monitoring data of user resources is dumped.
• off: The historical monitoring data of user resources is not dumped.

Default value: on

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: Retain the default value.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

user_metric_retention_time

Parameter description: Specifies the retention days of the historical monitoring data of user resources. This parameter is valid only when enable_user_metric_persistent is set to on.

Parameter type: integer.

Unit: day

Value range: 0–3650

• If this parameter is set to 0, the historical monitoring data of user resources 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

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1. The unit must be d if required.

Setting suggestion: Retain the default value.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

enable_instance_metric_persistent

Parameter description: Specifies whether the instance resource monitoring data is dumped. If this function is enabled, instance monitoring data is saved to the GS_WLM_INSTANCE_HISTORY system catalog. For details, see "System Catalogs and System Views > System Catalogs > GS_WLM_INSTANCE_HISTORY" in Developer Guide.

Parameter type: Boolean.

Unit: none

Value range:

• on: The instance resource monitoring data is dumped.
• off: The instance resource monitoring data is not dumped.

Default value: on

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: Retain the default value.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

instance_metric_retention_time

Parameter description: Specifies the retention days of the historical monitoring data of instance resources. This parameter is valid only when enable_instance_metric_persistent is set to on.

Parameter type: integer.

Unit: day

Value range: 0–3650

• If this parameter is set to 0, the historical monitoring data of instance resources is permanently stored.
• If the value is greater than 0, the historical monitoring data of instance resources is stored for the specified number of days.

Default value: 7

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1. The unit must be d if required.

Setting suggestion: Retain the default value.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

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.

Parameter type: enumerated type.

Unit: none

Value range:

• none: Resources are not monitored.
• query: Resources used at the query level are monitored.
• operator: Resources used at the query and operator levels are monitored.

Default value: query

Setting method: This is a USERSET parameter. Set it based on instructions provided in Table 1.

Setting suggestion: Retain the default value.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

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.

Parameter type: integer.

Unit: none

Value range: –1 to 2147483647

• –1 indicates that resource monitoring is disabled.
• A value ranging from 0 to 9 indicates that statements whose execution cost is greater than or equal to 10 will be monitored.
• A value greater than or equal to 10 indicates that statements whose execution cost exceeds this value will be monitored.

Default value: 100000

Setting method: This is a USERSET parameter. Set it based on instructions provided in Table 1.

Setting suggestion: Retain the default value.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

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 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.

Parameter type: integer.

Unit: second

Value range: 0 to 2147483647

• 0 indicates that historical information about all statements recorded in the real-time resource monitoring view are archived.
• If the value is greater than 0, historical information about a statement whose execution time exceeds this value will be archived.

Default value: 60

Setting method: This is a USERSET parameter. Set it based on instructions provided in Table 1. For example, if the value is 3600 without a unit, resource_track_duration indicates 3600s. If the value is 1h, resource_track_duration indicates 1 hour. If the unit is required, the value must be s, min, h, or d.

Setting suggestion: Retain the default value.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

dynamic_memory_quota

Parameter description: Specifies the memory quota in adaptive load scenarios, that is, the proportion of maximum available memory to total system memory.

Parameter type: integer.

Unit: none

Value range: 1 to 100

Default value: 80

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: Retain the default value.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

disable_memory_protect

Parameter description: Specifies whether to stop 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.

Parameter type: Boolean.

Unit: none

Value range:

• on: Memory protection is disabled.
• off: Memory protection is enabled.

Default value: off

Setting method: This parameter is a USERSET parameter and is valid only for the current session. Set it based on instructions provided in Table 1.

Setting suggestion: Retain the default value.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

query_band

Parameter description: Specifies the user-defined job type of the current session.

Parameter type: string.

Unit: none

Value range: a string.

Default value: ""

Setting method: This is a USERSET parameter. Set it based on instructions provided in Table 1.

Setting suggestion: Retain the default value.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

memory_fault_percent

Parameter description: Specifies the ratio of memory allocation failures during the memory fault test. This parameter is used only in the DEBUG version.

Parameter type: integer.

Unit: none

Value range: 0 to 2147483647

Default value: 0

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: Retain the default value.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

enable_bbox_dump

Parameter description: Specifies whether to enable the black box function and whether to generate core files when the core mechanism is not configured in the system. This function is valid only for CNs or DNs. For CM Agent, CM Server, GTM, and fenced UDF, the system core mechanism must be configured to capture core files.

Parameter type: Boolean.

Unit: none

Value range:

• on: The black box function is enabled.
• off: The black box function is disabled.

Default value: on

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: Retain the default value.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

The generation of core files by the black box function depends on the open ptrace API of the OS. If the permission is insufficient (errno = 1), ensure that the /proc/sys/kernel/yama/ptrace_scope configuration is correct.

bbox_dump_count

Parameter description: Specifies the maximum number of core files that are generated by GaussDB 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 when enable_bbox_dump is set to on.

When core files are generated concurrently, the number of files may be larger than the value of bbox_dump_count.

Parameter type: integer.

Unit: none

Value range: 1 to 20

Default value: 8

Setting method: This is a USERSET parameter. Set it based on instructions provided in Table 1.

Setting suggestion: Retain the default value.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

bbox_dump_path

Parameter description: Specifies the path where the black box core files are generated. This parameter is valid only when enable_bbox_dump is set to on.

Parameter type: string.

Unit: none

Value range: valid file path.

Default value: "". The default path where the black box core files are generated is "/proc/sys/kernel/core_pattern". If the path is not a directory or you do not have the write permission on the directory, black box core files will be generated under the data directory of the database.

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: Retain the default value.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

bbox_blanklist_items

Parameter description: Specifies the anonymized data items of black box core files. This parameter is valid only when enable_bbox_dump is set to on.

Parameter type: string.

Unit: none

Value range: a string of sensitive data items separated by commas (,).

Default value: "", which indicates that all supported sensitive data items of the core files generated by the black box are anonymized.

Currently, the following data items can be anonymized:

• SHARED_BUFFER: data buffer.
• XLOG_BUFFER: redo log buffer.
• DW_BUFFER: dual-write data buffer.
• XLOG_MESSAGE_SEND: buffer for sending primary/standby replication logs.
• WALRECEIVER_CTL_BLOCK: buffer for receiving primary/standby replication logs.
• DATA_MESSAGE_SEND: buffer for sending primary/standby replication data.
• DATA_WRITER_QUEUE: buffer for receiving primary/standby replication data.
• BUCKET_XLOG_MESSAGE_SEND: buffer for sending replay logs during bucket scale-out.

Setting method: This is a POSTMASTER parameter. Set it based on instructions provided in Table 1.

Setting suggestion: Retain the default value.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

enable_ffic_log

Parameter description: Specifies whether to enable the first failure information capture (FFIC) function. This function is valid only for CNs or DNs. For CM Agent, CM Server, GTM, and fenced UDF, the system core mechanism must be configured to capture core files.

Parameter type: Boolean.

Unit: none

Value range:

• on: The FFIC function is enabled.
• off: The FFIC function is disabled.

Default value: on

Setting method: This is a POSTMASTER parameter. Set it based on instructions provided in Table 1.

Setting suggestion: Retain the default value.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

enable_dynamic_workload

Parameter description: Specifies whether to enable the dynamic workload management function.

Parameter type: Boolean.

Unit: none

Value range:

• on: The dynamic workload management function is enabled.
• off: The dynamic workload management function is disabled.

Default value: off

Setting method: This is a POSTMASTER parameter. Set it based on instructions provided in Table 1.

Setting suggestion: Retain the default value.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

• If memory adaptation is enabled, you do not need to use work_mem to optimize the operator memory usage. The system will generate a plan for each statement based on the current workload, estimating the memory used by each operator and by the entire statement. In a concurrency scenario, statements are queued based on the system workload and their memory usage.
• In some cases, the optimizer cannot accurately estimate the number of rows and thereby underestimates or overestimates memory usage. If the memory usage is underestimated, the allocated memory will be automatically increased during statement running. If the memory usage is overestimated, system memory resources will not be fully used, and the number of statements waiting in a queue will increase, which probably results in low performance. In this case, you need to identify the statements whose estimated memory usage is much greater than the actual DN peak memory and optimize the performance by setting query_mem. For details, see "SQL Optimization Guide > Adjusting Key Parameters During SQL Optimization" in Developer Guide.

enable_dywlm_adjust

Parameter description: Specifies whether inaccurate resource values will be dynamically adjusted. This parameter must be set to a same value on CNs and DNs.

Parameter type: Boolean.

Unit: none

Value range:

• on: Inaccurate resource values will be dynamically adjusted.
• off: Inaccurate resource values will not be dynamically adjusted.

Default value: on

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: Retain the default value.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

enable_force_memory_control

Parameter description: Specifies whether to control simple queries based on memory usage when the concurrency control is enabled in a resource pool. This parameter must be set to a same value on CNs and DNs.

Parameter type: Boolean.

Unit: none

Value range:

• on: Simple queries are controlled.
• off: Simple queries are not controlled.

Default value: off

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: Retain the default value.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

enable_reaper_backend

Parameter description: Specifies whether the signal sent by a worker thread when it exits is collected by a separate thread.

Parameter type: Boolean.

Unit: none

Value range:

• on: This function is enabled.
• off: This function is disabled.

Default value: on

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: Retain the default value.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

bypass_workload_manager

Parameter description: Specifies whether to enable independent I/O management and control. This parameter must be used together with CNs and DNs.

If use_workload_manager is not set to on, this parameter can be used to enable the I/O control independently. After the I/O control is enabled, you can set io_limits or io_priority to configure control details.

Parameter type: Boolean.

Unit: none

Value range:

• on: The I/O control is enabled.
• off: The I/O control is disabled.

Default value:

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: Retain the default value.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

io_limits

Parameter description: Specifies the upper limit of input/output operations per second (IOPS).

Parameter type: integer.

Unit: none

Value range: 0 to 1073741823

Default value: 0

Setting method: This is a USERSET parameter. Set it based on instructions provided in Table 1.

Setting suggestion: Retain the default value.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

io_priority

Parameter description: Specifies the I/O priority for jobs that consume many I/O resources. It takes effect when the I/O usage reaches 50%.

Parameter type: enumerated type.

Unit: none

Value range:

• None: no limitation.
• Low: The IOPS is reduced to 10% of the original value.
• Medium: The IOPS is reduced to 20% of the original value.
• High: The IOPS is reduced to 50% of the original value.

Default value: None

Setting method: This is a USERSET parameter. Set it based on instructions provided in Table 1.

Setting suggestion: Retain the default value.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

io_control_unit

Parameter description: Specifies the unit used to count the number of I/Os during I/O control in row-store scenarios. This parameter must be set to a same value on CNs and DNs.

Set a certain number of I/Os as one unit. This unit is used during the I/O control.

Parameter type: integer.

Unit: none

Value range:1000 to 1000000

Default value: 6000

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: Retain the default value.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

session_respool

Parameter description: Specifies the resource pool associated with the current session.

If you set cgroup_name and then session_respool, the Cgroup associated with session_respool takes effect. If you reverse the order, the Cgroup associated with cgroup_name takes 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.

Parameter type: string.

Unit: none

Value range: name of the resource pool set by running create resource pool.

Default value: "invalid_pool"

Setting method: This is a USERSET parameter. Set it based on instructions provided in Table 1.

Setting suggestion: Do not use both cgroup_name and session_respool.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

session_statistics_memory

Parameter description: Specifies the memory size of a real-time query view.

Parameter type: integer.

Unit: KB

Value range: 5120 to 2147483647

Default value: 5120 (that is, 5 MB)

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1. For example, if the value is 16384 without a unit, session_statistics_memory indicates 16384 KB. If the value is 16MB, session_statistics_memory indicates 16 MB. The unit must be KB, MB, or GB if required.

Setting suggestion: You are advised to set this parameter to a value less than or equal to 50% of the value of max_process_memory.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

session_history_memory

Parameter description: Specifies the memory size of a historical query view.

Parameter type: integer.

Unit: KB

Value range: 10240 to 2147483647

Default value: 10240 (that is, 10 MB)

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1. For example, if the value is 16384 without a unit, session_history_memory indicates 16384 KB. If the value is 16MB, session_history_memory indicates 16 MB. The unit must be KB, MB, or GB if required.

Setting suggestion: You are advised to set this parameter to a value less than or equal to 50% of the value of max_process_memory.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

enable_transaction_parctl

Parameter description: Specifies whether to control transaction block statements and stored procedure statements.

Parameter type: Boolean.

Unit: none

Value range:

• on: Transaction block statements and stored procedure statements are controlled.
• off: Transaction block statements and stored procedure statements are not controlled.

Default value: on

Setting method: This is a USERSET parameter. Set it based on instructions provided in Table 1.

Setting suggestion: Retain the default value.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

topsql_retention_time

Parameter description: Specifies the retention period of historical TopSQL data in the gs_wlm_session_query_info_all and gs_wlm_operator_info tables.

Parameter type: integer.

Unit: day

Value range: 0–3650

• 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: 0

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1. The value cannot contain a unit.

Setting suggestion: Retain the default value.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

transaction_pending_time

Parameter description: Specifies the maximum queuing time of transaction block statements and stored procedure statements. This parameter is valid only when enable_transaction_parctl is set to on.

Parameter type: integer.

Unit: second

Value range: –1 to 1073741823.

• –1 or 0 indicates that no queuing timeout is specified for transaction block statements and stored procedure statements. The statements can be executed when resources are available.
• A value greater than 0 indicates that 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

Setting method: This is a USERSET parameter. Set it based on instructions provided in Table 1. The value cannot contain a unit.

Setting suggestion: Retain the default value.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

node_group_mode

Parameter description: Displays the current node group mode.

Parameter type: string.

Unit: none

Value range: name of the node group mode.

Default value: "node group"

Setting method: This is a fixed INTERNAL parameter. It can be viewed but cannot be modified.

Setting suggestion: This parameter can only be viewed.

Risks and impacts of improper settings: none

resilience_ctrlslot_available_maxpercent

Parameter description: Specifies the maximum percentage of threads in the thread pool that can be occupied by slow SQL statements. This parameter is valid only for SELECT statements executed by non-SYSADMIN/MONADMIN users.

Parameter type: integer.

Unit: none

Value range: 0 to 100

Default value: 100, indicating that slow SQL statements can occupy all threads in the thread pool.

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: Retain the default value.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

resilience_ctrlstmt_detect_timelimit

Parameter description: Specifies the execution time of a normal SQL statement after which it is marked as a slow SQL statement. The value 0 indicates that slow SQL statements are not identified. A value greater than 0 indicates that the SQL statement is marked as a slow SQL statement when its execution time exceeds the value of this parameter. This parameter is valid only for SELECT statements executed by non-SYSADMIN/MONADMIN users.

Parameter type: integer.

Unit: ms

Value range: 0 to 2147483647. 0 indicates that the slow SQL detection function is disabled.

Default value: 0

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1. For example, if the value is 6000 without a unit, resilience_ctrlstmt_detect_timelimit indicates 6000 ms. If the value is 6s, resilience_ctrlstmt_detect_timelimit indicates 6s. The unit must be ms, s, min, h, or d if required.

Setting suggestion: Set this parameter based on the average SQL execution duration of the real-time database.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

resilience_ctrlstmt_control_iopslimit

Parameter description: Specifies the maximum IOPS that can be used by slow SQL statements after normal SQL statements are marked as slow SQL statements. This parameter is valid only for SELECT statements executed by non-SYSADMIN/MONADMIN users.

Parameter type: string.

Unit: none

Value range: "Low", "Medium", "High", "None", or a value ranging from 0 to 2147483647. The lower the level, the stricter the control.

• "Low": low level.
• "Medium": medium level.
• "High": high level.
• "None": Logical I/O control for slow SQL statements is disabled.
• 0 to 2147483647: A smaller value indicates stricter and a larger value indicates looser.

Default value: "None"

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1. If this parameter is set to a number, the value must be a character string, for example, resilience_ctrlstmt_control_iopslimit = '1024'.

Setting suggestion: Set this parameter to a small value when I/O access is full and to a large value when I/O access is idle.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

session_max_dynamic_memory

Parameter description: Specifies the upper limit of the session-level memory. If the session memory usage exceeds the value of this parameter, an error is reported and the session is interrupted. This parameter is valid only when enable_memory_limit is set to on.

Parameter type: integer.

Unit: KB

Value range: –1 to 2147483647

Default value: –1, indicating no control.

Setting method: This is a USERSET parameter. Set it based on instructions provided in Table 1. The value cannot contain a unit.

Setting suggestion: Retain the default value.

Risks and impacts of improper settings: The parameter cannot be set to a small value. If the value is too small, the session fails to execute statements due to insufficient memory. If the parameter is set to a value by using method 3 in Table 2 but the value cannot be set larger due to insufficient memory, you can only exit the session to eliminate the restriction. If the value is less than 16 MB, a message is displayed.

max_concurrency

Parameter description: Specifies the upper limit of global concurrency.

Parameter type: integer.

Unit: none

Value range: –1 to 2147483647

Default value: –1, indicating no control.

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: A database administrator needs to adjust the value of this parameter based on the usage of system resources (such as CPU, I/O, and memory resources) to maximize the number of concurrent jobs and prevent system breakdown caused by excessive concurrent jobs.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

enable_workload_rule

Parameter description: Specifies whether to enable the SQL statement concurrency control.

Parameter type: Boolean.

Unit: none

Value range:

• on: The SQL statement concurrency control is enabled.
• off: The SQL statement concurrency control is disabled.

Default value: on

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: If the SQL statement concurrency control function is not required, set this parameter to off.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

workload_uncontrolled_users

Parameter description: Specifies the user whitelist for load management. Workload management is not performed on users in the whitelist. Currently, this parameter takes effect only for SQL statement concurrency control.

Parameter type: string.

Unit: none

Value range: a list of users separated by commas (,), for example, user1, user2, user3.

Default value: ""

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: Set this parameter based on service requirements. If the users without the SYSADMIN permission do not want to be restricted by workload management when running SQL statements, they can add this parameter.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.