AI Features

enable_ai_stats

Parameter description: Specifies whether to create or use intelligent statistics.

Parameter type: Boolean.

Unit: none

Value range:

• on: Intelligent statistics are created and used.
• off: Intelligent statistics are not created or used.

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: If you modify the settings during database running, the plan may deteriorate.

multi_stats_type

Parameter description: Specifies the type of statistics to be created when enable_ai_stats is set to on.

Value type: enumerated type.

Unit: none

Value range: "BAYESNET", "MCV", and "ALL"

• "BAYESNET": Only intelligent statistics are created.
• "MCV": Only traditional statistics are created.
• "ALL": Both traditional statistics and intelligent statistics are created.

Default value: "BAYESNET"

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.

ai_stats_cache_limit

Parameter description: Specifies the maximum number of models that can be cached when enable_ai_stats is set to on.

Parameter type: integer.

Unit: none

Value range: 30 to 1000

Default value: 100

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

Setting suggestion: Set this parameter based on the number of multi-column statistics models.

Risks and impacts of improper settings: If the value is too large, unnecessary memory is occupied. If the value is too small, models are frequently read from hard disks, deteriorating system performance.

enable_operator_prefer

Parameter description: Specifies whether to enable the operator preference rule. If the estimated costs are similar, the parameterized path is preferred for table join.

Parameter type: Boolean.

Unit: none

Value range:

• on: Parameterized path preference is enabled.
• off: Parameterized path preference is disabled.

Default value: off

There are two prerequisites for this parameter to take effect:

• The parameterized path is generated.
• The estimated cost of the parameterized path is similar to that of other index scan operators.

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

Setting suggestion: Retain the default value. You are advised to specify this parameter only in sessions or hints.

Risks and impacts of improper settings: If this parameter is modified, the plan may deteriorate.

enable_ai_watchdog

Parameter description: Enables or disables the AI watchdog function.

Parameter type: Boolean.

Unit: none

Value range:

• on: enabled.
• off: 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: Enabling this function occupies system resources.

enable_ai_watchdog_forcible_oom_detection

Parameter description: Forcibly enables or disables the OOM detection function of the AI watchdog. If this parameter is disabled, the system automatically determines whether to enable the OOM detection function based on the current database specifications. In automatic determination mode, the OOM detection function is enabled only when max_process_memory is set to 64GB or a larger value. The OOM detection function depends on the information obtained by the memory management module. Therefore, if the memory management module is disabled or invalid, the OOM detection function is not enabled.

Parameter type: Boolean.

Unit: none

Value range:

• on: enabled.
• off: disabled.

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: Enabling this function occupies system resources.

enable_ai_watchdog_healing

Parameter description: Enables or disables the self-healing function of the AI watchdog.

Parameter type: Boolean.

Unit: none

Value range:

• on: enabled.
• off: 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.

ai_watchdog_max_cpu_usage

Parameter description: Specifies the expected upper limit of the database CPU usage. The value is normalized based on the multi-core situation. If this parameter is set to 0, the system does not check the CPU usage.

Parameter type: floating point.

Unit: none

Value range: 0 to 1

Default value: 0.8

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: If the value is too large, exceptions may not be detected in a timely manner.

ai_watchdog_oom_dynamic_used_threshold

Parameter description: Specifies the expected upper limit of the dynamic memory usage of the database.

Parameter type: floating point.

Unit: none

Value range: 0 to 1

Default value: 0.95

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: If the value is too large, exceptions may not be detected in a timely manner.

ai_watchdog_oom_growth_confidence

Parameter description: Specifies the confidence level of the OOM detection algorithm.

Parameter type: floating point.

Unit: none

Value range: 0.1 to 1

Default value: 0.95

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.

ai_watchdog_oom_malloc_failures

Parameter description: Specifies the maximum number of consecutive memory allocation failures tolerated. If the number of consecutive memory allocation failures exceeds this value, the OOM detection function may be triggered.

Parameter type: integer.

Unit: none

Value range: 1 to 32000

Default value: 50

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: If the value is too small, alarms are frequently generated. If this value is too large, exceptions cannot be detected in a timely manner.

ai_watchdog_oom_other_used_memory_threshold

Parameter description: Specifies the expected upper limit of memory usage of other parts of the database.

Parameter type: integer.

Unit: MB

Value range: –1 to 1048576

Default value:

• If this parameter is set through the OM installation, the default value is –1.
  

  • When the value is –1, the upper limit of the other parts of the memory usage is specified based on the following rules:
    • If the value of max_process_memory is less than 300 GB, the upper limit of the other parts of the memory usage is 20 GB.
    • If the value of max_process_memory is greater than or equal to 300 GB and less than 600 GB, the upper limit of the other parts of the memory usage is 40 GB.
    • If the value of max_process_memory is greater than or equal to 600 GB, the upper limit of the other parts of the memory usage is 60 GB.
  • If the default value –1 is not used, the upper limit of the other parts of the memory usage is the value set by the user.
• If this parameter is not set through the OM installation, the default value is 20480.

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: If the value is too small, alarms are frequently generated. If this value is too large, exceptions cannot be detected in a timely manner.

ai_watchdog_oom_process_threshold

Parameter description: Specifies the expected percentage of the database process usage to the value of max_process_memory. When the threshold is reached, memory leakage determination is triggered.

Parameter type: floating point.

Unit: none

Value range: 0 to 10

Default value:

• If this parameter is set through the OM installation, the default value is 1.
• If this parameter is not set through the OM installation, the default value is 1.1.

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.

ai_watchdog_oom_shared_threshold

Parameter description: Specifies the expected upper limit of the shared memory usage of the database.

Parameter type: floating point.

Unit: none

Value range: 0 to 1

Default value: 0.4

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.

ai_watchdog_rto_restriction_time

Parameter description: Specifies the RTO threshold of the AI watchdog self-healing function. If the RTO threshold is exceeded, self-healing is not performed.

Parameter type: integer.

Unit: second

Value range: 0 to 36000

Default value: 600

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.

ai_watchdog_tolerance_times

Parameter description: Specifies the maximum number of consecutive abnormal events that can be tolerated by the AI watchdog before self-healing is started. This parameter can be used to avoid incorrect operations.

Parameter type: integer.

Unit: none

Value range: 0 to 100

Default value: 4

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.

ai_watchdog_tps_threshold

Parameter description: Specifies the lower limit of the expected TPS usage of the database instance. If the TPS usage is lower than the value of this parameter, the exception determination logic is triggered.

Parameter type: integer.

Unit: none

Value range: 0 to 32000

Default value: 2

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.

ai_watchdog_wait_time

Parameter description: Adjusts the waiting time. To prevent the database from frequently performing self-healing operations, the database waits for a period of time after startup.

Parameter type: integer.

Unit: second

Value range: 0 to 36000

Default value: 1800

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: If the value is too small, false alarms may be reported when the database is just started. If the value is too large, exceptions within the waiting time may not be detected.

ai_watchdog_warning_retention

Parameter description: Specifies the maximum number of alarm records that the AI watchdog can retain in the dbe_perf.ai_watchdog_detection_warnings view.

Parameter type: integer.

Unit: none

Value range: 0 to 32000

Default value: 20

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.