从 Postgres 数据库中快速删除
Fast delete from Postgres database
我目前有一个包含 180 table 的数据库 (postgres 10.7)。每个 table 通过外键（使用 ON UPDATE CASCADE, ON DELETE CASCADE）直接或间接链接到主 table projects。从 project table 中删除条目时，这有时可能需要几分钟，有时甚至几个小时，具体取决于链接到该项目的数据量。
我想知道从 projects table 中删除的最好最快的方法是什么。
目前，我正在删除以下内容：
SET CONSTRAINTS ALL DEFERRED;
DELETE FROM projects WHERE id=project_id;
我试过使用和不使用 SET CONSTRAINTS 部分——它确实没有效果。对我们来说不幸的是，TRUNCATE CASCADE 不起作用，因为我们只想删除一个项目，有时是几个项目，但绝不会全部删除。我们也有外键索引来尝试帮助它。
EXPLAIN 命令的输出（完整项目）：
"Delete on projects (cost=0.00..1.01 rows=1 width=6) (actual time=0.777..0.777 rows=0 loops=1)"
" Buffers: shared hit=2 read=1 dirtied=1"
" -> Seq Scan on projects (cost=0.00..1.01 rows=1 width=6) (actual time=0.040..0.040 rows=1 loops=1)"
" Buffers: shared read=1"
"Planning time: 7.545 ms"
"Trigger for constraint activity_filter_scenarios_project_fkey on projects: time=8.286 calls=1"
"Trigger for constraint added_dependency_scenarios_project_fkey on projects: time=2.769 calls=1"
"Trigger for constraint cap_flexing_sets_project_fkey on projects: time=3.028 calls=1"
"Trigger for constraint dependency_layer_scenarios_project_id_fkey on projects: time=3.391 calls=1"
"Trigger for constraint distributions_project_fkey on projects: time=1.519 calls=1"
"Trigger for constraint execution_queue_projectid_fkey on projects: time=6.041 calls=1"
"Trigger for constraint exf_imports_project_fkey on projects: time=29.521 calls=1"
"Trigger for constraint field_definitions_project_fkey on projects: time=4.295 calls=1"
"Trigger for constraint financial_scenarios_project_fkey on projects: time=4.157 calls=1"
"Trigger for constraint geos_full_solutions_project_fkey on projects: time=2.131 calls=1"
"Trigger for constraint geos_stope_scenarios_project_fkey on projects: time=1.218 calls=1"
"Trigger for constraint geosequencing_scenarios_project_fkey on projects: time=2.556 calls=1"
"Trigger for constraint geosequencing_stability_settings_project_fkey on projects: time=1.191 calls=1"
"Trigger for constraint gosp_scenarios_project_fkey on projects: time=0.992 calls=1"
"Trigger for constraint graph_requests_template_project_fkey on projects: time=2.211 calls=1"
"Trigger for constraint guidance_formula_sets_project_fkey on projects: time=5.801 calls=1"
"Trigger for constraint horizon_scenarios_project_fkey on projects: time=2.336 calls=1"
"Trigger for constraint max_lag_settings_project_id_fkey on projects: time=4.591 calls=1"
"Trigger for constraint mine_scenarios_project_fkey on projects: time=4.309 calls=1"
"Trigger for constraint project_history_project_fkey on projects: time=4.586 calls=1"
"Trigger for constraint run_configurations_project_fkey on projects: time=3.074 calls=1"
"Trigger for constraint run_settings_project_fkey on projects: time=2.468 calls=1"
"Trigger for constraint schedule_reevaluation_requests_project_fkey on projects: time=0.442 calls=1"
"Trigger for constraint seeds_project_fkey on projects: time=20.746 calls=1"
"Trigger for constraint stockpiles_project_fkey on projects: time=0.416 calls=1"
"Trigger for constraint tasks_project_fkey on projects: time=197.922 calls=1"
"Trigger for constraint ventilation_advanced_requirements_project_fkey on projects: time=0.336 calls=1"
"Trigger for constraint ventilation_advanced_scenarios_project_fkey on projects: time=0.255 calls=1"
"Trigger for constraint ventilation_requirement_configurations_project_fkey on projects: time=0.284 calls=1"
"Trigger for constraint ventilation_scenarios_project_fkey on projects: time=1.945 calls=1"
"Trigger for constraint activity_filter_operations_activity_filter_scenario_fkey on activity_filter_scenarios: time=75.510 calls=3"
"Trigger for constraint cap_analysis_requests_activity_filter_scenario_fkey on activity_filter_scenarios: time=6.031 calls=3"
"Trigger for constraint mine_scenarios_activity_filter_scenario_fkey on activity_filter_scenarios: time=0.200 calls=3"
"Trigger for constraint execution_queue_run_seed_fkey on execution_queue: time=0.818 calls=13"
"Trigger for constraint residual_requests_execution_id_fkey on execution_queue: time=2.147 calls=13"
"Trigger for constraint rm_o_attain_config_runid_fkey on execution_queue: time=1.494 calls=13"
"Trigger for constraint rm_o_attain_target_dates_runid_fkey on execution_queue: time=4.166 calls=13"
"Trigger for constraint rm_o_complete_runid_fkey on execution_queue: time=4.813 calls=13"
"Trigger for constraint rm_o_config_runid_fkey on execution_queue: time=12738.872 calls=13"
"Trigger for constraint rm_o_dependencymap_runid_fkey on execution_queue: time=980.347 calls=13"
"Trigger for constraint rm_o_generation_stats_runid_fkey on execution_queue: time=11.286 calls=13"
"Trigger for constraint rm_o_horizon_realization_scenarios_run_id_fkey on execution_queue: time=3.534 calls=13"
"Trigger for constraint rm_o_reset_stats_runid_fkey on execution_queue: time=6.277 calls=13"
"Trigger for constraint rm_o_run_config_runid_fkey on execution_queue: time=2.846 calls=13"
"Trigger for constraint rm_o_run_stats_runid_fkey on execution_queue: time=3.249 calls=13"
"Trigger for constraint rm_o_schedule_stats_runid_fkey on execution_queue: time=1.299 calls=13"
"Trigger for constraint rm_o_top_resets_runid_fkey on execution_queue: time=2.010 calls=13"
"Trigger for constraint rm_o_top_schedules_runid_fkey on execution_queue: time=4.507 calls=13"
"Trigger execution_queue_delete_trigger on execution_queue: time=26.856 calls=13"
"Trigger for constraint dependencies_exf_import_fkey on exf_imports: time=320.650 calls=1"
"Trigger for constraint imported_fields_exf_import_fkey on exf_imports: time=6.302 calls=1"
"Trigger for constraint production_rate_tables_exf_import_fkey on exf_imports: time=2.985 calls=1"
"Trigger for constraint resources_exf_import_fkey on exf_imports: time=8.282 calls=1"
"Trigger for constraint tasks_exf_import_fkey on exf_imports: time=7.571 calls=1"
"Trigger for constraint activity_filter_operations_length_field_fkey on field_definitions: time=0.607 calls=26"
"Trigger for constraint activity_filter_operations_weight_field_fkey on field_definitions: time=0.532 calls=26"
"Trigger for constraint attribute_capacity_scenarios_attribute_field_fkey on field_definitions: time=4.029 calls=26"
"Trigger for constraint blending_constraints_first_element_fkey on field_definitions: time=3.867 calls=26"
"Trigger for constraint blending_constraints_second_element_fkey on field_definitions: time=0.505 calls=26"
"Trigger for constraint cap_analysis_request_field_definitions_field_def_fkey on field_definitions: time=2.177 calls=26"
"Trigger for constraint capacity_condition_scenario_groups_text_field_definition_fkey on field_definitions: time=3.894 calls=26"
"Trigger for constraint capacity_definitions_field_definition_fkey on field_definitions: time=9.777 calls=26"
"Trigger for constraint contaminants_contaminant_field_fkey on field_definitions: time=4.365 calls=26"
"Trigger for constraint equipment_equipment_field_fkey on field_definitions: time=8.113 calls=26"
"Trigger for constraint equipment_movement_costs_movement_field_fkey on field_definitions: time=2.051 calls=26"
"Trigger for constraint financial_scenarios_precalculated_revenue_fkey on field_definitions: time=0.611 calls=26"
"Trigger for constraint other_properties_property_field_fkey on field_definitions: time=10.417 calls=26"
"Trigger for constraint plants_plant_field_fkey on field_definitions: time=11.845 calls=26"
"Trigger for constraint point_capital_profiles_field_definition_fkey on field_definitions: time=4.204 calls=26"
"Trigger for constraint price_profiles_field_definition_fkey on field_definitions: time=7.214 calls=26"
"Trigger for constraint products_grade_field_fkey on field_definitions: time=59.582 calls=26"
"Trigger for constraint sustaining_capital_profiles_field_definition_fkey on field_definitions: time=2.062 calls=26"
"Trigger for constraint financial_scenario_expenditure_triggers_financial_scenario_fkey on financial_scenarios: time=2.437 calls=1"
"Trigger for constraint mine_scenarios_financial_scenario_fkey on financial_scenarios: time=0.138 calls=1"
"Trigger for constraint guidance_formula_set_entries_guidance_formula_set_fkey on guidance_formula_sets: time=9.255 calls=6"
"Trigger for constraint run_configurations_guidance_formula_set_fkey on guidance_formula_sets: time=0.365 calls=6"
"Trigger for constraint cap_analysis_requests_max_lag_fkey on max_lag_settings: time=0.132 calls=1"
"Trigger for constraint max_lag_setting_entries_setting_id_fkey on max_lag_settings: time=21.339 calls=1"
"Trigger for constraint run_settings_max_lag_settings_fkey on max_lag_settings: time=0.391 calls=1"
"Trigger for constraint mine_scenario_attribute_capacities_mine_scenario_fkey on mine_scenarios: time=3.052 calls=2"
"Trigger for constraint mine_scenario_capacity_definitions_mine_scenario_fkey on mine_scenarios: time=12.044 calls=2"
"Trigger for constraint mine_scenario_contaminants_mine_scenario_fkey on mine_scenarios: time=4.243 calls=2"
"Trigger for constraint mine_scenario_equipment_mine_scenario_fkey on mine_scenarios: time=9.233 calls=2"
"Trigger for constraint mine_scenario_other_properties_mine_scenario_fkey on mine_scenarios: time=5.192 calls=2"
"Trigger for constraint mine_scenario_plants_mine_scenario_fkey on mine_scenarios: time=39.163 calls=2"
"Trigger for constraint mine_scenario_products_mine_scenario_fkey on mine_scenarios: time=11.046 calls=2"
"Trigger for constraint run_configurations_mine_scenario_fkey on mine_scenarios: time=0.309 calls=2"
"Trigger for constraint geosequencing_scenario_run_configuration_run_configuration_fkey on run_configurations: time=0.873 calls=11"
"Trigger for constraint gosp_run_configurations_run_configuration_fkey on run_configurations: time=0.705 calls=11"
"Trigger for constraint horizon_run_configurations_run_configuration_fkey on run_configurations: time=0.715 calls=11"
"Trigger for constraint ventilation_run_configurations_run_configuration_fkey on run_configurations: time=0.942 calls=11"
"Trigger for constraint attain_run_settings_run_settings_fkey on run_settings: time=15.667 calls=9"
"Trigger for constraint run_configurations_run_settings_fkey on run_settings: time=0.674 calls=9"
"Trigger for constraint run_configurations_seed_fkey on seeds: time=0.275 calls=2"
"Trigger for constraint capacity_triggers_task_fkey on tasks: time=258.381 calls=35236"
"Trigger for constraint dependencies_from_task_fkey on tasks: time=212.529 calls=35236"
"Trigger for constraint dependencies_to_task_fkey on tasks: time=197.221 calls=35236"
"Trigger for constraint financial_scenario_expenditure_triggers_task_fkey on tasks: time=257.965 calls=35236"
"Trigger for constraint geosequencing_dependencies_from_task_fkey on tasks: time=260.043 calls=35236"
"Trigger for constraint geosequencing_dependencies_to_task_fkey on tasks: time=244.659 calls=35236"
"Trigger for constraint geosequencing_scenario_subtask_dependencies_from_task_fkey on tasks: time=254.873 calls=35236"
"Trigger for constraint geosequencing_scenario_subtask_dependencies_to_task_fkey on tasks: time=246.340 calls=35236"
"Trigger for constraint max_lag_setting_entries_from_task_fkey on tasks: time=188.897 calls=35236"
"Trigger for constraint max_lag_setting_entries_to_task_fkey on tasks: time=173.290 calls=35236"
"Trigger for constraint plant_recovery_factor_profiles_task_fkey on tasks: time=292.398 calls=35236"
"Trigger for constraint production_field_values_task_fkey on tasks: time=390.591 calls=35236"
"Trigger for constraint task_distributions_task_fkey on tasks: time=358.768 calls=35236"
"Trigger for constraint task_resource_associations_task_fkey on tasks: time=174.215 calls=35236"
"Trigger for constraint text_field_values_task_fkey on tasks: time=471.291 calls=35236"
"Trigger for constraint ventilation_advanced_scenario_activities_activity_fkey on tasks: time=327.614 calls=35236"
"Trigger for constraint ventilation_regulators_task_fkey on tasks: time=257.876 calls=35236"
"Trigger for constraint ventilation_scenario_districts_task_fkey on tasks: time=252.948 calls=35236"
"Trigger for constraint activity_filter_operation_equip_activity_filter_operation_fkey1 on activity_filter_operations: time=5.147 calls=52"
"Trigger for constraint activity_filter_operation_equipm_activity_filter_operation_fkey on activity_filter_operations: time=4.241 calls=52"
"Trigger for constraint activity_filter_operation_field_lookups_filter_operation_fkey on activity_filter_operations: time=4.153 calls=52"
"Trigger for constraint activity_filter_operation_proper_activity_filter_operation_fkey on activity_filter_operations: time=7.740 calls=52"
"Trigger for constraint attain_activity_filter_operations_filter_operation_fkey on activity_filter_operations: time=14.577 calls=52"
"Trigger for constraint rm_o_gosp_realization_scenarios_reset_id_fkey on rm_o_reset_stats: time=2.566 calls=19"
"Trigger for constraint rm_o_top_resets_reset_id_fkey on rm_o_reset_stats: time=0.475 calls=19"
"Trigger rm_o_reset_stats_trigger on rm_o_reset_stats: time=1.611 calls=19"
"Trigger rm_o_run_stats_trigger on rm_o_run_stats: time=1.936 calls=13"
"Trigger for constraint graph_requests_solution_fkey on rm_o_schedule_stats: time=7.944 calls=70"
"Trigger for constraint horizon_scenario_schedules_schedule_fkey on rm_o_schedule_stats: time=2.137 calls=70"
"Trigger for constraint residual_request_results_schedule_id_fkey on rm_o_schedule_stats: time=2.776 calls=70"
"Trigger for constraint rm_o_airway_airflowdpm_solution_id_fkey on rm_o_schedule_stats: time=3.301 calls=70"
"Trigger for constraint rm_o_gosp_schedule_stats_stats_id_fkey on rm_o_schedule_stats: time=2.227 calls=70"
"Trigger for constraint rm_o_regulator_settings_solution_id_fkey on rm_o_schedule_stats: time=2.724 calls=70"
"Trigger for constraint rm_o_resource_usage_instance_splits_solution_fkey on rm_o_schedule_stats: time=15620.727 calls=70"
"Trigger for constraint rm_o_resource_usage_schedule_id_fkey on rm_o_schedule_stats: time=67.761 calls=70"
"Trigger for constraint rm_o_top_schedules_schedule_id_fkey on rm_o_schedule_stats: time=1.412 calls=70"
"Trigger for constraint schedule_geo_stability_evaluations_schedule_id_fkey on rm_o_schedule_stats: time=1.232 calls=70"
"Trigger for constraint schedule_reevaluation_request_schedules_solution_fkey on rm_o_schedule_stats: time=1.189 calls=70"
"Trigger for constraint schedule_reevaluation_result_scores_solution_fkey on rm_o_schedule_stats: time=1.165 calls=70"
"Trigger for constraint scheduledactivities_solution_id_fkey on rm_o_schedule_stats: time=17489.740 calls=70"
"Trigger for constraint activity_filter_operation_field_lookups_field_fkey on imported_fields: time=0.549 calls=20"
"Trigger for constraint added_dependencies_criterion_fkey on imported_fields: time=3.868 calls=20"
"Trigger for constraint added_dependencies_domain_fkey on imported_fields: time=0.342 calls=20"
"Trigger for constraint attain_run_settings_start_date_field_fkey on imported_fields: time=0.377 calls=20"
"Trigger for constraint field_definitions_imported_field_fkey on imported_fields: time=0.411 calls=20"
"Trigger for constraint geosequencing_scenario_subtask_configu_subtask_group_field_fkey on imported_fields: time=3.296 calls=20"
"Trigger for constraint geosequencing_scenario_subtask_configur_subtask_type_field_fkey on imported_fields: time=0.371 calls=20"
"Trigger for constraint geosequencing_scenario_subtask_filter_operati_filter_field_fkey on imported_fields: time=2.967 calls=20"
"Trigger for constraint geosequencing_stability_settings_text_field_definition_fkey on imported_fields: time=0.468 calls=20"
"Trigger for constraint grade_distributions_confidence_field_fkey on imported_fields: time=2.396 calls=20"
"Trigger for constraint guidance_formula_set_entries_mine_area_field_fkey on imported_fields: time=0.400 calls=20"
"Trigger for constraint guidance_formula_set_entries_rank_field_fkey on imported_fields: time=0.328 calls=20"
"Trigger for constraint max_lag_settings_text_field_id_fkey on imported_fields: time=0.356 calls=20"
"Trigger for constraint production_field_values_imported_field_fkey on imported_fields: time=12.350 calls=20"
"Trigger for constraint rm_o_attain_config_datefield_fkey on imported_fields: time=0.539 calls=20"
"Trigger for constraint run_settings_pin_marker_field_fkey on imported_fields: time=0.415 calls=20"
"Trigger for constraint saved_grade_realization_sets_product_field_fkey on imported_fields: time=0.745 calls=20"
"Trigger for constraint saved_realization_sets_product_field_fkey on imported_fields: time=0.603 calls=20"
"Trigger for constraint text_field_values_imported_field_fkey on imported_fields: time=22.514 calls=20"
"Trigger for constraint ventilation_advanced_scenarios_text_field_id_fkey on imported_fields: time=0.461 calls=20"
"Trigger for constraint equipment_resource_fkey on resources: time=0.504 calls=27"
"Trigger for constraint plants_resource_fkey on resources: time=0.404 calls=27"
"Trigger for constraint resource_availability_resource_fkey on resources: time=3.674 calls=27"
"Trigger for constraint resource_travel_data_resource_fkey on resources: time=3.485 calls=27"
"Trigger for constraint task_resource_associations_resource_fkey on resources: time=0.394 calls=27"
"Trigger for constraint mine_scenario_products_price_profile_fkey on price_profiles: time=0.113 calls=1"
"Trigger for constraint gosp_scenario_variables_product_fkey on products: time=1.283 calls=1"
"Trigger for constraint guidance_formula_set_entries_driving_product_fkey on products: time=0.074 calls=1"
"Trigger for constraint horizon_scenario_variables_product_fkey on products: time=1.319 calls=1"
"Trigger for constraint mine_scenario_products_product_fkey on products: time=0.071 calls=1"
"Trigger for constraint plant_blending_product_fkey on products: time=1.267 calls=1"
"Trigger for constraint plant_recovery_factor_profiles_product_fkey on products: time=0.093 calls=1"
"Trigger for constraint attribute_capacity_definitions_capacity_definition_fkey on capacity_definitions: time=1.561 calls=29"
"Trigger for constraint capacity_condition_scenarios_capacity_definition_fkey on capacity_definitions: time=5.234 calls=29"
"Trigger for constraint capacity_entries_capacity_definition_fkey on capacity_definitions: time=4.683 calls=29"
"Trigger for constraint capacity_flexing_capacity_definition_fkey on capacity_definitions: time=2.011 calls=29"
"Trigger for constraint capacity_triggers_capacity_definition_fkey on capacity_definitions: time=0.487 calls=29"
"Trigger for constraint mine_scenario_capacity_definitions_capacity_definition_fkey on capacity_definitions: time=0.398 calls=29"
"Trigger for constraint activity_filter_operation_equipment_groups_equipment_fkey on equipment: time=0.339 calls=15"
"Trigger for constraint equipment_maintenance_schedules_equipment_fkey on equipment: time=3.512 calls=15"
"Trigger for constraint equipment_movement_costs_equipment_fkey on equipment: time=0.328 calls=15"
"Trigger for constraint mine_scenario_equipment_equipment_fkey on equipment: time=0.311 calls=15"
"Trigger for constraint ventilation_advanced_requirements_entries_equipment_id_fkey on equipment: time=0.764 calls=15"
"Trigger for constraint ventilation_requirement_configuration_entries_equipment_fkey on equipment: time=0.533 calls=15"
"Trigger for constraint mine_scenario_equipment_sustaining_capital_profile_fkey on sustaining_capital_profiles: time=0.082 calls=1"
"Trigger for constraint mine_scenario_plants_sustaining_capital_profile_fkey on sustaining_capital_profiles: time=0.091 calls=1"
"Trigger for constraint sustaining_capital_profile_entr_sustaining_capital_profile_fkey on sustaining_capital_profiles: time=2.879 calls=1"
"Trigger for constraint activity_filter_operations_associated_plant_fkey on plants: time=0.195 calls=1"
"Trigger for constraint blending_configurations_plant_fkey on plants: time=3.046 calls=1"
"Trigger for constraint mine_scenario_plants_plant_fkey on plants: time=0.097 calls=1"
"Trigger for constraint plant_blending_plant_fkey on plants: time=0.063 calls=1"
"Trigger for constraint plant_recovery_factor_profiles_plant_fkey on plants: time=0.064 calls=1"
"Trigger for constraint plant_stockpiles_plant_fkey on plants: time=2.354 calls=1"
"Trigger for constraint activity_filter_operation_property_costs_property_fkey on other_properties: time=0.103 calls=1"
"Trigger for constraint mine_scenario_other_properties_other_property_fkey on other_properties: time=0.095 calls=1"
"Trigger for constraint mine_scenario_plant_recovery_factor_pr_mine_scenario_plant_fkey on mine_scenario_plants: time=4.542 calls=2"
"Trigger for constraint activity_filter_operation_equipment_groups_set_fkey on activity_filter_operation_equipment_sets: time=0.611 calls=47"
"Trigger for constraint rm_o_resource_instance_usage_usage_id_fkey on rm_o_resource_usage: time=120582.094 calls=770"
"Trigger for constraint rm_o_resource_usage_instance_splits_usage_id_fkey on rm_o_resource_usage: time=766.449 calls=770"
"Trigger for constraint scheduledactivitysplits_scheduled_id_fkey on scheduledactivities: time=20247.656 calls=2466520"
"Trigger for constraint gosp_graph_requests_request_id_fkey on graph_requests: time=3.064 calls=8"
"Trigger for constraint graph_result_activities_graph_request_fkey on graph_requests: time=2685.696 calls=8"
"Trigger for constraint graph_results_graph_request_fkey on graph_requests: time=14.874 calls=8"
"Trigger for constraint schedule_reevaluation_report_requests_request_id_fkey on graph_requests: time=5.249 calls=8"
"Trigger graph_requests_remove_trigger on graph_requests: time=1.159 calls=8"
"Trigger for constraint mine_scenario_plant_recovery_facto_recovery_factor_profile_fkey on plant_recovery_factor_profiles: time=0.223 calls=2"
"Trigger for constraint equipment_capacity_entry_quantities_capacity_entry_fkey on capacity_entries: time=8.177 calls=34"
"Trigger for constraint capacity_condition_scenario_groups_condition_scenario_fkey on capacity_condition_scenarios: time=0.132 calls=1"
"Trigger for constraint mine_scenario_capacity_definitions_condition_scenario_fkey on capacity_condition_scenarios: time=0.076 calls=1"
"Trigger for constraint graph_result_values_results_id_fkey on graph_results: time=425.842 calls=544"
"Execution time: 197948.209 ms"
触发器太多了！
有些条目看起来您毕竟还没有索引所有外键。仅举几例：
Trigger for constraint rm_o_resource_instance_usage_usage_id_fkey on rm_o_resource_usage: time=10825.136 calls=76
Trigger for constraint graph_result_activities_graph_request_fkey on graph_requests: time=120.998 calls=10
Trigger for constraint rm_o_resource_usage_instance_splits_usage_id_fkey on rm_o_resource_usage: time=2659.464 calls=76
Trigger for constraint rm_o_resource_usage_instance_splits_solution_fkey on rm_o_schedule_stats: time=1698.600 calls=14
但是大部分时间花在了 tasks 上的这两个触发器上：
Trigger for constraint max_lag_setting_entries_from_task_fkey on tasks: time=88356.439 calls=99876
Trigger for constraint max_lag_setting_entries_to_task_fkey on tasks: time=91443.464 calls=99876
这些似乎也没有被编入索引。怎么会比 tasks 上的所有其他触发器花费的时间长得多？
我目前有一个包含 180 table 的数据库 (postgres 10.7)。每个 table 通过外键（使用 ON UPDATE CASCADE, ON DELETE CASCADE）直接或间接链接到主 table projects。从 project table 中删除条目时，这有时可能需要几分钟，有时甚至几个小时，具体取决于链接到该项目的数据量。
我想知道从 projects table 中删除的最好最快的方法是什么。
目前，我正在删除以下内容：
SET CONSTRAINTS ALL DEFERRED;
DELETE FROM projects WHERE id=project_id;
我试过使用和不使用 SET CONSTRAINTS 部分——它确实没有效果。对我们来说不幸的是，TRUNCATE CASCADE 不起作用，因为我们只想删除一个项目，有时是几个项目，但绝不会全部删除。我们也有外键索引来尝试帮助它。
EXPLAIN 命令的输出（完整项目）：
"Delete on projects (cost=0.00..1.01 rows=1 width=6) (actual time=0.777..0.777 rows=0 loops=1)"
" Buffers: shared hit=2 read=1 dirtied=1"
" -> Seq Scan on projects (cost=0.00..1.01 rows=1 width=6) (actual time=0.040..0.040 rows=1 loops=1)"
" Buffers: shared read=1"
"Planning time: 7.545 ms"
"Trigger for constraint activity_filter_scenarios_project_fkey on projects: time=8.286 calls=1"
"Trigger for constraint added_dependency_scenarios_project_fkey on projects: time=2.769 calls=1"
"Trigger for constraint cap_flexing_sets_project_fkey on projects: time=3.028 calls=1"
"Trigger for constraint dependency_layer_scenarios_project_id_fkey on projects: time=3.391 calls=1"
"Trigger for constraint distributions_project_fkey on projects: time=1.519 calls=1"
"Trigger for constraint execution_queue_projectid_fkey on projects: time=6.041 calls=1"
"Trigger for constraint exf_imports_project_fkey on projects: time=29.521 calls=1"
"Trigger for constraint field_definitions_project_fkey on projects: time=4.295 calls=1"
"Trigger for constraint financial_scenarios_project_fkey on projects: time=4.157 calls=1"
"Trigger for constraint geos_full_solutions_project_fkey on projects: time=2.131 calls=1"
"Trigger for constraint geos_stope_scenarios_project_fkey on projects: time=1.218 calls=1"
"Trigger for constraint geosequencing_scenarios_project_fkey on projects: time=2.556 calls=1"
"Trigger for constraint geosequencing_stability_settings_project_fkey on projects: time=1.191 calls=1"
"Trigger for constraint gosp_scenarios_project_fkey on projects: time=0.992 calls=1"
"Trigger for constraint graph_requests_template_project_fkey on projects: time=2.211 calls=1"
"Trigger for constraint guidance_formula_sets_project_fkey on projects: time=5.801 calls=1"
"Trigger for constraint horizon_scenarios_project_fkey on projects: time=2.336 calls=1"
"Trigger for constraint max_lag_settings_project_id_fkey on projects: time=4.591 calls=1"
"Trigger for constraint mine_scenarios_project_fkey on projects: time=4.309 calls=1"
"Trigger for constraint project_history_project_fkey on projects: time=4.586 calls=1"
"Trigger for constraint run_configurations_project_fkey on projects: time=3.074 calls=1"
"Trigger for constraint run_settings_project_fkey on projects: time=2.468 calls=1"
"Trigger for constraint schedule_reevaluation_requests_project_fkey on projects: time=0.442 calls=1"
"Trigger for constraint seeds_project_fkey on projects: time=20.746 calls=1"
"Trigger for constraint stockpiles_project_fkey on projects: time=0.416 calls=1"
"Trigger for constraint tasks_project_fkey on projects: time=197.922 calls=1"
"Trigger for constraint ventilation_advanced_requirements_project_fkey on projects: time=0.336 calls=1"
"Trigger for constraint ventilation_advanced_scenarios_project_fkey on projects: time=0.255 calls=1"
"Trigger for constraint ventilation_requirement_configurations_project_fkey on projects: time=0.284 calls=1"
"Trigger for constraint ventilation_scenarios_project_fkey on projects: time=1.945 calls=1"
"Trigger for constraint activity_filter_operations_activity_filter_scenario_fkey on activity_filter_scenarios: time=75.510 calls=3"
"Trigger for constraint cap_analysis_requests_activity_filter_scenario_fkey on activity_filter_scenarios: time=6.031 calls=3"
"Trigger for constraint mine_scenarios_activity_filter_scenario_fkey on activity_filter_scenarios: time=0.200 calls=3"
"Trigger for constraint execution_queue_run_seed_fkey on execution_queue: time=0.818 calls=13"
"Trigger for constraint residual_requests_execution_id_fkey on execution_queue: time=2.147 calls=13"
"Trigger for constraint rm_o_attain_config_runid_fkey on execution_queue: time=1.494 calls=13"
"Trigger for constraint rm_o_attain_target_dates_runid_fkey on execution_queue: time=4.166 calls=13"
"Trigger for constraint rm_o_complete_runid_fkey on execution_queue: time=4.813 calls=13"
"Trigger for constraint rm_o_config_runid_fkey on execution_queue: time=12738.872 calls=13"
"Trigger for constraint rm_o_dependencymap_runid_fkey on execution_queue: time=980.347 calls=13"
"Trigger for constraint rm_o_generation_stats_runid_fkey on execution_queue: time=11.286 calls=13"
"Trigger for constraint rm_o_horizon_realization_scenarios_run_id_fkey on execution_queue: time=3.534 calls=13"
"Trigger for constraint rm_o_reset_stats_runid_fkey on execution_queue: time=6.277 calls=13"
"Trigger for constraint rm_o_run_config_runid_fkey on execution_queue: time=2.846 calls=13"
"Trigger for constraint rm_o_run_stats_runid_fkey on execution_queue: time=3.249 calls=13"
"Trigger for constraint rm_o_schedule_stats_runid_fkey on execution_queue: time=1.299 calls=13"
"Trigger for constraint rm_o_top_resets_runid_fkey on execution_queue: time=2.010 calls=13"
"Trigger for constraint rm_o_top_schedules_runid_fkey on execution_queue: time=4.507 calls=13"
"Trigger execution_queue_delete_trigger on execution_queue: time=26.856 calls=13"
"Trigger for constraint dependencies_exf_import_fkey on exf_imports: time=320.650 calls=1"
"Trigger for constraint imported_fields_exf_import_fkey on exf_imports: time=6.302 calls=1"
"Trigger for constraint production_rate_tables_exf_import_fkey on exf_imports: time=2.985 calls=1"
"Trigger for constraint resources_exf_import_fkey on exf_imports: time=8.282 calls=1"
"Trigger for constraint tasks_exf_import_fkey on exf_imports: time=7.571 calls=1"
"Trigger for constraint activity_filter_operations_length_field_fkey on field_definitions: time=0.607 calls=26"
"Trigger for constraint activity_filter_operations_weight_field_fkey on field_definitions: time=0.532 calls=26"
"Trigger for constraint attribute_capacity_scenarios_attribute_field_fkey on field_definitions: time=4.029 calls=26"
"Trigger for constraint blending_constraints_first_element_fkey on field_definitions: time=3.867 calls=26"
"Trigger for constraint blending_constraints_second_element_fkey on field_definitions: time=0.505 calls=26"
"Trigger for constraint cap_analysis_request_field_definitions_field_def_fkey on field_definitions: time=2.177 calls=26"
"Trigger for constraint capacity_condition_scenario_groups_text_field_definition_fkey on field_definitions: time=3.894 calls=26"
"Trigger for constraint capacity_definitions_field_definition_fkey on field_definitions: time=9.777 calls=26"
"Trigger for constraint contaminants_contaminant_field_fkey on field_definitions: time=4.365 calls=26"
"Trigger for constraint equipment_equipment_field_fkey on field_definitions: time=8.113 calls=26"
"Trigger for constraint equipment_movement_costs_movement_field_fkey on field_definitions: time=2.051 calls=26"
"Trigger for constraint financial_scenarios_precalculated_revenue_fkey on field_definitions: time=0.611 calls=26"
"Trigger for constraint other_properties_property_field_fkey on field_definitions: time=10.417 calls=26"
"Trigger for constraint plants_plant_field_fkey on field_definitions: time=11.845 calls=26"
"Trigger for constraint point_capital_profiles_field_definition_fkey on field_definitions: time=4.204 calls=26"
"Trigger for constraint price_profiles_field_definition_fkey on field_definitions: time=7.214 calls=26"
"Trigger for constraint products_grade_field_fkey on field_definitions: time=59.582 calls=26"
"Trigger for constraint sustaining_capital_profiles_field_definition_fkey on field_definitions: time=2.062 calls=26"
"Trigger for constraint financial_scenario_expenditure_triggers_financial_scenario_fkey on financial_scenarios: time=2.437 calls=1"
"Trigger for constraint mine_scenarios_financial_scenario_fkey on financial_scenarios: time=0.138 calls=1"
"Trigger for constraint guidance_formula_set_entries_guidance_formula_set_fkey on guidance_formula_sets: time=9.255 calls=6"
"Trigger for constraint run_configurations_guidance_formula_set_fkey on guidance_formula_sets: time=0.365 calls=6"
"Trigger for constraint cap_analysis_requests_max_lag_fkey on max_lag_settings: time=0.132 calls=1"
"Trigger for constraint max_lag_setting_entries_setting_id_fkey on max_lag_settings: time=21.339 calls=1"
"Trigger for constraint run_settings_max_lag_settings_fkey on max_lag_settings: time=0.391 calls=1"
"Trigger for constraint mine_scenario_attribute_capacities_mine_scenario_fkey on mine_scenarios: time=3.052 calls=2"
"Trigger for constraint mine_scenario_capacity_definitions_mine_scenario_fkey on mine_scenarios: time=12.044 calls=2"
"Trigger for constraint mine_scenario_contaminants_mine_scenario_fkey on mine_scenarios: time=4.243 calls=2"
"Trigger for constraint mine_scenario_equipment_mine_scenario_fkey on mine_scenarios: time=9.233 calls=2"
"Trigger for constraint mine_scenario_other_properties_mine_scenario_fkey on mine_scenarios: time=5.192 calls=2"
"Trigger for constraint mine_scenario_plants_mine_scenario_fkey on mine_scenarios: time=39.163 calls=2"
"Trigger for constraint mine_scenario_products_mine_scenario_fkey on mine_scenarios: time=11.046 calls=2"
"Trigger for constraint run_configurations_mine_scenario_fkey on mine_scenarios: time=0.309 calls=2"
"Trigger for constraint geosequencing_scenario_run_configuration_run_configuration_fkey on run_configurations: time=0.873 calls=11"
"Trigger for constraint gosp_run_configurations_run_configuration_fkey on run_configurations: time=0.705 calls=11"
"Trigger for constraint horizon_run_configurations_run_configuration_fkey on run_configurations: time=0.715 calls=11"
"Trigger for constraint ventilation_run_configurations_run_configuration_fkey on run_configurations: time=0.942 calls=11"
"Trigger for constraint attain_run_settings_run_settings_fkey on run_settings: time=15.667 calls=9"
"Trigger for constraint run_configurations_run_settings_fkey on run_settings: time=0.674 calls=9"
"Trigger for constraint run_configurations_seed_fkey on seeds: time=0.275 calls=2"
"Trigger for constraint capacity_triggers_task_fkey on tasks: time=258.381 calls=35236"
"Trigger for constraint dependencies_from_task_fkey on tasks: time=212.529 calls=35236"
"Trigger for constraint dependencies_to_task_fkey on tasks: time=197.221 calls=35236"
"Trigger for constraint financial_scenario_expenditure_triggers_task_fkey on tasks: time=257.965 calls=35236"
"Trigger for constraint geosequencing_dependencies_from_task_fkey on tasks: time=260.043 calls=35236"
"Trigger for constraint geosequencing_dependencies_to_task_fkey on tasks: time=244.659 calls=35236"
"Trigger for constraint geosequencing_scenario_subtask_dependencies_from_task_fkey on tasks: time=254.873 calls=35236"
"Trigger for constraint geosequencing_scenario_subtask_dependencies_to_task_fkey on tasks: time=246.340 calls=35236"
"Trigger for constraint max_lag_setting_entries_from_task_fkey on tasks: time=188.897 calls=35236"
"Trigger for constraint max_lag_setting_entries_to_task_fkey on tasks: time=173.290 calls=35236"
"Trigger for constraint plant_recovery_factor_profiles_task_fkey on tasks: time=292.398 calls=35236"
"Trigger for constraint production_field_values_task_fkey on tasks: time=390.591 calls=35236"
"Trigger for constraint task_distributions_task_fkey on tasks: time=358.768 calls=35236"
"Trigger for constraint task_resource_associations_task_fkey on tasks: time=174.215 calls=35236"
"Trigger for constraint text_field_values_task_fkey on tasks: time=471.291 calls=35236"
"Trigger for constraint ventilation_advanced_scenario_activities_activity_fkey on tasks: time=327.614 calls=35236"
"Trigger for constraint ventilation_regulators_task_fkey on tasks: time=257.876 calls=35236"
"Trigger for constraint ventilation_scenario_districts_task_fkey on tasks: time=252.948 calls=35236"
"Trigger for constraint activity_filter_operation_equip_activity_filter_operation_fkey1 on activity_filter_operations: time=5.147 calls=52"
"Trigger for constraint activity_filter_operation_equipm_activity_filter_operation_fkey on activity_filter_operations: time=4.241 calls=52"
"Trigger for constraint activity_filter_operation_field_lookups_filter_operation_fkey on activity_filter_operations: time=4.153 calls=52"
"Trigger for constraint activity_filter_operation_proper_activity_filter_operation_fkey on activity_filter_operations: time=7.740 calls=52"
"Trigger for constraint attain_activity_filter_operations_filter_operation_fkey on activity_filter_operations: time=14.577 calls=52"
"Trigger for constraint rm_o_gosp_realization_scenarios_reset_id_fkey on rm_o_reset_stats: time=2.566 calls=19"
"Trigger for constraint rm_o_top_resets_reset_id_fkey on rm_o_reset_stats: time=0.475 calls=19"
"Trigger rm_o_reset_stats_trigger on rm_o_reset_stats: time=1.611 calls=19"
"Trigger rm_o_run_stats_trigger on rm_o_run_stats: time=1.936 calls=13"
"Trigger for constraint graph_requests_solution_fkey on rm_o_schedule_stats: time=7.944 calls=70"
"Trigger for constraint horizon_scenario_schedules_schedule_fkey on rm_o_schedule_stats: time=2.137 calls=70"
"Trigger for constraint residual_request_results_schedule_id_fkey on rm_o_schedule_stats: time=2.776 calls=70"
"Trigger for constraint rm_o_airway_airflowdpm_solution_id_fkey on rm_o_schedule_stats: time=3.301 calls=70"
"Trigger for constraint rm_o_gosp_schedule_stats_stats_id_fkey on rm_o_schedule_stats: time=2.227 calls=70"
"Trigger for constraint rm_o_regulator_settings_solution_id_fkey on rm_o_schedule_stats: time=2.724 calls=70"
"Trigger for constraint rm_o_resource_usage_instance_splits_solution_fkey on rm_o_schedule_stats: time=15620.727 calls=70"
"Trigger for constraint rm_o_resource_usage_schedule_id_fkey on rm_o_schedule_stats: time=67.761 calls=70"
"Trigger for constraint rm_o_top_schedules_schedule_id_fkey on rm_o_schedule_stats: time=1.412 calls=70"
"Trigger for constraint schedule_geo_stability_evaluations_schedule_id_fkey on rm_o_schedule_stats: time=1.232 calls=70"
"Trigger for constraint schedule_reevaluation_request_schedules_solution_fkey on rm_o_schedule_stats: time=1.189 calls=70"
"Trigger for constraint schedule_reevaluation_result_scores_solution_fkey on rm_o_schedule_stats: time=1.165 calls=70"
"Trigger for constraint scheduledactivities_solution_id_fkey on rm_o_schedule_stats: time=17489.740 calls=70"
"Trigger for constraint activity_filter_operation_field_lookups_field_fkey on imported_fields: time=0.549 calls=20"
"Trigger for constraint added_dependencies_criterion_fkey on imported_fields: time=3.868 calls=20"
"Trigger for constraint added_dependencies_domain_fkey on imported_fields: time=0.342 calls=20"
"Trigger for constraint attain_run_settings_start_date_field_fkey on imported_fields: time=0.377 calls=20"
"Trigger for constraint field_definitions_imported_field_fkey on imported_fields: time=0.411 calls=20"
"Trigger for constraint geosequencing_scenario_subtask_configu_subtask_group_field_fkey on imported_fields: time=3.296 calls=20"
"Trigger for constraint geosequencing_scenario_subtask_configur_subtask_type_field_fkey on imported_fields: time=0.371 calls=20"
"Trigger for constraint geosequencing_scenario_subtask_filter_operati_filter_field_fkey on imported_fields: time=2.967 calls=20"
"Trigger for constraint geosequencing_stability_settings_text_field_definition_fkey on imported_fields: time=0.468 calls=20"
"Trigger for constraint grade_distributions_confidence_field_fkey on imported_fields: time=2.396 calls=20"
"Trigger for constraint guidance_formula_set_entries_mine_area_field_fkey on imported_fields: time=0.400 calls=20"
"Trigger for constraint guidance_formula_set_entries_rank_field_fkey on imported_fields: time=0.328 calls=20"
"Trigger for constraint max_lag_settings_text_field_id_fkey on imported_fields: time=0.356 calls=20"
"Trigger for constraint production_field_values_imported_field_fkey on imported_fields: time=12.350 calls=20"
"Trigger for constraint rm_o_attain_config_datefield_fkey on imported_fields: time=0.539 calls=20"
"Trigger for constraint run_settings_pin_marker_field_fkey on imported_fields: time=0.415 calls=20"
"Trigger for constraint saved_grade_realization_sets_product_field_fkey on imported_fields: time=0.745 calls=20"
"Trigger for constraint saved_realization_sets_product_field_fkey on imported_fields: time=0.603 calls=20"
"Trigger for constraint text_field_values_imported_field_fkey on imported_fields: time=22.514 calls=20"
"Trigger for constraint ventilation_advanced_scenarios_text_field_id_fkey on imported_fields: time=0.461 calls=20"
"Trigger for constraint equipment_resource_fkey on resources: time=0.504 calls=27"
"Trigger for constraint plants_resource_fkey on resources: time=0.404 calls=27"
"Trigger for constraint resource_availability_resource_fkey on resources: time=3.674 calls=27"
"Trigger for constraint resource_travel_data_resource_fkey on resources: time=3.485 calls=27"
"Trigger for constraint task_resource_associations_resource_fkey on resources: time=0.394 calls=27"
"Trigger for constraint mine_scenario_products_price_profile_fkey on price_profiles: time=0.113 calls=1"
"Trigger for constraint gosp_scenario_variables_product_fkey on products: time=1.283 calls=1"
"Trigger for constraint guidance_formula_set_entries_driving_product_fkey on products: time=0.074 calls=1"
"Trigger for constraint horizon_scenario_variables_product_fkey on products: time=1.319 calls=1"
"Trigger for constraint mine_scenario_products_product_fkey on products: time=0.071 calls=1"
"Trigger for constraint plant_blending_product_fkey on products: time=1.267 calls=1"
"Trigger for constraint plant_recovery_factor_profiles_product_fkey on products: time=0.093 calls=1"
"Trigger for constraint attribute_capacity_definitions_capacity_definition_fkey on capacity_definitions: time=1.561 calls=29"
"Trigger for constraint capacity_condition_scenarios_capacity_definition_fkey on capacity_definitions: time=5.234 calls=29"
"Trigger for constraint capacity_entries_capacity_definition_fkey on capacity_definitions: time=4.683 calls=29"
"Trigger for constraint capacity_flexing_capacity_definition_fkey on capacity_definitions: time=2.011 calls=29"
"Trigger for constraint capacity_triggers_capacity_definition_fkey on capacity_definitions: time=0.487 calls=29"
"Trigger for constraint mine_scenario_capacity_definitions_capacity_definition_fkey on capacity_definitions: time=0.398 calls=29"
"Trigger for constraint activity_filter_operation_equipment_groups_equipment_fkey on equipment: time=0.339 calls=15"
"Trigger for constraint equipment_maintenance_schedules_equipment_fkey on equipment: time=3.512 calls=15"
"Trigger for constraint equipment_movement_costs_equipment_fkey on equipment: time=0.328 calls=15"
"Trigger for constraint mine_scenario_equipment_equipment_fkey on equipment: time=0.311 calls=15"
"Trigger for constraint ventilation_advanced_requirements_entries_equipment_id_fkey on equipment: time=0.764 calls=15"
"Trigger for constraint ventilation_requirement_configuration_entries_equipment_fkey on equipment: time=0.533 calls=15"
"Trigger for constraint mine_scenario_equipment_sustaining_capital_profile_fkey on sustaining_capital_profiles: time=0.082 calls=1"
"Trigger for constraint mine_scenario_plants_sustaining_capital_profile_fkey on sustaining_capital_profiles: time=0.091 calls=1"
"Trigger for constraint sustaining_capital_profile_entr_sustaining_capital_profile_fkey on sustaining_capital_profiles: time=2.879 calls=1"
"Trigger for constraint activity_filter_operations_associated_plant_fkey on plants: time=0.195 calls=1"
"Trigger for constraint blending_configurations_plant_fkey on plants: time=3.046 calls=1"
"Trigger for constraint mine_scenario_plants_plant_fkey on plants: time=0.097 calls=1"
"Trigger for constraint plant_blending_plant_fkey on plants: time=0.063 calls=1"
"Trigger for constraint plant_recovery_factor_profiles_plant_fkey on plants: time=0.064 calls=1"
"Trigger for constraint plant_stockpiles_plant_fkey on plants: time=2.354 calls=1"
"Trigger for constraint activity_filter_operation_property_costs_property_fkey on other_properties: time=0.103 calls=1"
"Trigger for constraint mine_scenario_other_properties_other_property_fkey on other_properties: time=0.095 calls=1"
"Trigger for constraint mine_scenario_plant_recovery_factor_pr_mine_scenario_plant_fkey on mine_scenario_plants: time=4.542 calls=2"
"Trigger for constraint activity_filter_operation_equipment_groups_set_fkey on activity_filter_operation_equipment_sets: time=0.611 calls=47"
"Trigger for constraint rm_o_resource_instance_usage_usage_id_fkey on rm_o_resource_usage: time=120582.094 calls=770"
"Trigger for constraint rm_o_resource_usage_instance_splits_usage_id_fkey on rm_o_resource_usage: time=766.449 calls=770"
"Trigger for constraint scheduledactivitysplits_scheduled_id_fkey on scheduledactivities: time=20247.656 calls=2466520"
"Trigger for constraint gosp_graph_requests_request_id_fkey on graph_requests: time=3.064 calls=8"
"Trigger for constraint graph_result_activities_graph_request_fkey on graph_requests: time=2685.696 calls=8"
"Trigger for constraint graph_results_graph_request_fkey on graph_requests: time=14.874 calls=8"
"Trigger for constraint schedule_reevaluation_report_requests_request_id_fkey on graph_requests: time=5.249 calls=8"
"Trigger graph_requests_remove_trigger on graph_requests: time=1.159 calls=8"
"Trigger for constraint mine_scenario_plant_recovery_facto_recovery_factor_profile_fkey on plant_recovery_factor_profiles: time=0.223 calls=2"
"Trigger for constraint equipment_capacity_entry_quantities_capacity_entry_fkey on capacity_entries: time=8.177 calls=34"
"Trigger for constraint capacity_condition_scenario_groups_condition_scenario_fkey on capacity_condition_scenarios: time=0.132 calls=1"
"Trigger for constraint mine_scenario_capacity_definitions_condition_scenario_fkey on capacity_condition_scenarios: time=0.076 calls=1"
"Trigger for constraint graph_result_values_results_id_fkey on graph_results: time=425.842 calls=544"
"Execution time: 197948.209 ms"
触发器太多了！
有些条目看起来您毕竟还没有索引所有外键。仅举几例：
Trigger for constraint rm_o_resource_instance_usage_usage_id_fkey on rm_o_resource_usage: time=10825.136 calls=76
Trigger for constraint graph_result_activities_graph_request_fkey on graph_requests: time=120.998 calls=10
Trigger for constraint rm_o_resource_usage_instance_splits_usage_id_fkey on rm_o_resource_usage: time=2659.464 calls=76
Trigger for constraint rm_o_resource_usage_instance_splits_solution_fkey on rm_o_schedule_stats: time=1698.600 calls=14
但是大部分时间花在了 tasks 上的这两个触发器上：
Trigger for constraint max_lag_setting_entries_from_task_fkey on tasks: time=88356.439 calls=99876
Trigger for constraint max_lag_setting_entries_to_task_fkey on tasks: time=91443.464 calls=99876
这些似乎也没有被编入索引。怎么会比 tasks 上的所有其他触发器花费的时间长得多？