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@kmorozov
Created October 15, 2021 19:28
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MySql optimizer trace. With prepared statement
{
"steps": [
{
"statement_parameters": [
"LONGLONG",
"LONGLONG"
]
},
{
"join_optimization": {
"select#": 1,
"steps": [
{
"condition_processing": {
"condition": "WHERE",
"original_condition": "((`samples`.`device_id` = 5852) and (`samples`.`device_id` is not null) and (`samples`.`id` <> 188315308))",
"steps": [
{
"transformation": "equality_propagation",
"resulting_condition": "((5852 is not null) and (`samples`.`id` <> 188315308) and multiple equal(5852, `samples`.`device_id`))"
},
{
"transformation": "constant_propagation",
"resulting_condition": "((5852 is not null) and (`samples`.`id` <> 188315308) and multiple equal(5852, `samples`.`device_id`))"
},
{
"transformation": "trivial_condition_removal",
"resulting_condition": "((`samples`.`id` <> 188315308) and multiple equal(5852, `samples`.`device_id`))"
}
]
}
},
{
"substitute_generated_columns": {
}
},
{
"table_dependencies": [
{
"table": "`samples`",
"row_may_be_null": false,
"map_bit": 0,
"depends_on_map_bits": [
]
}
]
},
{
"ref_optimizer_key_uses": [
{
"table": "`samples`",
"field": "device_id",
"equals": "5852",
"null_rejecting": true
}
]
},
{
"rows_estimation": [
{
"table": "`samples`",
"range_analysis": {
"table_scan": {
"rows": 179018862,
"cost": 1.85e7
},
"potential_range_indexes": [
{
"index": "PRIMARY",
"usable": true,
"key_parts": [
"id"
]
},
{
"index": "samples_organization_id_foreign",
"usable": false,
"cause": "not_applicable"
},
{
"index": "samples_basestation_id_created_at_index",
"usable": false,
"cause": "not_applicable"
},
{
"index": "samples_reverse_device_id_created_at_organization_id_index",
"usable": true,
"key_parts": [
"device_id",
"created_at",
"organization_id",
"id"
]
}
],
"setup_range_conditions": [
],
"group_index_range": {
"chosen": false,
"cause": "not_group_by_or_distinct"
},
"skip_scan_range": {
"potential_skip_scan_indexes": [
{
"index": "PRIMARY",
"usable": false,
"cause": "query_references_nonkey_column"
},
{
"index": "samples_reverse_device_id_created_at_organization_id_index",
"usable": false,
"cause": "query_references_nonkey_column"
}
]
},
"analyzing_range_alternatives": {
"range_scan_alternatives": [
{
"index": "PRIMARY",
"ranges": [
"id < 188315308",
"188315308 < id"
],
"index_dives_for_eq_ranges": true,
"rowid_ordered": true,
"using_mrr": false,
"index_only": false,
"rows": 89509436,
"cost": 9.12e6,
"chosen": true
},
{
"index": "samples_reverse_device_id_created_at_organization_id_index",
"ranges": [
"5852 <= device_id <= 5852"
],
"index_dives_for_eq_ranges": true,
"rowid_ordered": false,
"using_mrr": false,
"index_only": false,
"rows": 647136,
"cost": 550775,
"chosen": true
}
],
"analyzing_roworder_intersect": {
"usable": false,
"cause": "too_few_roworder_scans"
}
},
"chosen_range_access_summary": {
"range_access_plan": {
"type": "range_scan",
"index": "samples_reverse_device_id_created_at_organization_id_index",
"rows": 647136,
"ranges": [
"5852 <= device_id <= 5852"
]
},
"rows_for_plan": 647136,
"cost_for_plan": 550775,
"chosen": true
}
}
}
]
},
{
"considered_execution_plans": [
{
"plan_prefix": [
],
"table": "`samples`",
"best_access_path": {
"considered_access_paths": [
{
"access_type": "ref",
"index": "samples_reverse_device_id_created_at_organization_id_index",
"rows": 647136,
"cost": 550774,
"chosen": true
},
{
"access_type": "range",
"range_details": {
"used_index": "samples_reverse_device_id_created_at_organization_id_index"
},
"chosen": false,
"cause": "heuristic_index_cheaper"
}
]
},
"condition_filtering_pct": 50,
"rows_for_plan": 323568,
"cost_for_plan": 550774,
"chosen": true
}
]
},
{
"attaching_conditions_to_tables": {
"original_condition": "((`samples`.`device_id` = 5852) and (`samples`.`id` <> 188315308))",
"attached_conditions_computation": [
],
"attached_conditions_summary": [
{
"table": "`samples`",
"attached": "((`samples`.`device_id` = 5852) and (`samples`.`id` <> 188315308))"
}
]
}
},
{
"optimizing_distinct_group_by_order_by": {
"simplifying_order_by": {
"original_clause": "`samples`.`created_at` desc",
"items": [
{
"item": "`samples`.`created_at`"
}
],
"resulting_clause_is_simple": true,
"resulting_clause": "`samples`.`created_at` desc"
}
}
},
{
"reconsidering_access_paths_for_index_ordering": {
"clause": "ORDER BY",
"steps": [
],
"index_order_summary": {
"table": "`samples`",
"index_provides_order": false,
"order_direction": "undefined",
"index": "samples_reverse_device_id_created_at_organization_id_index",
"plan_changed": false
}
}
},
{
"finalizing_table_conditions": [
{
"table": "`samples`",
"original_table_condition": "((`samples`.`device_id` = 5852) and (`samples`.`id` <> 188315308))",
"final_table_condition ": "(`samples`.`id` <> <cache>(188315308))"
}
]
},
{
"refine_plan": [
{
"table": "`samples`",
"pushed_index_condition": "(`samples`.`id` <> <cache>(188315308))",
"table_condition_attached": null
}
]
},
{
"considering_tmp_tables": [
{
"adding_sort_to_table": "samples"
}
]
}
]
}
},
{
"join_execution": {
"select#": 1,
"steps": [
{
"sorting_table": "samples",
"filesort_information": [
{
"direction": "desc",
"expression": "`samples`.`created_at`"
}
],
"filesort_priority_queue_optimization": {
"limit": 1,
"chosen": true
},
"filesort_execution": [
],
"filesort_summary": {
"memory_available": 262144,
"key_size": 9,
"row_size": 75,
"max_rows_per_buffer": 2,
"num_rows_estimate": 18446744073709551615,
"num_rows_found": 331495,
"num_initial_chunks_spilled_to_disk": 0,
"peak_memory_used": 166,
"sort_algorithm": "std::sort",
"unpacked_addon_fields": "using_priority_queue",
"sort_mode": "<fixed_sort_key, additional_fields>"
}
}
]
}
}
]
}
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