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| {
"steps": [
{
"join_preparation": {
"select#": 1,
"steps": [
{
"expanded_query": "/* select#1 */ select `students`.`id` AS `id`,`students`.`name` AS `name`,`students`.`age` AS `age`,`students`.`class` AS `class`,`students`.`created_at` AS `created_at`,`students`.`updated_at` AS `updated_at` from `students` where (`students`.`class` = 10)"
}
]
}
},
{
"join_optimization": {
"select#": 1,
"steps": [
{
"condition_processing": {
"condition": "WHERE",
"original_condition": "(`students`.`class` = 10)",
"steps": [
{
"transformation": "equality_propagation",
"resulting_condition": "multiple equal(10, `students`.`class`)"
},
{
"transformation": "constant_propagation",
"resulting_condition": "multiple equal(10, `students`.`class`)"
},
{
"transformation": "trivial_condition_removal",
"resulting_condition": "multiple equal(10, `students`.`class`)"
}
]
}
},
{
"substitute_generated_columns": {
}
},
{
"table_dependencies": [
{
"table": "`students`",
"row_may_be_null": false,
"map_bit": 0,
"depends_on_map_bits": [
]
}
]
},
{
"ref_optimizer_key_uses": [
{
"table": "`students`",
"field": "class",
"equals": "10",
"null_rejecting": false
}
]
},
{
"rows_estimation": [
{
"table": "`students`",
"range_analysis": {
"table_scan": {
"rows": 107,
"cost": 24.5
} ,
"potential_range_indexes": [
{
"index": "PRIMARY",
"usable": false,
"cause": "not_applicable"
},
{
"index": "idx_class",
"usable": true,
"key_parts": [
"class",
"id"
]
}
] ,
"setup_range_conditions": [
] ,
"group_index_range": {
"chosen": false,
"cause": "not_group_by_or_distinct"
} ,
"analyzing_range_alternatives": {
"range_scan_alternatives": [
{
"index": "idx_class",
"ranges": [
"10 <= class <= 10"
] ,
"index_dives_for_eq_ranges": true,
"rowid_ordered": true,
"using_mrr": false,
"index_only": false,
"rows": 5,
"cost": 7.01,
"chosen": true
}
] ,
"analyzing_roworder_intersect": {
"usable": false,
"cause": "too_few_roworder_scans"
}
} ,
"chosen_range_access_summary": {
"range_access_plan": {
"type": "range_scan",
"index": "idx_class",
"rows": 5,
"ranges": [
"10 <= class <= 10"
]
} ,
"rows_for_plan": 5,
"cost_for_plan": 7.01,
"chosen": true
}
}
}
]
},
{
"considered_execution_plans": [
{
"plan_prefix": [
] ,
"table": "`students`",
"best_access_path": {
"considered_access_paths": [
{
"access_type": "ref",
"index": "idx_class",
"rows": 5,
"cost": 4,
"chosen": true
},
{
"access_type": "range",
"range_details": {
"used_index": "idx_class"
} ,
"chosen": false,
"cause": "heuristic_index_cheaper"
}
]
} ,
"condition_filtering_pct": 100,
"rows_for_plan": 5,
"cost_for_plan": 4,
"chosen": true
}
]
},
{
"attaching_conditions_to_tables": {
"original_condition": "(`students`.`class` = 10)",
"attached_conditions_computation": [
] ,
"attached_conditions_summary": [
{
"table": "`students`",
"attached": null
}
]
}
},
{
"refine_plan": [
{
"table": "`students`"
}
]
}
]
}
},
{
"join_execution": {
"select#": 1,
"steps": [
]
}
}
]
}
|
