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| {
"steps": [
{
"join_preparation": {
"select#": 1,
"steps": [
{
"expanded_query": "/* select#1 */ select `people`.`name` AS `name`,count(0) AS `cnt`,group_concat(distinct `people`.`card` separator ',') AS `gd_card` from `people` where ((`people`.`age` > 10) and (`people`.`age` > -(1)) and (1 = 1) and (`people`.`age` < 99)) group by `people`.`name` having (`cnt` > 1) order by `cnt` desc limit 20000"
}
]
}
},
{
"join_optimization": {
"select#": 1,
"steps": [
{
// 处理搜索条件
"condition_processing": {
"condition": "WHERE",
// 原始搜索条件
"original_condition": "((`people`.`age` > 10) and (`people`.`age` > -(1)) and (1 = 1) and (`people`.`age` < 99))",
"steps": [
{
// 等值传递转换
"transformation": "equality_propagation",
"resulting_condition": "((`people`.`age` > 10) and (`people`.`age` > -(1)) and (1 = 1) and (`people`.`age` < 99))"
},
{
// 常量传递转换
"transformation": "constant_propagation",
"resulting_condition": "((`people`.`age` > 10) and (`people`.`age` > -(1)) and (1 = 1) and (`people`.`age` < 99))"
},
{
// 去除没用的条件
"transformation": "trivial_condition_removal",
"resulting_condition": "((`people`.`age` > 10) and (`people`.`age` > -(1)) and (`people`.`age` < 99))"
}
]
}
},
{
"condition_processing": {
"condition": "HAVING",
"original_condition": "(`cnt` > 1)",
"steps": [
{
"transformation": "constant_propagation",
"resulting_condition": "(`cnt` > 1)"
},
{
"transformation": "trivial_condition_removal",
"resulting_condition": "(`cnt` > 1)"
}
]
}
},
{
// 替换虚拟生成列
"substitute_generated_columns": {}
},
{
// 表的依赖信息
"table_dependencies": [
{
"table": "`people`",
"row_may_be_null": false,
"map_bit": 0,
"depends_on_map_bits": []
}
]
},
{
"ref_optimizer_key_uses": []
},
{
// 预估不同单表访问方法的访问成本
"rows_estimation": [
{
"table": "`people`",
"const_keys_added": {
"keys": [
"name_age_key"
],
"cause": "group_by"
},
"range_analysis": {
// 全表扫描的行数及成本
"table_scan": {
"rows": 109674,
"cost": 22482
},
// 分析可能使用的索引
"potential_range_indexes": [
{
"index": "PRIMARY",
"usable": false,
"cause": "not_applicable"
},
{
"index": "card_UNIQUE",
"usable": false,
"cause": "not_applicable"
},
{
"index": "name_age_key",
"usable": true,
"key_parts": [
"name",
"age",
"id"
]
}
],
"setup_range_conditions": [],
"group_index_range": {
"chosen": false,
"cause": "not_applicable_aggregate_function"
},
// 分析各种可能使用的索引的成本
"analyzing_range_alternatives": {
"range_scan_alternatives": [
{
"index": "name_age_key",
"chosen": false,
"cause": "unknown"
}
],
"analyzing_roworder_intersect": {
"usable": false,
"cause": "too_few_roworder_scans"
}
}
}
}
]
},
{
"considered_execution_plans": [
{
"plan_prefix": [],
"table": "`people`",
"best_access_path": {
"considered_access_paths": [
{
"rows_to_scan": 109674,
"access_type": "scan",
"resulting_rows": 4060.8,
"cost": 22480,
"chosen": true
}
]
},
"condition_filtering_pct": 100,
"rows_for_plan": 4060.8,
"cost_for_plan": 22480,
"chosen": true
}
]
},
{
// 尝试给查询添加一些其他的查询条件
"attaching_conditions_to_tables": {
"original_condition": "((`people`.`age` > 10) and (`people`.`age` > -(1)) and (`people`.`age` < 99))",
"attached_conditions_computation": [],
"attached_conditions_summary": [
{
"table": "`people`",
"attached": "((`people`.`age` > 10) and (`people`.`age` > -(1)) and (`people`.`age` < 99))"
}
]
}
},
{
"clause_processing": {
"clause": "ORDER BY",
"original_clause": "`cnt` desc",
"items": [
{
"item": "count(0)"
}
],
"resulting_clause_is_simple": false,
"resulting_clause": "`cnt` desc"
}
},
{
"clause_processing": {
"clause": "GROUP BY",
"original_clause": "`people`.`name`",
"items": [
{
"item": "`people`.`name`"
}
],
"resulting_clause_is_simple": true,
"resulting_clause": "`people`.`name`"
}
},
{
"reconsidering_access_paths_for_index_ordering": {
"clause": "GROUP BY",
"steps": [],
"index_order_summary": {
"table": "`people`",
"index_provides_order": true,
"order_direction": "asc",
"index": "name_age_key",
"plan_changed": true,
"access_type": "index"
}
}
},
{
"refine_plan": [
{
"table": "`people`"
}
]
},
{
"creating_tmp_table": {
"tmp_table_info": {
"table": "intermediate_tmp_table",
"row_length": 130,
"key_length": 0,
"unique_constraint": false,
"location": "memory (heap)",
"row_limit_estimate": 129055
}
}
},
{
"sort_using_internal_table": {
"condition_for_sort": "(`cnt` > 1)",
"having_after_sort": null
}
}
]
}
},
{
"join_execution": {
"select#": 1,
"steps": [
{
"creating_tmp_table": {
"tmp_table_info": {
"table": "intermediate_tmp_table",
"row_length": 84,
"key_length": 0,
"unique_constraint": false,
"location": "disk (InnoDB)",
"record_format": "packed"
}
}
},
{
"filesort_information": [
{
"direction": "desc",
"table": "intermediate_tmp_table",
"field": "cnt"
}
],
"filesort_priority_queue_optimization": {
"usable": false,
"cause": "not applicable (no LIMIT)"
},
"filesort_execution": [],
"filesort_summary": {
// 排序过程中持有的行数
"rows": 27045,
// 参与排序的行数，InnoDB 返回的行数
"examined_rows": 34054,
// 排序使用的临时文件数量
"number_of_tmp_files": 24,
// 内存排序使用的内存大小
"sort_buffer_size": 25744,
// 排序模式
"sort_mode": "<sort_key, rowid>"
}
}
]
}
}
]
}
|
