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| *************************** 1. row ***************************
# 分析的查询语句是什么
QUERY: SELECT * FROM s1 WHERE
key1 > 'z' AND
key2 < 1000000 AND
key3 IN ('a', 'b', 'c') AND
common_field = 'abc'
# 优化的具体过程
TRACE: {
"steps": [
{
"join_preparation": { # prepare阶段
"select#": 1,
"steps": [
{
"IN_uses_bisection": true
},
{
"expanded_query": "/* select#1 */ select `s1`.`id` AS `id`,`s1`.`key1` AS `key1`,`s1`.`key2` AS `key2`,`s1`.`key3` AS `key3`,`s1`.`key_part1` AS `key_part1`,`s1`.`key_part2` AS `key_part2`,`s1`.`key_part3` AS `key_part3`,`s1`.`common_field` AS `common_field` from `s1` where ((`s1`.`key1` > 'z') and (`s1`.`key2` < 1000000) and (`s1`.`key3` in ('a','b','c')) and (`s1`.`common_field` = 'abc'))"
}
]
}
},
{
"join_optimization": { # optimize阶段
"select#": 1,
"steps": [
{
"condition_processing": { # 处理搜索条件
"condition": "WHERE",
# 原始搜索条件
"original_condition": "((`s1`.`key1` > 'z') and (`s1`.`key2` < 1000000) and (`s1`.`key3` in ('a','b','c')) and (`s1`.`common_field` = 'abc'))",
"steps": [
{
# 等值传递转换
"transformation": "equality_propagation",
"resulting_condition": "((`s1`.`key1` > 'z') and (`s1`.`key2` < 1000000) and (`s1`.`key3` in ('a','b','c')) and (`s1`.`common_field` = 'abc'))"
},
{
# 常量传递转换
"transformation": "constant_propagation",
"resulting_condition": "((`s1`.`key1` > 'z') and (`s1`.`key2` < 1000000) and (`s1`.`key3` in ('a','b','c')) and (`s1`.`common_field` = 'abc'))"
},
{
# 去除没用的条件
"transformation": "trivial_condition_removal",
"resulting_condition": "((`s1`.`key1` > 'z') and (`s1`.`key2` < 1000000) and (`s1`.`key3` in ('a','b','c')) and (`s1`.`common_field` = 'abc'))"
}
]
}
},
{
# 替换虚拟生成列
"substitute_generated_columns": {
}
},
{
# 表的依赖信息
"table_dependencies": [
{
"table": "`s1`",
"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": "`s1`",
"range_analysis": {
"table_scan": { # 全表扫描的行数以及成本
"rows": 9688,
"cost": 2036.7
} ,
# 分析可能使用的索引
"potential_range_indexes": [
{
"index": "PRIMARY", # 主键不可用
"usable": false,
"cause": "not_applicable"
},
{
"index": "idx_key2", # idx_key2可能被使用
"usable": true,
"key_parts": [
"key2"
]
},
{
"index": "idx_key1", # idx_key1可能被使用
"usable": true,
"key_parts": [
"key1",
"id"
]
},
{
"index": "idx_key3", # idx_key3可能被使用
"usable": true,
"key_parts": [
"key3",
"id"
]
},
{
"index": "idx_key_part", # idx_keypart不可用
"usable": false,
"cause": "not_applicable"
}
] ,
"setup_range_conditions": [
] ,
"group_index_range": {
"chosen": false,
"cause": "not_group_by_or_distinct"
} ,
# 分析各种可能使用的索引的成本
"analyzing_range_alternatives": {
"range_scan_alternatives": [
{
# 使用idx_key2的成本分析
"index": "idx_key2",
# 使用idx_key2的范围区间
"ranges": [
"NULL < key2 < 1000000"
] ,
"index_dives_for_eq_ranges": true, # 是否使用index dive
"rowid_ordered": false, # 使用该索引获取的记录是否按照主键排序
"using_mrr": false, # 是否使用mrr
"index_only": false, # 是否是索引覆盖访问
"rows": 12, # 使用该索引获取的记录条数
"cost": 15.41, # 使用该索引的成本
"chosen": true # 是否选择该索引
},
{
# 使用idx_key1的成本分析
"index": "idx_key1",
# 使用idx_key1的范围区间
"ranges": [
"z < key1"
] ,
"index_dives_for_eq_ranges": true, # 是否使用index dive
"rowid_ordered": false, # 使用该索引获取的记录是否按照主键排序
"using_mrr": false, # 是否使用mrr
"index_only": false, # 是否是索引覆盖访问
"rows": 266, # 使用该索引获取的记录条数
"cost": 320.21, # 使用该索引的成本
"chosen": false, # 是否选择该索引
"cause": "cost" # 因为成本太大所以不选择该索引
},
{
# 使用idx_key3的成本分析
"index": "idx_key3",
# 使用idx_key3的范围区间
"ranges": [
"a <= key3 <= a",
"b <= key3 <= b",
"c <= key3 <= c"
] ,
"index_dives_for_eq_ranges": true, # 是否使用index dive
"rowid_ordered": false, # 使用该索引获取的记录是否按照主键排序
"using_mrr": false, # 是否使用mrr
"index_only": false, # 是否是索引覆盖访问
"rows": 21, # 使用该索引获取的记录条数
"cost": 28.21, # 使用该索引的成本
"chosen": false, # 是否选择该索引
"cause": "cost" # 因为成本太大所以不选择该索引
}
] ,
# 分析使用索引合并的成本
"analyzing_roworder_intersect": {
"usable": false, # 是否使用Intersection索引合并
"cause": "too_few_roworder_scans" # 因为索引获取的记录主键值不是有序的，并且索引获取的记录数很小，回表的代价很小，没有必要访问多个B+树索引求交集再回表
}
} ,
# 对于上述单表查询s1最优的访问方法
"chosen_range_access_summary": {
"range_access_plan": {
"type": "range_scan", # 访问方法
"index": "idx_key2", # 使用的索引
"rows": 12, # 使用该索引获取的记录条数
"ranges": [
"NULL < key2 < 1000000" # 索引的范围区间
]
} ,
"rows_for_plan": 12,
"cost_for_plan": 15.41,
"chosen": true
}
}
}
]
},
{
# 分析各种可能的执行计划
#（对多表查询这可能有很多种不同的方案，单表查询的方案上边已经分析过了，直接选取idx_key2就好）
"considered_execution_plans": [
{
"plan_prefix": [
] ,
"table": "`s1`",
"best_access_path": {
"considered_access_paths": [
{
"rows_to_scan": 12,
"access_type": "range",
"range_details": {
"used_index": "idx_key2"
} ,
"resulting_rows": 12,
"cost": 17.81,
"chosen": true
}
]
} ,
"condition_filtering_pct": 100,
"rows_for_plan": 12,
"cost_for_plan": 17.81,
"chosen": true
}
]
},
{
# 尝试给查询添加一些其他的查询条件
"attaching_conditions_to_tables": {
"original_condition": "((`s1`.`key1` > 'z') and (`s1`.`key2` < 1000000) and (`s1`.`key3` in ('a','b','c')) and (`s1`.`common_field` = 'abc'))",
"attached_conditions_computation": [
] ,
"attached_conditions_summary": [
{
"table": "`s1`",
"attached": "((`s1`.`key1` > 'z') and (`s1`.`key2` < 1000000) and (`s1`.`key3` in ('a','b','c')) and (`s1`.`common_field` = 'abc'))"
}
]
}
},
{
# 再稍稍的改进一下执行计划
"refine_plan": [
{
"table": "`s1`",
"pushed_index_condition": "(`s1`.`key2` < 1000000)",
"table_condition_attached": "((`s1`.`key1` > 'z') and (`s1`.`key3` in ('a','b','c')) and (`s1`.`common_field` = 'abc'))"
}
]
}
]
}
},
{
"join_execution": { # execute阶段
"select#": 1,
"steps": [
]
}
}
]
}
# 因优化过程文本太多而丢弃的文本字节大小，值为0时表示并没有丢弃
MISSING_BYTES_BEYOND_MAX_MEM_SIZE: 0
# 权限字段
INSUFFICIENT_PRIVILEGES: 0
1 row in set (0.00 sec)
|
