没有索引,就是全表扫描, type 就是 ALL
问MySQL:强制使用IN(.)索引的不同access_typeEN主键索引（PRIMARY） 数据列不允许重复，不允许为NULL，...
mysql access_type MySQL Access Type MySQL is a popular relational database management system (RDBMS) that allows users to store, retrieve and manipulate data efficiently. When working with MySQL, it is important to understand the different access types that can be used to optimize the performance ...
查询计划使用index merge 时,会在explain sql 的 access type 列有"index_merge",key 列会 包含所有参与merge的列, key_length 包含一个所用索引的最长关键部分的列表。举个Intersection例子: Intersection 以下代码块注释中提到的知识点略多 代码语言:javascript 代码运行次数:0 运行 AI代码解释 ##无论optimizer ...
type (JSON name: access_type) The join type. For descriptions of the different types, see EXPLAIN Join Types. possible_keys (JSON name: possible_keys) The possible_keys column indicates the indexes from which MySQL can choose to find the rows in this table. Note that this column is ...
{"table": {"table_name":"s1","access_type":"ALL","possible_keys": ["idx_key1"],"rows_examined_per_scan":9895,"rows_produced_per_join":989,"filtered":"10.00","cost_info": {"read_cost":"914.80","eval_cost":"98.95","prefix_cost":"1013.75","data_read_per_join":"1M"},"us...
"access_type": "index", "possible_keys": [ "PRIMARY"], "key": "idx_purpose_code", "used_key_parts":["purpose_code"], "key_length": "387", "rows_examined_per_scan":851, "rows_produced_per_join":851, "filtered": "100.00", ...
{ "table_name": "t_func", "access_type": "range", "possible_keys": [ "idx_log_time_normal" ], "key": "idx_log_time_normal", "used_key_parts": [ "log_time" ], "key_length": "6", "rows_examined_per_scan": 1401, "rows_produced_per_join": 1401, "filtered": "100.00"...
TIMERWAIT: 706768928900000 ACCESSMODE: READ WRITE ISOLATION_LEVEL REPEATABLE READ AUTOCOMMIT NO NUMBER_OF_SAVEPOINT: 0 NUMBER_OF_ROLLBACK_TO_SAVEPOINT 0 NUMBEROF_RELEASE_SAVEPOINT: 0 OBJECT_INSTANCE_BEGIN: NULL NESTINGEVENT_ID: 2 NESTING_EVENT_TYPE ...
[root@zs~]# mysql -uroot -pEnter password: ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES)[root@zs ~]# mysql -uroot -pEnter password: ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES)#我们有可能刚刚接手别人的 M...