MySQL explain：修订间差异

2018年9月18日 (二) 09:16的版本

mysql> explain SELECT COUNT(*) FROM vehicle_prod WHERE fin LIKE '%00000' \G
*************************** 1. row ***************************
           id: 1
  select_type: SIMPLE
        table: vehicle_prod
   partitions: NULL
         type: index
possible_keys: NULL
          key: idx_vehicle_prod_fin
      key_len: 203
          ref: NULL
         rows: 3182812
     filtered: 11.11
        Extra: Using where; Using index
1 row in set, 1 warning (0.00 sec)

其中：

id select_id The SELECT identifier
select_type None The SELECT type
table table_name The table for the output row
partitions partitions The matching partitions
type access_type The join type
possible_keys possible_keys The possible indexes to choose
key key The index actually chosen
key_len key_length The length of the chosen key
ref ref The columns compared to the index
rows rows Estimate of rows to be examined
filtered filtered Percentage of rows filtered by table condition
Extra None Additional information

@@ 第1行： / 第1行： @@
 <pre>
-mysql> explain SELECT COUNT(*) FROM vehicle_prod WHERE fin LIKE '%00000';
+mysql> explain SELECT COUNT(*) FROM vehicle_prod WHERE fin LIKE '%00000' \G
-+----+-------------+--------------+------------+-------+---------------+----------------------+---------+------+---------+----------+--------------------------+
+*************************** 1. row ***************************
-| id | select_type | table        | partitions | type  | possible_keys | key                  | key_len | ref  | rows    | filtered | Extra                    |
+           id: 1
-+----+-------------+--------------+------------+-------+---------------+----------------------+---------+------+---------+----------+--------------------------+
+  select_type: SIMPLE
-|  1 | SIMPLE      | vehicle_prod | NULL       | index | NULL          | idx_vehicle_prod_fin | 203     | NULL | 3182812 |    11.11 | Using where; Using index |
+        table: vehicle_prod
-+----+-------------+--------------+------------+-------+---------------+----------------------+---------+------+---------+----------+--------------------------+
+   partitions: NULL
+         type: index
+possible_keys: NULL
+          key: idx_vehicle_prod_fin
+      key_len: 203
+          ref: NULL
+         rows: 3182812
+      filtered: 11.11
+        Extra: Using where; Using index
 row in set, 1 warning (0.00 sec)
 </pre>
+其中：
+*id	select_id	The SELECT identifier
+*select_type	None	The SELECT type
+*table	table_name	The table for the output row
+*partitions	partitions	The matching partitions
+*type	access_type	The join type
+*possible_keys	possible_keys	The possible indexes to choose
+*key	key	The index actually chosen
+*key_len	key_length	The length of the chosen key
+*ref	ref	The columns compared to the index
+*rows	rows	Estimate of rows to be examined
+*filtered	filtered	Percentage of rows filtered by table condition
+*Extra	None	Additional information
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