MySQL explain:修订间差异

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已建立頁面,內容為 "<pre> mysql> explain SELECT COUNT(*) FROM vehicle_prod WHERE fin LIKE '%00000'; +----+-------------+--------------+------------+-------+---------------+-------------…"
 
Riguz留言 | 贡献
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第1行: 第1行:
<pre>
<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
1 row in set, 1 warning (0.00 sec)
1 row in set, 1 warning (0.00 sec)
</pre>
</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
[[Category:Datebase]]
[[Category:Datebase]]

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