四：Mysql存儲引擎簡介

首先經過命令行查看一下mysql的存儲引擎

mysql> show ENGINES;
+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+
| Engine             | Support | Comment                                                        | Transactions | XA   | Savepoints |
+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+
| FEDERATED          | NO      | Federated MySQL storage engine                                 | NULL         | NULL | NULL       |
| MRG_MYISAM         | YES     | Collection of identical MyISAM tables                          | NO           | NO   | NO         |
| MyISAM             | YES     | MyISAM storage engine                                          | NO           | NO   | NO         |
| BLACKHOLE          | YES     | /dev/null storage engine (anything you write to it disappears) | NO           | NO   | NO         |
| CSV                | YES     | CSV storage engine                                             | NO           | NO   | NO         |
| MEMORY             | YES     | Hash based, stored in memory, useful for temporary tables      | NO           | NO   | NO         |
| ARCHIVE            | YES     | Archive storage engine                                         | NO           | NO   | NO         |
| InnoDB             | DEFAULT | Supports transactions, row-level locking, and foreign keys     | YES          | YES  | YES        |
| PERFORMANCE_SCHEMA | YES     | Performance Schema                                             | NO           | NO   | NO         |
+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+
9 rows in set (0.00 sec)

這個是我本地看的，不大明顯，找了個網上的圖片

能夠看到mysql的引擎以及各個引擎的狀況

若是查看mysql如今使用的那個引擎，能夠利用命令

show variables like 'storage_engine'

mysql> show variables like 'storage_engine';
+----------------+--------+
| Variable_name  | Value  |
+----------------+--------+
| storage_engine | InnoDB |
+----------------+--------+
1 row in set (0.00 sec)

能夠看出使用的是InnoDB引擎

如何查看錶的引擎

mysql> show table status from fmcm_test where name='xadmin_userwidget';
+-------------------+--------+---------+------------+------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+-------------+------------+-----------------+----------+----------------+---------+
| Name              | Engine | Version | Row_format | Rows | Avg_row_length | Data_length | Max_data_length | Index_length | Data_free | Auto_increment | Create_time         | Update_time | Check_time | Collation       | Checksum | Create_options | Comment |
+-------------------+--------+---------+------------+------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+-------------+------------+-----------------+----------+----------------+---------+
| xadmin_userwidget | InnoDB |      10 | Compact    |    0 |              0 |       16384 |               0 |        16384 |         0 |              1 | 2016-06-16 05:57:12 | NULL        | NULL       | utf8_general_ci |     NULL |                |         |
+-------------------+--------+---------+------------+------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+-------------+------------+-----------------+----------+----------------+---------+
1 row in set (0.00 sec)

能夠看出使用的是InnoDB引擎

若是須要轉還表的引擎，能夠使用alter table mytable ENGINE=InnoDB

以下

mysql> alter table xadmin_userwidget ENGINE='MyISAM'
    -> ;
Query OK, 0 rows affected (0.03 sec)
Records: 0  Duplicates: 0  Warnings: 0

改變引擎成功，

如今在查看一下該表的引擎

mysql> show table status from fmcm_test where name= 'xadmin_userwidget';
+-------------------+--------+---------+------------+------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+---------------------+------------+-----------------+----------+----------------+---------+
| Name              | Engine | Version | Row_format | Rows | Avg_row_length | Data_length | Max_data_length | Index_length | Data_free | Auto_increment | Create_time         | Update_time         | Check_time | Collation       | Checksum | Create_options | Comment |
+-------------------+--------+---------+------------+------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+---------------------+------------+-----------------+----------+----------------+---------+
| xadmin_userwidget | MyISAM |      10 | Dynamic    |    0 |              0 |           0 | 281474976710655 |         1024 |         0 |              1 | 2017-01-13 13:06:34 | 2017-01-13 13:06:34 | NULL       | utf8_general_ci |     NULL |                |         |
+-------------------+--------+---------+------------+------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+---------------------+------------+-----------------+----------+----------------+---------+
1 row in set (0.00 sec)

能夠看出來引擎那一選項已經改成MyISAM引擎。

在mysql中沒有規定服務器必定要使用一種引擎，能夠針對不一樣的表使用不一樣的引擎，在SUPPORT列中若是是YES表示能夠使用，No表示不能夠使用，DEFAULT表示默認的引擎

待續