Migrating a table from MyISAM to Aria_MariaDB Cookbook-QQ阅读女生现言网

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Migrating a table from MyISAM to Aria

MariaDB ships with the MyISAM and Aria storage engines, among many others. The main difference between these two is that Aria is crash safe, whereas MyISAM is not. Being crash safe means that an Aria table can recover from catastrophic power loss or other unexpected failures in a much better way than a MyISAM table can. If we use MyISAM tables, an easy upgrade is to convert them to Aria tables.

Getting ready

Import the ISFDB database as described in the Importing the data exported by mysqldump recipe in this chapter.

How to do it...

Open the mysql command-line client and connect to the isfdb database.
Run the following command line:
```
ALTER TABLE authors ENGINE=Aria;
```
The ALTER command will then change the table so that it uses the Aria storage engine.

After it has finished, a message similar to the following will be displayed:

Query OK, 110829 rows affected (3.14 sec) 
Records: 110829 Duplicates: 0 Warnings: 0

If our system is older or is under heavy load and it takes longer than 5 seconds for ALTER TABLE to complete, we'll see a progress message letting us know how much of the task has been completed, updated every 5 seconds, until the task is finished.

How it works...

The ALTER TABLE command changes a table in two stages. First, it creates a new table identical in every way to the old table, except that the new table has the changes specified by the command. In our case, the only change is to use the Aria storage engine instead of the MyISAM storage engine. Then, the command copies all of the data to the new table.

In the second stage, ALTER TABLE removes the old table and renames the new table with the name of the old table.

On a table like authors that only has around a hundred thousand rows, the conversion is quick and easy; however, on a table with several billion rows, the conversion process will take significantly longer.