问题
On my site I have a visitor's table with 10 million rows.
Every request to the site inserts row to the table, in case the table is locked (usually in optimize query) visitors can't get into the site
The table engine is MyISAM and I want to change it to InnoDB
I have few questions:
- How can I change the table engine without stoping my site from working
- There is a way to optimize InnoDB table without locking it
回答1:
The easiest way is
ALTER TABLE table_name ENGINE = InnoDB;
If you use InnoDB engine you should not worry about locking tables, because this engine locks data by rows.
回答2:
oleksii.svarychevskyi is right, InnoDB uses row level locks, but if you do
ALTER TABLE table_name ENGINE = InnoDB;to change table_name from MyIsam to InnoDB, there will be a metadata locking (at table level) because the original table engine was MyIsam.
If you try to do an UPDATE over table_name, this UPDATE will be enqueued until the ALTER TABLE ends (if you do a SHOW FULL PROCESSLIST you will see a "Waiting for table metadata lock" message associated to the UPDATE).
来源：https://stackoverflow.com/questions/21527588/mysql-changing-table-engine-myisam-to-innodb