Shulou(Shulou.com)06/01 Report--

Adding fields is painful, and tables need to be rebuilt, especially for large tables at the level of 100 million. Although Online DDL can avoid locking tables, if it takes 30 minutes to execute on the master database, then the master-slave replication will be delayed if you copy to the slave database. With the instant ADD COLUMN feature, the fields are added as long as the soot is popped, and you can enjoy the flexibility and convenience of unstructured storage like MongoDB.

Limit

1. If AFTER is specified, the field must be in the last column, otherwise the table will be re-established

2. Not applicable to ROW_FORMAT = COMPRESSED

3. DROP COLUMN needs to rebuild the table.

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