per value from 1 byte to 2 bytes; this requires a table copy. Adding members in the middle of the list causes renumbering of existing members, which requires a table copy. 

•Changing the definition of a spatial column to remove the SRID  attribute. (Adding or changing an SRID attribute does require a rebuild and cannot be done in place because the server must verify that all values have the specified SRID value.) 

•As of MySQL 8.0.14, changing a column character set, when these conditions apply: 

•The column data type is CHAR , VARCHAR , a TEXT  type, or ENUM . 

•The character set change is from utf8mb3  to utf8mb4 , or any character set to binary . 

•There is no index on the column. 

•As of MySQL 8.0.14, changing a generated column, when these conditions apply: 

•For InnoDB  tables, statements that modify generated stored columns but do not change their type, expression, or nullability. 

•For non- InnoDB  tables, statements that modify generated stored or virtual columns but do not change their type, expression, or nullability. 

An example of such a change is a change to the column comment. 

•Renaming an index. 

•Adding or dropping a secondary index, for InnoDB  and NDB  tables. See Section 15.12.1, “Online DDL Operations” . 

•For NDB  tables, operations that add and drop indexes on variable-width columns. These operations occur online, without table copying and without blocking concurrent DML actions for most of their duration. See Section 23.5.11, “Online Operations with ALTER TABLE in NDB Cluster” . 

•Modifying index visibility with an ALTER INDEX  operation. 

•Column modifications of tables containing generated columns that depend on columns with a DEFAULT value if the modified columns are not involved in the generated column expressions. For example, changing the NULL  property of a separate column can be done in place without a table rebuild. 

ALTER TABLE  operations that support the INSTANT  algorithm include: 

•Adding a column. This feature is referred to as “Instant ADD COLUMN ” . Limitations apply. See Section 15.12.1, “Online DDL Operations” . 

•Adding or dropping a virtual column. 

•Adding or dropping a column default value. 

•Modifying the definition of an ENUM  or SET  column. The same restrictions apply as described above for ALGORITHM=INSTANT . 

•Changing the index type. 

•Renaming a table. The same restrictions apply as described above for ALGORITHM=INSTANT . 

For more information about operations that support ALGORITHM=INSTANT , see Section 15.12.1, “Online DDL Operations” . 

