Online DDL improve：instant algorithm supports more ALTER
InnoDB: InnoDB now supports ALTER TABLE ... DROP COLUMN operations using ALGORITHM=INSTANT.
Operations that support ALGORITHM=INSTANT only modify metadata in the data dictionary. Table data is unaffected, making the operations instantaneous. If not specified explicitly, ALGORITHM=INSTANT is used by default by DDL operations that support it.
Prior to MySQL 8.0.29, an instantly added column could only be added as the last column of the table. From MySQL 8.0.29, an instantly added column can be added to any position in the table.
Instantly added or dropped columns create a new row version. Up to 64 row versions are permitted. A new TOTAL_ROW_VERSIONS column was added to the INFORMATION_SCHEMA.INNODB_TABLES table to track the number of row versions.
For more information about DDL operations that support ALGORITHM=INSTANT, see Online DDL Operations.
