Concurrent DML but Table Copy Still Required

Concurrent DML but Table Copy Still Required
Some other ALTER TABLE operations allow concurrent DML, and are faster than MySQL 5.5 and prior:
the table-copying operation is optimized, even though a table copy is still required:
• Adding, dropping, or reordering columns.
• Adding or dropping a primary key.
• Changing the ROW_FORMAT or KEY_BLOCK_SIZE properties for a table.
• Changing the nullable status for a column.
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