Online DDL Performance and Concurrency Non-partitioning online  ALTER TABLE  operations on partitioned tables follow the same rules that apply to regular tables. However,  ALTER TABLE  performs online operations on each table partition, which causes increased demand on system resources due to operations being performed on multiple partitions. For additional information about  ALTER TABLE  partitioning clauses, see Partitioning Options, and Section 13.1.9.1, “ALTER TABLE Partition Operations” . For information about partitioning in general, see Chapter 24,  Partitioning . Online DDL improves several aspects of MySQL operation: •Applications that access the table are more responsive because queries and DML operations on the table can proceed while the DDL operation is in progress. Reduced locking and waiting for MySQL server resources leads to greater scalability, even for operations that are not involved in the DDL operation. •Instant operations only modify metadata in the data dictionary. No metadata locks are taken on the table, and table data is unaffected, making operations instantaneous. Concurrent DML is unaffected. •Online operations avoid the disk I/O and CPU cycles associated with the table-copy method, which minimizes overall load on the database. Minimizing load helps maintain good performance and high throughput during the DDL operation. 15.12.2 Online DDL Performance and Concurrency Partitioning Clause Instant In Place Permits DML Notes EXCHANGE PARTITION No Yes Yes ANALYZE PARTITION No Yes Yes CHECK PARTITION No Yes Yes OPTIMIZE PARTITION No No No ALGORITHM  and LOCK  clauses are ignored. Rebuilds the entire table. See Section 24.3.4, “Maintenance of Partitions” . REBUILD PARTITION No Yes* No ALGORITHM=INPLACE, LOCK={DEFAULT| SHARED| EXCLUSIVE}  is supported. REPAIR PARTITION No Yes Yes REMOVE PARTITIONING No No No Permits ALGORITHM=COPY , LOCK={DEFAULT| SHARED| EXCLUSIVE} 3190