- 15.13.1 Overview of Online DDL
- 15.13.2 Performance and Concurrency Considerations for Online DDL
- 15.13.3 SQL Syntax for Online DDL
- 15.13.4 Combining or Separating DDL Statements
- 15.13.5 Examples of Online DDL
- 15.13.6 Implementation Details of Online DDL
- 15.13.7 How Crash Recovery Works with Online DDL
- 15.13.8 Online DDL for Partitioned InnoDB Tables
- 15.13.9 Limitations of Online DDL
Improved responsiveness and availability in busy production environments, where making a table unavailable for minutes or hours is not practical.
The ability to adjust the balance between performance and concurrency during a DDL operations using the
LOCK=EXCLUSIVEblocks access to the table entirely.
LOCK=SHAREDallows queries but not DML.
LOCK=NONEallows full query and DML access to the table.
LOCK=DEFAULTor omitting the
LOCKclause permits as much concurrency as possible depending on the type of DDL operation.
Avoidance of disk space usage and I/O overhead associated with copying the table and reconstructing secondary indexes.