- 14.13.1 Online DDL Overview
- 14.13.2 Online DDL Performance and Concurrency
- 14.13.3 Online DDL SQL Syntax
- 14.13.4 Simplifying DDL Statements with Online DDL
- 14.13.5 Online DDL Implementation Details
- 14.13.6 Online DDL and Crash Recovery
- 14.13.7 Online DDL for Partitioned Tables
- 14.13.8 Online DDL Limitations
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.