Lock promotion
Lock promotion is the action of exchanging one lock on a resource for a more restrictive lock on the same resource, held by the same application process.
Example
An application reads data, which requires an IS lock on a table space. Based on further calculation, the application updates the same data, which requires an IX lock on the table space. The application is said to promote the table space lock from mode IS to mode IX.
Effects
When promoting the lock, Db2 first waits until any incompatible locks held by other processes are released. When locks are promoted, they are promoted in the direction of increasing control over resources: from IS to IX, S, or X; from IX to SIX or X; from S to X; from U to X; and from SIX to X.
