Is the Apply Process Encountering Contention?
An apply server is a component of an apply process. Apply servers apply DML and DDL changes to database objects at a destination database. An apply process may use one or more apply servers, and the parallelism apply process parameter specifies the number of apply servers that may concurrently apply transactions. For example, if parallelism is set to 5, then an apply process uses a total of five apply servers. An apply server encounters contention when the apply server must wait for a resource that is being used by another session. Contention may result from logical dependencies. For example, when an apply server tries to apply a change to a row that a user has locked, then the apply server must wait for the user. Contention also may result from physical dependencies. For example, interested transaction list (ITL) contention results when two transactions that are being applied, which may not be logically dependent, are trying to lock the same block on disk. In this case, one apply serv
