Background Processes

ASnn

Logical Standby / Streams Apply Process Reader Server or Apply Server

Computes dependencies between logical change records (LCRs) and assembles messages into transactions (Reader Server)

Applies LCRs to database objects or passes LCRs and user messages to their appropriate apply handlers (Apply Server)

When the reader server finishes computing dependencies between LCRs and assembling transactions, it returns the assembled transactions to the coordinator process. Query V$STREAMS_APPLY_READER for information about the reader server background process.

An apply server receives the transactions from the coordinator background process, and either applies database changes in LCRs or sends LCRs or messages to apply handlers. Apply servers can also enqueue a queue. If an apply server encounters an error, then it then tries to resolve the error with a user-specified conflict handler or error handler. If an apply server cannot resolve an error, then it rolls back the transaction and places the entire transaction, including all of its messages, in the error queue. When an apply server commits a completed transaction, this transaction has been applied. When an apply server places a transaction in the error queue and commits, this transaction also has been applied. Query V$STREAMS_APPLY_SERVER for information about the apply server background process.

The coordinator process name is ASnn, where nn can include letters and numbers.

Database instance