Waiting for an Event That is Not Related to Another Session

In these cases, nothing is written to the log initially because such waits are common and are usually transient. If the Apply server is waiting for the same event after a certain interval of time, the Apply server writes a message to the alert log and Apply process trace file. For example, apply server A001 may write a message similar to the following:

A001: warning -- apply server 1, sid 26 waiting for event:
A001: [log file sync] ...

This is a contention issue. The DBA will have to examine the root cause of the log file sync wait. The messages written to alert the log are informational. 

Waiting for an Event that is Related to a Non Apply Server Session

The Apply server writes a message to the alert log and the Apply process trace file immediately. For example, apply server A001 may write a message similar to the following:

A001: warning -- apply server 1, sid 10 waiting on user sid 36 for event:
A001: [enq: TM - contention] name|mode=544d0003, object #=a078,
      table/partition=0