Multiple choice

In which situations does the Log Writer (LGWR) process write the redo entries from the redo log buffer to the current online redo log group?

  1. When a transaction commits

  2. When a rollback is executed

  3. When the redo log buffer is about to become completely full (90%)

  4. Before the DBWn writes modified blocks in the database buffer cache to the data files
Reveal answer Fill a bubble to check yourself
A,D Correct answer
Explanation

LGWR writes redo entries to online redo log files at two key times: when a transaction commits (to ensure durability) and before DBWn writes dirty buffers to data files (to maintain recovery capability). Rollbacks do not trigger LGWR writes, and the buffer writes at 1/3 full, not 90%.

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