Which two are true about LGWR?

A)LGWR always writes to the redo logs each time a COMMIT occurs.

B)LGWR always writes to the redo logs each time a ROLLBACK occurs.

C)LGWR never writes a single COMMIT to the redo logs.

D)LGWR may write to the redo logs when DBWR writes a dirty buffer.

E)Multiple COMMITs can be written by LGWR in the same write request.

F)LGWR always writes to the redo logs when DBWR writes a dirty buffer.

Answer: DE

赵：AF=>DE

冉：

DE 两个答案更妥，D 比 F 要好，因为 D 答案用了 may 没有用 always

E 答案给的是 group commit 的概念，即在 lgwr 正在执行时，其他会话发生的 commit 可以做为一组，随后一起提交。