SMON是System Monitor Process的简称，是oracle非常核心的进程。
Smon 进程有哪些作用：
- temporary space reclamation:Creates and manages the temporary tablespace metadata
- data dictionary cleanup:Cleans up the data dictionary when it is in a transient and inconsistent state(obj$,ind$…)
- undo tablespace management：Maintains the undo tablespace by onlining, offlining, and shrinking the undo segments based on undo space usage statistics
- Recover Dead transaction
- Instance Recovery,In an Oracle RAC database, the SMON process of one instance can perform instance recovery for other instances that have failed
- Free Space COALESCE
- Maintains the SCN to time mapping table used to support Oracle Flashback