1) First, know the directory where the control file, data file, and log file are located and the related usage of the table space, and optimize the Top-level SQL statement
select * from v$logfile
select * from v$log
select * from v$datafile
select * from v$controlfile
2) Know the path to the warning log file
show parameter background_dump_dest ;
or
select * from v$parameter where name like '%background_dump_dest%'
3) Know if the database is archived and the database name
select * from v$database
4) Know the SGA allocation
select * from v$parameter where name like '%sga%'
5) Observe the system performance and the corresponding waiting events
6) Check the hit rate of the buffer pool
select sum(pinhits)/sum(pins) * 100 from v$librarycache
7) Check the sorting part (disk sorting and memory sorting)
select * from v$sysstat where name like '%sort%'
8) wait event
select * from v$session_wait
select * from v$session_event
select * from v$system_event
9) transaction fallback rate
select * from v$sysstat where name like '%user commits%' or name like '%transaction rollbacks%'
select * from dba_rollback_segs
select * from v$waitstat
select * from v$transaction
10) How to recover if the data file is damaged or lost
11) How to recover if the log file is damaged or lost?
alter system switch logfile
12) How to restore control file corruption
13) Rman backup