14. How to build a backup control file?
Answer: Alter Database Backup Control File to TRACE.
15. How many states have been introduced by the database normal startup?
Solution: Startup Nomount - Database instance start
STARTUP MOUNT - Database Database
STARTUP OPEN - Database Open
16. Which Column can be used to distinguish between V $ view and GV $ view?
Answer: INST_ID indicates a specific INSTANCE in the cluster environment.
17. How to generate an Explain Plan?
Solution: Run UTLXPLAN.SQL. Create a Plan table
Using Explain Plan Set Statement_ID = 'TST1' INTO PLAN_TABLE for a specific SQL statement
Run UTLXPLP.SQL or UTLXPLS.SQL to view Explain Plan
18. How to increase the hit rate of buffer cache?
Solution: When the database is busy, the Buffer Cache Advisory tool is applied, query V $ db_cache_advice. If necessary, you can use the ALTER System Set DB_Cache_SIZE command.
19. What is the right method of ORA-01555?
Solution: The specific error message is Snapshot Too Old Within Rollback SEG, you can usually solve the problem by increasing Rollback Seg. Of course, you need to look at the specific SQL text that causes the error.
20. Interpret $ Oracle_Home and $ ORACLE_BASE?
Solution: Oracle_base is the root of Oracle, Oracle_Home is the directory of Oracle products.
