Oracle DBA daily renewal (3)

What should I know first as an Oracle DBA in a completely new environment?

Here, we will not talk about those major aspects, such as understanding the overall situation of the entire IT environment. If you already know this, you need to face these living databases. here we have summarized some general ideas to face a database first, so as to quickly understand the environment overview you are facing.

This is not a textbook, but some experiences and experiences. For this problem, everyone's understanding is different. WelcomeWe will continue to make improvements.

1. First, you must understand the version and platform of the current Oracle database.
This is very important. After a long time, I still know which version of your database is and on which system it runs. It is not very sad, so I personally think this is the first step to understand. The following scripts help you obtain the required information.
Select * from V $ version;
Select * From dba_registry_database;
Select dbid, name, open_mode, database_role, platform_name from V $ instance;
Select dbms_utility.port_string from dual;

Set serveroutput on
Declare
Ver varchar2 (100 );
Compat varchar2 (100 );
Begin
Dbms_utility.db_version (ver, compat );
Dbms_output.put_line ('version: '| ver | 'compatible:' | compat );
End;
/
2. Next, you need to know which components are installed in your database.
Select * From dba_registry;
　
3. Do you know whether the environment is a single machine or a cluster?
There are many methods to determine this. Here I will provide a method to determine it using dbms_utility.
Set serveroutput on

Declare
Inst_tab dbms_utility.instance_table;
Inst_cnt number;
Begin
If dbms_utility.is_cluster_database then
Dbms_utility.active_instances (inst_tab, inst_cnt );
Dbms_output.put_line ('-' | inst_tab.first );
Dbms_output.put_line (to_char (inst_cnt ));
Else
Dbms_output.put_line ('not a clustered database ');
End if;
End;
/
4. Is the volume uard configured?
Select protection_mode, protection_level, remote_archive, database_role, dataguard_broker, guard_status
From v $ database;
5. Is the archive mode used?
Conn/As sysdba
Archive log list;
Select log_mode from V $ database;
　
6. Have you used the flashback database feature?
Select flashback_on from V $ database;
If yes, check the FRA configuration.
7. Are force logging and supplemental logs used?
Select force_logging, supplemental_log_data_min, supplemental_log_data_pk, supplemental_log_data_ui,
Supplemental_log_data_fk, supplemental_log_data_all
From v $ database;
8. Understand the composition of Control Files
Select * from V $ controlfile;
9. Understand the composition of log files
Select L. Group #, LF. type, LF. Member, L. bytes, L. Status log_status, LF. Status logfile_status
From v $ log L, V $ logfile lf
Where l. Group # = lf. Group #
Order by 1, 3;
10. Understand the composition and location of the parameter file
Show parameter spfile
Create spfile from pfile...
Create pfile from spfile;
Create spfile from memory;
Create pfile from memory;
11. Learn more about the instance
Select instance_name, host_name, status, archiver, database_status, instance_role, active_state
From v $ instance;
12. User and password Problems
Is the default password used?
Is profile used?
Is password verification function used?
How does one verify user identity?
Whether the password is case sensitive or not.
Select name, value from GV $ parameter where name = 'Resource _ limit ';
Select profile, resource_name, limit from dba_profiles order by 1, 2;

Select username, profile from dba_users where account_status = 'open' order by 1;
　
Select D. username, U. account_status
From dba_users_with_defpwd D, dba_users u
Where D. Username = U. username and account_status = 'open'
Order by 2, 1;
　
13. Whether block change tracking is enabled
Select filename, status, bytes from V $ block_change_tracking;
14. What features are used )?
Dbms_feature_usage_report
　
15. Planning of tablespaces and data files
Everyone is familiar with this and will not write it.
　
16. Character Set
Select * From database_properties;
　
17. Whether the invalid object exists in the system
Select owner, object_type, count (*)
From dba_objects
Where status = 'invalid'
Group by owner, object_type;
18. Further steps
Is ASM used?
What is the current system backup method and policy?
What is the network file configuration?
　
19. Check the recent alert logs to obtain useful information.
20. run several performance analysis reports to see how the system is running recently.
21. Run an RDA report to collect the complete system status report.