显示Oracle DB中表的上次访问时间

Question

I'm using Oracle RDBMS for database. I'm trying to clean up the database and want to know if certain tables are even used any more. I require the last accessed time of these tables to reach a conclusion.

Please note that I need the timestamp of the latest SELECT query. I've solutions for finding timestamp of other activities like UPDATE , ALTER , etc. I'm looking specifically for SELECT timestamp.

Any help is appreciated.

Answer 1

您可以使用AUDIT(traditional auditing) ：

AUDIT SELECT ON table_name;

Answer 2

Yes, @lad2025 is right, I'd use AUDIT to find out who is accessing the tables.

To switch it on, just use:

AUDIT SELECT ON scott.emp  BY ACCESS;
AUDIT SELECT ON scott.dept BY ACCESS;  

You can then see which tables are audited by querying:

SELECT * 
FROM DBA_OBJ_AUDIT_OPTS 
WHERE owner='SCOTT';

OWNER OBJECT_NAME OBJECT_TYPE SEL
SCOTT DEPT        TABLE       A/A
SCOT  EMP         TABLE       A/A

If somebody selects from one of the audited tables, it appears in the audit trail:

SELECT * FROM scott.emp;

SELECT os_username, username, obj_name, action_name, timestamp
  FROM DBA_AUDIT_TRAIL 
 WHERE timestamp BETWEEN SYSDATE-7 AND SYSDATE
   AND owner = 'SCOTT' 
   AND action=3
 ORDER BY timestamp DESC;

OS_USERNAME USERNAME OBJ_NAME ACTION NAME TIMESTAMP
xxxx        yyy      EMP      SELECT      2018-05-30 08:01:07

To switch it off again, use:

NOAUDIT ALL ON scott.emp;
SELECT * FROM DBA_OBJ_AUDIT_OPTS WHERE OWNER='SCOTT';

OWNER OBJECT_NAME OBJECT_TYPE SEL
SCOTT DEPT        TABLE       A/A

Be cautious, though. One row is added to the audit trail for each SELECT, so watch it carefully, it can generate a lot of data very quickly.