Table modifications



It is an interesting oracle feature.. This feautore allows you to now when a table or a row was modified last time...

Each oracle table has a pseudocolum called ora_rowscn, this pseudocolum contains last scn in which a row was modified.
So if you need a table last modification date (DML point of view) you can do this..
SQL> select  scn_to_timestamp(MAX(ora_rowscn)) FROM OWNER1.TEMP;

SCN_TO_TIMESTAMP(MAX(ORA_ROWSCN))
---------------------------------------------------------------------------
09-FEB-18 03.22.18.000000000 PM

This select works selecting the max oracle SCN (System Change Number, each transaction in database generates a new SCN), so the max(scn) is the last DML in the table...

Same way you can see when a specific row was modified last time by:

SQL> select  scn_to_timestamp(ora_rowscn) FROM OWNER1.TEMP where ID=13;

SCN_TO_TIMESTAMP(ORA_ROWSCN)
---------------------------------------------------------------------------
08-FEB-18 02.12.14.000000000 PM

Comments

Post a Comment

Popular posts from this blog

Oracle Historical Session Information with ASH >10g

Image
In Oracle 10.2 and above with ASH is very useful to see the number of sessions active and connected to a database over time: You can use this 2 views to obtain this information: v$sysmetric_history --> This is a sort term view, that contains data of last hour by intervals of minutes dba_hist_sysmetric_summary -->This is a long term view, that contains data of last month by intervals of 1 hour. v$sysmetric_history and dba_hist_sysmetric_summary contains information a lot of different metrics information, so the first thing we need to do is to filter metric type. With this query you can select a list of all metric types: set linesize 190 col METRIC_NAME for a100 select METRIC_ID, METRIC_NAME from v$sysmetric_history group by METRIC_ID, METRIC_NAME ; for example, if you are looking for metrics related with connected sessions to database, you can do: SQL> set linesize 190 col METRIC_NAME for a100 select METRIC_ID, METRIC_NAME from v$sysmetric_history where lo
Read more

Purging and archiving Oracle alert.log and listener.log

As i said in " Purging Oracle traces with ADRCI " ADRCI does not work properly for alert.log and listener.log, so in this article i´m going to study who to do this tasks externally, with unix tools. 1-With logrotate Linux-command. I think this is the best option if you have an Oracle linux because it can be setup easily... Put this lines in a config file but modifing your alert.log and listener.log paths # alert log /oracle/db/diag/rdbms/orcl/orcl/trace/alert_orcl.log { monthly rotate 13 notifempty missingok copytruncate nocreate } # listener log /oracle/db/diag/tnslsnr/wcp12cr2/listener/trace/listener.log { weekly rotate 53 notifempty missingok copytruncate nocreate } i put them into alert_logrotate.conf as you can see: [oracle@wcp12cr2 Documents]$ ls -ltr alert_logrotate.conf -rw-r--r--. 1 oracle oinstall 593 Oct 5 03:08 alert_logrotate.conf [oracle@wcp12cr2 Documents]$ cat alert_logrotate.conf # see "man logrotate" for details # rotate log files
Read more

Check sessions and processes limits in Oracle

Oracle database has a gv$resource_limit view to check if any database resource reach his connection limit: set linesize 190 set pages 200 select * from gv$resource_limit; INST_ID RESOURCE_NAME CURRENT_UTILIZATION MAX_UTILIZATION INITIAL_ALLOCAT LIMIT_VALUE ---------- ------------------------------ ------------------- --------------- --------------- ------------ 1 processes 44 300 300 300 1 sessions 52 215 512 512 1 enqueue_locks 30 295 6480 6480 1 enqueue_resources 24 165 2472 UNLIMITED 1 ges_procs 0 0 0 0 1 ges_ress 0 0
Read more