Correct calculation and running of current_scn in Oracle10g

The following articles mainly explain how current_scn in Oracle10g is correctly computed and run. We all know that Oracle10g introduces current_scn in the v $ database view. In fact, this SCN comes from the underlying table, indicates the current SCN.

In Oracle9i, we can use dbms_flashback.get_system_change_number to obtain the SCN of the system.

But note that current_scn is still different. Let's take a look at the next query:

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oracle@danaly ~]$ sqlplus '/ as sysdba'   
  
SQL*Plus: Release 10.2.0.1.0 - Production on Thu Jun 21 10:15:08 2007  
  
Copyright (c) 1982, 2005, Oracle. All rights reserved.  
  
Connected to:  
  
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production  
  
With the Partitioning, Oracle Label Security, OLAP and Data Mining Scoring Engine options  
  
SQL> @scn  
  
SQL> col current_scn for 99999999999999999  
  
SQL> select current_scn from v$database;  
  
CURRENT_SCN  
  
8910961765228  
  
SQL> select dbms_flashback.get_system_change_number current_scn from dual;  
  
CURRENT_SCN  
  
8910961765228  
  
SQL> select dbms_flashback.get_system_change_number current_scn from dual;  
  
CURRENT_SCN  
  
8910961765228  
  
SQL> select current_scn from v$database;  
  
CURRENT_SCN  
  
8910961765229  
  
SQL> select dbms_flashback.get_system_change_number current_scn from dual;  
  
CURRENT_SCN  
  
8910961765229  
  
SQL> select dbms_flashback.get_system_change_number current_scn from dual;  
  
CURRENT_SCN  
  
8910961765229  
  
SQL> select current_scn from v$database;  
  
CURRENT_SCN  
  
8910961765230  
 

We can see that the query of current_scn will directly lead to the improvement of SCN, but not in other ways. That is to say, the current_scn here is like a Sequence, and the query will increase. This is also easy to understand. Only by enhancing the Current SCN can v $ database ensure that the obtained SCN is Current. But what if no query is performed? This value will certainly not grow. The above content is an introduction to the current_scn computing of Oracle10g. I hope you will have some gains.