SCN on Scale of Time & SCN of a ROW

In the last post we have discussed about SCN structure and generation schemes, now we will see relation of SCN with timestamp and association with data populated in database tables.

SCN to TIMESTAMP: SCN is actually generated based on timestamp as well. So it’s easy to check timestamp from SCN and vice versa. Handy conversion features are available only from Oracle 10g onwards, but still from older versions Oracle had system object SYS.SMON_SCN_TIME, which can provide you the same information after some simple calculations.

In 10g onwards, there are two built-in functions to give the timestamp and SCN mapping details timestamp_to_scn() & scn_to_timestamp()

SQL> select scn_to_timestamp(current_scn-rownum) tm,
timestamp_to_scn(scn_to_timestamp(current_scn-rownum)) scn, current_scn-rownum
from v$database
connect by level <=5;

TM                                        SCN         CURRENT_SCN-ROWNUM
----------------------------------- ----------------- ------------------
14-AUG-12 AM               1274785            1274785
14-AUG-12 AM               1274784            1274784
14-AUG-12 AM               1274782            1274783
14-AUG-12 AM               1274782            1274782
14-AUG-12 AM               1274781            1274781

Oracle Documentation is saying that both functions actually trying to give approximate SCN or timestamp value. Here are the definitions:

TIMESTAMP_TO_SCN: takes as an argument a timestamp value and returns the approximate system change number (SCN) associated with that timestamp. The returned value is of datatype NUMBER. This function is useful any time you want to know the SCN associated with a particular timestamp.
Read more of this post

Pierre blog

Pierre Forstmann Oracle Database blog


Oracle databases, storage and the high-performance world of flash memory

Future Veterans

Ramblings about Oracle

Ranjeet Srivastava

Smile! You’re at the best blog ever

Kevin Closson's Blog: Platforms, Databases and Storage

Platform, Database and Storage Topics

Real Life Database / SQL Experiences : An Oracle Blog from Vivek Sharma

Being an Oracle Professional, I like to share all my Real Life Performance Tuning Challenges and Experiences. The Content and Views on this site are my own and not necessarily those of Oracle. While, I write on my real life experiences, the resolutions mentioned are solely mine. Comments / Criticisms are always a welcome.

Frits Hoogland Weblog

IT Technology; Oracle, linux, TCP/IP and other stuff I find interesting


Dominic Brooks on Oracle Performance, Tuning, Data Quality & Sensible Design ... (Now with added Sets Appeal)

ASM Support Guy

Just Another Crazy Oracle DBA

Exadata Certification

Just Another Crazy Oracle DBA

Carlos Sierra's Tools and Tips

Tools and Tips for Oracle Performance and SQL Tuning

Sangram keshari's Oracle Blog

The Fusion Middleware Administration & Database Administration Blog

Amit Saraswat

Just Another Crazy Oracle DBA

Oracle Scratchpad

Just another Oracle weblog

The Tom Kyte Blog

Just Another Crazy Oracle DBA

Hemant's Oracle DBA Blog

Just Another Crazy Oracle DBA

Uwe Hesse

about Database Technology

Richard Foote's Oracle Blog

Focusing Specifically On Oracle Indexes, Database Administration and Some Great Music