OT RE: Common Oracle RDBMS Misconceptions

Yea, "hit ratios" are never important.

Ever.

For anything.

-----Original Message-----
Sent: Tuesday, June 26, 2001 2:01 PM
To: Multiple recipients of list ORACLE-L

Based on Gaja's book, tune based on waits not based on hit ratios.

Tom Terrian
Oracle DBA
WPAFB - DAASC
tterrian_at_daasc.dla.mil
937-656-3844

-----Original Message-----
Sent: Tuesday, June 26, 2001 1:05 PM
To: Multiple recipients of list ORACLE-L

All right folks, I'm collecting misconceptions, of the type held by newbies and
oldtimers alike. My OOW proposal this year is for a presentation and paper on a
whole laundry list of these things, similar to what I wrote for hot backup. I
want to share what I have so far and solicit input for your favorites (pet peeves). I most certainly will credit individuals and this list for any ideas I
glean.

So far my favorite misconceptions are:

• Hot backup stops writing to datafiles
• All network communication is done through the listener
• Always 'switch logfile' after (before, inbetween) hot backups
• Media recovery is required if you crash during backup mode
• Cold backup once a week ("just in case," "as a 'baseline'")
• Export is a good way to back up your database
• Shutdown abort is bad, crash recovery time is as long as 'shutdown immediate'
• Listener.log/alert.log clearing confusion
• ORA-1555 can be solved by setting transaction (use specific rollback seg)
• Big batch jobs should use one big RBS
• ORA-600 means you have corruption / just call support for ORA-600
• Lots of extents are bad
• Databases can't be renamed
• Select count (1) is better than count (*).
• Listeners have to be started before the instance
• NOLOGGING turns off logging for all operations
• Oracle Corp. won't support NFS datafiles
• checkpoint not complete - misguided solutions
• Must reinstantiate standby after failover by recopying
• redolog size change requires outage

What's *your* pet misconception?

--
Jeremiah Wilton
http://www.speakeasy.net/~jwilton

On Tue, 26 Jun 2001, novicedba wrote:

> I visited Jeremiah Wilton's web page http://www.speakeasy.net/~jwilton
> I was shocked to read Hot backup mode explained
> If this is true then I may be a victim of a disease called
> 'Common Oracle RDBMS Misconceptions' . Somebody help me!! (Jim carrey-MASK
style)
> Please help me. If some one has few more articles like this enlighten me

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Author: Jeremiah Wilton
  INET: jwilton_at_speakeasy.net

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