Smart File Creation with Oracle Exadata

Hi ,

From last week  , I completed Oracle Exadata POC with my customer and I'm very surprised with Exadata performance because first time I hearing about Exadata performance , I just say "I don't trust it" , "I can tuning sql , db performance faster than it."  ok , don't talk to much.
This section I would like to proof concept of Smart file create on Oracle Exadata Feature.
See the follow Test case during  S.. XXX  Machine V.S. Exadata Machine.
Note
-S... XXX disk I/O per sec around 384 MB /sec
-Number of disks is equal in +DATA diskgroup.

S.. XXX Machine
CHATCHAI_K > create tablespace TEST datafile '+DATA' size 30G , '+DATA' size 30G , '+DATA' size 30G , '+DATA' size 30G;

Tablespace created.

Elapsed: 00:06:15.23

----------------------------------------------------------------------------

Exadata Machine
EXADATA_HALF_RACK > create tablespace TEST datafile '+DATA' size 30G , '+DATA' size 30G , '+DATA' size 30G , '+DATA' size 30G;

Tablespace created.

Elapsed: 00:01:11.70


"Oh it faster" why it faster ? , I looking for v$sysstat relate optimizing file creation that oracle don't  format any new data block in memory and sending through interconnect but I simply say hey ! storage server I would like to create 4 datafile each size 30G let do it for me  , everyting offloading to the cell storage no format block level and more task on database server , This feature is call "Smart File Creation"

Cheer ,

How to disable ADDM after AWR snapshot

Do not apply step in this topic to production environment becuase changing internal parameter leading oracle software to unsupport by global support.

I believe many of dba love ADDM  , it is good friend but some senior or dba who had a lot of tuning expriece may don't trust or like it  , someone talk Hey ! I would like to use my knowledge for anlyze the system , how is going on  , how to leave it from his/her life because it so alluring to use.
the follow is step to disable addm :
 
  $ sqlplus /nolog
  CHATCHAI_K > conn / as sysdba
  CHATCHAI_K > alter system set "_addm_auto_enable"  = false scope=both sid='*';
 
Cheer !!
However ADDM is a good utility to helping you to faster tracking the overall system performance analysis and any sql statement may have a problem compare with the period time.

Oracle NULL=NULL or NULL is NULL ?

I'm believe many of people confuse  null = null is equal null is null or not ? , which method should be, how about performance or something elase ,
however This topic we'll prove oracle treat the null value together

Considerate the easier example :
   CHATCHAI_K> select sysdate from dual where null=null
   no row selected
   CHATCHAI_K> select sysdate from dual null is null
   sysdate
   -
   31-OCT-10

from example  it prove  oracle NULL is not equal to NULL, but in some database vendor such as Sybase null is equal to null  , therefore when you migrate database from one to another , your application may retrieve a wrong result that is not database processing wrong but it is just work difference that you need to understand !

Cheer !

How do I change the name of the oracle database

Hi all this is first post in my web blog   , I'm database consult (oracle & mysql) , I would like to share some tip , technique and new technology of oracle and mysql to helping people be successful to  , from first topic we'll going  to how to change oracle database name as
here is step by step :
 
1. Backup the database first ( via alter tablespace begin backup , rman or some backup tools) (the process of backup that beyond scope of my topic.)

2. Logon to database and shutdown :
      $ sqlplus /nolog
      SQL> conn / as sysdba
      SQL> select count(1) from v$transaction
      or in RAC used gv$transaction instead.
      SQL> shutdown immediate;
      SQL> startup mount;
 3.  Call DBNEWID utility with sysdba
       $ nide target=sys/password dbname=new_name setname=yes
 4.   Shutdown database
 5.   Change New name :
       $ sqlplus /nolog
       SQL> conn / as sysdba
       SQL> startup nomount;
       SQL> alter system set db_name=new_name scope=spfile;
       SQL> shutdown immediate;
 6.   Create new password file
        $ orapwd file=$ORACLE_HOME/dbs/pwdnew_name.ora password=password entries=5
 7.    Reset ORACLE_SID environment in .profile (aix,solaris) or .bash_profile(linux)
        Change to
            ORACLE_SID=new_name;export ORACLE_SID
        or in the shell terminal try
            export ORACLE_SID=new_name
 8.    Alter listener.ora and tnsname.ora settings to match the new database and restart listener by:
        $ lsnrctl reload
  9.   Startup (no resetlog require for change database name only)
        $ sqlplus /nolog
        SQL> conn / as sysdba
        SQL> startup