Asif Momen

• Column
• Partition / sub-partition
• Table
• Materialized view
• Tablespace

The IMCS is populated by a set of background processes. Objects are populated into the IMCS either in a prioritized list soon after database start-up or after they are queried for the first time.

Like other Oracle Database Options, you make NO changes in your application to start benefiting from the In-Memory Option. It is completely transparent to the applications. Also, Oracle Optimizer is fully aware of the column format and automatically utilizing IMCS when required.

• Enable and disable In-Memory Option
• In-Memory Option at various levels
• In-Memory Space pressure
• In-Memory background processes
• In-Memory with compression levels
• In-Memory statistics
• In-Memory and Data Pump Export
• In-Memory with Multi-tenant Option

AWR Warehouse is a central repository configured for long term AWR data retention. It stores AWR snapshots from multiple database sources. Increasing AWR retention in the production systems would typically increase overhead and cost of mission critical databases. Hence, offloading the AWR snapshots to a central repository is a better idea. Unlike AWR retention period of default 8 days, the AWR Warehouse default retention period is "forever". However, it is configurable for weeks, months, or years. 

For more information on AWR Warehouse click on the following link for a video tutorial. 

http://www.youtube.com/watch?v=StydMitHtuI&feature=youtu.be

1. Alignment with Oracle’s new multi-tenant architecture
2. Cost saving. You save on license fee as single tenant deployments do not attract Multi-tenant option license fee. License is applicable should you have two or more PDBs.
3. Upgrade/patch your single PDB from 12.1.0.1 to 12.x easily with reduced downtime
4. Secure separation of duties (between CDBA & DBA)
5. Easier PDB cloning

Oracle Database Express Edition 11gR2 has been released. You may download the software and documentation following below links:

• Oracle Database Express Edition 11gR2 Software
• Oracle Database Express Edition 11gR2 Documentation

Happy downloading !!!

IOUG is organizing a two-day virtual Exadata Conference on 29-30 Jan, 2014. More importantly the virtual conference is FREE. Following is the agenda as per the IOUG's website:

29-Jan-2014 (Wednesday)

10-11am CST 11am-12pm CST            12-1pm CST 30-Jan-2014 (Thursday)

10-11am CST 11am-12pm CST         12-1pm CST
For more information and registration click on the below link:

http://www.ioug.org/exavirtual2014

Data Security has taken a front seat in terms of IT Security lately. Database security is an area of information security that is concerned with the use of security controls to protect databases. Organizations are trying to protect their databases from both internal and external threats. 

In this regard, Oracle has put up an online Database Security Assessment on their website. You may now check how secure your database is by answering few simple questions. 

Below is the link for Oracle's Database Security Assessment:

http://www.oracle.com/us/media/survey/index-191234.html


I am also sharing top ten most common database security vulnerabilities by ZDNet. Below is the link for the same:


http://www.zdnet.com/the-top-ten-most-common-database-security-vulnerabilities-7000017320/


Wishing you a secure database !!!

I installed Oracle Enterprise Manager Cloud Control 12c soon after it's release in a virtual environment for the purpose of testing. I normally save passwords, ip-address, ports, and other details in a text file. But unfortunately, I was not able to locate the file for this particular VM.

However, it was easy to reset the password following these steps:

1) Stop OMS (leaving the Admin Server up)
2) Modify SYSMAN password
3) Stop all OMS components
4) Start OMS
5) Login to Oracle EMCC-12c with the new password



1) Stop OMS (leaving the Admin Server up)

Stop the OMS without "-all" as shown below:

[oracle@emcc bin]$ ./emctl stop oms
Oracle Enterprise Manager Cloud Control 12c Release 2
Copyright (c) 1996, 2012 Oracle Corporation.  All rights reserved.
Stopping WebTier...
WebTier Successfully Stopped
Stopping Oracle Management Server...
Oracle Management Server Successfully Stopped
Oracle Management Server is Down
[oracle@emcc bin]$


2) Modify SYSMAN password

[oracle@emcc bin]$
[oracle@emcc bin]$ ./emctl config oms -change_repos_pwd -use_sys_pwd -sys_pwd XXXXX -new_pwd mynewpassword
Oracle Enterprise Manager Cloud Control 12c Release 2
Copyright (c) 1996, 2012 Oracle Corporation.  All rights reserved.

Changing passwords in backend ...
Passwords changed in backend successfully.
Updating repository password in Credential Store...
Successfully updated Repository password in Credential Store.
Restart all the OMSs using 'emctl stop oms -all' and 'emctl start oms'.
Successfully changed repository password.
[oracle@emcc bin]$

3) Stop all OMS components

[oracle@emcc bin]$ ./emctl stop oms -all
Oracle Enterprise Manager Cloud Control 12c Release 2
Copyright (c) 1996, 2012 Oracle Corporation.  All rights reserved.
Stopping WebTier...
WebTier Successfully Stopped
Stopping Oracle Management Server...
Oracle Management Server Already Stopped
AdminServer Successfully Stopped
Oracle Management Server is Down
[oracle@emcc bin]$
[oracle@emcc bin]$

4) Start OMS

[oracle@emcc bin]$ ./emctl start oms
Oracle Enterprise Manager Cloud Control 12c Release 2
Copyright (c) 1996, 2012 Oracle Corporation.  All rights reserved.
Starting Oracle Management Server...
Starting WebTier...
WebTier Successfully Started
Oracle Management Server Successfully Started
Oracle Management Server is Up
[oracle@emcc bin]$


5) Login to EMCC-12c

I was able to login to the EMCC-12c console with the new password without any issues.

For more information refer to MOS - 1365930.1

I found the following Database Architecture Diagram for Oracle Database 12c on Oracle Education's website. It lists all the processes and the relationship between processes and other database components. I recommend you to take a print on A3 paper.



And below is a YouTube link which gives database architecture overview.

Oracle Database 12c Architecture Overview


Update - 1 (11-Jul-2013):

Below is Oracle Database 12c Multi-Tenant Architecture Diagram:

• Database Upgrade Assistant (DBUA)
• Manual Upgrade
• Transportable Tablespaces
• Datapump export/import
• Oracle Streams
• Oracle GoldenGate

1. Backup Oracle database
2. Stop the database
3. Stop listener
4. Change ORACLE_HOME environment variable in the bash profile of “oracle” user
5. Launch Oracle 12c Installer (./runInstaller)

Click "Next" and chose "Skip software updates".


Click "Next" and select "Upgrade an existing database". When you select this option Oracle will install Oracle 12cR1 software and then automatically launch DBUA to upgrade the databases.


Click "Next" and continue as shown in the screenshots below:







Make sure all the warnings are resolved before proceeding with the next step. In my case, I ignored the warning as this is a test database and the swap size is almost closer to the expected value.




 After installing the software and completing Net configuration, Oracle Universal Installer will launch DBUA to upgrade existing databases.



I ignored the warnings as this is our test database. You would like to resolve these warning for your production, development, testing, etc databases.









 Well, that's it. My database is now upgraded to Oracle Database 12c.

SQL> select * from v$version;

BANNER CON_ID
---------------------------------------------------------------------------- ----------
Oracle Database 12c Enterprise Edition Release 12.1.0.1.0 - 64bit Production      0
PL/SQL Release 12.1.0.1.0 - Production      0
CORE 12.1.0.1.0 Production       0
TNS for Linux: Version 12.1.0.1.0 - Production      0
NLSRTL Version 12.1.0.1.0 - Production      0

SQL> 

Today while installing Oracle 11gR2 (11.2.0.3) 64-bit on RHEL 6.1 64-bit on a VMWare box, I received the mentioned error. Looking up at MOS wasn't fruitful. However, this seems to be an RHEL bug.


bash-4.1$ ./runInstaller 
Starting Oracle Universal Installer...

Checking Temp space: must be greater than 120 MB.   Actual 27976 MB    Passed
Checking swap space: must be greater than 150 MB.   Actual 4031 MB    Passed
Checking monitor: must be configured to display at least 256 colors.    Actual 16777216    Passed
Preparing to launch Oracle Universal Installer from /tmp/OraInstall2013-07-01_03-12-27AM. Please wait ...bash-4.1$ #
# An unexpected error has been detected by HotSpot Virtual Machine:
#
#  SIGSEGV (0xb) at pc=0x00007f33a28c8d70, pid=2400, tid=139859082229520
#
# Java VM: Java HotSpot(TM) 64-Bit Server VM (1.5.0_30-b03 mixed mode)
# Problematic frame:
# C  [ld-linux-x86-64.so.2+0x14d70]
#
# An error report file with more information is saved as hs_err_pid2400.log
#
# If you would like to submit a bug report, please visit:
#   http://java.sun.com/webapps/bugreport/crash.jsp
#

bash-4.1$ 

Yesterday, I received an email update from MOS Hot Topics Email alert regarding a knowledge article which discusses how to connect to an Oracle database whose background processes are killed.

I bet every DBA must have encountered this situation at least once. When I am in this situation, I normally use "shutdown abort" to stop the database and then proceed with normal startup. 

After receiving the email, I thought of reproducing the same. My database (TGTDB) is 11.2.0.3 running on RHEL-5.5. The goal is to kill all Oracle background process and try to connect to the database.

Of course you don't want to test this in your production databases. 

SQL> select * from v$version;

BANNER
--------------------------------------------------------------------------------
Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production
PL/SQL Release 11.2.0.3.0 - Production
CORE    11.2.0.3.0      Production
TNS for Linux: Version 11.2.0.3.0 - Production
NLSRTL Version 11.2.0.3.0 - Production

SQL> 

Below is the list of background processes for my test database "TGTDB":

Let us try to update a record. 


SQL> 
SQL> update test.emp  set ename = 'test' where eno = 2;

1 row updated.

SQL>        

Wow, one record was updated. But when you try to commit/rollback, the instance gets terminated. And it makes sense as the background processes responsible for carrying out the change have all died.

SQL> 
SQL> commit;
commit
     *
ERROR at line 1:
ORA-03113: end-of-file on communication channel
Process ID: 8917
Session ID: 87 Serial number: 7


SQL> 

Following is the error message recorded in the database alert log:



Wed Mar 13 01:41:44 2013
USER (ospid: 8917): terminating the instance due to error 472
Instance terminated by USER, pid = 8917

References:

1. Successfully Connect to Database Even if Background Processes are Killed [ID 166409.1]

The Oracle Linux team has announced the availability of Oracle Enterprise Linux (OL) 6.4. You can download OEL-6.4 from Oracle's EDelivery website (the link is below):

https://edelivery.oracle.com/EPD/Search/handle_go

To learn more about OL-6.4 click on the below link.

http://docs.oracle.com/cd/E37670_01/E39522/html/

Happy downloading!!! 

expdp test/test DIRECTORY=data_pump_dir TABLES=t1,t2,t3,t4,t5 DUMPFILE=test.dmp QUERY=\"WHERE id IN \(SELECT common_table.id FROM common_table\)\"

Starting with RACcheck 2.2.0, RACcheck support is extended to Oracle Single Instance Databases, Oracle Restart and RAC One Node configurations. 


I downloaded the latest version of the tool and tested it against my play database. Below is a sample RACcheck output from a single instance database:






Refer to the MOS document mentioned below to learn more about RACcheck tool. You may download the latest version of RACcheck from My Oracle Support (MOS).

References: 

RACcheck - RAC Configuration Audit Tool [ID 1268927.1]

Bugs and performance degradation are part of database upgrade stories and we have witnessed yet another post-upgrade bug after upgrading our database from Oracle 10gR2 (10.2.0.5) to Oracle 11gR2 (11.2.0.2). 

Following query (I have simplified the query for the demonstration purpose) was running happily within Oracle 10gR2:


SQL>
SQL> select * from ( select TRUNC(dt,'MM')
  2          from test
  3          group by TRUNC(dt,'mm'));

TRUNC(DT,
---------
01-JAN-13

SQL>


However, the same query started to throws an error (ORA-00979) when executed in Oracle 11gR2 (11.2.0.2): 


SQL> select * from v$version;

BANNER
--------------------------------------------------------------------------------
Oracle Database 11g Enterprise Edition Release 11.2.0.2.0 - 64bit Production
PL/SQL Release 11.2.0.2.0 - Production
CORE    11.2.0.2.0      Production
TNS for Linux: Version 11.2.0.2.0 - Production
NLSRTL Version 11.2.0.2.0 - Production

SQL> 


SQL> select * from ( select TRUNC(dt,'MM')
          from test
          group by TRUNC(dt,'mm'));
  2    3  select * from ( select TRUNC(dt,'MM')
                             *
ERROR at line 1:
ORA-00979: not a GROUP BY expression


SQL> 






Bug 11067251 - False ORA-979 with TRUNC(date, format) or ROUND(date, format) - superceded [ID 11067251.8]


Apparently, you hit the bug when you use either TRUNC or ROUND functions in an inline view. Executing the same query with little modification (removing inline view) in 11.2.0.2 was however successful.


SQL> select TRUNC(dt,'MM')
 from test
group by TRUNC(dt,'mm');
  2    3  
TRUNC(DT,
---------
01-JAN-13

SQL> 

The above bug confirms that 11.2.0.2 is affected and proposes following two workarounds: 

1) Use NO_MERGE hint or
2) Disable view merging "_simple_view_merging=false" 

As it was not possible to rewrite the application at this point, so we disabled view merging at the system level. Well, disabling view merging at the system level might appear as a bad choice but I think it is a right decision at this time. We will soon be upgrading this database to 11.2.0.3. This will kill two birds with one stone, a) bug fix and b) upgrading to the latest patch level (who knows what new bugs are waiting for us ???).

References: 

• My Oracle Support:  Bug 11067251 - False ORA-979 with TRUNC(date, format) or ROUND(date, format) - superceded [ID 11067251.8]

Coursera is offering courses free online. The courses are delivered from faculty members of top universities in the world. You may find more information on the courses at:

https://www.coursera.org/


Happy learning !!!

Blogging right from Tom's session "database new features". Here are the new features as they are discussed:

1. Identity Columns

Remember I blogged on this topic earlier.

2. Default on null

A default value is inserted into the column When it's null.

3. Improved defaults - metadata only defaults

Now add new default columns to a table on the fly. 12c does that for you.

4. Increased size limit for Varchar2 and NVarchar2

The column types can be upto 32k.

5. Row Pattern Matching

Efficient SQL functionality for reporting row patterns like identifying V and W patterns for your stock

6. Partitioning Improvements

Online partition movement without using DBMS_REDEFINITION. Efficient global index management during DROP and TRUNCATE partition operation.


7. Hybrid Histograms

Jonathan Lewis spoke on this topic. I think more information on this is available on his blog.

8. Session private statistics for GTTs

Table and index statistics are held private for each session.

9. Temporary UNDO
Undo for temporary tables can now be managed in TEMP. Reduces the amount of undo generated in undo tablespace and redo generation.

10. Pluggable databases

Read Roels blog for this one. He has a good blog post on this

http://roelhartman.blogspot.com/

Blogging live from OOW session on "Enhancements in Oracle RAC". Following are few Oracle RAC 12c new features being discussed in this session as I post:

1. Application Continuity

2. Oracle Flex ASM
With this feature, database instances use remote ASM instances. 

3. Oracle ASM Disk Scrubbing
Checks for logical data corruptions and repair them automatically.

4. Enhancements to Policy-based Databases
Actively utilizes different sized servers

5. What - if analysis for server pool management

6. Standardized deployment and patching 
Introducing GHS, rapid home provisioning and gold images

7. A new "ghctl" command for better patching

8. Oracle Utility Cluster

9. Dynamic IP Management and name resolution made easy

10. IPv6 Based IP Addresses Support for client connectivity

11. Multi-purpose Installation

12. Oracle installer will run Fix-up scripts & "root.sh" scripts across nodes. You don't have to run the scripts manually on RAC nodes.



Exciting new features !!!

I would like to thank all the attendees for attending my session "Very Large Databases (VLDB): Challenges and Opportunities". I am glad, the hall was full to it's capacity. :)

You may download the presentation by logging into OOW-2012 schedule builder. 

I request all the attendees to kindly rate my session by logging into OOW: Schedule Builder.

See you all !!!