Oracle Database 12c: In-Memory Option

Starting with Oracle Database 12cR1 (, a new static pool in the SGA is designed to store data in the columnar format and is called In-Memory Column Store (IMCS). Each table column is stored as a separate structure in IMCS. The In-Memory column store does not replace the buffer cache, rather supplements by storing data in columnar format.

Following the levels at which IMCS can be enabled at:

AWR Warehouse

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 (more...)

Benefits of Single Tenant Deployments

While presenting at a database event, I had a question from one of the attendees on benefits of running Oracle databases in Single Tenant Configuration.  I thought this would be a nice if I post it on my blog as it would benefit others too.

From Oracle documentation, “The multitenant architecture enables an Oracle database to function as a multitenant container database (CDB) that includes zero, one, or many customer-created pluggable databases (PDBs). A (more...)

Oracle Database Express Edition 11g Release 2: Released

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

Happy downloading !!!

IOUG’s 2014 Exadata Virtual Conference

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
Minimizing Risks with Database Consolidation on Exadata using I/O Resource Manager (IORM)
Speaker: Sameer Malik, Exadata Technical Architect, Accenture
11am-12pm CST           
Introduction to the New Oracle Database In-Memory Option
Speaker: Kevin Jernigan, Senior Director, Oracle
12-1pm CST
Understand the Flash storage and (more...)

Oracle Database Security Assessment

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 (more...)

Forgot SYSMAN Password? Here’s How to Regain Access to EMCC-12c

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 (more...)

Oracle Database 12: Architecture Diagram

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.


Upgrading Oracle Database to 12.1.0 (Oracle 12c)

There are different ways of upgrading to the latest release of Oracle database and Oracle provides multiple methods to upgrade. Few are listed below:
  • Database Upgrade Assistant (DBUA)
  • Manual Upgrade
  • Transportable Tablespaces
  • Datapump export/import
  • Oracle Streams
  • Oracle GoldenGate
I chose DBUA to upgrade my test database as it was the (more...)

“An unexpected error has been detected by HotSpot Virtual Machine” Error While Launching Installer

Today while installing Oracle 11gR2 ( 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 (more...)

Connecting to Oracle Database Even if Background Processes are Killed

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 running on RHEL-5.5. The goal is to kill all Oracle background process and try to connect to (more...)

Oracle Linux 6.4 Announced

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):

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

Happy downloading!!! 

Exporting Multiple Tables on a Common Filter

To be frank, I consider myself novice when it comes to advanced export/import requirements. This is because I don’t deal with these utilities on a day-to-day basis.

A simple requirement came across my desk to export selected tables from a schema based on a common filter.

Say, you have 5 tables T1, T2, T3, T4, and T5. All have “ID” as the primary key column and you have to export data from these tables only if it is found in COMMON_TABLE. The COMMON_TABLE stores “ID” to be exported.

The first place that I look for solution is “Oracle (more...)

RACcheck for Single Instance Databases

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:

[oracle@localhost raccheck]$ ./raccheck -v

RACCHECK  VERSION: 2.2.0_20121109
[oracle@localhost raccheck]$ 
[oracle@localhost raccheck]$ 
[oracle@localhost raccheck]$ ./raccheck -a

List of running databases
1. testdb
2. None of above

Select databases from list for checking best practices. For multiple databases, select 1 for All or comma separated number like 1,2 etc [1-2][1].
. .

Checking (more...)

Bug: ORA-00979: not a GROUP BY expression

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 ( to Oracle 11gR2 ( 

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

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



However, the same query started to throws an error (ORA-00979) when executed in Oracle 11gR2 (11.2. (more...)

Online Free Courses from World’s Best Universities

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:

Happy learning !!!

OOW-2012: Oracle 12c New Features

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


Oracle RAC 12c: New Features

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 (more...)

OOW-2012: Very Large Databases (VLDB): Challenges and Opportunities

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 !!!


PARALLEL_MIN_TIME_THRESHOLD initialization parameter controls which statements are candidate for parallelism. 

As per MOS, this parameter is set to 10 seconds while Oracle documentation claims that it is set to 30 seconds. Now who's correct ??? Seems like it's a documentation bug.

Below are the links to both Oracle documentation and MOS article: