OTN Article : Oracle Database 12c, O que acontece em um CDB quando um PDB tem ser recuperado

OTN - Oracle Technology Network Latina America continue publish our articles. Our 7th technical article published on OTN in Portuguese Language at 20th August. This article entitled : Oracle Database 12c, O que acontece em um CDB quando um PDB tem ser recuperado written by Joel Perez (Oracle ACED), Mahir M. Quluzade (OCE) and Rodrigo Mufalini (Oracle ACE) .

It is a link of article: http://www.oracle.com/technetwork/pt/articles/database-performance/cdb-quando-pdb-tem-ser-recuperado-2270042-ptb.html

Thanks to my friends, Joel and Rodrigo, for their (more...)

Commit scalability

I am learning about how well commits scale on Oracle 11.2 and so far they seem to scale surprisingly well.

I’ve looked at two waits – log file parallel write and log file sync.  Based on documents I’ve read on Oracle’s support site log file parallel write represents the time it takes to do one write to the redo logs.  For mirrored redo logs the log file parallel write time includes the (more...)

Viewing ASM trace files in VIM: Which Way Do You Use?


A couple of people have asked me recently about a classic problem that most DBAs know: how to view ASM trace files in the VIM editor when the filenames start with a + character. To my surprise, there are actually quite a few different ways of doing it. Since it’s come up, I thought I’d list a few of them here… If you have another one to add, feel free to comment. I know that (more...)

Oracle 12c ( database step by step installation guide on redhat linux 5.6


Download Document here

Oracle 12c database installation guide on redhat linux 5.6

OTech Magazine Issue #4: Summer 2014 Published

OTech Magazine - The independent magazine for Oracle professionals. Yesterday fourth issue of the OTech Magazine, the independent magazine for Oracle professionals published.

 In this issue also included my article: Oracle Database 12c: Cross Platform Transport non-CDB to PDB using RMAN Backup Sets

You can download online OTech Magazine #4 Isssue - Summer 2014

Summary of article

We can create a PDB using upgraded database (non-CDB) and can be adopt the 12.1 non-CDB into (more...)

New Tips and Techniques page

In case you haven’t noticed it – and chances are you haven’t noticed because I just created it! :) – I’ve added a new page called “Tips and Techniques” to the website. It’s where I keep a random collection of odd items I’ve come across that might be of interest yet don’t deserve a full blog post. It’s sort of like a FAQ list, but not necessarily with the “F”. :)

You can reach it either via (more...)

Block size and multirow DML peformance

While 8k is the default block size, Oracle supports other block sizes, too. Smaller block sizes (more commonly, 4k) are encouraged for OLTP workloads to reduce concurrency, and even smaller block size, 2k, is recommended for databases running on “Advanced format” (or “4K”) storage. Oracle documentation warns us of possible implications when storing larger rows in 2k/4k blocks, such as potentially larger space overhead due to metadata, or even possibility of row chaining. What it (more...)

LOB Length

It’s funny how you can make little savings in work all over the place in Oracle if you’re prepared to look a little closely at what’s going on. Here’s a quirky little example with LOBs and function calls that might just have some greater relevance in other situations. Here’s a little data set, and two queries that I might run against it:

create table tbl(
	c1      clob
lob (c1) store as c_lob(
	disable storage  (more...)

Zone Map Zone ID’s

Just a quick follow up to my previous post on how Zone ID's are calculated.

Let's take the following example:
SQL> select rid, sys_op_zone_id(rid) zone_id
2 from
3 (
4 select chartorowid('AAAS5KAAHAAABYDAAA') rid
5 from dual
6 );

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

Recalling that extended ROWID has the following format (a nice picture from Oracle Documentation):

In the binary format that would correspond to:
  • Data Object Number -- 32 bits
  • Relative File (more...)

Oracle 11204 Clusterware upgrade – ASM glitch

Yet another tough challenge thrown at my team right after the disaster recovery (DR) simulation drill which performed barely couple of weeks ago. The new task (challenge) in hands is to upgrade the existing four cluster environments from to as Oracle already stopped supporting v11.2.0.2.

Although last week we had a 3 node successfully upgrade track record, we encountered ASM upgrade troubles whilst running (more...)

In Search of Plan Stability (Part 1) – August 27 webinar

Register by clicking here.

Hope you'll join me!

kgxgncin: CLSS init failed with status 3

At the end of September, I will be walking 26.2 miles (the marathon distance) in aid of Great Ormond Street Hospital If you find the post below useful and you have any money to spare, you might like to click on the Just Giving link on the right of this page and sponsor me.

I had a problem with an Oracle database producing trace files every few minutes. Here (more...)

Why am I seeing “Result: Failed. Insufficient resource available” messages?

This is an interesting point that came up recently, where someone had a DBaaS environment running on an Exadata system for a couple of months, with no issues.  It has recently started to return errors on the Database Cloud Self Service portal in the “Placement Algorithm” region:

Constraint : Number Of Databases
Current Resource Usage: 18
Total Resource Available: 10
Maximum Limit Defined: 10
Requested Value: 1
Total Resource that can be used: 10

Weblogic Start Failure: Empty Initial Replica

This post is to address a failed Weblogic start in EM12c.  The fix is performed on a Windows host, but the fix can easily be for any EM12c environment that experiences this issue.  In the below instructions, just replace the %OMS_BASE% for Windows Env Var to $OMS_BASE for Linux/Unix.

Issue:  OMS Fails to Start and Points to Weblogic Issue in EMGC_OMS1.out File.

Error in Out File:  <Critical> <WebLogicServer> <BEA-000386> <Server subsystem (more...)

Zone Maps

Zone Maps is a new feature that got officially introduced in so I've decided to take a closer look.

From the Oracle Documentation:
For full table access, zone maps allow I/O pruning of data based on the physical location of the data on disk, acting like an anti-index.

Let's start by creating a test table:
SQL> create table t pctfree 95 clustering by linear order (n) as
2 select level (more...)

What Is Oracle Elapsed Time And Wall Time With A Parallelism Twist

What Is Oracle Elapsed Time And Wall Time With Parallelism Twist

In this post I'm focusing on Oracle Database SQL elapsed time, adding parallelism into the mix and then revisiting wall time. What initially seems simple can take some very interesting twists!

If you are into tuning Oracle Database systems, you care about time. And if you care about time, then you need to understand the most important time parameters: what they are, their differences, (more...)

12c metadata only default values for NULL columns

Before 11g if you added a new column to a table then Oracle had to lock and physically update all rows in the table. Possibly a painful process :) 11g helped with that a little, giving metadata only default values for NOT NULL columns, so the change was done only in data dictionary, not in the table data.

SQL> create table default_values (
  2    id number primary key
  3  );

Table created.

SQL> insert into  (more...)

SQL Mini-challenge entry: Kim Berg Hansen v6

by Kim Berg Hansen

Okay, okay, Iggy, you want one buffer get? I’ll do it ;-)

Actually two different versions that might be useful in different circumstances. First one goes like this:

create materialized view log on employees with rowid, commit scn
   (employee_id, job_id, first_name, last_name, department_id)
   including new values;
create materialized view log on departments with rowid, commit scn
   (department_id, location_id)
   including new values;
create materialized view log on locations with rowid, commit scn

find out which device mapped with oracle asm disk

Step 1 :


[oracle@asmoracle ~]$ /etc/init.d/oracleasm listdisks



Step 2 :

[oracle@asmoracle ~]$ /etc/init.d/oracleasm querydisk -d DISK1
Disk “DISK1″ is a valid ASM disk on device /dev/sdc1[8,33]

The device noted here is (8,33), so go to


[root@asmoracle dev]# ls -l sd*
brw-r—– 1 root disk 8, 0 Aug 18 08:39 sda
brw-r—– 1 root disk 8, 1 Aug 18 08:39 sda1
brw-r—– 1 root disk 8, 2 (more...)

“You’re A Real ACE”

Recently I was declared, for want of a better word, an Oracle ACE. I was nominated by someone I respect and admire; just the nomination itself was enough, really, to make my day. When I received notification that I had been selected I was truly surprised. I immediately thanked my nominator, who told me:

"Still, it is just a nomination form, and you did all the work that
made it so impressive. Congratulations!"

Honestly, (more...)