12c: CONNECTING TO PDB'S WITH SAME NAME

When you create a PDB, the database automatically creates and starts a service inside the CDB.The service has the same name as the PDB. It is possible that the name of the service will collide with an existing service name which is registered with the same listener. For example if two or more CDBs on the same computer system use the same listener, and the newly established PDB has the same service name as another PDB in these CDBs, then a collision occurs.

You must not attempt to operate a PDB that causes a collision with an existing service name.

Top 12 New Features of Oracle 12c Summarized

Top 12 Features of Oracle 12C Summarized. This article is also available at www.ondemanddb.com
Summary: The Oracle 12C means different things to different people. It all depends on which areas you are looking at, as there are improvements in many areas. Summarized below is the list of Top 12 Features of Oracle 12C as I see it. I have summarized below, the top 12 which I found interesting.

About Apps 11i Clone – A Human Touch

Apps clone is like cloning a human being. Please read the detail below.

1) Run adpreclone on DB/CM/AP tiers

This is pre-requisite step of cloning 11i prod and will not change anything in any system. This script will only create on $COMMON_TOP, a directory called "clone", with a basic structure of executable, scripts, templates and java files. Later to the creation of the clone directory, the process picks up important information of your source system with which upgrades the necessary templates for the process adcfgclone that was carried out in the target server.

Deterministic function vs scalar subquery caching. Part 1

articles: 

I recently did a comparison caching mechanisms of scalar subquery caching(SSC) and deterministic functions in 11.2. Unfortunately, I do not have enough time to do a full analysis, so I will post it in parts.

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Oracle Database 12c: New Features - Pluggable Databases

articles: 

Oracle Database 12c: New Features – Pluggable Databases by Michael Rajendran

Introduction

The COST column of EXPLAIN PLAN

The COST column cannot be used to compare execution plans. Punkt.

What data type should I use: CHAR or VARCHAR2???

articles: 

Hi,

We all know that CHAR and VARCHAR2 are two different datatypes used for storing strings in Oracle. When I asked many people about what’s the difference exactly, all were saying VARCHAR2 can be used for variable sized character strings. As I’m not satesfied with the answer, as always, I’ve decided to do my own experiments on these two. Please find the exercise I’ve performed below.

SQL> create table t1 (col1 char(10), col2 varchar2(10));

Table created.

SQL> insert into t1 values(‘Oracle’,'Oracle’);

1 row created.

“ORA-01081: cannot start already-running ORACLE” While creating a new Database

articles: 

Hi Geeks,

When I was doing a research on Oracle Database creation, through DBCA, last week, I came across a very interesting scenario which I couldn’t stop sharing with you :)

I have a cluster of machines (don’t confuse it with a RAC cluster but just a group of machines required for my application deployment) with 11.2.0.2 installed and a Database instance running.

I got a requirement to remove everything accumulated in the machine as a result of the Oracle installation and the Database creation: The installation directories, the datafiles, oratab entries etc…

Can you create objects in a READ ONLY tablespace?

Hi Oracle geeks,

Last Friday, I’ve noticed a strange thing happening in my 11.2.0.3 Database: I’m able to create objects in a tablespace which is marked READ ONLY !!!

Don’t believe this?? See the below

SQL> create tablespace ro datafile ‘/xxx/RO.DBF’ size 10M AUTOEXTEND ON;
Tablespace created.

SQL> alter tablespace ro read only;
Tablespace altered.

SQL> select status from dba_tablespaces where tablespace_name=’RO’;
STATUS
———
READ ONLY

SQL> sho user
USER is “CSM“

Key Value Pair Data Model

articles: 

I have just joined an in flight project and find the lead data modeler has created a name value pair data model.

The reason given was flexibility of data model considering some records can have as many as 900 attributes. The .Net application team seem to be loving it, as they can code everything with very few tables in mind.

I feel the model is difficult to query, difficult to load and difficult to syndicate and in all likelyhood will suffer from poor performance. Also the data model can't be considered as a rich metadata repository and difficult to understand.

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