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12c Database : Managing PDB’s

Starting/Stopping CDB and PDBs

The traditional approach of starting and stopping databases is now only valid for CDB. So in order to start and stop CDB you will use the familiar startup and shutdown commands.

PDBs don’t get automatically started with CDB. Even if your CDB is up and running it is possible […]

12c Database : Create PDB’s , Plug & Unplug

Create & Plug and Unplug PDB’s

To Create PDB’s the following methods can be followed


From PDB Seed

Cloning from a existing PDB using

Locally Remotely through DB Link

Plugging in

Plugging in an unplugged DB (unplug and plug as database into same container database) Plugging in a NON-CDB  as […]

12c Database : Truncate with Cascade

From 12c onwards,

Oracle 12c introduced truncate with cascade so when truncate operates on master table the child table rows also get truncated automatically.

SCOTT@PDB > create table MASTER ( 2 ID number generated always as identity PRIMARY KEY, 3 NAME VARCHAR2(20) 4 ); Table created. SCOTT@PDB > create table CHILD ( 2 ID […]

12c Database : RMAN backups and recovery with PDB

RMAN backup scenarios in 12c,

With the advent of 12c PDB/CDB rman backup has changed a lot while taking backups or restoration.

Backups on PDB or CDB “BACKUP PLUGGABLE DATABASE” – To take backups for a pluggable database “BACKUP DATABASE” – “BACKUP DATABASE;” on root container backs up the whole container includes SEED Container […]

12c Database: New groups for OS Authentication and New Sys roles and users

From 12c onwards we have seperate roles to be created for OS Authentication

Prior to 12c we have OSDBA, OSOPER, OSASM, OSDBA, OSOPER groups

From 12c onwards,

OSBACKUPDBA maps to backupdba by default and is used to allow users to backup the database. Users in this group can connect as SYSBACKUP and have their […]

How to determine to collect histograms or not (Even oracle determines by same)

From Oracle 10g, the Oracle SMON (System Monitor) process regularly gathers information on columns that are used in query predicates and updates them automatically into a table named COL_USAGE$ in the SYS schema. Unlike the MON_MOD$ table, also in the SYS schema, which records table-level DML activity such as the number of rows changed by […]

12c Database : Managing Parameters in Container databases

In a container architecture, the parameters for PDB will inherit from the root database. That means if statistics_level=all in the root that will cascade to the PDB databases.

You can over ride this by using Alter system set, if that parameter is pdb modifiable, there is a new column in v$system_parameter for the same.

The […]

12c Database : New Background Processes

Here is the filtered tables after comparison of 11g with 12c Background Processes.

Name Expanded Name Short Description Long Description External Properties AQPC AQ Process Coordinator Per instance AQ global coordinator AQPC is responsible for performing administrative tasks for AQ Master Class Processes including commands like starting, stopping, and other administrative tasks. This process is […]

12c Database : How does data dictionary will be shared for multiple databases?

Architecture of Data dictionary in view of multiple containers in a Single SGA

The above diagram requires a explanation.

Data Dictionary

A data dictionary resides in CDB is shared (definitions) between CDB & PDB, for those objects that are system (internal) For example: AWR is global, TAB$, OBJ$ etc.A data dictionary objects or […]

12c Database : Commons users & Local Users

Before to 12c, when using a single database the user management is pretty straight , create a user and assign the privileges or roles and manage it.

In view of multitenant architecture, where multiple databases exists managing multiple databases with a single users can be cumbersome, For example you a host that hosts 10 applications […]