RDBMS Server

Oracle RDBMS Server Articles

The ever expanding UNDO tablespace.


During a quite evening of my last on-call bout I was alerted from our monitors that the UNDO tablespace was running out of free space. Thought of adding of a new data file and be done with it; When I checked the current allocation for this tablespace it was already at 40G - couldn't believe what I was seeing. The undo_retention was set to 7200 and max query length in v$undostat was not that high. One column that did caught my eye was the tuned_undoretention, its value was way very high.

Performing a quick and efficient Performance Tuning audit


Checks to be performed at the machine level (note the example is Red Hat Linux)

run queue should be ideally not more than the number of CPU’s on the machine

At the maximum it should never be more than twice the number of CPU’s.

This is denoted by the column ‘r’ in the vmstat output shown below

vmstat – 5

face:/opt/oracle>vmstat 5
procs memory swap io system cpu
r b swpd free buff cache si so bi bo in cs us sy id wa
4 1 488700 245704 178276 12513572 0 1 10 17 48 1365 40 12 43 5

How to import table with custom type


When importing table that contained custom type, you will encounter an oracle error as shown below:
Import of table containing object type(s) fails with IMP-00061 IMP-00063

RMAN checksyntax


RMAN is recommended for backups/restore of oracle databases.It is a very powerful tool and has variety of useful features.There is 'checksyntax' feature in RMAN which allows one to check RMAN scripts syntactically without executing it.This feature is available from 10G release 2.It proves to be useful for checking scriptsfor live databases where one doesnt have leisure to execute scripts any time and any times!!

bash-3.00$ vi rman_bkp.rman

ORA_ROWSCN for capturing row level changes


I've been working on way to capture changed rows using ora_rowscn for part of an ETL routine. Here are some details of what I've tested and found.

By default, the ora_rowscn pseudo column reports the scn at block level. This means that rows sharing the same block will have the same ora_rowscn, and if one row were to be changed, then scn would be altered for both blocks.

Oracle 10g Data Guard – Quick Switchover with Physical Standby Database


Once the standby database is setup using Data Guard and works properly, you may want to test switchover, or perform switchover to reduce primary database downtime during OS upgrades or hardware upgrades. (To set up a Physical Standby database, please refer to my OraFAQ blog “Oracle 10g – Manually Create a Physical Standby Database Using Data Guard”.)

A switchover allows the primary database to switch roles with its standby database. There is no data loss during a switchover. You can switch back to the original Primary database later by performing another switchover.

How to Identify OS or Oracle 64 bit or 32 bit


How to Identify OS or Oracle 64 bit or 32 bit on Unix
It is very common question which version of oracle I need to install. 32 bit or 64 bit? As a 64-bit operating system can support either a 32-bit database or a 64-bit database. A 32-bit operating system cannot support a 64-bit database. So, version identification of the OS is necessary prior to install oracle. The following procedure will hopefully help you.

Oracle 10g - Manually Create a Physical Standby Database Using Data Guard


Step-by-step instructions on how to create a Physical Standby Database on Windows and UNIX servers, and maintenance tips on the databases in a Data Guard Environment.

Mohammad taj's picture

Why I Choose Oracle as My Career?


There are some question which asked frequently on forums from every oracle newbie.

1. Which Oracle Certification I choose ?

Here I will explain in details.

There types of Oracle Certification we can do.
1. Oracle DBA
2. Oracle Developer
3. Oracle Application DBA

1. Oracle DBA

The person which maintain Oracle Database called Oracle Database Administrator.
There are some frequent work for Oracle DBA
1. Database Backup Responsibity.
2. Database Performance Tunning
3. Database Basic Administration Like " user creation, database security"

Mohammad taj's picture

How to compile Invalid Object?


There are five ways to recompile invalid objects in schema.

5. Manually Recompile



This procedure is equivalent to the following SQL statement:


Exec dbms_ddl.alter_compile ( type , schema, name);
Schema : Database Username

Name : Objects name



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