Saturday, June 28, 2014

Tablespace Reorganization

Tablespace Reorganization

Tablespace reorganization is a process of reorganizing the contents of a tablespace to reclaim free space from the datafiles of a tablespace. When a datafiles is resized (shrink), the size of a datafiles can only be reduced till the high water mark (last allocated extent to

Tuesday, June 24, 2014

ORA-01031 insufficient privileges - While logging in AS SYSDBA

OS Authentication is a setup whereby we can log into the oracle database as SYSDBA or SYSOPER without supplying any password because OS user (currently logged in) is already authenticated to log into the database as a privileged user. This is handy specially if you have forgotten the SYS password (another way to recover SYS password is

Sunday, June 22, 2014

Oracle IO Consumption - Throughput (IOPS) and Transfer Rate (MBPS)

Oracle Database IO Requirements (Throughput/IOPS and Transfer Rate/MBPS)

If we plan to migration an Oracle database to a new/different hardware, planning for storage is also a very important thing. It is good to find out the IO requirements of the database so that a better decision could be made while purchasing the storage. Storage speed is

Friday, June 20, 2014

Online Partition Move

As you know that Oracle partition is a database object used to partition the table’s data into multiple segments which might be stored in different tablespace for the manageability purposes. There are several partition operations that can be performed on the partitions which are called partition maintenance operations and one of them is the “partition move” which means: to move partition from one

Wednesday, June 18, 2014

Online Datafile Move or Rename

Here I am going to discuss one of my favourite new feature of Oracle 12c which has taken the down time away from the DBAs while moving or renaming a datafile online. There is no requirement of any downtime during this operation

Sunday, June 15, 2014

Oracle Segment Adviser Recommendations and Redo/Undo Generation During Segment Shrink

Since Oracle 10g, Oracle provided facility to reclaim the unused space from Tables and Indexes by using"ALTER TABLE <TABLE_NAME> SHRINK SPACE | COMPACT"  command.
Before we go through details of Oracle Segment Adviser Recommendations, it should be noted that during shrink space operation, a lot of undo and redo data is

Friday, May 30, 2014

Implementing Class of Secure Transport (COST)

To safeguard against security vulnerability (CVE-2012-1675) as published here, COST (Class of Secure Transport) parameter is used to restrict any remote instance to get registered with the listener running on a database server. This is done by adding a parameter SECURE_REGISTER_<LISTENER_NAME> = (TCP) in the listener.ora file

Sunday, May 18, 2014

RMAN Backup Performance

Finishing an RMAN backup on time (fast) is usually what every DBA looks for. Here I would be discussing my experience of RMAN backup scenarios which I tested for speed and performance. Environment details are as follows.

Tuesday, May 13, 2014

Converting a Failed Over Standby Database Back to Standby Database

I have seen some articles on the internet for reinstating a primary database after a failover (using flashback database technology – if FLASHBACK RETENTION time has not exceeded), but I was not able to find a document to revert or reinstate a “failed-over” standby database (which has now become primary) back to a standby database (using FLASHBACK technology).

Wednesday, April 23, 2014

ORA-01624 log needed for crash recovery of instance

It is quite common to see the error ORA-01624 while dropping a redo log group. The full error text is similar to “log <log_group#> needed for crash recovery of instance <instance_name (thread #)”.

As we know that Log Writer (LGWR) has the responsibility to write

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