Please see my other blog for Oracle EBusiness Suite Posts - EBMentors

Search This Blog

Note: All the posts are based on practical approach avoiding lengthy theory. All have been tested on some development servers. Please don’t test any post on production servers until you are sure.

Monday, December 29, 2014

Resetting unrecoverable_time in v$datafile

When you create a table or index as NOLOGGING, the database does not generate redo log records for the operation. Thus, you cannot recover objects created with NOLOGGING, even if you run in ARCHIVELOG mode. If you cannot afford to lose tables or indexes created with NOLOGGING, then make a backup after the unrecoverable table or index is created. 

Thursday, December 25, 2014

Raw Device Setup for ASM


Today one of the DBA requested to have the ASM instance based on raw devices. I provided the below  as a quick demo.

Wednesday, December 24, 2014

Using OCLUMON to analyze Cluster Health

Cluster Health Monitor & OCLUMON

The Cluster Health Monitor (CHM) stores real-time operating system metrics in the CHM repository that you can use for later triage with the help of Oracle Support should you have cluster issues.

It consists of System Monitor Service, Cluster Logger Service, CHM Repository

Thursday, December 11, 2014

ASMCA tabs Volume and ASM Cluster File System are grayed out

DBA wanted to create the ACFS but got the Volume and Cluster File System grayed out.


ORA-01427 While running DBMS_HM.RUN_CHECK

  2      DBMS_HM.RUN_CHECK('Dictionary Integrity Check', 'HC1');
  3  END;
  4  /

Wednesday, December 10, 2014

Configuring ACFS (Standalone Server) 11gR2


Client has standalone GI installation  and wants to check the ACFS feature.


Oracle ACFS is designed as a general-purpose, single-node and clusterwide file system that delivers support for customer file system application data maintained outside of Oracle Database. Users and applications can access and manage Oracle ACFS using native operating system file system application programming interfaces (APIs) and command-line interface (CLI) tools. Users can also manage Oracle ACFS with Oracle Enterprise Manager.

Tuesday, December 09, 2014

Configuring Oracle Grid Infrastructure for a standalone server (11gR2)

1- One of our DBA already had installed Oracle (11gR2 RDBMS on Linux 5.8
2- After some times, client requested to use the ASM as test to know its capabilities so DBA was given the task to have the GI installed and configured without disturbing the current environment.

Wednesday, December 03, 2014

Exadata: Defining the Threshold for Exadata Cell

In Exadata an alert is automatically triggered when a predefined hardware or software issue is detected, or when a metric exceeds a threshold. By default, there are no thresholds defined but you can define your own if you want.

Tuesday, December 02, 2014

Exadata: Index Elimination


In some cases, Exadata Smart Scan may deliver better query performance than using an index. However, this may not always be the case. Even in cases where an index delivers better query performance you might choose to remove it if you determine that the un-indexed query performance is acceptable and the index is otherwise unnecessary. Removing unnecessary indexes saves space and improves DML performance by eliminating the maintenance operations associated with the index. 

Monday, December 01, 2014

Exadata: Using Hybrid Columnar Compression


We have a table TRANSACTION_LOG with more than 10 million rows , estimated size of table is 640MB. We want to  examine the performance of Exadata Hybrid Columnar Compression and want compare predicted and actual compression ratios using an example dataset, so that we can use HCC for our logging tables. We also want to examine how bulk data loading and query operations are affected using the different compression modes.