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Database Feed

Oracle Database, Oracle 10g, Oracle 11g, Oracle XE, Oracle RAC, Oracle Instant Client, Oracle Data Guard and Oracle Exadata resources, news, and support articles.

Disjunction

Disjunction (logical OR) is known to cause various performance problems, from extreme parse times (e.g. here) to sub-optimal plans. A common solution to such problems is getting rid of OR’s by “OR expansion” (i.e. rewrite via UNION ALL), although it doesn’t work in 100% cases. In this post, I will consider an example of an OR problem that can be solved differently.

Here is the setup:

Video Tutorial: XPLAN_ASH Active Session History - Part 2

The next part of the video tutorial explaining the XPLAN_ASH Active Session History functionality has been published. In this part I begin the actual walk-through of the script output.

More parts to follow.

New Version Of XPLAN_ASH Utility - In-Memory Support

A new version 4.21 of the XPLAN_ASH utility is available for download. I publish this version because it will be used in the recent video tutorials explaining the Active Session History functionality of the script.

As usual the latest version can be downloaded here.

This is mainly a maintenance release that fixes some incompatibilities of the 4.2 version with less recent versions (10.2 and 11.2.0.1).

EBS 12.2 Essential Bundle Fixes for AD Delta 5 and TXK Delta 5 (Doc ID 1934471.1)

EBS 12.2 Essential Bundle Fixes for AD Delta 5 and TXK Delta 5 (Doc ID 1934471.1)

if any of the below features are interesting to your deployment then please review the doc and apply the essential bundle patches on 12.2.5 environment. Hope this helps to stabilize your environment.

Section 4: Features and Fixes in the Current Code level
The bundle fixes include implementation of the following AD and TXK features and fixes.

4.1: AD Features and Fixes

Backdoor vulnerability puts Oracle database users at risk

Companies using Oracle's database engine to support their enterprise application and information storage needs should consider consulting Oracle experts to help them patch a bug that could allow infiltrators to completely take over their systems. 

Map OS Groups To Administrative Privileges After Installation

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During installing database software, user is prompted to enter names of various operating system groups mapping to various administrative privileges (SYSDBA, SYSOPER, SYSBACKUP, SYSKM, SYSDG). One might map one operating system group to multiple administrative privileges if role separation is not desired.  In case the need for role separation arises later, the mapping can be specified by updating  $ORACLE_HOME/rdbms/lib/config.c file and then relinking it. This post explains the various steps.

Method R and parallelism (another real-life example)

In my previous post I mentioned method R as probably the most efficient approach to SQL optimization. However, it is important to focus on correct metrics for it to work correctly.
Consider this example (once again, the query is still running, so the only reliable diagnostic tool at our disposal is SQL real-time monitor):

Integrity of EBS patches

How do you ensure that your EBS patches have not been altered in any way since downloading from support?

How to resolve the text behind v$views?

This is a common problem I have and I never write it down (except now). For example, today I wanted to know what the valid parameters for _serial_direct_read were:

SQL> select * from v$parameter_valid_values where name ='_serial_direct_read';

no rows selected

OK so if Oracle doesn’t tell me then maybe I can work it out? Getting the view_text has worked in the past:

Korean publication of "Reverse Engineering for Beginners" book is available for pre-order!

I'm very happy to announce that Acorn publisher in South Korea did huge amount of work in translating and publishing my "Reverse Engineering for Beginners" book in Korean language.

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