Radoslav Rusinov's Oracle Blog

Luca Canali and ASM Metadata Internals

2006-06-14T21:12:00.000+03:00

In a recent technical paper Luca Canali explains how to find the mapping between physical storage, ASM allocation units, and database files by querying the undocumented X$ tables.By using the information retrieved from X$KFFXP table he succeeded to:Retrieve a file directly from ASM disksMonitor how the extents in a datafile are allocated across ASM disksMonitor how a datafile is spread across ASM

Christo Kutrovsky's Blog

2006-06-11T20:23:00.000+03:00

If you’ve missed to notice – Christo Kutrovsky started his own professional blog dedicated mainly to the Oracle database.Christo Kutrovsky is an Bulgarian Oracle professional currently working in Canada as a Senior Database/System Administrator for The Pythian Group.His blog is a part of the corporate blog of The Pythian Group.The blog is only two-months old but

The Flashback Database Feature

2006-05-25T19:14:00.000+03:00

IntroductionThe Flashback Database is one of the most powerful new features in Oracle 10g coming as a part of Backup & Recovery enhancements.In this post you can find the result of my research and shared experience about this feature.What is the Oracle Flashback Database?Flashback Database is a part of the backup & recovery enhancements in Oracle 10g Database that are called Flashback

Backup & Recovery Presentation

2006-05-01T17:11:00.000+03:00

Two weeks ago I had a presentation in front of Bulgarian Oracle User Group about Backup & Recovery Enhancements in Oracle 10g.The agenda of the presentation:Flash Recovery AreaFlashback Technology EnhancementsSpace Pressure & Database HangsPhysical Backup & Recovery EnhancementsIt includes information about enhancements in Oracle 10g (Release 1 and Release 2) related to Human Errors (

Back to Blogging

2006-05-01T17:04:00.000+03:00

Finally, after 6 months of silence I am writing my first post.In the past several months I didn’t have any free time to update my blog but now I am trying to change this. I hope that I will be able to write here much more frequently.I have a lot of interesting topics to write about. Some of them:- Presentation about Backup & Recovery Enhancements in Oracle 10g that I gave in front of the

A Simple Chapter from the "Cost-Based Oracle Fundamentals" is available for download

2005-11-02T12:57:00.000+02:00

A simple chapter from the Jonathan Lewis's book is available for download at this address: Chapter 05: The Clustering FactorThe book will be available for shipping in 5th of November at Amazon online bookstore: Cost-Based Oracle Fundamentals

How to test our Oracle database environment for free

2005-10-25T09:12:00.000+03:00

If you want to benchmark your new Oracle9i/10g database environment before to put it in production as a part of your migration procedure, then may be you are one of these who are facing with the problem: How to test my database, where to find a proper tool or program and how much I must pay for that?I just want to share a links to several free programs that can help you to test your Oracle

Oracle Database 10g: Best Practices for Windows Deployments

2005-09-27T17:09:00.000+03:00

This presentation is given on the Oracle OpenWorld this year. You can download it from here: Oracle Database 10g: Best Practices for Windows DeploymentsAnother interesting presentation from OOW 2005 is this one: What They Didn't Print in the Doc - HA Best Practices by the Gurus from Oracle Maximum Availability Architecture Team

Oracle Database 10g Release 2 for Windows

2005-09-09T10:58:00.000+03:00

Oracle have released the official version of 10g R2 for Windows.The software can be downloaded from here: Oracle Database 10g DownloadsThe Windows-related documentation for R2 is already available as well: Oracle Database 10g Relase 2 Documentation Library

Oracle 10g ASM vs. Linux Filesystems, Part 2

2005-09-09T09:13:00.000+03:00

Andrew Carr let me to know that there is an interesting follow up to the ASM vs. LVM article on the Wim Coekaerts Blog: ASM vs LVM Wim Coekaerts is the Director of Linux Engineering at Oracle. The post is discussing the interaction between OS buffercache and Oracle buffercache and how they are affected by using ASM or Linux filesystem.

Bitmap Indexes - History and Future

2005-09-07T21:05:00.000+03:00

A small introduction: Bitmap indexes are tailored to data warehouses.In its simplest form, a bitmap index on an index consists of one vector of bits (i.e., bitmap) per attribute value, where the size of each bitmap is equal to the number of records in the indexed relation. For example, if the attribute is day of the week, then there would be seven bitmap vectors for that attribute, one for each

Oracle 10g ASM vs. Linux Filesystems for non-RAC systems

2005-09-01T11:16:00.000+03:00

Bert Scalzo has published an interesting article in Linux Journal that compares the performance of non-RAC Linux systems, which are using the new Oracle 10g feature - ASM versus using of Linux filesystems: Optimizing Oracle 10g on Linux: Non-RAC ASM vs. LVM

A Big Set of Oracle Presentations from NYOUG

2005-08-26T11:41:00.000+03:00

On the web site of The New York Oracle Users Group (NYOUG) you can find some very interesting presentations from the recent NYOUG events:June 2005Things You “Know” - from Tom Kyte, Oracle CorporationResource Mapping: A Wait Time-Based Methodology for Database Performance Analysis – from Matt Larson, Confio SoftwarePresents the Resource Mapping Methodology and how it can be used for Wait-Event

Once More Into The Fray

2005-08-25T08:45:00.000+03:00

Mike Ault has published an answer to all comments about the recent published article from Don Burleson: Once More Into The FrayAdded from Rado: All of the comments (from Tom Kyte and other visitors) after the above blog post was deleted from Mike as he declares into his post and here: Comment on "Getting Credible Information" blog postAdded from Rado: Sorry but now I just have discovered that

The _PGA_MAX_SIZE post is updated

2005-08-23T20:50:00.000+03:00

I have updated my post about the _PGA_MAX_SIZE hidden parameter with additional information that pop-up in the past few days.I will appreciate any comments and corrections about my points if you think that they are wrong or you just have more valuable information that I can add to this post.

Oracle OPatch Security Holes

2005-08-23T09:05:00.000+03:00

A new white paper is coming from one of the leading security companies - NGS (Next Generation Security) Software Ltd.It will be related to discovered problems after using of the OPatch utility for applying of Oracle patches and the title is "Patch Verification of Oracle Database Servers".Some quotes from this Eweek news story: Security Firm: Oracle Opatch Leaves Firms Uncovered:A total of more

Pete Finnigan's Weblog

2005-08-22T18:28:00.000+03:00

Pete Finnigan has mentioned my blog in his Oracle Security weblog, especially the security-related post: How to see the MOD_PLSQL passwords in clear textThanks to him for his comments!I want to note that this information can be found at his book: Oracle Security Step-by-Step (Version 2.0) as step 8.1.2 from Phase 8 - Application Servers and the Middle Tier.Additional information online:Fact

The Don Burleson's article

2005-08-21T14:17:00.000+03:00

Added from Rado (23 August): Don updated his article again yesterday (see the link below). Now it is more detailed and there are lot of quoted documents.But there is again some questionable information:No RAM sort may use more than 5% of pga_aggegate_target or _pga_max_size, whichever is smaller. This means that no task may use more than 200 megabytes for sorting or hash joins.Again, for serial

The _PGA_MAX_SIZE hidden parameter

2005-08-18T19:38:00.000+03:00

Check the following links for more details regarding to my previous post (Management of the Oracle9i PGA): Discussion from Don Burleson's Oracle forum: Question for Don, Regarding _pga_max_size Article from Ora!Ora!Oracle mail magazine: Sort Metalink discussion thread: high pga_aggregate_target but low "cache hit percentage" Metalink discussion thread: PGA memory usage exceeding

Management of the Oracle9i PGA

2005-08-18T10:43:00.000+03:00

If you think that your PGA can be configured properly just by increasing of the PGA_AGGREGATE_TARGET parameter, think twice - it is NOT!See this article from Don Burleson: Undocumented secrets for super-sizing your PGAIt shows that there are two hidden parameters that can help for proper using of the PGA. Otherwise, Oracle will never use more than 200 MB for the whole PGA nor will it use more

Using of BULK COLLECT and FORALL for better performance

2005-08-16T20:38:00.000+03:00

Lets see some quotes from the Oracle documentation:---PL/SQL engine executes procedural statements but sends SQL statements to the SQL engine, which executes the SQL statements and, in some cases, returns data to the PL/SQL engine.Too many context switches between the PL/SQL and SQL engines can harm performance. That can happen when a loop executes a separate SQL statement for each element of a

Strange behaviour of the CBO, part 2

2005-08-11T11:08:00.000+03:00

After playing around with setting of columns to allow NULL values or not (setting COL1 and COL3 to allow NULL values, test and put it again to their default condition) and precomputing statistics, the issue from previous post become more unclear.Now the structure of the table is the same like it was before, statistics are fresh but cost for the execution plan is always 175. It doesn't matter what

Strange behaviour of the CBO, part 1

2005-08-10T19:36:00.000+03:00

The following interesting issue does not have clear explanation till now.I have query that is using the following predicates. ... AND COL1 LIKE '%%' AND COL2 LIKE '%%' AND COL3 LIKE '%%' AND COL4 LIKE '%%' ...May be I should explain from where is coming this strange query.If you are developping some application and you

How to see the MOD_PLSQL passwords in clear text

2005-08-10T17:37:00.000+03:00

If you have some web-based PL/SQL application then you can be interested in the following information.May be many DBAs who have been involved in the database security have asked themselves: "How to be sure that my DAD files hides well the application schema passwords?"Well, Oracle doesn't have very good solution for this problem.Lets take a look at one DAD file used from an Oracle Application

Forcing Oracle to use LOGGING mode

2005-08-10T16:43:00.000+03:00

I've just read an interesting newsletter about that how we can force the database (or some tablespace) to use the LOGGING mode for all operations. For example, lets imagine that we don't want someone improperly to start some operation in NOLOGGING mode that will lead the database to impossibility of performing of full database recovery after media failure. This could be important issue if a