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Category Archives: Performance

So many DBAs; yet so many performance problems

There are many applications and databases around, performing and scaling just as supposed to. We very seldom hear about these project. Of course, this could be small applications with small loads; or, on the other hand, this could be well design application with well written code, and well maintained databases. Yet there are so many […]

Posted 19 September 2012 † Lasse Jenssen § Architecture § Database Design § DBA § Java § Oracle ‡ Comments (0) °

Batch: Using partitions and “deleting” local indexes for fast DML

Recently I was presented a batch job with unacceptable running times. Especially the first stage of loading and normalizing data, just took to long time. When doing trace I found that about 70 percent of the time was spent doing inserts and updates towards to tables. For both of these, Oracle was reading way more […]

Posted 01 September 2012 † Lasse Jenssen § Oracle ‡ Comments (0) °

Oracle and Hibernate: Not always best friends

I’m definitely not a Java or Hibernate expert. But I have worked with Oracle for the last 15 years since version 7.3.4. I’ve also spend the last 10 years focusing and working mainly with performance issues within Oracle databases or within the code accessing Oracle databases. Lately many of the projects I’ve been working on […]

Posted 30 August 2012 † Lasse Jenssen § Java § Oracle § SQL ‡ Comments (0) °

After upgrading from Oracle 9i to 11g

Saturday we upgraded one of our Oracle databases in production from version 9 to 11g Release 2. Yes – you heard right! From Oracle 9i … Well it’s a long story, and I’ll leave that for now. What I do want to blog about is some of the changes in Oracle 11g. I’ve used Oracle […]

Posted 09 February 2012 † Lasse Jenssen § 11g New Feature § Oracle ‡ Comments (0) °

When to rebuild an Oracle index?

For several years now it’s has been clear that we shouldn’t just rebuild an index. In the worst case this could make performance even worse than it used to be (for the next following days). So the question is “What indexes should be rebuilt?”. I just read this article from Jonathan Lewis that might just […]

Posted 05 January 2012 † Lasse Jenssen § DBA § Oracle § Script ‡ Comments (0) °

DBMS_XPLAN.DISPLAY

In Oracle 9i the DBMS_XPLAN package was introduced. One of the most used functions in this package has been the DISPLAY function. From version 10g this package was extended to include two other related functions: the DISPLAY_CURSOR and the DISPLAY_AWR functions. In this note I´ll take a look at the function first introduced in 9i […]

Posted 02 January 2012 † Lasse Jenssen § Oracle § SQL ‡ Comments (0) °

Oracle Statistics: A summery

In this blog I want to collect my notes regarding the different Oracle statistics. This will definetly not be a complete overview, but only a summary of my findings and readings about more or less useful parameters that I stumble a cross. If you have experiences or knowledge that should be added, please post a […]

Posted 10 November 2011 † Lasse Jenssen § Oracle ‡ Comments (0) °

Useful articles regarding statistics on partitions

One of the blogs that I´ve been following is Doug’s Oracle Blog. Doug has for instance written a series of articles regarding statistics on partitions. This series is definetly worth reading, and you can find the first article here: http://oracledoug.com/serendipity/index.php?/archives/1562-Statistics-on-Partitioned-Tables-Part-1.html

Posted 27 October 2011 † Lasse Jenssen § DBA § Oracle ‡ Comments (0) °