Recently I was involved in a project where I had to trace the database calls of an application based on Oracle Portal 10.1.4. The basic requirements were the following: Tracing takes place in the production environment Tracing has to be enable for a single user only Instrumentation code cannot be added to the application Given […]
In 2003 I published a paper entitled Debugging PL/SQL and Java Stored Procedures with JPDA. Its aim was to describe how to debug PL/SQL and Java code deployed into the database with JDeveloper 9i. Two weeks ago a reader of my blog, Pradip Kumar Pathy, contacted me because he tried, without success, to do something […]
The book Der Oracle DBA (Hanser, 2011), which was written in German, is at last available! I say “at last” because the authors worked on this project for not less than two years. Who are the authors? Several colleagues of mine at Trivadis (Mirko Hotzy, Konrad Häfeli, Daniel Steiger, Sven Vetter, Peter Welker), Andrea Held, […]
The STATISTICS_LEVEL parameter controls a bunch of features. In addition to the STATISTICS_LEVEL, also the V$STATISTICS_LEVEL view provides a list of the ones it controls. SQL> SELECT statistics_name, description, activation_level 2 FROM v$statistics_level 3 ORDER BY 3 DESC, 1; STATISTICS_NAME DESCRIPTION ACTIVATION_LEVEL ————————————– ———————————————————— —————- Active Session History Monitors active session activity using MMNL TYPICAL […]
At page 189 of TOP I wrote the following piece of text: In summary, with the initialization parameter optimizer_secure_view_merging set to TRUE, the query optimizer checks whether view merging could lead to security issues. If this is the case, no view merging will be performed, and performance could be suboptimal as a result. For this […]
A reader of this blog, Paresh, asked me how I was able to find out the logic behind ITL waits without having access to Oracle code. My reply was: I wrote a test case that reproduce ITL waits and a piece of code that monitors them. Since other readers might be interested, here is the […]
In recent releases Oracle has silently changed the behavior of ITL waits. The aim of this post it to describe what has changed and why. But, first of all, let’s review some essential concepts about ITLs and ITL waits. Interested Transaction List The Oracle database engine locks the data modified by a transaction at the […]
In this post I pointed out that I like to have a copy of the documentation in PDF format on my notebook. In the same post, and its comments, I also described how I generate the scripts I use to download the files. Recently I updated the scripts and, as a result, I thought to […]
At page 383 of my book I wrote the following sentence (BTW, the same information is also provided by Table 9-3 at page 381): With B-tree indexes, IS NULL conditions can be applied only through composite B-tree indexes when several SQL conditions are applied and at least one of them is not based on IS […]
Last January I wrote a post with the following content: Upgrading critical applications can be very difficult. One of the main problems is that for reasons of availability, long downtimes cannot be periodically scheduled. Therefore, for such applications, it is desirable to implement online upgrades. This requires that the application in question, as well as […]