Today’s post is dedicated to the Metalink SR identified by the number 6468252.994. I know, this number says nothing to you. For me, however, it’s a very well known number. The reason is quite simple… Even if I open this SR almost two years ago (to be precise, September 5, 2007), it was closed few […]
Wrong Information about Temporary Space Usage in V$SQL_PLAN_STATISTICS_ALL and DBMS_XPL...
As you can read in the documentation, the columns MAX_TEMPSEG_SIZE and LAST_TEMPSEG_SIZE in the dynamic performance view V$SQL_WORKAREA provide information about the size of the temporary segment used for a specific workarea. The values are given in bytes. Let’s perform a test to check this information… Create a test table that contains about 1MB of […]
Virtual Column-Based Partitioning Might Lead to Wrong Results
As of Oracle Database 11g it is possible to use a virtual column as partition key. In this post I do not want to discuss how it works and whether this is good or not… Instead, I would like to show you that the feature might lead to wrong results. First of all, I would […]
Oracle AD4J Installation on Linux
Today I tried to install Oracle AD4J on a Linux server that I have at home. The installation procedure is really simple and fully described here. Unfortunately, when I tried to access the console for the first time (that access is one of the installation steps), the HTTP server returned an internal server error (500). […]
Invisible Indexes and Hints
In this post I would like to remove some misinformation about the utilization of hints with invisible indexes. Let’s start by providing you what two sources say about that topic: Oracle Database 11g: New Features for DBAs and Developers (by Sam R. Alapati and Charles Kim, page 132) “If you want the optimizer to take […]
Long Parses
From time to time I have to fight against long parses. In this post I would like to share with you what happened to a customer of mine while upgrading from 9.2.0.7 to 10.2.0.3 (10.2.0.4 was not yet available at that time). The parse of a complex SQL statement took 5 seconds in 9.2.0.7. Not […]
Operation CONNECT BY WITH FILTERING
It happened to me several times to being asked about the mysterious full table scan in CONNECT BY operations. In this post I would like to share with you some of the information I wrote about it in my book (pages 233 to 236) . The operation CONNECT BY WITH FILTERING is used to process […]