On Thuesday, March 24th, 2009 at 9 a.m. I will speak at Berufsschule Wiesau about general matters of IT performance. Papers and the presentation are available online now: Handout “IT-performance” Slides Regards Martin Klier EDIT: That’s a nice article about the event on the school’s webpage. Thanks! […]
Year: 2009
Oracle: Specify the number of occurrences before metric alerting starts
It’s not possible to specify a minimum of consecutive occurrences before alerting starts in in Enterprise Manager, it will always scream out at first time touching the line. But you can do so in command line. Just execute DBMS_SERVER_ALERT.SET_THRESHOLD with parameter consecutive_occurrences set to a value >1. It’s a very nice way to stop annoying […]
Oracle Explain Plans or Execution Plans: Guess or Reality?
Oracle finally desupported the rule-based optimizer with version 10g. Since 9i, users are good adviced to make themself familiar with the cost-based-optimizer (CBO). In order to understand what happens with your statement after parsing with CBO involved, and to be able to tune your queries, displaying, understanding and optimizing explain- or execution plans is essential. […]
Get Oracle User DDL with dbms_metadata
Sometimes you have to recreate a user in a DB, and you like it to be the same as before again. To have its DDL at hand is usually rather convenient. DBMS_METADATA is a great toolbox to get it, my example is just a short but hopefully useful excerpt of its possibilities: set long 200000 […]
Oracle 11g JDBC driver hangs blocked by /dev/random – entropy pool empty
On a headless (=without console) network server, the 11g JDBC driver used for (java) application connect may cause trouble. In my case, it refused to connect to the DB without any error, trace or log entry. It simply hung. After several hours, it connected one time, and freezed again. Remote debugging done by the development […]
Creating Oracle AWR reports quicksheet
For comparing, classifying, benchmarking and forecasting databases, Oracle’s Automatic Workload Repository (AWR) is neat. (But remember! You will need a diagnostics pack license for that as described here and here – if you need a free technology for performance monitoring, consider using Craig Shallahamer’s OSM toolkit.) This post simply describes the package calls to create […]
Setting ulimit -m in AIX
AIX has its own rules, as I have to discover these days. Coming across ulimit, I found out that smitty configures value A here and value B completely elsewhere. Hardest one so far has been “ulimit -m” (“Specifies the size of physical memory, in number of K bytes.” a user can assign), since I could […]
“Basics of Database Technology” again
Tomorrow, there will be a version 2.0 of a lecture from last year, again for 9th-formers of Augustinus Weiden. The handout and the presentation are online now, we will see what Friday brings. Usn […]