http://fredcoulson.com/blog/fred On the database I blog. Fri, 11 Jun 2010 23:59:32 +0000 http://backend.userland.com/rss092 en I am happy to announce that my Three Normal Forms tutorial has been translated into Spanish by Roberto Fernandez. You can download it here. http://fredcoulson.com/blog/fred/index.php/2010/06/11/3-normal-forms-spanish-translation/ In my apartment building people often leave books they no longer want in the lobby for others to pick up if they want. Usually it's nothing interesting, but the other day someone left a truly incredible artifact: the Microsoft Excel Version 1.04 manual, from 1986. This is a true historical document. ... http://fredcoulson.com/blog/fred/index.php/2010/01/02/ancient-treasure/ End-to-end performance tuning is something you hear more and more about. I have seen many presentations about how the "modern" DBA has to be intimately concerned with all layers of the application stack and cannot just focus on the database. I'm on board with that, but the reality is, I ... http://fredcoulson.com/blog/fred/index.php/2009/09/25/debugging-ora-01001-invalid-cursor/ Here's a cautionary tale about not doing your homework first. There's this Oracle 10.2 database on a Windows 2003 server that I manage. I noticed a big hard drive attached to it that was just sitting there unused, so I asked the sysadmin if I could use it for RMAN backups, ... http://fredcoulson.com/blog/fred/index.php/2009/07/23/backup-failure-one-rmans-odyssey/ Yesterday I had to shutdown a production reporting database (Oracle version 10.2.0.4) so they could add RAM to the server. The shutdown immediate wasn't going fast enough to suit me, so I logged into a second session and issued a shutdown abort. "No problem," I thought. I already had permission ... http://fredcoulson.com/blog/fred/index.php/2009/07/10/what-happened-to-my-automatic-instance-recovery/ The v$osstat view shows certain OS-level metics such as number of CPUs, current system load, accumulated IO time, etc. Starting in 10gR2, it also records PHYSICAL_MEMORY_BYTES, which is the total size of physical memory on the server. See the documentation. I think I found an anomaly. On one particular database I ... http://fredcoulson.com/blog/fred/index.php/2009/03/20/vosstat-anomaly/ I had a little excitement with the cursor: pin S wait on X wait event when a client's website came grinding to a halt. The first thing I checked was blocking sessions... col username form a12 col event form a25 word_wrapped col blocking_session head "BLOCKING|SID" select sid, username, event, blocking_session, seconds_in_wait, wait_time from v$session where state = ... http://fredcoulson.com/blog/fred/index.php/2009/03/16/cursor-pin-s-wait-on-x/ Sometimes I find the need to test disk IO rates, especially in the context of one of those delightful intra-office debates where the DBAs are blaming the lousy hardware for bad database performance and the sysadmins are blaming the lousy database. You can perform a simple test of disk IO using ... http://fredcoulson.com/blog/fred/index.php/2009/03/13/testing-disk-io-with-the-o_direct-flag/ In Oracle, the standard way to calculate the difference (delta) between two values is using the LAG() analytic function. For example... Suppose you've got a table of numeric values-- create table t as select rownum id, value from v$sesstat where value > 0 / select * from t; ID ... http://fredcoulson.com/blog/fred/index.php/2009/03/11/calculating-the-delta-between-two-row-values/ After a long hiatus, I'm resuming my activity on this blog, devoting it mostly to Oracle and other database matters. http://fredcoulson.com/blog/fred/index.php/2009/03/09/back-in-the-blog/