John Watson's blog
Submitted by John Watson on Sat, 2016-08-20 02:11
Indexes may improve the performance of SELECT statements, but what about DML? This simple demo shows how bad they can be.
Submitted by John Watson on Fri, 2016-08-12 03:44
Many developers find that their code fails with ORA-942, but when they test the failing statement from the SQL> prompt, it works. Why, and what can you do to fix it?
Submitted by John Watson on Fri, 2016-05-20 06:09
I first came across partitioning with release 7, when it didn't exist. Like many DBAs, I simulated it by writing a lot of application code. You can still do this – and you may have to if you haven't bought Enterprise Edition plus the partitioning option. Here's another way to do it, with partitioned views.
Submitted by John Watson on Fri, 2016-03-25 09:33
The cost based optimizer makes decisions that can be hard to understand. One of the hardest may be why it chooses indexed or scan access paths: a burning question for many DBAs.
Submitted by John Watson on Sat, 2016-03-05 06:04
DB Time is the time spent by the database server executing user calls. What is this composed of? CPU time, waiting time, and IO time.
Submitted by John Watson on Sat, 2015-10-10 06:01
Proxy authentication has been around since release 9i, but it isn't widely used. It can be a very useful facility for giving certain users access to high privileges without having to give them any direct grants or roles, and avoids many of the problems of using shared accounts. It is of course fully audited.
Submitted by John Watson on Mon, 2015-09-07 10:46
Standard Edition release 184.108.40.206 is now available. Download it from the usual locations. But along with the great news, comes some news that is not so great: the licensing model has changed.
Submitted by John Watson on Sat, 2015-07-25 10:00
Following previous blog re BASIC compression, here are a couple of simple tests with Advanced Compression - which is supposed to survive conventional DML.
Submitted by John Watson on Thu, 2015-07-09 11:59
BASIC table compression is included with Enterprise edition, and can achieve respectable compression ratios. But beware! Subsequent DML may be disastrous.
Submitted by John Watson on Sat, 2015-04-25 13:56
The ability to quiesce the database was introduced in release 9, but to this day I find that many people are not aware of it. It can be really useful - so let's describe it. I'll begin by positioning the quiesce capability: when is it useful. Then detail how to do it, then reverse engineer the mechanism.