John Watson's blog

Partitioning and Oracle Standard Edition

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.

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When is an index access path better than a full table scan?

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.

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What is DB Time? Where has it gone?

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.

Proxy authentication

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.

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Standard Edition release 12.1.0.2: licensing...

Standard Edition release 12.1.0.2 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.

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ADVANCED table compression: an improvement

Following previous blog re BASIC compression, here are a couple of simple tests with Advanced Compression - which is supposed to survive conventional DML.

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BASIC table compression: use with care

BASIC table compression is included with Enterprise edition, and can achieve respectable compression ratios. But beware! Subsequent DML may be disastrous.

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How and why to quiesce the database

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.

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Book review: Brian Peasland, Oracle RAC Performance Tuning

Excellent book - I've just posted this review on Amazon:

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Tuning SQL with dynamic sampling

Another example of what I think of as "the self-tuning database". Setting optimizer_dynamic_sampling=11 can fix many performance problems, without the DBA needing to use his brain at all.

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