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March 2012

Index Upgrades

Listening to a presentation by Paul Matuszyk on extended statistics yesterday, I learned something that I should have spotted ages ago. Here’s a little demo script to introduce the point:

create table t1
with generator as (
	select	--+ materialize
		rownum id
	from dual
	connect by
		level <= 1000)
	rownum			id,
	mod(rownum,100)		n1,
	mod(rownum,100)		n2,
	mod(rownum,100)		n3,
	lpad(rownum,10,'0')	small_vc,
	rpad('x',100)		padding
	generator	v1,
	generator	v2
	rownum <= 1000000;

create index t1_i1 on t1(n1, n2, n3);

-- collect stats, no histograms.

The Truth About Exercise and 100 Rep Challenge…

A couple of days ago I watched an episode of Horizon on the BBC iPlayer called The Truth About Exercise. If you can’t use BBC iPlayer, you can read about the show here. It was a pretty interesting show. The take-home messages were:


Hello all, first of all, I wanted to tell you that this is not a challenge. I have tried to find a solution for my below question, but I couldn't. I asked for help on some forums like orafaq and OTN but no one helped me. I am expecting atleast some help here. I have set up a single instance standbys for rac databases. Now, I need to offload the backups from the primary on to the standbys. I learnt a few points to achieve this. 1. cancel managed recovery 2. connect to target(standby) and catalog and backup the standby 3. put standby in managed recovery mode. I think following these steps, I can restore primary(?). Now, My question is, how can I use these standby backups to clone/refresh databases? I tried it by connecting to target(primary), catalog and auxiliary but rman is using the primary backups instead of standby's to refresh the auxiliary database. If anyone can help me with their suggestions that would be great. I have a 11202 oracle on a linux box. Few followups to my question at this link

Read the answer...

More Linux Articles (RHCSA)…

I put a few more Linux articles live yesterday.

Karen Morton

Meanderings of one who is lucky enough to have her avocation be her vocation.

Update Available For SLOB — The Silly Little Oracle Benchmark.

It’s not really a benchmark, nor silly but it had a silly bug in the driver script ( The bug is fixed and the updated tar archive is available here:

If you compare before and after results you may find that your AWR rates per second for physical I/O and Logical I/O are different. That’s due to the bug. The old version scoped a sleep in the AWR reporting period! Yes, a silly bug in a silly little Oracle benchmark. Only a slob would let that linger.

This is just a short note that the next part of my Dynamic Sampling series has been posted on

This time I highlight how to configure Dynamic Sampling - the first part focusing on the available session/statement levels. The next part will be posted soon and explains some other important concepts regarding Dynamic Sampling behaviour.

Unfortunately these topics are not covered very well by the official documentation. In fact the best coverage used to be in the documentation of the initial release that included Dynamic Sampling (9iR2). You can find the link to that old documentation version in the article over there.

Another Hotsos Symposium in the books

Another Hotsos Symposium is in the books (well, the main Symposium is over with only the Training Day remaining tomorrow). As usual, it was a phenomenal event. Hotsos has got it down to a science on how to deliver a 5 Diamond event and it just seems to get better every year. My thanks go out to everyone at Hotsos who work so hard to make this event happen (special nod to Rhonda B and Becky G...sounds like a new girl band, huh?). It's a week chock full of the best technical information on Oracle performance you're going to find anywhere, a lot of great food, superb networking and "get-to-know" you time with other attendees, and (last, but not least) a fantastic themed party night to top it all off. This year's party theme was "Steampunk". The attire I donned for this photo is indicative of the genre if you're wondering what the heck Steampunk is (more photos here).

Repairman Jack: Conspiracies…

Conspiracies is the third book in the Repairman Jack series by F. Paul Wilson.

Jack is hired to look for a missing woman who happens to be part of a very exclusive conspiracy theory group. What’s more she went missing just before presenting her Grand Unification Theory, that supposedly explains the true root of all conspiracies through all the ages. Coincidence?

I really liked this story. I’m not into conspiracy theories myself, but I can see why they are fascinating to people. That constant spiral of the lack of evidence because the evidence is being withheld. It kinda draws you in.

Book offer

Hotsos 2012:
One of the session’s I attended yesterday (6th March) was Karen Morton speaking about grouping in SQL. Karen is a member of the Oak Table network, knows what she’s talking about, and speaks well. So you’ll be pleased to hear that one of the first slide she showed was about an offer from Apress for the book Pro Oracle SQL that she co-authored with several other members of the Oak Table.

Until April 8th, if you supply the code OR4SQ8 when you order this book from Apress you get a 40% discount on the price.

I haven’t been able to find an officlal statement of this fact online, or a confirmation for the code; and Karen wasn’t 100% sure whether the deal applied to the hard copy, electronic copy, or both; but when Apress did something similar for Oracle Core the code did apply to the hard copy.