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May 2010

Advert: UKOUG Scottish Conference next week

Is it really that time already? I'll be working in London, but for those of you who can make it, this just in from Thomas Presslie ...

"The annual Scottish Oracle Conference is being held in Glasgow on 27th May 2010.  Now with five streams and keynote by David Callaghan, Senior Vice President Oracle, UK, Ireland and Israel a local event in Scotland not to be missed!   More information can be found at The OUG Scotland Chairman, Thomas Presslie, has some free places to give away to readers of Doug's Oracle Blog.  Please email Thomas for details of the discount code for registration."

Sorry I'll miss it :-(

double trouble

In the latest Quiz Night, I asked how you could make a query more efficient by changing a two table join into a three table join – with the clue that my third table was a repeat of the first table. Gary Myers, in comment 4,  provided the type of answer I was looking for. Sometimes [...]

Resource Manager and 11g

I will get back to the stats stuff at some point, but I'm quite busy at the moment working on something that I can't talk too much about, but which is throwing up enough generic issues to talk about. This is one that I meant to blog about ages ago when I first noticed it but when it caused us some problems last week, it was a useful reminder.

In summary you need to be careful when you upgrade to 11g because Resource Manager is enabled by default!

I don't want to blog about the ins and outs of Resource Manager and whether it's a good thing or not, but I do think this is a pretty extreme change to implement without a lot of surrounding publicity. It's a bit like the auto stats gather job that appeared in 10g that caused so many problems for Oracle users. It seems like it might be a good idea, but would you really want to introduce it on to a stable system that you're upgrading to 11g?

But rather than just talk about the change, I wanted to highlight how I first realised it was going on ...

Adverts: ... and a special invitation

I've been meaning to blog about a couple of interesting events coming up in London during the same week in the very near future - the week after next.

Oracle University are running - Advanced Oracle 10g Performance Analysis and Tuning with Kyle Hailey on 3rd - 4th June. For those of you who aren't aware of Kyle, he was one of the primary movers behind tools like OEMs Top Activity when he worked at Oracle, one of the guys behind, is a member of the Oak Table Network and has a long history in the Oracle world. You can read more about him at his website.

Meanwhile Miracle Benelux are running two of Tanel Poder's seminars back to back. Advanced Oracle SQL Tuning (1st -3rd June) followed immediately by Oracle Partitioning and Parallel Execution for Performance on 4th June. I imagine most readers are more than familiar with Tanel's work via his blog, presentations and forum contributions and know that he's absolutely top-notch.

They both look like terrific events and I would have attended one of them if it wasn't for the fact that I have a holiday booked in the U.S. that week. Which one? I really don't know because I know they'll both be excellent, so I suggest you read the agendas carefully and pick the one that you think has the most appropriate agenda for your needs.

Blog Roll

You may have noticed that the blogroll in the right-hand panel has recently become a lot shorter. As I pointed out a couple of weeks ago, the Oak Table Network has a new website (which is in my blogroll) that includes an aggregator for all the Oak Table members so I’ve started removing individual Oakies [...]

Oracle Exadata V2 - Flash Cache

One of the things I didn’t really talk about in my first post on Exadata was the flash cache component of the storage servers. They are a key component of the “OLTP” claims that Oracle is making for the platform. So let’s talk about the hardware first. The storage servers have 4 of the Sun Flash Accelerator F20 PCIe cards. These cards hold 96G each for a total of 384G on each storage server. That’s well over a terabyte on the smallest quarter rack configuration. Here’s what they look like:

Note that they are only installed in the storage servers and not in the database servers. The cards are usually configured exclusively as Flash Cache, but can optionally have a portion defined as a “ram disk”.

Oracle has a White Paper here:

Exadata Smart Flash Cache and the Sun Oracle Database Machine

This white paper was published in late 2009 and it is specific to V2. It has some good information and is well worth reading. One of the comments I found interesting was the discussion of carving a piece of the Flash Cache out as a “disk”. Here’s the quote:

Xtrace: an Oracle session trace browser – exec flow

Tracing a session is extremely useful when you need to investigate how a client interacts with the database - the client could be an application of yours, a third-party application, or an Oracle module such as dbms_stats or dbms_mview. To get the perfect picture of the client-server dialogue, you "simply" need to consider all EXEC lines in the trace file, and associate to each line the executed statement and the bind variable values; a very tedious and error-prone task when done manually, that Xtrace can make for you (and for free).

Let's see the tool in action. Consider tracing a call to this stored procedure, that executes a recursive SQL statement :

AMIS Query: An Evening with Oracle ACE Director Doug Burns…

On the 18th of June I am very happy to have arranged an internal mini masterclass for my DBA colleagues and some AMIS customer DBA peers. The evening before on the Thursday the 17th of June (btw. no important World Cup soccer games going on during this Thursday evening) Doug agreed to present his "How I learned to Love Pictures - Oracle 10g/11g Performance Analysis Using OEM" presentation, he held, among others, during the Oracle Open World 2009 Unconference sessions and this years Hotsos 2010 Symposium.

If all goes well ;-) ...

...You will enjoy during this evening a really great presentation on how much information you can get out of those Oracle Enterprise Manager performance diagnostic and tuning pages.

Keep an eye out on this blog site. Agenda and how to register will follow shortly. I keep you posted.


AMIS Query: A (hacking :) event with Oracle ACE Director Pete Finnigan

Zoals al aangekondigd in een eerdere blogpost heeft AMIS in samenwerking met Miracle Benelux, Masterclass trainingen, de mogelijkheid om vlak voor de twee daagse Masterclass in Utrecht van Oracle ACE Director en Oracle Security expert Pete Finnigan uit Engeland, een AMIS Query te organiseren. Beveiliging van je data en de focus hierop is vaak een ondergeschoven kindje. Iedereen is zich er waarschijnlijk wel van bewust dat data verlies via beveiligingslekken door bijvoorbeeld architectuur, programmatuur of onderliggende ondersteunende software, een gevoelig punt is in de organisatie. Het security gedachtengoed heeft echter ook impact op design en performance.

Een stukje van de sluier, van het beveiligings gedachtengoed, zal Pete Finnigan met ons delen tijdens de 25e Mei.

Hierbij de agenda voor de avond:

  • Vanaf 17:30/18:00 uur is iedereen welkom voor het diner.
  • Vanaf 19:00 uur “Oracle Database Security – (The True State?)“:
    • Focus op database security werk
    • Enkele realistische “hacking” demo’s / scenario’s
    • Discussie stuk t.a.v. de getoonde hacking demo’s
    • De correcte manier om data te beveiligen
  • Rond 21:00 uur afsluiting van de avond

Er is nog plaats maar meld je wel op tijd aan via deze pagina (Event Registration Form – Dutch) voor deze AMIS Query op 25ste Mei met Pete Finnigan.


There was a news item in the UK last week about a man in Chideock, Dorset who staged a protest about the volume of heavy traffic that has to come through the village where he lives. A pedestrian crossing has recently been installed on the road, using traffic-light control. So one morning he decided to [...]