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Hotsos 2010 – Presenters, Presentations, Presenting

I never find it very easy to try to capture the atmosphere during a conference, the presenting part, the presentations or the discussions, for example, you could have with the presenters. Hotsos is such a cool and unique event were you have the opportunity, to listen but also to interact. The amount of people that attend isn’t that big, only a few hundreds, but they share all the same passion, the passion to improve on performance, mostly Oracle related. It has only two tracks and its not uncommon that people present and than go afterwards to a presentation to listen in what the other presenter has to say.

Due to the fact that it is manageable in terms of choice, located on a convenient location and well organized, you have the opportunity to pick just the thing you like and most of the time not miss out on “the other” presentation you would have liked to see. Besides that people stay in (overnight in the Hotel), so discussions about the technology, the method or an example during a presentation will be discussed in far more detail than you normally would do, from presenter to presenter or from presenter to the guy that attended and vice versa. The fact that all have the passion for performance or that they realize that performance is a beast with various angles to approach, bounds, and every point, every question is one to be heard and/or discussed. On equal terms. If you have seen my video impressions of Hotsos in 2009, you get a bit of what I am trying to say.

Anyway, not being a native speaker and with my new “flip” at hand (Ultra HD), I just show you how much fun and interesting stuff is going on, probably this will do more right to those presentations than me trying to explain what all those new ideas which were that popped into my head during this years Hotsos Symposium…although…sometimes technology helps and sometimes it just doesn’t…or is it a VMware thing Doug…?

My agenda is not that much different then the one from Doug. The moment it is mentioning RAC related stuff, then I probably would have been attending the other guy.

The Monday started great with a small introduction of Tom Kyte’s generally unknown other qualities…


Ohhh…and I wasn’t the one, by the way, that was giggling… On a more serious note, the following clip will show how Tom Kyte handles date time conversions, if remembering birth dates.

Alas I didn’t manage to film a more serious piece of his keynote, so sorry. The “flip” thing was a new attempt to capture the atmosphere and I wasn’t sure how it would workout…and as you noticed, using the zoom function on the “Ultra HD” flip, is not a good idea…

The conceptual presentation of Alex Gorbatchev was cool and well thought out. To give you an impression I have two clips that are a good representation of the humor and the topics that were discussed during his “Battle Against Any Guess” presentation. The first part is a good example why it is sometimes handy to be lazy…

In his more serious section of his presentation, Alex discusses the use of checklists…

As always, Cary Millsap’s presentation was very useful and I really love his way of presenting (it looks easy – but it isn’t – very clearly discussing the topic). In this case the presentation topic was “Lessons Learned” about testing and the boundaries you should respect, if your test set-up should be useful. Apparently he tested his idea’s, once again, this time using his daughter as a test subject addressing the issue: “Can she lift 15 pounds…?”

Besides Sales guys being addressed, Cary sums it up on how cool it is to test stuff until it breaks…

Doug Burns had a very unlucky day. Sometimes the demo setup was working, sometimes it didn’t. Having a presentation that only consisted out of demo’s, and only a few slides for starters at hand, he had to improvise. In the end, as you can see here on his blog site, he had only time for 30 minutes doing his demo’s. Seen the presentation already during Oracle Open World in 2009 during a “Unconference” session, I can only say: wow, what did those people miss out… but alas, that’s the risk of doing demo’s. Sometimes it goes wrong…

So here how Doug tries to save the presentation via going in on more detail on Swingbench and tips and advice while using Oracle Enterprise Manager…or with other words: What you can do with a bit of Scottish humor to save the day…

…and how we finally got to the part were I guy saved Doug’s presentation (regarding the demo’s) using a wireless gadget, that probably fixed the issue with the routing table that messed it all up. Oh and a tip to all those life savers out there: “Never type in your secret password while it is being displayed on the big screen…” (we now you bluffed regarding changing it…). ;-)

The last clip is from Kevin Closson’s presentation while he explains a bit about “Why do we still think a CPU is a CPU…”.

Apparently he likes cuddly toys as well…

Ohhh, did I tell that I did well regarding my presentation? I did. How I know? Due to the fact that I encountered most of my audience afterwards (4) during the Disco Night event on Tuesday and they all liked it (total of 7!). They bought me beer even. Cool. Should do it more often, this presenting thing. The other 200+ people who went to Tanel Poder’s presentation, which is their bad luck. If they only knew what they were missing out on. I mean even Doug was positive in his Scottish way trying to tell me. So in all, not bad for a newbie during Hotsos. At that time slot all 200+ plus 7 people had a good show for their money; if only I could have attended Tanel’s… Hmmm.


PS. Before I forget. I would like to thank Toon Koppelaars for reviewing my presentation and giving me some useful advice.

Always Check Your Backups

So this is a 2 node RAC cluster on RHEL that was recently upgraded from to Since then clusterware restarts crs every few hours (8 in fact). A little research suggests that this can indicate problems with the automated OCR backup.  The first thing therefore is to check the state of the backups. [server] [...]

Thank you for

Thank you for all those who attended my webcast today on SQL Plan Management for All India Oracle User Group. It was a privilege to present before you and to be able to address your questions. I am sorry I couldn;t read all the questions properly; since it was extremely difficult to see the questions scrolling up in the tiny chat window. Also, as the webcast was designed, I couldn't hear anything the attendees were saying.

The presentation and the associated SQL scripts are available here. The article I referred to can be found here.

If you have a question regarding that specific webcast, please post a comment here and I will address it here. Please, limit your questions to the material discussed in the webcast only.

Hands On Labs with Data Guard

I have been planning on publishing more Hands On Labs for Data Guard on Oracle’s Technology Network using the Amazon Elastic Cloud (EC2) as the lab systems. But while I am working on more of them I thought I should post a note about the “OpenWorld 2009 Active Data Guard Hands On Lab” that we have already published. Please head for for a set of exercises designed to introduce you to Active Data Guard in Oracle 11g Release 2 as well as some basic configuration and testing exercises.  On that page is the download link for the handbook where you will find instructions on how to get going with my Amazon Cloud Machine (AMI)  image and all the exercises.

I am hoping to do a new and improved version of this hands on lab at OpenWorld 2010 which will include Active Data Guard functionality that I just did not have time to get into last year’s lab.  That new Hands On Lab will be published on OTN after OpenWorld.

Keep an eye on this category for announcements on any other training.


Back Again

So if all goes well the blog should be back again, now powered by WordPress. The blogger posts have made it back, but apparently 2006-2008 never existed. Fortunately it’s probably only me that cares. Those who know me personally will know that I moved jobs, and therefore needed to understand what the “private blogging” position [...]

On "Is a computer science degree a good goal?"

Dan Fink's "Is a computer science degree a good goal?" has gotten my wheels going. I think it's important to note this:

Computer Science ≠ Information Technology

Not only are these two disciplines not equal, neither is a subset of the other.

One of my most memorable culture shocks coming out of school into the Oracle domain was how many people didn't understand the difference between computer science, which is a specialized branch of mathematics, and information technology, which is a specialized branch of business administration. They both deal with computers (the IT major more than the CS one, actually), so of course there's risk that people will miss the distinction.

Over dinner Friday night with some of my friends from Percona, we touched on one of the problems. It's difficult for a technical major in school to explain even to his family and friends back home what he's studying. I remember saying once during my senior year as a math major, "I haven't seen a number bigger than 1 since I was a sophomore." I heard a new one tonight: "I got to the level where the only numbers in my math books were the page numbers."

It's difficult for people who don't study computer science to understand who you are or how the min/max kd-trees and deterministic finite automata and predicate calculus and closures that you're studying are different from the COBOL and SQL and MTBFs and ITIL that the IT majors are studying. It's easy to see why laypeople don't understand how these sets of topics arrange into distinctly different categories. What continually surprises me is how often even IT specialists don't understand the distinction. I guess even the computer science graduates soften that distinction when they take jobs doing tasks (to make a living, of course) that will be automated within ten years by other computer scientist graduates.

I agree with Dan and the comments from Tim, Robyn, Noons, Gary, and David about where the IT career path is ultimately headed in the general case. What I don't believe is that the only career path for computer scientists and mathematicians is IT. It's certainly not the only career path for the ones who can actually create things.

I believe that college (by which I mean "University" in the European sense) is a place where the most valuable skill you learn is how to learn, and that, no matter what your major, as long as you work hard and apply yourself to overcoming the difficult challenges, there will be things in this world for you to do to earn your way.

I really hope that the net effect of a depressed, broken, and downward-trending IT industry is not that it further discourages kids from engaging in math and computer science studies in school. But I don't want for so many of our kids today who'll be our adults of tomorrow to become just compartmentalized, highly specialized robots with devastatingly good skills at things that nobody's really willing to pay good money for. I think that the successful human of the future will need to be able to invent, design, create, empathize, teach, see (really see), listen (not just hear), learn, adapt, and solve.

...Just exactly like the successful human of the past.

Inserts Experiencing an Increasing CPU Consumption

Last week I had to analyze a strange performance problem. Since the cause/solution was somehow surprising, at least for me, I thought to share it with you.
Let me start by quickly describing the setup and what was done to reproduce the problem:

Database version: Oracle Database 11g Enterprise Edition Release (64-bit)
Operating system: Solaris 10 (SPARC)
To [...]

Hotsos 2010 – About swag, the Oscars and other stuff

Its Sunday and its raining outside. The nice weather on Saturday (approx. sunny / 20 degrees Celsius) has gone. After a decent flight on Friday where I actually made it to switch in Houston from the international Continental flight, going through customs and pick the next one, a domestic Continental Express flight, within the boundaries of 1 and 1/2 hour. I was so fast that switching for one flight to the other, that apparently my luggage didn’t manage to travel with the last flight. So after I found out that my luggage was still somewhere in Houston, I got from Dallas Love Field to the Omni Hotel in Las Colinas, Irving, where the Hotsos conference will be held again. The whole area is a bit in shambles because they are rebuilding a lot of the environment. While getting to the Grapevine Mills mall yesterday, I noticed that they also a building a new Irving Convention Center along the highway. Another addition to the already crowded Dallas/Plano/Irving Metroplex.

After doing some shopping on Saturday (and found a great shop that printed text on t-shirts from scratch, behold some new XML swag 8-) ), probably the only day I get the chance, I just caught up with Mark Bobak afterward, while he was driving to get some dinner outside the hotel. We ended up in a Boston Pizza revenue enjoying a pizza and a burger. Talked about Mark’s, probably biggest Oracle XMLDB environment implementation worldwide, its status / challenges after I had been helping him for 3, 4 weeks doing the POC end August 2009 on an Oracle 11.2 environment. We also discussed speaking on Hotsos, if not only because it starts to sink in that I will be speaking on this performance driven symposium. It will be Mark’s second presentation and my first… As always I am open for suggestions from more seasoned colleagues like Mark, so we had a good laugh and shared some tips. I already had the pleasure of seeing Mark’s presentation during UKOUG 2009, so I hope he will forgive me that’s probably one of the presentations that I will have to skip on Tuesday.

Afterward we caught up with Mark Farnham and Doug Burns at the Omni Hotel premises. It didn’t take long before Doug and I called it a night. Went out for a last smoke before I got to my room, were I (can’t help myself) tried to solve a last Oracle XMLDB OTN Forum question. Its Sunday while I am writing this. I got brutal woken up by Gerwin Hendriksen at 8.30 AM. Doug called it during breakfast (Gerwin, Doug and me) me being a slacker; I just call it too early… If not only, besides trying to get into the rhythm of the Dallas timezone, also to see some of the Oscars which I now have the opportunity to see it “live” on the television instead of seeing a summery of it on a Dutch channel.

On a side-note, you probably know that Tanel’s presentation on Tuesday isn’t that interesting. I mailed him some months ago, if he wouldn’t be in for a single trip to the Bahamas or something for that particular Tuesday afternoon, but he replied that I shouldn’t be to worried, because his presentation on Tuesday didn’t have any demo’s and most people wouldn’t be that interested in that one therefore anyway. Some one or two people would probably go to my presentation instead, if not only due to the fact that he has 3 presentations in total plus a training day where people might go to / choose from. One of the advantages of having been invited as a member to the OAKTable network. You can always build upon a fellow member.

Back to working on my presentation, its raining outside anyway…


I think I have the room next to Doug’s… He really should get those toys in order (TV noise all over the place). The hotel walls aren’t that thick as they once were…

Who's using a database link?

Every once in awhile it is useful to find out which sessions are using a database link in an Oracle database. It's one of those things that you may not need very often, but when you do need it, it is usually rather important.

Unfortunately for those of us charged with the care and feeding of the Oracle RDBMS, this information is not terribly easy to track down.

Some years ago when I first had need to determine which sessions were at each end of database link, I found a script that was supplied courtesy of Mark Bobak. When asked, Mark said he got the script from Tom Kyte. Yong Huang includes this script on his website, and notes that Mark further attributed authorship in Metalink Forum thread 524821.994. Yong has informed me that this note is no longer available.  I have found the script in other locations as well, such Dan Morgan's website. So now you know the scripts provenance.

Here's the script, complete with comments.  Following the script is an example of usage.

#eeeeee; border: 1px dashed rgb(153, 153, 153); color: black; font-family: Andale Mono,Lucida Console,Monaco,fixed,monospace; font-size: 12px; line-height: 14px; overflow: auto; padding: 5px; width: 100%;">-- who is querying via dblink?
-- Courtesy of Tom Kyte, via Mark Bobak
-- this script can be used at both ends of the database link
-- to match up which session on the remote database started
-- the local transaction
-- the GTXID will match for those sessions
-- just run the script on both databases

Select /*+ ORDERED */
substr(s.ksusemnm,1,10)||'-'|| substr(s.ksusepid,1,10) "ORIGIN",
substr(g.K2GTITID_ORA,1,35) "GTXID",
substr(s.indx,1,4)||'.'|| substr(s.ksuseser,1,5) "LSESSION" ,
0, decode( bitand(ksuseflg,4096) , 0,'INACTIVE','CACHED'),
) "S",
substr(w.event,1,10) "WAITING"
from x$k2gte g, x$ktcxb t, x$ksuse s, v$session_wait w, v$session s2
where g.K2GTDXCB =t.ktcxbxba
and g.K2GTDSES=t.ktcxbses
and s.addr=g.K2GTDSES
and w.sid=s.indx
and s2.sid = w.sid

Now let's take a look a the results of the script.

Logging on to DB1 as system, create a database link to db2 using the SCOTT account:

#eeeeee; border: 1px dashed rgb(153, 153, 153); color: black; font-family: Andale Mono,Lucida Console,Monaco,fixed,monospace; font-size: 12px; line-height: 14px; overflow: auto; padding: 5px; width: 100%;">create database link scott_link connect to scott identified by "tiger" using 'db2';

Make sure it works:

#eeeeee; border: 1px dashed rgb(153, 153, 153); color: black; font-family: Andale Mono,Lucida Console,Monaco,fixed,monospace; font-size: 12px; line-height: 14px; overflow: auto; padding: 5px; width: 100%;">system@db1 SQL> select sysdate from dual@scott_link;

03/05/2010 10:13:00

1 row selected.

Now logon to DB1 as sysdba and run who_dblink.sql:

#eeeeee; border: 1px dashed rgb(153, 153, 153); color: black; font-family: Andale Mono,Lucida Console,Monaco,fixed,monospace; font-size: 12px; line-height: 14px; overflow: auto; padding: 5px; width: 100%;">sys@db1 SQL> @who_dblink

--------------------- ----------------------------------- ---------- ---------- - ----------
oraserver.-21901 DB1.d6d6d69e.3.16.7190 500.15059 SYSTEM I SQL*Net me

1 row selected.

Now do the same on DB2:

#eeeeee; border: 1px dashed rgb(153, 153, 153); color: black; font-family: Andale Mono,Lucida Console,Monaco,fixed,monospace; font-size: 12px; line-height: 14px; overflow: auto; padding: 5px; width: 100%;">sys@db2 SQL> @who_dblink

--------------------- ----------------------------------- ---------- ---------- - ----------
ordevdb01.-21903 DB1.d6d6d69e.3.16.7190 138.28152 SCOTT I SQL*Net me

1 row selected.

How do you identify the session on the database where the database link connection was initiated?

Notice that the output from DB1 shows the PID in the ORIGIN column.  In this case it is 21901.

Running the following SQL on DB1 we can identify the session from which the SYSTEM user initiated the database link connection:

#eeeeee; border: 1px dashed rgb(153, 153, 153); color: black; font-family: Andale Mono,Lucida Console,Monaco,fixed,monospace; font-size: 12px; line-height: 14px; overflow: auto; padding: 5px; width: 100%;">select
b.sid SID,
b.serial# SERIAL#,
from v$session b,
v$process d,
v$sess_io e,
b.sid = e.sid
and b.paddr = d.addr
and b.username is not null
-- added 0.0000001 to the division above to
-- avoid divide by zero errors
-- this is to show all sessions, whether they
-- have done IO or not
--and (e.consistent_Gets + e.block_Gets) > 0
-- uncomment to see only your own session
--and userenv('SESSIONID') = b.audsid
order by

---------- ------ -------- -------------------- ------------------------
SYS 507 12708 oracle 22917

SYSTEM 500 15059 oracle 21901

2 rows selected.

The session created using the SCOTT account via the database link can also be seen using the same query on DB2 and looking for the session with a PID of 21903:

#eeeeee; border: 1px dashed rgb(153, 153, 153); color: black; font-family: Andale Mono,Lucida Console,Monaco,fixed,monospace; font-size: 12px; line-height: 14px; overflow: auto; padding: 5px; width: 100%;">USERNAME    SID SERIAL# OSUSER  PROCESS
---------- ---- ------- ------- ------------
SCOTT 138 28152 oracle 21903
SYS 147 33860 oracle 22991
146 40204 oracle 24096

3 rows selected.

who opened that DB Link

very nice analysis of tracking down who has a dblink open on another database