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How NOT to present November 30, 2010

Posted by mwidlake in Meeting notes.
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I’m at the UKOUOG this week and, as ever, the presentations vary in quality. Most are excellent {or even better than that}, some are not. I was in one first thing this morning and, I have to say, it was rushed, garbled, unclear and there was a definite air of unease and panic. I’m not even sure the guy got to his big point and I could think of at least three major things he did not mention at all.

I think his main problem was just starting off in a rush and never settling down. You see, I was stuck on the top floor of my Hotel and had to run to the venue. Yes, the poor presentation was by me :-(.

I usually present well {modesty forbids me from saying I am a very good presenter – but modesty can take a hike, my ego knows I am capable of giving great presentations}. I am one of those lucky people for whom presenting has never been particularly frightening and, in fact, I find it easier to present to a group of people than talk with them.

But not today. I was already worried about the session, have been for weeks, as I was doing interactive demos. But last night I ran through it, wrote down the names of the scripts and the slide numbers so I could just bang through them and timed it all. 50 mins, I would skip one unneeded section. Calm. I got a reasonable night’s sleep, got up early and ran through it all one more time, making sure my Big Point demo worked. And it did. Yes.

Went down to breakfast, had breakfast and back to the room to pick up my stuff. And realised I was late. Less than 10 minutes to do the 5 minutes over to the venue. So I fled the room, stuffing my laptop in my bag. But not my notes. Or my conference pass. I did not think of this as I stood on the top floor of the hotel, I just thought “where are the lifts?”. They were all below me, ferrying hungry people to and from breakfast. After what seemed like an hour and was only 4 or 5 minutes I decided 16 flights of stairs was OK to go down and, to give me credit, I managed those stairs and the few hundred yards to the venue in pretty good time. I did pause for a few seconds at floor 7, I think, when I remembered my notes. Too late.

But I was now panicked and arrived as a dash. I had to mess about with the Audio Visual guy to get going and started 2 mins past my slot start – and then did the 5 minutes of non-relevant stuff I had decided to drop. It was game over from there, I was failing to find the correct scripts, I was skipping relevant sections and I was blathering instead of just taking a few seconds to calm down and concentrate.

Oh well, my first time in a large room at the UKOUG and I messed up. At least I had the key lesson drummed into me. TURN UP EARLY!!!!

Advert – UKOUG conference, end of November October 30, 2010

Posted by mwidlake in Meeting notes.
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1 comment so far

The best Oracle event in the calendar (in my opinion) is only a month away now. From Monday 30th November to Wednesday 1st December the UK Oracle User group Technical and E-Business Suite (TEBS) conference is running. {Being old-school I still think of it as the UKOUG conference but the user group also run other conferences for eg Siebel, Peoplesoft and the up-coming JD Edwards event, dedicated to those segments of the constantly growing world of Oracle}.

I love the TEBS conference. I loved it when I knew almost nobody else attending it because of the breadth and quality of the technical presentations. When I was a manager I liked the fact I could mix going to the technical stuff to going around the demo booths and seeing if any of the services on offer were of interest. And now that I know more people who attend the event, I love catching up with them and also meeting new people who maybe I only knew before by name or reputation.

The social events around the conference are no where near in the same league as those at Oracle Open World – which means that the UKOUG ones are not massive and unfeeling, but of a size where you can bump into friends and be introduced to other people. {And, I should add, the UKOUG staff do an excellent job of organising them}. I’d say half the people I know in the Oracle world I met at the conference.

So having said how much I like the conference, the question is, am I presenting this year? There seems to be an inverse relationship to the number of years I have been attending and the number of talks I do. Back in 2004 I did 3, in 2005 and 06 it was 2, 2007 was 1. 2008 I had to skip the event and last year all my proposed talks were rejected. I blame the fact that the quality and number of abstracts submitted goes up each year.

The good news (or bad news, depending on your opinion) is that I am presenting again this year, first thing on Tuesday at 08:45

My SQL is suddenly performing badly and nothing has changed. Why?

I’m actually very nervous about this presentation as I want to not only describe why SQL might change how well it performs but also demonstrate the reasons – and how you detect them. Demonstrations take an age to prepare and, as fellow presenters know, have this nasty habit of dying under your feet. I’ve not got a lot of spare time at present so I already feel I am behind schedule!

I’ll also be curious how many people from the MySQL field drift into the room thinking it is part of the MySQL stream {which runs on the Wednesday}. Sadly the talk will be of no use at all to them as it is very specific to Oracle!

Despite the presenting duties, I’m really looking forward to the event. I’d love to meet anyone who reads my blog, whether you like it or not. Just stop me and say “hi” if you see me around.

Advert – MI SIG on 5th October September 13, 2010

Posted by mwidlake in Meeting notes.
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The next UK Oracle User Group (UKOUG) Management and Infrastructure SIG is coming up in a few weeks – 5th October in the Oracle City Office. You can find the latest agenda here. If you do not know what we (the MI SIG) cover, it is basically technical topics at a slightly broader level. So not so much example code but how feature X works or how to use Y over 100 databases plus. We also touch on management issues, which I always worry will put some potential attendees of,f but in fact nearly always goes down very well.

We have an excellent line up of topics and presenters for this meeting. Does Exadata work in the real world? Peter Scott will be presenting some of what he has learned doing this. Want to know about oracle’s latest licensing options and how to save money? Alex Sandercock from Turnstone Services will be talking about that. Confused about how storage is changing and how the database interacts with it? James Moorle will cover that one.

It has been a real struggle getting the agenda together for this meeting, I can’t believe we have ended up with such a strong one in the end. I mean, I am not even having to bore everyone with my voice again.

The first problem was I just failed to get the organising started. As the Chair, it is my main function to sort out the meetings. It was always “tomorrow” as I had so much on for every “today”.

The second problem was we were up against Oracle Open World. We had a few people “in hand” who had indicated they would be happy to do a talk for us, but were scheduled to do OOW. I thought it was a bit mean to turn us down for some obscure vendor event in the US. So we moved our event by a month.

The final problem was that we still had trouble with speaker availability, as it was now so close (it might not seem close if you are considering going to a meeting, but if you are being asked to sign up to preparing and giving a presentation, 5 weeks is not a lot of notice).

It all came together in the end, with the help of the co-chairs, especially Neil Chandler.

I know I have said this before, but I struggle to understand why SIG meetings are not flooded with people coming to them. It is free training in effect (if your organisation is a member of the UKOUG – £80 otherwise, I think). All the presenters are experts, often presenting similar talks to those given at Oracle Open World or the UKOUG Conference. OK, it is a day not working in the office but as well as the “free training” you meet up with other people who have similar work issues as you. I find it invaluable to have a circle of external people I can occasionally say “What do you think of this” to. The meeting other people is aided by us retiring to a pub after the event, for those inclined to do so.

I try to get to SIGs when I can and in fact, if I was not at my own on the 5th, I’d like to be at the modelling and architecture one – I’ve been meaning to get to that one for ages.

Saturday Philosophy – The unbelievably small world of VLDBs June 12, 2010

Posted by mwidlake in VLDB.
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9 comments

Yesterday I posted about the potential for a Oracle in Science community within the UK Oracle user group {and wider for that matter, there is after all a world Oracle Life Science community but it is currently less vibrant than it was, sadly}.

My friend and occasional drinking partner Peter Scott replied to say he felt there was “a place for a SIG for stonking great databases” {now wouldn’t SGDB be a better TLA than VLDB? :-) }.

Well, I would agree but for one small detail. An apparent lack of anyone willing to be part of the community.

When I was building a very considerable VLDB {and I’m sorry I keep going on about it, I’ll try and stop soon} back in the early to mid 2000’s I seemed to be working in a vacuum of information, let alone prior experience. Yes, there was stuff in the Oracle manuals about how big things could theoretically be made and some vague advice on some aspects of it, but an absolute lack of any visible Oracle customers with anything even approaching the sizes I was contemplating. 2TB was about the limit and I was already way beyond that. Was this because I really was pushing the boundaries of database size? Well, I have since found out that whilst I was up there just behind the leading edge, there were several databases much, much bigger than mine and others already envisioned that might hit the Petabyte level, let alone Terabyte.

The thing is, no one would speak about them. At all.

We were left to do it all pretty much from scratch and it would not have been possible if I had not spent years building up with VLDBS as the definition of a VLDB size increased, plus of course cracking support by the other DBAs and Systems Admins around me. And to be fair, Oracle Corp helped us a lot with our efforts to build these massive databases. Interestingly, one Oracle Consultant would regularly tell me that our systems really were not so unusually big and there were plenty larger. He usually said this when I asked, exasperatedly as something else failed to scale, if Oracle had every tested things at this level :-). But despite constantly asking to meet with these people with massive systems, so we could exchange war stories and share advice, and being promised such contacts by Oracle, they never materialized except for CERN – who we already talked to as a fellow scientific organisation – and Amazon, who it turns out did things in a very different way to us {but it was really good to talk to them and find out how they did do their big databases, thanks guys}. Both were at the same scale or just behind where we were.

This is because most of the people with massive oracle databases will not talk about them as they are either run by the largest financial organisations, are to do with defense or in some other way just not talked about. In his comment Peter refers to a prior client with an OLTP-type system that is now around the PB scale. I would be pretty sure Peter can’t say who the client is or any details about how the system was designed.

So although I think there is a real need for a “stonking great databases” forum, I think there is a real problem in getting a user community of such people/organisations together. And if you did, none of the members would be allowed to say much about how they achieved it, so all you could do would be sit around and brag about who has the biggest. There is an Oracle community about such things, called the Terabyte Club, but last I knew it was invite-only and when I managed to get invited, it turned out that mine was biggest by a considerable margin, so I was still not meeting these elusive groups with 500TB databases. Maybe there is an Oracle-supported über database society but as I never signed the official secrets act might not have been eligible to play.

If I am wrong and anyone does form such a user group (or is in one!) I would love to be a member and I would strive to present and help.

I’ll finish with what appears to be a contradiction to what I have just written. There already is a UKOUG User Group that deals with large systems and I chair it – the Management and Infrastructure SIG. {sorry, the info on the web page could do with some updating}. Part of what we cover is VLDBs. But we also cover Very Many DataBases (companies with thousands of instances) and Very Complex DataBases plus how you go about the technical and management aspects of working in a massive IT Infrastructure. It might be that we could dedicate a meeting to VLDBs and see how it goes, but I know that whilst many who come along are dealing with database of a few TB, no one is dealing with hundreds of TB or PB database. Either that or they are keeping quiet about it, which takes us back to my main point. The MI SIG is probably the closest to a VLDB SIG we have in Europe though, and is a great bunch of people, so if you have a VLDB and want to meet some fellow sufferers, we have our next meeting on 23rd September in the Oracle City office.

Friday Philosophy – The Science of Oracle June 11, 2010

Posted by mwidlake in Friday Philosophy, Meeting notes.
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3 comments

The title to this blog is very misleading. It is not about scientifically understanding how Oracle technologies work or even about the technology itself.

It is actually about the fact that a lot of scientific organisations, both academic and commercial, work with Oracle technology in ways to do directly with the science {as opposed to using it for CRM, HR or tracking students and results, which they also do but I’m not interested in that}.

If you have worked in Academia or charitable scientific organisations it can be a little suprising that Oracle is used so much, as it is expensive and corporate – there is a tendency to be poor and anti-corporate in such environments. But the thing is, Oracle is able to handle large amounts of complex data, in many formats, in many ways, and most programming languages can easily access the data in the database. You can achieve a lot with just PL/SQL and Java of course.

Commercial scientific organisations, like large Pharmaceuticals, use it for the same reasons of course, but for them the cost is not such an issues {I can imagine IT managers in such organisations going “It damn well IS an issue!” but trust me, not in the same critical way}.

What is the point of this blog? Well, it’s about user communities. The scientific community have a tendency to push the Oracle database further than most Oracle users do. Take data volumes. I worked for many years for the UK-side of the Human Genome Project and part of what I did was create an Oracle database that scaled to 100TB. Even now that is pretty large but I was designing and implementing it back in 2004-2005. The data volumes CERN are going to have to handle for the Large Hadron Collider just dwarf that, and they only hold summarised data of summaries of the actual raw scientific data generated.

Another aspect is coping with very rapid change, for example systems to support lab processes. This is similar to your standard factory management system except that the level of change can be daunting. The process can change, well, weekly, as the science and techniques improve in the lab. Those scientist might even completely change what they are doing when some unexpected avenue opens up. I say “might”, seemed to happen every month.

In scientific organisations there tends to be more openness about what and how they do things. Academic and charitable scientific organisations tend to put less barriers in the way of exchanging knowledge than corporations do and so that encourages more exchange of information. When I was working in the area I was positively encouraged to go to conferences and present. Obviously this is not always true and scientific corporations, like Pharmaceuticals, have gained {rightly or wrongly} a reputation for being very reticent about sharing any knowledge at all. But often the individuals involved will share.

So, the scientific community push areas of the technology very hard, they tend to be an open bunch of people, cost is often critical and, the final thing I have not mentioned, is that they often speak a language only vaguely recognisable as English, due to the jargon. Sounds like a community to me.

The real reason I mention all this is that it looks like, after about 4 years of considering and discussing having a science SIG {Special Interest Group} in the UKOUG, I will finally be putting together an agenda for an initial meeting for such a thing. I wonder if it will be a success?

Northern Server Technology Day – Advert April 22, 2010

Posted by mwidlake in Meeting notes.
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I’m a bit late doing this, but next week is the UKOUG Northern Server Technology Day.
As the title suggests, this is a day of technical presentations for Oracle users in the North of England. Of course, it is open to any UKOUG member (and anyone else, for a small fee), but the idea behind it is to provide a user group event for those who are not based in the South of England and so might struggle to the usual events. This year the day is being held in Leeds, which is where I was at college, so I am more than happy to return to my old stomping ground and support the day with a presentation on Database Statistics.

There are other, probably much better, presentations by David Kurtz, John Hallas, John Scott, Piet de Visser and David Phizacklea too. I’ve seen them all do their stuff before and it should be a cracking day. Check out the agenda via the link at the top of this post.

If you are an Oracle user who is based up in the North and have an interest in the meeting, I would urge you to make the extra effort to attend. It is a constant complaint that the UKOUG is biased towards having events in Reading, London and the Midlands and not a lot elsewhere, but to have events further afield there needs to be an active and interested audience to justify the event. The better the event is supported, the more likely it is to continue and prosper and potentially attract other UKOUG SIG meetings North.

Actually, on that note, I will also mention the Scotland 2010 conference meeting, a must for Oracle users in Scotland or those who would like to mix a technical conference with visiting Scotland {and I have to say, I do enjoy visiting Scotland}. Not sure yet if I can get there myself this year :-(

Friday Philosophy – I killed a presentation April 1, 2010

Posted by mwidlake in Friday Philosophy, performance, statistics.
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9 comments

Well, this week saw the latest Management and Infrastructure SIG. I won’t go into the SIG meeting itself just now, maybe later this weekend. If you want an opinion on it, you might like to see what Graham Oaks said.

Being Chair of the SIG I have to find presenters. Being also one of those rare people who enjoys presenting, I know I can always tap one person to present. Me. {If only I could sing, play an instrument, act, do impression, put both my ankles behind my ears(*) or anything that was of any general interest, getting an audience would be so much easier}.

I decided to tackle a topic I have tried before and which I previously did a very poor show of: “General principles on gathering database statistics”.
It is not a title to strike joy into the soul, I know, but it is really important to getting good and reliable performance out of any modern Oracle database. Even other Oracle DBA types tend to find the topic worthy but boring, but I seem to have been forced to know a lot about it and I’ve become sadly very passionate about it.

So, I tried again. I mean, how long should it take to describe the issues with database statistics and the general principles to gathering them? I took my old presentation and stripped out all code, all SQL syntax, all listing of tables and got it down to describing the process. Then I started adding the bits and pieces you need to know to get this half-right. 132 slides. Hmmmm

I tried again and took it higher level. 48 slides. I can do 48 slides in something between 45 minutes and an hour. I was ready.

I had the last presentation slot of the day. I figure if I am going to foist myself on the audience, they should have the right to leave before I start, without missing any of the good stuff. I had 3/4 of the day’s attendees still with me when I started.

I think I killed my audience. Actually, I know I killed my audience. I lost a few as the slot progressed {I kidded myself they had to get back to the office/catch a train} and I made the fatal mistake of not shutting up when I had done 45 minutes. You see, there was all this important stuff I had not mentioned yet! Thankfully, I had a friend in the second row and when I saw him lose the will to live, I stopped. I’d been at it for 70 minutes. What we really needed was the Chair to shut me up but I was the chair.

Anyway, I came away from the talk with two realisations.

  • The topic of gathering database statistics is too large to cover in one presentation session.
  • It really is very boring, even when you are passionate about it.

I think I have no choice but to make this a blog thread (as I threatened to do so about 1 month ago). But I have also promised myself to finish off SQL Audit before I start a new thread and that was 3 months ago.

So I think I am going to have to put some time into this blogging lark. It’s OK though, I seem to go on about database statistics so much that even my cat is staring to avoid me. I’ll just stop watching Star Trek and drinking wine in the evenings and switch to preparing technical blogs. And drinking wine of course.

(*) Up until 2007 I could do this. I get out more now. Despite the stats fixation

Advert for the Management and Infrastructure SIG March 24, 2010

Posted by mwidlake in Management, Meeting notes.
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4 comments

I’m a bit late doing this (life is just too busy at the moment) but I want to mention the next Management and Infrastructure Special Interest Group meeting of the UKOUG next Week. Tuesday 30th, being held in Oracle’s London City office.

I get asked by people what exactly the MI SIG is? {Honest, I do, I got asked twice this month alone!}. Is it a management meeting or is it another one of the technical SIGs, like the UNIX, RDBMS and RAC/HA SIGs? I’ve struggled to come up with a single line to sum it up. Other than to say “Both”.

It might be easier to sum up the target audience. The MI SIG is for technical people who need to deal with Oracle as a component of a large IT environment. Most of the audience could knock up a PL/SQL script to create a new set of tablespaces each month, would be able to instal Oracle {if given a couple of days and the manuals to peek at} and could explain two-phase commit. Maybe.
But what they have to deal with in their working lives are things like using Grid Control to manage 500 instances, understand what options are there for providing disaster recovery {if not the exact commands to eg set up physical standby or active/passive RAC}, knowing enough about storage options to make a sensible decision on which is best for each type of Oracle system they have. So it is a technical SIG, but covering general principles and, well, Infrastructure.

And the Management? Well, when the SIG started this bit was really interesting to me. When you have a lot of IT going on, especially in large organisations, the people looking after Oracle are not the people looking after Networks, or Storage, or Backups or half a dozen other things. And you probably have a team of people doing all that Oracle stuff with/for you. So you have to hire staff and keep ‘em happy and deal with teams who you have no power over but you need them to do stuff for you. And that Management part can be a lot harder than the technology, especially if you never planned on being a manager but just woke up one day with that monkey on your back.

So with the technical aspects of Large IT Infrastructure comes the management component too. The SIG is there for that audience.

I chair this SIG, so I am more than a little bit biased, but I think it is a good line-up of talks for this up-coming meeting. We have two talks on using OEM/Grid Control, one around using it for deploying clusters, one about how you go about integrating it with the likes of LDAP, Kerbros and using the Custom Metrics, ie plugging it into the wider infrastructure.

We also have a presentation on the latest/greatest Exadata2, from some Oracle friends.

To wrap up the technical talks I am going to try and explain some of the guiding principles for gathering statistics for you oracle databases. Not the details of DBMS_STATS command syntax, but why you need good stats, how you get them and the issues we all seem to end up facing with it.

Balancing the techical side is a talk on Birkman and understanding teams and people.

So, you can see it is a line-up matching the diversity of the SIG’s purpose.

As I said earlier, I initially was very interested in the management side of the SIG and I worried I would be pretty lonely in that opinion. For various reasons, those of us on the technical side tend not to have much time for those “soft skills” we associate with management theory. However, when I took over the SIG over a year ago, I asked the audience if they would want some talks on hiring staff, dealing with people, motivation… Over 60% of the audience said “YES!”. Quite loudly. About 30% said “OK, so long as we get technical stuff as well”. 6% said “over my dead body”.

I think the reason so many wanted the management side as well is, whether we like it or have an affinity for it or not, it is part of the job. And so we need to be able to do it. Personally, I quite like the human side of IT, but my wife tells me I am strange.

If your organisation has UKOUG membership it is free to come along to the SIG (one person per membership, excluding Bronze membership) Anyone can come along for £80. You would be very welcome and I am sure you will learn new stuff. Don’t let the fact that we retire to a pub afterwards where the chair buys a round sway your decision to come along at all.

Dealing with Bind Issues December 1, 2009

Posted by mwidlake in Meeting notes, performance.
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11 comments

One of the presentations I have seen today was on handling bind values. I can’t say it was, for me, the best I have seen this week, I’ve done a lot of work on binds in the past so I had come across most of the material before. Should I have bothered?

Well, there was one little gem in there which struck me as very simple and potentially very effective.

Bind variables and histograms are not a good mix, as has been commented on many, many times. In essence, if your data in a column is skewed so that some values match very few records and others match a large number, when oracle sees a SQL statement with a bind value being compared to that column, it peeks at the first value being passed in with the bind and uses it to decide on the plan (this is pre 11G, by the way).
That plan is then used for every execution of that sql statement until it is thrown out the SGA. Which is jolly unfortunate if all the values subsequently passed in via the bind do not suit the plan. 

The solutions to this usually boil down to one of three approaches; remove the histograms on the column in question so that all values are treated equally;stop it being a bind/prevent bind peeking; force the “bad” plan out of the SGA and hope the next parse gets a better plan.

All have their merits and drawbacks.

Well, in this presentation there was a fourth solution. Something like this:

if :status in (1,2,3) then
  select /*+ cardinality (t1 100000) */
  from table_1 t1
      , table_t t2
  where t1.status=:status
  and....;
else
  select /*+ cardinality (t1 100) */
  from table_1 t1
      , table_t t2
  where t1.status=:status
  and....;
end;

I might be missing something blindingly obvious here (and this might be a common solution that has just passed me by), but it seems to me to be a simple and effective solution that could be used in many situations.

I also learnt that it is rare not to find at least one good thing out of any presentation, so long as you keep paying attention.

UKOUG So Far December 1, 2009

Posted by mwidlake in Meeting notes.
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2 comments

It is the start of the second day (actually, an hour in, have a small “one beer too many” issue to cope with so I missed the first session) and so far I’ve very much enjoyed the event.

I saw several good talks yesterday. highlights for me were; Graham Wood’s talk on ASH, Alex Gorbachev on ASM and Doug Burn’s talk on parallel processing. Doug’s talk fell foul of the curse of all talks, the carefully prepared and tested demo deciding not to play, but a few of us clustered around his laptop to see the final results after the event.

I really wanted to get to Randolf Geist’s talk but one of the “problems” with having been coming to the conference for so many years is meeting up with people you have not seen for ages, getting into a conversation and realising that the next set of sessions started 10 minutes ago.

Today my chairing duties start, with Luca Canli from CERN talking about compressing very large data sets, which is something that is highly pertinent to my current work.

Tomorrow I chair 4 sessions:
Larry Carpenter on DataGuard 11GR2. Larry is an old friend, he gave us some excellent support on Dataguard 5 or 6 years ago.
Piet de Visser on Good Indexing. Piet is up against Jonathan Lewis and James Moorle and he has joked to me that it could be just him and me in the room, but I doubt that. I don’t want to discourage anyone from going to see JAmes and Jonathan (both give cracking presentations) but heck, come and see Piet :-)
I’m then chairing Christian Antogini, talking on parallel processing. I’ve never “Met” Christian, I’ve been in a couple of large discussions where he was also there, so I am looking forward to meeting him properly.
My final Chairing duty is right at the end of the last day, when only the die-hards and those who’s train ticket is pre-booked late in the day remain :-)
I’ll be chairing Husnu Sensoy who is talking about backing up enormous database, which many of you will know is a topic close to my heart. That should be a fine rounding off of the conference.

My aim today is to get to a few more sessions and get through the evening without drinking that one beer too many.

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