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Friday Philosophy – It’s not “Why Won’t It Work!” it’s “What Don’t I Understand?”

I had a tricky performance problem to solve this week. Some SQL was running too slow to support the business need. I made the changes and additions I could see were needed to solve the problem and got the code running much faster – but it would not run faster consistently. It would run like a dream, then run slow, then run like a dream again 2 or 3 times and then run like a wounded donkey 3 or 4 times. It was very frustrating.

For many this would provoke the cry of “Why won’t it work!!!”. But I didn’t, I was crying “What don’t I understand???”. {I think I even did a bit of fist-pounding, but only quietly as my boss was sitting on the desk opposite me.}

I think I’ve always been a bit like that in respect of How Things Work”, but it has been enhanced within me by being blessed to work with or meet people for whom it is more important for them to understand why something is not working than fixing it.

Friday Philosophy – Identifying and Nullifying Fake Urgency

You know how it goes. You get a call/mail/text with something along the lines of “I need to know all the details of customer orders placed on Tuesday 7th by customers based in Botswana – and I need it ASAP, by end of play today at the latest”. So you skip lunch, drop that task you have been trying to get around to doing all week and work out how to resolve the issue that has just been dropped on you. It takes a lot of effort and you finally get it sorted out around an hour after you told your girlfriend/boyfriend/cat you would be leaving the office that day – and mail it off to the requestor. You might even call them to let them know it is done, but oddly they don’t answer.

Next day, you see the guy who wanted this urgent request and ask if it was what they wanted “Oh, I have not looked at it yet – but thanks for doing it.”

OUGN 2012 Second Day – Out on the Open Seas

As I said yesterday, I am not one for blogging about conferences. So what the heck, I’ll do another post on this one :-) .

You might have picked up on the fact that I am not very good on the sea and have a lot of nervousness about this idea of spending 2 days on an ocean-going liner. So today is the day we move over to being on the water, the OUGN conference proper. I’m delighted to say I am not the only one nervous about this boat lark, Marie Colgan {or, as I should be calling her, “The Optimizer Lady” – since Doug Burns christened her back at the UKOUG 2011 conference} feels the same. There is nothing better to reduce one’s apprehension about something than finding someone else who is just as if not more anxious about it. I suspect this is an evil way to think but I can’t help it.

OUGN 2012 First Day – First Panic

I’m not really one for blogging about conferences – I mean who cares what someone else saw being presented? But this is the first time I have stopped moving long enough (and been in contact with the internet world) to blog and my brain is too fried to do a technical one.

Friday Philosophy – The Inappropriate Use of Smart Phones

I’m kind of expecting to get a bit of a comment-kicking over this one…

I never much liked mobile phones – Yes they are incredibly useful, yes they allow countries that lack a ground-based telephony network to create a nationwide system, yes they allow communication all the time from almost anywhere. That last point is partly why I dislike them. {Actually, I don’t like normal phones much, or how some people {like my wife} will interrupt a conversation to dash across the room to answer it. It’s just a person on the phone, it will take a message if someone wants to say something significant. If someone calls your name out in a crowd, do you abandon the people you are talking to, dash across the room and listen to them exclusively? No, so what act that way over a phone?}.

The Most Brilliant Science Graphic I Have Ever Seen

The below link takes you to an absolutely fantastic interactive demonstration of the relative size of everything. Everything. Stop reading this and go look at it, when it finishes loading, move the blue blob at the bottom of the screen left and right.

The Relative_scale_of_everything

The raw web link is:

http://www.primaxstudio.com/stuff/scale_of_universe/scale-of-universe-v1...

The web page says scale_of_the_universe but it should be relative_scale_of_everything_in_the_universe. Did you go look at it? NO!?! If it’s because you have seen it before then fair enough – otherwise stop reading this stupid blog and Look At It! NOW! GO ON!!!

Yes, I do think it is good.

Friday Philosophy – When Things Feel Wrong

I got pinged by someone else missing the Friday Philosophy today {BTW, Good news, the technical blogs start again on Monday}, so…

Take a look at the below. It is a rather pleasant spot of countryside on Sao Migel in the Azores, where the area in the foreground has been converted into a bit of a garden to take advantage of the natural beauty.

Friday Philosophy – Should I Be a Twit?

Something I have been pondering for a while now is should I join in with the “happening crowd” and sign up to Twitter? I know, I’m two or three years behind the times on this, but more and more people who I like have signed up – even Doug Burns now uses twitter and he used to be negative about it in the same way as I. I’ve asked a few of these friends what they think.

Friday Philosophy – The One Absolute Requirement for System Success

Alternative title “The lady from Patient Admin – she says YEEESSSS!!!!!!”

What must you always achieve for an IT system to be a success?

  • Bug free? Never happens.
  • Within budget/time frame? That would be nice.
  • Includes critical business functionality? Please define critical.
  • Secure? Well, it’s important for many systems but then it is often lacking (even when it is important).
  • That it is to specification? Well we all know that’s wrong.

There is only one thing that an IT system must always achieve to be a success.

User Acceptance.

For an individual system other considerations may well be very important, but the user acceptance is, I think, non-negotiable.

Friday Philosophy – Human Tuning Issues

Oracle Tuning is all about technical stuff. It’s perhaps the most detail-focused and technical aspect of Oracle Administration there is. Explain Plans, Statistics, the CBO, database design, Physical implementation, the impact of initialisation variables, subquery factoring, sql profiles, pipeline functions,… To really get to grips with things you need to do some work with 10046 and 10053 traces, block dumps, looking at latching and queueing…

But I realised a good few years ago that there is another, very important aspect and one that is very often overlooked. People and their perception. The longer I am on an individual site, the more significant the People side of my role is likely to become.

Here is a little story for you. You’ll probably recognise it, it’s one that has been told (in many guises) before, by several people – it’s almost an IT Urban Myth.

When I was but a youth, not long out of college, I got a job with Oracle UK (who had a nice, blue logo back then) as a developer on a complex and large hospital system. We used Pyramid hardware if I remember correctly. When the servers were put in place, only half the memory boards and half the CPU boards were initiated. We went live with the system like that. Six months later, the users had seen the system was running quite a bit slower than before and started complaining. An engineer came in and initiated those other CPU boards and Memory boards. Things went faster and all the users were happy. OK, they did not throw a party but they stopped complaining. Some even smiled.

I told you that you would recognise the story. Of course, I’m now going to go on about the dishonest vendor and what was paid for this outrageous “tuning work”. But I’m not. This hobbling of the new system was done on purpose and it was done at the request of “us”, the application developers. Not the hardware supplier. It was done because some smart chap knew that as more people used the system and more parts of it were rolled out, things would slow down and people would complain. So some hardware was held in reserve so that the whole system could have a performance boost once workload had ramped up and people would be happy. Of course, the system was now only as fast as if it had been using all the hardware from day one – but the key difference was that rather than having unhappy users as things “were slower than 6 months ago”, everything was performing faster than it had done just a week or two ago, and users were happy due to the recent improvement in response time. Same end point from a performance perspective, much happy end point for the users.

Another aspect of this Human side of Tuning is unstable performance. People get really unhappy about varying response times. You get this sometimes with Parallel Query when you allow Oracle to reduce the number of parallel threads used depending on the workload on the server {there are other causes of the phenomena such as clashes with when stats are gathered or just random variation in data volumes}. So sometimes a report comes back in 30 minutes, sometimes it comes back in 2 hours. If you go from many parallel threads to single threaded execution it might be 4 hours. That really upsets people. In this situation you probably need to look at if you can fix the degree of parallelism that gives a response time that is good enough for business reasons and can always be achieved. OK, you might be able to get that report out quicker 2 days out of 5, but you won’t have a user who is happy on 3 days and ecstatic with joy on the 2 days the report is early. You will have a user who is really annoyed 3 days and grumbling about “what about yesterday!” on the other 2 days.

Of course this applies to screens as well. If humans are going to be using what I am tuning and would be aware of changes in performance (ie the total run time is above about 0.2 seconds) I try to aim for stable and good performance, not “outright fastest but might vary” performance. Because we are all basically grumpy creatures. We accept what we think cannot be changed but if we see something could be better, we want it!

People are happiest with consistency. So long as performance is good enough to satisfy the business requirements, generally speaking you just want to strive to maintain that level of performance. {There is one strong counter-argument in that ALL work on the system takes resource, so reducing a very common query or update by 75% frees up general resource to aid the whole system}.

One other aspect of Human Tuning I’ll mention is one that UI developers tend to be very attuned to. Users want to see something happening. Like a little icon or a message saying “processing” followed soon by another saying “verifying” or something like that. It does not matter what the messages are {though spinning hour glasses are no longer acceptable}, they just like to see that stuff is happening. So, if a screen can’t be made to come back in less than a small number of seconds, stick up a message or two as it progresses. Better still, give them some information up front whilst the system scrapes the rest together. It won’t be faster, it might even be slower over all, but if the users are happier, that is fine. Of course, Oracle CBO implements this sort of idea when you specify “first_n_rows” as the optimizer goal as opposed to “all_rows”. You want to get some data onto an interactive screen as soon as possible, for the users to look at, rather than aim for the fastest overall response time.

After all, the defining criteria of IT system success is that the users “are happy” -ie accept the system.

This has an interesting impact on my technical work as a tuning “expert”. I might not tune up a troublesome report or SQL statement as much as I possibly can. I had a recent example of this where I had to make some batch work run faster. I identified 3 or 4 things I could try and using 2 of them I got it to comfortably run in the window it had to run in {I’m being slightly inaccurate, it was now not the slowest step and upper management focused elsewhere}. There was a third step I was pretty sure would also help. It would have taken a little more testing and implementing and it was not needed right now. I documented it and let the client know about it, that there was more that could be got. But hold it in reserve because you have other things to do and, heck, it’s fast enough. {I should make it clear that the system as a whole was not stressed at all, so we did not need to reduce system load to aid all other things running}. In six months the step in the batch might not be fast enough or, more significantly, might once more be the slowest step and the target for a random management demand for improvement – in which case take the time to test and implement item 3. (For those curious people, it was to replace a single merge statement with an insert and an update, both of which could use different indexes).

I said it earlier. Often you do not want absolute performance. You want good-enough, stable performance. That makes people happy.