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Friday Philosophy – Picture Theft!!! July 28, 2011

Posted by mwidlake in Blogging, Friday Philosophy, Perceptions.
Tags: , , ,
7 comments

Last week’s Friday Philosophy was a bit of a moan about how hard I find it to make nice graphics, how long it takes and no one seems to care that much about the results.

Well, after those two days effort on the pictures and the afore mentioned moan, irony of irony, someone has stolen one of my graphics!. So someone likes my efforts ;-). It is the one that represents how you scan down the levels of an index and then link across to the table via the rowid.

Before I go any further I better make it clear that I am not really upset about it at all :-). In fact, since the scoundrel included a link back to my web page and they are considerably better known than I, my little blog has had a big up-swing in traffic as a result, which is nice. Mind you, as the person who borrowed my diagram is SQL Server expert Steve Jones, of SQLSeverCentral/Redgate fame, most of my new audience are probably pretty focused on the SQL Server RDBMS and not Oracle, so unlikely to make many return visits unless they are work across the RDBMS boundaries.

What also gives me a little smile is that I have stumbled over the fact that I myself, back in November 2009, was looking for such a diagram {of the way Oracle steps down the index to the leaf blocks, gets the rowid and then straight to the table row} to ‘borrow’ for a post of my own on BLevel and heights of indexes. I even confessed at the time to looking for and failing to find one to use…

Humour aside, it set me to thinking though. Borrowing content is a perennial and thorny issue.

Occasionally someone will start putting content out on their blog or web site and it turns out that much of that content is directly obtained from other peoples’ blogs and websites – copy&pasted straight in or with little changes. That is generally seen by the original author as unacceptable and once they find out they object. In such cases it sometimes seems the culprit is unaware of this being a transgression and, once it is explained that they have effectively stolen many hours or days of someone’s efforts, they remove the material. Others seem aware this is theft but do not care until caught. Occasionally the culprit sees no error in their ways at all, even when challenged, as the material had been put “out there” so they now consider it free to all. I certainly do not agree. Perhaps the worst thing you see though is people including parts of published books, or even putting the whole book out there for download. Such people should of course have their hands stapled to their backsides in punishment, that is simple theft. Writing blogs takes a long time and effort, writing technical books takes forever and monumental effort. I know from friends that the financial return for such efforts is pitiful enough as it is.

On the other side of the coin, many of us put our stuff out there on the web to be read and used and are very happy for it to spread, to be borrowed from and disseminated. Like nearly all DBAs and developers, over the years I have written lots of little SQL scripts to pull information out of the data dictionary or do little database management tasks. I happily give away copies of these to anyone who wants them (and you can get them off my web site if you like, but just pretend it is not my website, as it is truly awful). All I ever ask is that whoever takes them leaves my name in them.

I think that is core to the issue. I suspect many of us bloggers are happy for small parts of our output to be borrowed so long as credit is given. I certainly am {but please note, this is my personal opinion – other bloggers may object very strongly and any repercussions on you in respect of taking material from other blogs and web sites is your concern}. However, Volume is also part of it. The larger the chunk you borrow, the more acknowledgement I would need to be happy about it. Borrowing a single diagram or a paragraph out of a page of text is OK, given I am cited for it. Taking most of a post would probably not, unless you asked first, were really nice about it and about me. Nicking a set of course notes I wrote is certainly unacceptable, no matter how much you put “originally written by that wonderful Martin Widlake” on it.

So, I think you need to cite the source as “payment” for using it. Perhaps the best way to do it is by simply linking to the material rather than putting it on your blog/website, but that does not work if you need the content within yours to make sense. In which case, I think Steve Jones’ approach of putting the content in his and including a link is reasonable. It might have been nice if there was a comment saying where the image came from but I can live without it. Despite my joking about it giving me more hits to my blog, it does not matter that his is a popular web site and gives me more hits. Even if a site gets no traffic, if someone has borrowed a small part of my output but cited me as the source, I’m cool with that.

The problem though is judging what is a “small” part to borrow and what is acceptable to the original author. We all perceive such things differently. So the safest thing is to ask the original author. If I want to use an idea that came from someone else in one of my blogs or a solution they came up with, I always ask and I ask if they want to be cited. This includes discussions in email or in the pub. I ask. If when preparing my blogs I learn a lot from someone else’s blog, I stick in a link and a comment, even though I will have written my own text. I hope that so far I have not upset anyone when I borrow a little.

Photos are a different issue though. I am not going to even attempt to cover that one!

Snowdon viewed from Yr Aran

If you Really Can’t Solve a “Simple” Problem.. March 11, 2011

Posted by mwidlake in Friday Philosophy, Perceptions, Testing.
Tags: , ,
12 comments

Sometimes it can be very hard to solve what looks like a simple problem. Here I am going to cover a method that I almost guarantee will help you in such situations.

I recently had a performance issue with an Oracle database that had just gone live. This database is designed to scale to a few billion rows in two key tables, plus some “small” lookup tables of a few dozen to a couple of million rows. Designing a system of this scale with theory only is very dangerous, you need to test at something like the expected volumes. I was lucky, I was on a project where they were willing to put the effort and resource in and we did indeed create a test system with a few billion rows. Data structure and patterns were created to match the expected system, code was tested and we found issues. Root causes were identified, the code was altered and tested, fine work was done. Pleasingly soon the test system worked to SLAs and confidence was high. We had done this all the right way.

We went live. We ramped up the system to a million records. Performance was awful. Eyes swung my way… This was going to be easy, it would be the statistics, the database was 2 days old and I’d warned the client we would need to manage the object statistics. Stats were gathered.
The problem remained. Ohhh dear, that was not expected. Eyes stayed fixed upon me.

I looked at the plan and I quickly spotted what I knew was the problem. The below code is from the test system and line 15 is the key one, it is an index range scan on the primary key, within a nested loop:

   9 |          NESTED LOOPS                       |                           |     1 |   139 |    37   (3)| 00:00:01 |       
* 10 |           HASH JOIN SEMI                    |                           |     1 |    50 |    11  (10)| 00:00:01 |       
* 11 |            TABLE ACCESS BY INDEX ROWID      | PARTY_ABCDEFGHIJ          |     3 |   144 |     4   (0)| 00:00
* 12 |             INDEX RANGE SCAN                | PA_PK                     |     3 |       |     3   (0)| 00:00:01 |       
  13 |            COLLECTION ITERATOR PICKLER FETCH|                           |       |       |            |          |       
  14 |           PARTITION RANGE ITERATOR          |                           |    77 |  6853 |    26   (0)| 00:00:01 | 
* 15 |            INDEX RANGE SCAN                 | EVEN_PK                   |    77 |  6853 |    26   (0)| 00:00:01 | 

On the live system we had an index fast full scan (To be clear, the below is from when I had tried a few things already to fix the problem, but that index_fast_full_scan was the thing I was trying to avoid. Oh and, yes, the index has a different name).

|   9 |          NESTED LOOPS                 |                           |     1 |   125 |  1828   (3)| 00:00:16 |
|  10 |           NESTED LOOPS                |                           |     1 |    63 |     2   (0)| 00:00:01 |
|* 11 |            TABLE ACCESS BY INDEX ROWID| PARTY_ABCDEFGHIJ          |     1 |    45 |     2   (0)| 00:00:01 |
|* 12 |             INDEX UNIQUE SCAN         | PA_PK                     |     1 |       |     1   (0)| 00:00:01 |
|* 13 |            INDEX UNIQUE SCAN          | AGR_PK                    |     1 |    18 |     0   (0)| 00:00:01 |
|  14 |           PARTITION RANGE ITERATOR    |                           |     1 |    62 |  1826   (3)| 00:00:16 |
|* 15 |            INDEX FAST FULL SCAN       | EVE_PK                    |     1 |    62 |  1826   (3)| 00:00:16 |

Now I knew that Oracle would maybe pick that plan if it could get the data it wanted from the index and it felt that the cost was lower than doing multiple range scans. Many reasons could lead to that and I could fix them. This would not take long.

But I could not force the step I wanted. I could not get a set of hints that would force it. I could not get the stats gathered in a way that forced the nested loop range scan. I managed to alter the plan in many ways, fix the order of tables, the types of joins, but kept getting to the point where the access was via the index fast full scan but not by range scan. I thought I had it cracked when I came across a hint I had not known about before, namely the INDEX_RS_ASC {and INDEX_RS_DESC} hint to state do an ascending range scan. Nope, no joy.

By now, 8 hours had passed trying several things and we had a few other people looking at the problem, including Oracle Corp. Oracle Corp came up with a good idea – if the code on test runs fine, copy the stats over. Not as simple as it should be as the test system was not quite as-live but we did that. You guessed, it did not work.

So what now? I knew it was a simple problem but I could not fix it. So I tried a technique I knew had worked before. I’d long passed the point where I was concerned about my pride – I emailed friends and contacts and begged help.

Now, that is not the method of solving problems I am writing about – but it is a damned fine method and I have used it several times. I highly recommend it but only after you have put a lot of effort into doing your own work, if you are willing to give proper details of what you are trying to do – and, utterly crucially, if you are willing to put yourself out and help those you just asked for help on another day.

So, what is the silver bullet method? Well, it is what the person who mailed me back did and which I try to do myself – but struggle with.

Ask yourself, what are the most basic and fundamental things that could be wrong. What is so obvious you completely missed it? You’ve tried complex, you’ve been at this for ages, you are missing something. Sometimes it is that you are on the wrong system or you are changing code that is not the code being executed {I’ve done that a few times over the last 20 years}.

In this case, it was this:

Here is my primary key:

EVEN_PK EABCDE 1 AGR_EXT_SYS_ID
EVEN_PK EABCDE 2 EXT_PRD_HLD_ID_TX
EVEN_PK EABCDE 3 AAAMND_DT
EVEN_PK EABCDE 4 EVT_EXT_SYS_ID
EVEN_PK EABCDE 5 EABCDE_ID

Except, here is what it is on Live

EVE_PK EABCDE 1 EVT_EXT_SYS_ID
EVE_PK EABCDE 2 EABCDE
EVE_PK EABCDE 3 AGR_EXT_SYS_ID
EVE_PK EABCDE 4 EXT_PRD_HLD_ID_TX
EVE_PK EABCDE 5 AAAMND_DT

Ignore the difference in name, that was an artifact of the test environment creation, the key thing is the primary key has a different column order. The DBAs had implemented the table wrong {I’m not blaming them, sometimes stuff just happens OK?}.
Now, it did not alter logical functionality as the Primary Key is on the same columns, but as the access to the table is on only the “leading” three columns of the primary key, if the columns are indexed in the wrong order then Oracle cannot access the index via range scans on those values! Unit testing on the obligatory 6 records had worked fine, but any volume of data revealed the issue.

I could not force my access plan as it was not possible – I had missed the screaming obvious.

So, next time you just “know” you should be able to get your database (or code, or whatever) to do something and it won’t do it, go have a cup of tea, think about your last holiday for 5 minutes and then go back to the desk and ask yourself – did I check that the most fundamental and obvious things are correct.

That is what I think is the key to solving what look like simple problems where you just can’t work it out. Try and think even simpler.

Where is Sun? January 3, 2011

Posted by mwidlake in Friday Philosophy, Perceptions.
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3 comments

First of all, may I wish everyone who comes by my blog a heartfelt Happy New Year.
Secondly, I promise I’ll blog more often and more on technical aspects this year than I have for most of 2010.
Thirdly, I’ll admit the title to this blog is nothing to do with the hardware company now owned by Mr Larry Ellison, but is about the huge glowing ball of fire in the sky (which we have not seen a lot of here in England and Wales for the last couple of weeks – not sure about Scotland but I suspect it has been the same). I apologise for the blatantly misleading (and syntactically poor) title.

A quick question for you – It is the depths of winter for most of us, and it has been unusually cold here in the UK and much of Europe. When are we, as a planet, furthest from the Sun during winter? January the 1st? The Shortest day (21st December)? The day the evening start drawing out (December 14th)?
I think many in the Northern Hemisphere will be surprised to learn that we are closest to the sun today (3rd Jan 2011). A mere 147.104 million kilometers from the centre of our solar system. I mentioned this to a few friends and they were all taken aback, thinking we would be furthest from the warmth of the sun at the depths of our winter.

Come the 4th July 2011 it is not only some strange celebration in the US about having made the terrible decision to go it alone in the world {Joke guys!}, but is the day in the year that the Earth is furthest from the sun – 152.097 million kilometers. That is about 3.39% further away and, as the energy we receive from the sun is equal to the square of the distance, does account for a bit of a drop in the energy received. {Surface of a sphere is 4*pi*(R{adius}squared), you can think of the energy from the sun as being spread over the sphere at any given distance}.

Some of you may be wondering why this furthest/closest to the sun does not match the longest/shortest day. As some of you may remember, I explained about the oddities of the shortest day not matching when the nights start drawing out about this time last year. It is because as we spin around our own pole and around the sun, things are complicated by the fact that the earth “leans over” in it’s orbit.

Check out this nice web site where you can state the location and month you want to see sunrise, sunset, day length and (of particular relevance here) the distance from the sun for each day.

I find it interesting that many of the things us most of us see as “common sense” are often not actually right (I always assumed that the shortest day coincided with both the evenings starting to draw out and mornings getting earlier until I stumbled across it when looking at sunset times – I had to go find a nice Astronomer friend to explain it all to me). I also like the fact that a very simple system – a regularly spinning ball circling a large big “fixed point” in a fixed way – throws up some oddities due to little extra considerations that often go overlooked. Isn’t that so like IT?

That lean in the Earth’s angle of spin compared to the plane we revolve around the sun is slowly rotating too, so in a few years (long, long, long after any of us will be around to care) then the furthest point in the orbit will indeed match the northern hemisphere winter. Again like IT, even the oddities keep shifting.

Friday Philosophy – Run Over by a Bus December 3, 2010

Posted by mwidlake in Friday Philosophy, Perceptions.
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7 comments

I chaired a session at the UKOUG this week by Daniel Fink, titled “Stop Chasing your tail: Using a Disciplined Approach to Problem Diagnosis”. It was a very good talk, about having a process, an approach to solving your IT problems and that it should be a process that suits you and your system. All good stuff and I utterly agree with what he said.

But it was a passing comment Daniel made that really set me thinking. It was something like:

You should be considering how people will look after the system after you have gone, the classic ‘what will we do if you are hit by a bus’….. No, I don’t like thinking like that, that phrase… I prefer ‘after you win the lottery and retire to a great life’.

It just struck a chord with me. Mr Fink’s {and I do go all formal when I intend respect} take on this is a far more positive way of looking at the situation of leaving the system in a state that others can look after once you are no longer able to help. The “Bus” phrase is very, very common, at least in the UK and I suspect in the US, and it is a very negative connotation. “Make sure it all works as something nasty is going to happen to you, something sudden, like being smeared across the tarmac by 25 tons of Greyhound doing 50mph, something basically fatal so you can’t prepare and you can’t help any more”. So, not just moved on, but dead.

Daniel made me realise that we should be looking at this from totally the other perspective and that doing so is much, much, much better. “Make it work so that they love you, even when you have gone away to a happier situation – one involving no road-based unpleasantness at all”.

Everyone leaves their job eventually and I like to think it is often for more positive reasons. Like retiring, or a better job {better for you, but a real shame for your old company as they like you so much}, moving to a new area, attempting a dream. Yes, sometimes (depressingly often at present) it is because you get made redundant or things go bad with your managers, or HR take over the organisation. But even so, better to leave knowing you did so with your professional duty intact I think. It’s one way of winning in a losing situation.

If turning the “bus” metaphor into a “lottery” metaphor results in the response in your brain of “well, when I do leave rich and happy, I still want to leave a painful mess behind me” – then it may indicate that you better leave where you are working as soon as possible in any case? As it is not a good situation and you are deeply very unhappy about it.

Up until now I have sometimes used a far more gruesome but less fatal phrase for the concept of making sure things continue after you leave and can no longer help, which is “involved in a freak lawnmower accident”. As in, can’t type but not dead. I’m going to stop using it, I’ve decided that even with my macabre sense of humour, it really is not a good way to think about doing your job properly. Daniel, your attitude is better. Thank you.

Oh, if you went along to the conference you can get the latest version of Daniel’s talk slides from the UKOUG web site (try this link), otherwise, he has a copy here – pick “papers and presentations”. It has lots of notes on it explaining what the slides mean (ie, what he actually says), which I think is a very nice thing for him to have spent the time doing.

The Immoral Unfairness of Contracts October 11, 2010

Posted by mwidlake in Perceptions, Private Life.
Tags: ,
10 comments

You can tell from the title that this is going to be a rant…

Do you remember the last time you signed a contract for a job? Did you read all the terms, conditions and clauses? How angry did it make you? If you did not read it, dig it out and do so. It will ruin your whole day.

I do a mixture of contracting and consulting to provide bread on the table and catfood in the cat bowl and I get to sign a lot of contracts. And they send me mad as so many of them have such outrageously immoral, unfair and, I strongly suspect, illegal clauses in them. But if you don’t sign, you don’t get a job.

If the contract says they can get rid of me on a week’s notice, but I have to give them a month, I insist they pick one or the other and it applies to both parties. If there is a clause saying everything I think of belongs to them then I say no – if it is based on their intelectual property or code specific to their application, then it is theirs and I will comply utterly, but if it is the sort of generic data dictionary query that all these client rely on me to use to do my job, it is mine and I want the right to use it {and give it to other people, like I gave it to you, Mr Client}. Another clause that seems to be becoming rampant in the UK contracting arena is the 40-hour working week and signing away any right to complain. I absolutley object to that as it has been proven scientifically that continuous long hours are detrimental to health. If I choose to do 40, 50 hours in a week (and I often do) it is my choice but they damned well are not going to insist on it. I also know if I do the 50 hours for too long, my productivity and quality drops – and I think we all know this is the real case.

There is often a discussion with the actual people you work with, how the contract is just “admin” and they would never treat you in the way it says they can and “just sign it and forget it as we know you will do the job and we will never use clause 17.3.2 on you”. And they probably won’t, but it makes the contract a big, fat lie at best and a potential stick to beat you with at worst.

A few years ago I decided that I had had enough of this and I now challenge the worst of these clauses and I have had some succes. I also challenge them because, just once or twice, I have had someone try and take advantage of me due to these clauses. Usually recruitment agencies, I have to say.

With small organisations I usually can agree fair and equitable terms. With larger organisations it is a fight but I can usually get some sense into the agreement. But with international corporations, it is a blank refusal. They do not need me, they can buy in someone else and they damn well ain’t going to negotiate or treat you as an equal.

I’m facing this one right now. I’m looking at the contract and the blank refusal by the faceless (and probably deeply annoyed {and overworked}) minion in Admin to even consider a single letter change to a contract. And I am thinking “well sod you and your job and your immoral and bullying contract then”. This morning I really considered walking off site and sacrificing any chance of payment to “punish” such unbending unfairness.

But I probably won’t, I’ll probably roll over and sign the abusive, vile document because I have already been on-site for a week and I like the people I work with, I like the job and I want their project to succeed. And the potential unfair aspects of the contract will probably never be a real issue. So why can’t they just be fairer and why does it make me so absolutely incandescant with rage?

*sigh*

Friday Philosophy – The Best IT Person I Have Met September 24, 2010

Posted by mwidlake in Friday Philosophy, Perceptions.
Tags: , ,
3 comments

I’ve had the pleasure of working with and meeting a lot of talented and capable people in IT – some of them have even been nice people too :-) {In fact, most people I have met do not match that annoying myth about IT’s reputation for social awkwardness). However, for me one person sticks out in my mind as the best person I have worked with in IT.

It’s Barry. I’m pretty sure none of you have met Barry, and in fact as I knew Barry back in 1996 I’m not so sure I would recognise him (and I have no hope of remembering his last name) if I met him now.

Barry and I met when I got press-ganged into a Unix system administration team. I was just getting started at being an Oracle Performance person and knew very little about Unix Sys admin. But, for reasons I won’t go into now, I went home on the Friday as an “Oracle expert” and came in on the Monday to find my desk had been physically lifted and moved into the Unix sys admin corral and I was now a “Sys Admin not-expert”. My protestations were listened to – and then ignored, with the information that if I did “not knuckle down and get on with it”, the money would stop flowing. So, rather dazed and just a tad unhappy with the situation, I sat – and sulked – at my desk. And there, sat next to me, was Barry.

You are probably expecting me to now tell you that Barry knew Unix sys admin inside out and how he took me under his wing and showed me the ropes. Well, he didn’t. I have no idea where they got Barry from, I think he was a pro-C developer, but he had just been similarly abused by management and deposited into a team he had not signed up for. And he knew even less about being a sys admin than I did. I at least knew my way around a few monitoring commands like top, w, ps, “glance” etc.

Barry was also not very quick with IT. Don’t get me wrong, he was not stupid, but he was not one of these people who just had an affinity for technology and spent all his spare time building their own media server when CD-ROMS for PCs were still quite new. In fact, he seemed to find the whole of IT to be something of a challenge.

What Barry had though was enthusiasm, commitment and curiosity. Not in an annoying, bouncing all over the place crying “this is great” way, but more a case of “OK, server Falcon has run out of disk space. What can I do about it? How do I find out where the storage has all gone, who is using it and can I get it back off them?”. And he would set to. He’d start with what he knew (which was little more than the “Man” {Online Manual} command in the first week) and the bits he could suck out of my head and work through it. Every few minutes he’d be tapping me on the shoulder and saying things like “Look, you can get information about disk usage here, and map it to the real physical disks by greping for this”.

It was Barry’s attitude that made him stand out, and also his ability to infect you with the same attitude. I started off in that team furious and demoralized, determined to find a new position and resign ASAP. But Barry got over his annoyance and started working. He asked me for advice and discussed the issues over with me, even though I was as clueless as him. When he found something he showed me it. When I found something, he was keen to learn it.

Between us, we got by. We knew very little and it was hard work, but because Barry was not daunted and would keep working on the problem until he had it sorted, he dragged me along with him. Often I would still be there with him into the evening, sorting something out when everyone else had gone home. He did not just take on every problem people came to us with though, he would stick with what he felt was the biggest issue until it was sorted, and he would keep with it, and ask for help, and try what you suggested.

{oddly enough , the worst person I ever worked with was already in this team. Maybe that is why the others left and Barry and I were pulled in!}

It only lasted a few months as we both escaped to jobs more suited to our skills, but I learnt a few things. One was that a crummy job could be made a lot better just by your attitude and another was that some people (Barry, not me) had a real talent for enthusing people and thus getting things done. And also, that you did not have to be highly intelligent or knowledgeable to do a very good job. That’s lucky for me, then :-)

Team Work & The Science of Slacking July 23, 2010

Posted by mwidlake in Friday Philosophy, Management, Perceptions.
Tags: , , ,
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We all know that working in a team is more efficient than working on your own (and I did say a week or two back how I was enjoying the rare privilege of working in a team of performance guys). Many of us also know about team dynamics and creating a balanced team of ideas people, completer-finishers, implementers, strategists and so forth. Those of use who have been exposed to training courses or books on team management know all these good things about teams and how we are supposed to get the most out of them.

How many of us, though, have been introduced to the work of the French Agronomist Max Ringelmann and the aspect of teams named after him, the Ringelmann Effect? In summary the Ringelmann Effect proposses that people in teams try less hard than they do when working alone. Especially if they think no one is watching them.

Back at the start of the 20th century Ringelmann tested out his ideas using a tug-of-war experiment. He would get people to pull on a rope as hard as they could and record their efforts using a strain gauge. Then he would get them to pull on the rope as part of a team, from 2 to 8 people. As soon as people were part of a team, they pulled less hard. With two people in the team, each pulled 93% as hard as on their own, with three people this dropped down to 85% and with 4 it was just 77%. By the time there were 8 people in the team, effort was down to 50%.

This idea of shirking work more and more as the team increased in size became established in modern psychology and was given Mr Ringelmann’s name. Psychologists explain that when someone is part of a group effort then the outcome is not solely down to the individual and, as such, is not totally in their control. This acts as a demotivating factor and the person tries that little bit less hard. The larger the team, the greater the demotivation and the more significant the drop in effort. Ringelmann found that effort was down to 50% in a team of 8 so how bad can the impact of the team be? I think most of us have at least witnessed, and quite possibly been in, the position of feeling like just a cog in a massive corporate team machine. Thoroughly demotivating (though, of course, we all of us still tried as hard as we could, didn’t we?).

The effect is also know under the far more entertaining title of Social Loafing.

Monsieur Ringelmann was far kinder at the time and pointed out that these chaps pulling on the rope could well have been suffering from a lack of synergy. They had not been trained together to pull as a team so that could account for the drop in effort, they were not synchronising their effort.

However, in the 1970’s Alan Ingham in Washington University revisited Ringelmanns work and he was far sneekier. Sorry, he was a more rigorous scientist. He used stooges in his team of rope-pullers, blindfolds and putting the one poor person pulling for real at the front of the team pulling the rope. Thus he could record the effort of the individual. Ingham found that there was indeed a drop in efficiency due to the team not pulling as one. But sadly, this was not the main factor. It remained that the drop in effort was mostly down to the perceived size of the rest of the team. The bottom line was proven to be the human capacity to try less hard when part of a team and that the drop in effort was directly proportional to the size of the team.

We are of course not immune to this effect in the IT world and someone has even gone to the effort of checking that out, James Suleiman and Richard T Watson.

It seems the ways to reduce this problem are:-

  • Don’t give people boring jobs.
  • Don’t give the same job to several people and let them know they all have the same job.
  • Ask people how they are getting on and give them mini-goals along the way.
  • Atually reward them for success. Like saying “thank you” and NOT giving them yet another boring, hard job to do as they did the last one so well.

I think it is also a good argument for keeping teams small {I personally think 5 or 6 people is ideal} and split up large projects such that a single team can cope. Then give tasks to individuals or pairs of people.

If you like this sort of thing you might want to check out one of my first blog post (though it is more an angry rant than a true discussion ofthe topic) which was on the Dunning-Kruger effect, where some people are unaware of their own limitations – though I did not know it was called the Dunning-Kruger effect until others told me, which only goes to show that maybe I am not aware of my own limits… Read the comments or click through to the links from there to get a better description of some people’s inability to guage their own inabilities.

Friday Philosophy – The power of cooperation June 27, 2010

Posted by mwidlake in Friday Philosophy, Perceptions, performance.
Tags: , ,
3 comments

Being the person responsible for the performance of an Oracle-based system can be an oddly lonely working experience. It can also be a very gregarious position as you get to meet a lot of people and discuss lots of different aspects of many systems – all systems seem to have performance issues and so people come along to you, hoping you can identify a “work faster” database setting for them.

But you are often the only person who specialises in Oracle performance. You generally need to be in an organisation that is very large or where performance is key to success for there to be justification for dedicating a person to the topic. To have more than one person dedicated to performance your organisations has to have a very strong focus on getting the best performance out of the Oracle and related systems {or really, really atrocious performance issues :-) }. So usually there is no one else around who is as experienced (or more so) as yourself to discuss such things over with or ask for a second opinion.

Which is why I am very lucky at the moment. I’m working in a team of oracle performance people. There are 2.5 of us (one is a manager with other responsibilities, so he only counts as half). Being able to say “Hey, Dave, What do you think of the wait times on scattered reads?” or “how in heck do I force this nested subquery on a view to use a hash join?” and get some other ideas is very valuable.

What is also interesting is how opinions and preferred techniques on tuning can be different and just as valid. As an example, last week I was working on a poorly performing statement. I was at home and it was the evening, so I was not communicating with the rest of the team. I managed to get the code down from 40 minutes to just under 20 by using a combination of a LEADING and USE_HASH hint. I sent the code back to the user. Only to see that within thirty seconds of each other my colleague Graeme had also sent the user a response, again getting the code down to around 20 minutes. Graeme had pulled a chunk of the code into a subquery factoring “WITH” clause and added cardinality hints. Totally different changes.

So Graeme and I then had a “philosophical” discussion about the different changes {“Mine is best” – “No! Mine is, yours is all bloated and complex”- “Your hint is less future-flexible!!!”}. Only joking, we actually discussed the changes and why we each chose what we did. Graeme commented that is showed that tuning was an art and not a science and I countered that it was a science, as we had both identified where we felt the execution plan could be improved but used different techniques to get there. The thing is, Oracle is so complex and has so many options to influence the optimiser that you have flexibility to chose different tools and techniques.

We had both identified the same main improvement but had each come up with different tweaks for later in the plan.

The end result was that we went with Graeme’s main plan {he is bigger than me} but we pulled in my tweak. That bought the execution time down to around 10 minutes, so about four times faster over all and twice as fast of either of us alone. That is one of the advantages of not working alone.

We also then discussed how we could get this code down to seconds with the use of either Materialized views or changing the process that generated the report to do so incrementally and store the daily results. Until one of us realised we had reached the boundary of compulsive tuning disorder. The report running in 10 minutes was enough improvement to satisfy the business, the report was only going to be run over the next couple of months, so spending a day or two re-working it further was going to be fun – but of no advantage to the business. We told each other to finish for the day. So another advantage of not working alone is that not only do you get more technical input but your help prevent each other losing sight of the overall aim.

It really does help to have two people working on the same area.

{There is a sneaky way of getting beyond being a lone performance specialist. If you are in an organisation long enough you can usually find some other idiot who is silly enough to want to learn more about performance and you can train them up. It does not take long before they know enough to start coming up with things you never thought of. Oracle is, after all, full of many ways to do the same thing and you can’t know it all}.

I’m still here, honest May 18, 2010

Posted by mwidlake in Blogging, Perceptions, Private Life.
Tags: ,
3 comments

In the last 24 hours I’ve had four emails asking if I am OK – Apparently I am not blogging or bothering people via email! Well, I am OK (and thanks guys for the concern), I was just knackered.

Rule 1 of blogging “no one cares about you as an individual” (and, I am glad to say, that is a myth. Even in the zero-physical-contact medium of electronic communication, some have been concerned about my silence. Humanity may yet have a future)

Truth is, I damaged myself trying to get healthier {so it is back to the eating pies and drinking beer for me!*} and that caused lack of sleep and more unhealth and I ended up very, very, very tired and I was reduced to putting all my energy into doing the day job.

This has nothing to do with a Blog on technology and database, of course.

Ahh, but Yes, it does, it actually has a hell of a lot to do with it. I have been tired, hard-pressed and under-performing. So I concentrated on doing my primary job and nothing else. So I have not blogged and I have not emailed people and I have not generally helped as much as I would like.

The thing is, if you think of your comrades and fellow staff (and, for some of you, the people who work for you) most people around you could well be the same. The primary directive of business, at present, is to get everything for your current task out of the staff right now. That is the prime directive, push the staff hard to get x, y and z done. Or, for those of you working under an Agile Methodology, the handful of tasks in front of you for this sprint {or whatever the hell terminology is for your take on the “Get It Done NOW” methodology}.

I have had no bandwidth to do more than my day job of late. And I stopped helping. I think some current working practices and philosophies have the same, chronic effect.

Is this a good thing? I will let you decide.

For myself, I’ve had a week walking in Snowdonia (and I was not fit enough to get the best out of the time, but mentally it was a God-send). I thought nothing about technology; I thought very little at all. I walked up hills, I drank beer and wine and I ate lots of pies. And I now feel good.

I know I am doing better work now than I was 2 weeks ago.

So, I hope to start doing proper technical blogs again in the next week or so. But right now, having had a week of total down-time, I am ready and need to do my day job again. And they pay me, so I better go off and do it! Expect a proper technical blog next week.

{* I joke about damaging myself getting fitter, but I feel condemned to point out that being generally fitter and healthier is a good thing, even if you hurt yourself getting there. It is better to be old and fit than old and decrepit. Or old and dead. :-) I’m full of happy thoughts like that…}

Making Things Better Makes Things Worse February 11, 2010

Posted by mwidlake in development, Management, Perceptions.
Tags: , ,
12 comments

This could be a Friday Philosophy but I’ve got a couple of those lined up already. Anyway, I am suffering at work at the moment. I’m encountering a phenomenon that I have talked about with Dennis Adams a couple of times. It probably has a proper term, but basically it is the odd situation that when you make things better, you get more complaints. {Dennis, do you know the proper term?}

{Update. Dennis was good enough to link to this paper he wrote on customer feedback}

Anyway, Let me explain. You have an application sitting on a database. The screens are slow, the reports take an age to come out, your might even have considerable system instability and unplanned outages. The users are not unhappy. They were unhappy last year. Now they are just cynical and they just expect the system to be slow, unresponsive, flaky. So they do not report any problems.

Then things change. The system gets some much-needed care and attention and now the slowest reports get tuned up, the screens come back faster and less spontaneous department-wide coffee breaks are caused by the system crashing. Everything gets better. But not for the help desk, now they start getting calls. “This report is too slow”. “Why can’t I jump straight from the customer screen to the pending orders screen?”. This happens because the users now realise that something can be done. There is a point in complaining as there is a chance their piece of misery could be made better. I certainly went through this many years ago when I inherited a system that crashed every week. No one mentioned it, they just went to tea and complained about it. The first time it crashed after I arrived I could not believe that no one had called before I had realised it had died. Once it had been up solidly for a couple of months, then when it crashed boy did we hear about it!

Also, when you improve a system and things generally get better, occasionally something will improve and then fall back a bit. Hardly anyone says “thanks” for the initial improvement but they will say something if it improves and then drops back.

That is what is happening for my main client at the moment. The system was not that bad, but it needed some help. Why else would I be there? I’ve been beavering away with the rest of the team and we are making things better, so far mostly at an underlying “getting the overall system straight” level. A new chap has joined to help concentrate on performance and he is really making inroads into specific things, individual reports and processes that need a good sorting out.

So now that things are getting better and performance is generally improving, anything that is still slow is being brought up by the development and support teams. Also, we’ve made a few things slower (I’m sorry, it just happens like that) and they certainly get mentioned.

So, I’m busy. And I could get annoyed at people asking why X is slower when Y and Z are faster. But I don’t, because Dennis explained this counter intuitive theory to me.

I know things are getting better as people are annoyed as opposed to apathetic :-)

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