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IOTs by the Oracle Indexing Expert January 10, 2012

Posted by mwidlake in Blogging, performance.
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I’m really pleased to see that Richard Foote has started a series on Index Organized Tables. You can see his introductory post on the topic here. As ever with Richard, he puts in lots of detail and explanation and I’ve been a fan of his blogging style for a long time.

I’ve got a few posts on the topic left to do myself, maybe this competition will spur me to get on and write them!

What I will also be very interested to see is the different way we will cover the same topic. Richard has already put in a block dump and dug into the details a little at a low level about how the data is stored, which I have not done. He has also shown how using an IOT instead of a fully overloaded index (where you create an index covering all the columns of the table, to avoid visiting the table for other columns) results in not only saving the space taken up by the redundant heap table but that the IOT index is smaller than the fully overloaded index. This is due to the lack of a rowid.

I put in occasional pictures and maybe write more about how the example matches real world situations. If you want, you can look back at my own introduction to the topic.

I’m sure this is going to be an excellent series and I’ll be following it myself.

Friday Philosophy – In Search of a Woodlouse December 16, 2011

Posted by mwidlake in Blogging, Friday Philosophy, humour, Private Life.
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I don’t carry business cards around with me. I just never, ever think to get some done (either properly or with my trusty printer) and maybe this says something about my personal failings to sell myself. If anyone wants to contact me I tell them my email address and if they look confused I just say “ahh, Google me”. You see, having a very odd Surname means I am easy to find. {Reading this back I guess it could be interpreted as saying “I am so famous you will find me” but that is way, way, way from my meaning – I am going on the very unusual name that I have and nothing other than that!}

If you google (Bing, Alta Vista, whatever) “Widlake” you will get, probably on the first page – Brian Widlake who was a BBC journalist and had a key interview with Nelson Mandela; Widlake Farm B&B down in Looe, Cornwall ; a court case with BAA (nothing to do with me); an accountancy firm called Holmes Widlake; Me! Hey, not bad for some IT geek! It shows there are not many “Widlake”s out there.

If you search on “Martin Widlake” it’s pretty much just lonely little me. This is good as it means I am easily found. In the past I’ve searched on the names of friends and found it really hard to identify the exact person as there are so many people called “Kate Bush” or “Nicole Kidman” or “Stephen Hawking”.

However, my suggestion is seriously flawed and I should know this due to a conversation I have at least once a week. “And your name is, Sir?” “Martin Widlake”. Pause, faint sounds of rustling paper…”I’m sorry, could you say that again?” “Martin Widlake, with an ‘I’” (rustle rustle rustle) “I’m sorry sir, I can’t find any ‘Woodlock’/’Woodlake’/’Woodleg’/’Wideleg’/’Wiglig’ at all.” {choose word of choice, there are several more}. Carefull spelling ensues and even then, something in the brain of some people cannot shake off the “Wood” and get to “Wid”. And yes, I know about the Martin, Martyn and suggestion about ‘I’.

I had someone come up to me at the OUG conference last week and say they had tried to track me down after last years’ event and could not. No “Martin Woodlouse” to be found. *sigh*.

“martin oracle” does not help, it finds that toe-rag Martin Bach {OK, I admit it, Martin Bach is pretty damned hot at Oracle, and oh so annoyingly a nice bloke), Martin Nash in Oracle Corp {fair enough, and again a nice bloke} , James Martin the cook {what the…? but that will please the realcuddleytoys}, oracle religious Association but I ain’t going anywhere near that…I’m a page or two in, which is not bad actually, I can be happy with that.

My wife has it just as bad. She had a nice, obvious Surname {Parker} before I conned her into marrying me {and I did suggest we adopt her Surname when we married}. She joined one company a few years back where, due to her speaking a couple of eastern European languages, they decided she was (phonetically) “Susan Vidlaaackay”. They seemed to find the real Surname more confusing than their assumption.

So, I am easy to find, but only if you actually know me and my odd Surname. Otherwise, “Martin Woodlock”, “Martin Woodlake”, “Martin Woodleg”, “Martin Wiglake”, “Martin Widesnake” {if only}, “Martin Wiglig”, “Martin Wideneck”, “Martin Wicklick”, “Martin Widelake”, “Martin Windleg”, “Martin Woodlouse” and (my favourite) “Marvin Wetleg” are all terms I somehow need to get into web search engines, if I want people to find me with ease.

Does anyone know of any other takes on my name that people think they know me by? Any rude suggestions or ones based on my being shorter than R2-D2 will be deleted with prejudice!

How deep to dig – Another Opinion and Another Good Blog November 22, 2011

Posted by mwidlake in Blogging, UKOUG.
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I think I’ve posted before about how deep a good DBA should dig into solving issues, as opposed to fixing them as soon as possible and moving on to the next urgent task.

Well, a friend of mine, Neil Chandler, has just posted on this topic, giving his reasons why you don’t run a 10046 trace on production. Neil raises some good points about how difficult it can be to get permission to do something as intrusive as a 10046 trace on a production system as well as the fact that most problems can be solved way before you get down to the level of tracing. Especially if it is not your job to go around solving the problems that have stumped the in-house team, which is the lot of many people who are recognised as being very good with Oracle.

That leads me onto a slightly different topic. For every one of those technicians who’s names you know there are at least a dozen who are just as good but not as visible. Some of us choose to make more “noise” {blogging, presenting, writing articles} so we become visible. Others also support the user community but in a less noticeable way, some even positively choosing to keep a lower profile. Neil is one of those. He’s a very good Oracle and SQL*Server DBA and also very knowledgeable about Unix OS’s and SANs/storage {though he would maybe argue he is not – don’t believe him}. When he comes along to the pub his is an opinion worth listening to {once he’s finished demeaning me that is, and I’m sure he will give me a hard time about this article about him next time we meet} and when I’ve asked his opinion he has never failed to help. Neil also supports the UKOUG, he’s been deputy chair of one of the SIGs since it’s inception – but he refuses to be chair, has kept away from presenting and he keeps in the background.

So, I was very happy when Neil started blogging. It is a mixture of technical stuff and observations on the IT world, all written in a very comfortable style – Look back at his previous post on timestamps not being impacted by FIXED_DATE. A nice piece of information to tuck into your bag of “things to be aware of”.

So, a belated welcome to the world of blogging Neil. I think it is a blog worth watching.

Friday Philosophy – Should I Be a Twit? October 21, 2011

Posted by mwidlake in Blogging, Friday Philosophy, Perceptions.
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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.

I’ve always resisted the whole micro-blogging world, probably due to the comments made by people about how much dross is tweeted and what a time sink it can be, something the people I asked all mentioned. And partly, being candid, because I know one of my faults is to shoot my mouth off before engaging my brain, especially if annoyed. If it takes 20 seconds to do a tweet, I shudder to think some of the things I might have put out there in the heat of the moment or when in the pub. Pub talk is fine, so long as it is kept in the pub. With a blog, it takes me so long to write them I tend to calm down before sending, if I am angry.

Also, tweets are not my style. I don’t know if you have noticed but I can be a little verbose {this means I spout several sentences where 5 words would do}. Can I be succinct enough to say anything anyone else would want to read?

That’s the writing of tweets, what about the following? I could just be a passive follower. But how many? This is part of the advice given to me by Neil Chandler and also Doug, to only follow a few people so that you do not just drown in an endless feed of stuff. I guess that anything good gets re-tweeted and so you see stuff not just by those you follow but the best bits of what they follow? Neil also suggested that part of what makes twitter work is joining in, don’t just be passive.

Something about Twitter that does bug me a lot, and this is just part of the whole texting/smartphone/constant communication thing of modern life, is when people you are spending social time with just sit staring at their bloody phone. I just find that really rude and I also think it’s a bit depressing when you see three or four people in the pub or restaurant, all staring at their smartphones and not communicating with each other. You might as well stay in bed. Alone. {Oh good grief what a terrible thought! Do couples who do social media now just sit in bed with their phones in front of them, ignoring their supposed love of their life?}

But of course there are advantages to Twitter. There is a lot of interesting stuff that goes on only in the twitter world and some of the tweets I have seen have been hilarious. It’s far more lightweight than blogging, something you can do in a quiet moment. Though Doug suggests this is why you get so much dross about travelling, people catch up on twitter when bored and also tweet then. Niall Litchfield made a very interesting point to me in that it allows you to keep up on a large range of topics and see new ideas and thoughts more. I like that. In fact, Niall sent me an excellent list of reasons for and against, which I’ll {almost} finish on.

From Niall:


Reasons for :

- I get vicarious updates from a large number of sources on a large number of subjects. (Oracle,SQL,Science,Politics)
- It can suit my short and acerbic style from time to time.
- More people are doing it
- It indirectly promotes me (albeit with a somewhat misleading image)
- I find stuff I wouldn’t otherwise have found
- I have engaged with product managers I probably wouldn’t have done

Reasons not:
- time wasting
- addictive
- it promotes me in a misleading way
- it can annoy others

I like it because I’m an information junkie and like to keep abreast of stuff in several areas. It can be a colossal waste of time and irritate immensely.


I think I might well give it a go and that leads to my last thought. If I am going to enter the world of twitter, I am going to have to get a new phone. My current one is so basic that it does little more than just make and receive calls. But a single charge lasts a week.

Friday Philosophy – Blogging Style and Aim August 12, 2011

Posted by mwidlake in Blogging, Friday Philosophy.
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I’ve recently looked back at some of my earlier blog postings and also some notes I made at the time I started. I had a few aims at the start, pretty much in this order:

  • A place to put all those Oracle thoughts and ideas, for my own benefit
  • Somewhere to record stuff that I keep forgetting
  • I’d started commenting on other blogs and felt I was maybe too verbal on them
  • To increase my profile within the Oracle community
  • To share information, because I’m quite socialist in that respect
  • To learn more

It very quickly morphed into something slightly different though.

Firstly, it is not really somewhere that I record thoughts and ideas or where I record stuff that I forget. When I am busy, I sometimes only get half way to the bottom of resolving an issue or understanding some feature of Oracle. I tend to create little documents about them but I can lose track of them. I initially intended to put these on my blog. The thing is though, I don’t feel I can blog about them because I might be wrong or I raise more questions than I answer. I don’t think a public blog about technology is a good place to have half-baked ideas and I certainly don’t want people:

  1. reading and believing something that is wrong
  2. thinking I do not know what I am talking about
  3. seeing my rough notes as boy are they rough, often with naughty words in them and slang. Converting them to a familly-friendly format takes time. 

You see, there is the point about increasing my profile in the community. Part of me hates the conceit that you have to be seen as all-knowing or never wrong, as no one is all-knowing and never wrong. In fact, I think most of us find it hard to like people who put themselves as such.  But if I put out a blog saying “it works this way” and I am wrong or I simply say it in a clumsy way or I assume some vital prior knowledge, I could be making people’s lives harder not easier, so I spend a lot of effort testing and checking. It takes me a lot, lot longer to prepare a technical blog than I ever thought it would before I started. And yes, I accept I will still get it wrong sometimes.

Another consideration is that I make my living out of knowing a lot about Oracle. If I post a load of blogs saying something like “gosh I wish I understood how Oracle locks parts of the segment as it does an online table rebuild and handles the updates that happen during it”, then I obviously don’t know about that. Or I put out a post about how I currently think it works and I’m wrong. Tsch, I can’t be that good! How much should I have to think about how I am selling myself as a consultant? There is a difference between being liked and being perceived as good at what you do. If you want someone to design a VLDB for you, you probably don’t care if s/he is a nice person to spend an evening in the pub with - but you certainly care if they seem to be fundamentally wrong about oracle partitioning.

Balancing that, if you saw my recent post on Pickler Fetch you will see that I was wrong about a couple of things and there was some stuff I did not know yet. But I learnt about those wrong things and lack of knowledge, so I feel good about that. That was one of my original aims, to learn. Not only by having to check what I did but by people letting me know when I was wrong.

What about style? I can be quite flippant and, oh boy, can I go on and on. I know some people do not like this and, if you want a quick solution to an oracle problem, you probably do not want to wade through a load of side issues and little comments. You just want to see the commands, the syntax and how it works. Well, that is what the manuals are for and there a lot of very good web sites out there that are more like that. If you do not like my verbose style then, hey that’s absolutely fine.  But I like to write that way and so I shall.

So after over 2 years of blogging, I seem to have settled into a style and my aims have changed.

  • I try to be helpful and cover things in detail.
  • I try to polish what I present a lot, lot more than I do for my own internal notes. Maybe too much.
  • I’m going to write in a long-winded way that some people will not enjoy but it is my style.
  • I’m going to try and worry less about looking perfect as I am not.

I suppose what I could do is start a second, private blog with my half-baked stuff on it. But I just don’t think I’ve got the time :-)





Advertising appearing? August 10, 2011

Posted by mwidlake in Blogging.

I’m curious – is anyone visiting my blog seeing some form of advertising popping up?

I ask as there is a section on “links clicked” in the stats page and rather than the usual traffic of people clicking on the oaktable logo or people in my blogroll, the most common link is for ecopressed-dot-com. I’ve never heard of them. When I go in to my blog I don’t seen anything but then it knows it is “me” so maybe it would not.

I’m not too bothered about it, after all WordPress are hosting my blog for pretty much nothing {I pay them some outrageous sum of a few US dollars a year so I can alter my CSS file and thus make the layout wider}. I’m just curious.

I wonder if this is a result of increased traffic to my site? I’m still fairly small-fry compared to lots of other sites but as I’ve been putting out more stuff of late I think I’m going up the web rankings. Oddly enough, those pictures of bullets I put on last Friday’s philosophy have been very popular. I can’t help but feel that most people looking for information on bullets are going to find a blog about IT somewhat disappointing :-)

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

Posted by mwidlake in Blogging, Friday Philosophy, Perceptions.
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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

There is life in the old dog yet… March 14, 2011

Posted by mwidlake in Blogging.

My Blog has been unforgivably quiet of late. All I can say in my defence is “work”. I’ve blogged about this before, and mentioned it in presentations, but most of us are too tied up in the day job to test things properly, let alone blog or in other ways present on how things work. We fix the problem in front of us and move on to the next “critical, absolute priority 1A plus, must-be-fixed-today” issue. So like most of you, that has been my life for…ohh, months.
{I makes me even more thankful to those who continually find the time to test properly and blog about what they have found, on top of their “earning” work}

However, my working life is looking like it will return to a more reasonable balance soon.

So, this blog post is a statement of intent that I WILL be blogging again in the next week or so. OK, so this post is not of any use to anyone reading, but it means I now feel morally obliged to follow up on the statement (and that is actually the intent of this blog post).

I’m going to blog on two technical areas.

One is gathering Stats, which I am utterly sick of and tired of doing in my working life. So I figure if I tell anyone who will listen all I know about gathering system, fixed object, dictionary and object stats and give some hints as to what I have come to think of as methods and techniques for doing so, I might not have to think about it any more. I can tell people to read my blog and not hire me to do it for them. Maybe a career limiting move but I was never that bright :-)

The second topic will be Index Organised Tables (IOTs). They are great. Ohhh, they have drawbacks and concerns, after all no tuning trick is For Free and I know one person (who I shall refer to only as Dave) who’s career was almost destroyed due to an Oracle 9 to 10 “feature” on IOTs involving corruption. But IOTs are {in my opinion} a vastly under-used feature of Oracle and could be useful to many Oracle sites. If anyone wants help with them, I’ll let you hire me for that and I will come and help gladly. So long as no bl00dy stats are involved :-)

So, having drawn my own line in the sand to do some Technical Blogs (I actually have enough waffle-based Friday Philosophy topics to last 2 years but have promised myself to balance them with decent technical posts) I better go and write them.

Advert – a new Blog to watch August 24, 2010

Posted by mwidlake in Blogging.
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A friend of mine who’s work and attitude towards Oracle performance and architecture I respect has just started blogging, so I thought I would give him a mention. Dave Webster, welcome to the world of blogging.

I know from some discussions with Dave about blogging that he has a lot of things he wants to cover (and he knows an awful lot; he has been working on especially OLTP-type performance for many years). So, no pressure Dave, but I expect lots of good stuff from you :-)

What, me? An OakTable member? August 23, 2010

Posted by mwidlake in Uncategorized.
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The title rather gives it away, but I have been invited to become a member of the OakTable network. For anyone not aware of the OakTable, it is a group of some of the very best Oracle practitioners around and you would recognise many of the names in the group. Most of them also present at conferences around the globe and set up the Oak Table challenge at various of these venues, where they try and address any oracle-based question you might have.

All of them are very bright, all are very knowledgeable.

Which is where I come a little unstuck. Without wanting to sound like some vapid actor at a Hollywood award ceremony decrying “I am so unworthy of this nomination”, whilst secretly thinking “I so deserve this”… Well, my initial thought when receiving the invite was “I am so unworthy…”. I’ve had the weekend to think about it though. And I still think “I am so unworthy…”

I’m actually on record as suggesting that we might also need a “Formica Table”, though the only online reference to it I can now find {I MUST put my old presentations on my web site} is from the archives of Andrew Clark’s Radiofreetooting blog about a presentation I did at the UKOUG in 2007. {Follow the link and search for Widlake or Formica, it is way down the bottom}. If you can’t be bothered looking at the original, Andrew said this:

I was particularly taken with the Formica Table. This would be a forum where “not bad” DBAs answered questions which fitted 95% of all scenarios; sort of an Oak Table For The Rest Of Us.

I think his quote of me was actually better than the original. The idea was that the real experts on the Oak Table {is it actually one word guys? “OakTable”!?} deal with the hard, tricky, complex issues and this secondary formica table could deal with the rest of the world. Because I could just about cope with formica level. The intention being, of course, that I would sit on said plastic-laminate-coated-chipboard table.

Am I being falsely modest here? I do not think I am. I know I am good at what I do and I know I have achieved some impressive things. I also know most people who employ me ask me to stay longer (and I usually do). But I am realistic. I’m very good but I am not fantastic (at Oracle anyway :-) ). And no way as capable as many OakTable members. But the people on the OakTable have some other things in common. From the home page of the website:

The OakTable network is a network for the Oracle scientist, who believes in better ways of administering and developing Oracle based systems.

The impression I get from spending some time with the handful of members of the OakTable that I already know is that they generally all feel that you need to not only be knowledgeable about Oracle (or whatever area of knowledge you are interested in) but you need to be able to demonstrate and show that the knowledge is real. You create test cases and try things out. Just saying “you should use a large block size for data warehouses” is just not really enough, it is so much more powerful if you can say why you think this is so and then produce test cases to show that. And if someone produces a test case to show the opposite, well you need to reconsider. It is what is at the core of the scientific method. You test things and have to adapt or change if the tests refute your theory. If someone will not provide test cases or real-world examples to support their facts, they are in fact, opinions. Which is fine, just don’t sell them as facts.

The other common thread is a willingness (and perhaps a worrying compulsion) to teach. I’ve seen many of the OakTable present and I know a lot of them do courses all over the globe. Sometimes it is paid work, often it is not, it is done as a benefit to the community. That is nearly always the case with user group presentations.

I’m figuring that is why I’ve been invited to join. Technically, most if not all the OakTable are a step or three better than me and I reserve my right to respect that. But I really believe in demonstrating what you think is going on with Oracle is what is really going on and I have an almost worryingly compulsive willingness to teach.

So, have I turned down the invite? Are you kidding!?! It’s great to be invited and I really look forward to having more to do with this bunch of talented and helpful people. And I am also looking forward to contributing my little bit to the group and, through it, to the wider Oracle community.

It is slightly ironic that I have been asked to join a group of people right now who are characterised by their willingness and drive to scientifically investigate and then disseminate information on Oracle-based technology when I have spent the last month doing nothing of the sort. I have been digging ditches, cleaning out ponds, chopping down trees and doing major DIY, all of which I am utterly unsuited to but I enjoy. So I now feel obliged to stop that, pick up a keyboard and continue to investigate the edges of my ignorance. I’ll try and keep you informed of progress.

Oh, and I have another problem now. How do I get the OakTable Icon onto this blog? Somewhere on the right I think…


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