Wednesday, November 30, 2005

UKOUG Development Engineering SIG

Yesterday was my first real SIG on my own. My co-chair Guy Mortenson couldn't make it and the agenda was wholly organised by me. So I await the feedback with trepidation. The good news is that Guy and I were re-elected unopposed. Not that the UKOUG is a banana republic, but as Chair I had to preside over the election process...

I think the agenda was quite balanced: we had two items on new technology (HTMLDB and JDeveloper, two items on old technology (Forms) and I filled Guy's clowning role by delivering a short skit called "The worst week of my professional career".

The core audience for the DE SIG remains Forms developers; there's some people using Java but no-one using PHP or .NET and no interest in .NET. As an organiser I find the problem ith Forms is finding something new to say. Pretty much the only topics that are in the slightest bit fresh are highly technical investigations into the plumbing of Oracle application server. Kavitha Prakash from Oracle Support confirmed this to me afterwards; she said that pretty much all of the calls Support get are about app server configuration, deployment and debugging; there are almost no calls on coding problems. Gavin Leith of Sopra Newell and Budge gave an interesting talk on JDAPI, a Java tool for programatically tweaking Forms programs. This would have been useful to know about two years back when I was migrating a Forms client/server project to 9i web Forms, but to be frank I hope never to touch Forms again.

The talk that seemed to generate the most interest was given by David Richard of on HTMLDB. This was actually part 2 of a presentation that he started to give at the previous SIG in June. This time he actually managed to demonstrate his case study application and show some of the wiring under the hood. The application was a tactical solution for the NHS. This both proved the complexity of apps that we can build with HTMLDB and (I think) hinted at the limitations of the tool: A4C was a fantastic project to knock up in five weeks but it would be a nightmare to maintain. The problems of configuration management and code visibility in a metadata repository would get too pressing. Still, it inspired me. Last Friday my project manager showed me his latest spreadsheet for estimating and I told him we should be doing it soem other way; as I type this I am installing HTMLDB so that I can do it better.

Lastly Duncan Mills demonstrated his favourite new features in the new JDeveloper 10.3. I have to say the Java Server Faces implementation looks very good. My sole reservation is that it is so huge. Even Duncan had to look at his crib sheets to wrangle some piece of syntax. He's been living with this for most of the year: if he doesn't know it all, what hope is there for the rest of us? This is a serious point. Just to build a pop-up LOV required choosing a widget from a list of many dozens of options. Can there possibly be enough time to master these tools before the Java caravan moves on and there's a whole new set of APIs to learn?

Thursday, November 17, 2005

How To Be A Good Guru

In her engaging UKOUG presentation on being a newbie Lisa Dobson devoted a large chunk of time to Being A Good Newbie. That is, how to post questions on Oracle-related lists in the manner most likely to elicit a helpful response. We might summarise this advice as don't poke the tigers.

Lisa didn't have the OTN Forums on her list of, er, lists but we get a lot of newbies posting questions there. Partly it's just location, location, location: the Oracle site is the obvious first port of call when you need help1. Also, it is not a forum where the really big beasts - the Oak Table chaps - visit and the level of discussion hardly ever descends to hex dumps of block headers and other such esoterica. Hence newbies are perhaps less likely to feel embarassed about posting simple questions. This is obviously a good thing but it does impose a burden on us soi disant experts who volunteer to answer their questions. So, in homage to Eric Raymond's seminal guide to list etiquette for newbies I am modestly proposing some advice to would-be responders. And, yes, I know I still regularly break these guidelines.

How to Answer Questions the Smart Way

#1. Don't answer questions to which you don't know the answer

Obvious really, but it's very easy to think you know something about the database that is no longer true, or maybe never was. For instance it has been a long time since anybody asserted that explicit cursors performed better than implicit ones, but people still proferred this advice long after it had ceased to be true. Be sure that if you do post something factually incorrect your peers will gleefully expose your bloomer to the wider world. It is better to post the right solution second than be first with a wrong one.

It is perfectly okay to research an answer. Indeed, one of the benefits of answering questions on the forums is that we discover stuff we didn't know. Questions coming from out of leftfield can tell teach us interesting (and sometimes even useful) things about how the database works.

#2. Explain yourself

Eric Raymond advises newbies to approach technical gurus in a supplicatory fashion. They are supposed to treat lists as resources of last resort, to kowtow before the collective wisdom and then present a detailed description of their problem, including complete specifics of environment and configuration, plus all the things they've already tried and all the manuals, whitepapers, etc they've already read, before humbly beseeching us for the merest crumb of assistance. Of course the ungrateful wretches never do this but we should still respond graciously.

It's not enough to dash off the correct answer. Consider whether its correctness will be obvious to the questioner. If not, try to explain why it's the correct answer. That way there's less chance that the questioner will be posting an almost identical question next week. Whenever possible include a link to the relevant part of the manual. Linking to a specfic heading in a chapter is better than just linking to the Table of Contents, but the manual is not always tagged the way we would like. Similarly, if you need more information, explain what else you need to know and why you need to know it. If you want (say) an explain plan and you suspect they don't know what that is, link to the manual.

#3. Give as little assistance as necessary

The most effective form of learning is discovering things for ourselves. Teaching someone how to diagnose their own code (use SQL> SHOW ERROR, look up the error, check the syntax in the online documentation) is better than just rewriting their code for them. Not least because in rewriting the code we are likely to break some business rule we do not understand.

#4. Show your workings

When answering a SQL related post it is always best to include a worked through example. Take a tip out of Tom Kyte's practice: use cut'n'paste from SQL*Plus to demonstrate that what you have asserted is in fact the case. This is a corollary of #1.

If, for reasons of time or environment (for instance you do not access to a database) it is acceptable to post untested code, provided:

  • you indicate it is such;
  • you think an untested code sample is more helpful than no code sample at all;
  • you think it is probably correct. Heh.

Nothing exposes a poseur faster than a piece of code that doesn't even compile, so make sure you cover yourself.

#5. Use humour judiciously

Many people using the forums do not have English as their first language. Humour does not always travel well between cultures. Some questioners will not be expecting humour in a work context2. Furthermore, even amongst English speakers, humour can be difficult to spot without the non-verbal signifiers that accompany barroom banter. In particular irony is a tough one to pull off. Still, humour is a Good Thing and can liven up some dry reads so by all means be witty (if you can - lame jokes are, well, lame). It is helpful to use emoticons to signify that your preceding line was intended humourously, even if they are a debasement of the high standards of English literature. Jane Austen never posts on Oracle lists anyway :)

Oh, and sarcasm is right out (see #6).

#6. If you can't say something nice don't say anything at all

Just like your mother told you.

There are no stupid questions only stupid answers. If someone has posted a question you don't think is worthy of an answer then don't bother answering. Remember: you're a volunteer, there is no compulsion, you are choosing to answer the question. So, the person is not wasting your time by asking a stupid question, you are wasting your own time by typing a stupid (angry, sarcastic or belittling) answer. By all means explain what is wrong with the question, show how it could have been phrased better or request more details. If some newbie has posted "my code doesn't work", ask them to describe the observed behaviour, to explain the difference from expected behaviour and to paste in the error message and callstack (if appropriate).

If somebody seems to be particularly unreasonable - posting an URGENT!!! question on Saturday and then whinging in follow-ups that nobody has responded - feel free to explain to them that you are a volunteer, this is a free service and there is no SLA. In fact, if they want an answer within a set timeframe they should stop being so darned cheap and spring for a support contract. Also, if I suspect the poster is a student looking for me to do their homework I always ask for a course credit (Not being American I have no idea what this means).

#7. Avoid jargon, baffling acronyms and idiolects

Fnord. This is just another way of demonstrating your superiority over the OP. Of course, like wit, you can use such stuff if you think your audience will get it. Alternatively, embed a link to the Jargon Dictionary, although this rather undermines the point of using abbreviations. LOL.

#8. Never never never just respond with RTFM. Not ever.

Telling some newbie "RTFM" is an act of pure arrogance. It just feeds the respondent's ego without helping that questioner learn anything, except maybe not to ask for help in the forum again. Barbara Boehmer taught me this one. Keep in mind that the Oracle FM is huge; there are dozens of books and the search engine fronting the online version ain't that great. At the very least, post "RTFM" and a link to a relevant part of TFM. That way at least they will know where to go the next time they need to find out something.

STFW is at least as bad and arguably worse. Googling for information about Oracle problems takes a lot of skill, not just in filtering queries but in knowing which results can be trusted. There are plenty of snakeoil merchants out there. (You may think you know who I am talking about but there are others too).

#9. Meditate on eternity

Other people will read your posts in the future, because they will come up in search results. Obviously if these people are using the OTN Forum search engine they'll probably be after an answer to some completely different question but Google also indexes the OTN Forums. So try to make your answers suitable for a wider audience. Besides, as Jakob Nielsen observed in another context, your future boss may be reading.

#10. Keep your newbie mind

We were all newbies once. We are all still newbies in some dimension of the database, it's just too big for one mind to know everything. Even Tom Kyte occasionally farms out questions to Sean Dillon, Cameron O'Rourke et alia. So the next time you find yourself about to type a withering riposte to some "dumb" question just remember: one day, in some forum or other, you will ask a dumb question and an arrogant, big-brained geek is going to squash you like a fly.

1. Unfortunately this means people do assume their questions will be answered by Oracle employees and therefore there is some SLA we have to meet. In fact most OTN forums have little or no active Oracle participation (the HTMLDB, Developer and JDeveloper forums being honourable exceptions).

2. Here is my favourite example (the words are approximate, this is from memory). The questioner ask a generically "stupid" question, "How can I improve the performance of my database?". A wag responded (using the UBB [code] markup so it looked authentic):


The original posted replied, "I tried this command but it failed due to illegal option". Which is funny but also rather cruel.

Tuesday, November 15, 2005

Another rainy day in this twenty-first century metropolis

Yesterday I decided to do a bit of work at home, as I wanted to do some data modelling (documentation, documenation, doncha just luv it?) and, for some tedious reason, I have Visio Professional on my home laptop but only Standard on my work machine.

First I decided it was finally time I activated my licence. Not having internet access at home meant having to do it over the phone. I can see now why the web method is recommended; typing in seven sets of six digits twice, once on the phone keypad the second on the computer with the added fun of pressing the phone hash key after every set is not a lot of fun. Particularly when you have a four-year-old boy registering their displeasure at you being on the phone by playing a toy synthesizer in the most unmusical fashion possible. Because I'm a masochist I registered my Office licence at the same time. Of course, MS don't seem to think people will register two products so I have to hang-up and redial.

Then I discovered that Visio doesn't support cut'n'paste of multiple lines into the Entity Definition column sheet (unless there's some trick I need to discover). After a while the repetition got to me so I decided I would be better off trying reverse engineering. Only I didn't have the database schema on my home laptop (having cleared 9i to install XE), so it's into the office after all.

On the way I decide to go to the parcel office to collect my latest consignment from Amazon. After all, I have Tooting Bec tube station at the end of my road and it's only one stop. And they are work-related books. Except that the Nortyhern Line is undergoing emergency engineering so there are no trains going south. Because it's be raining the traffic is blocked solid so I decide to walk instead of waiting for a bus. This is a sound decision: in the fifteen minutes it takes me to walk to the parcel office I overtake about half-a-dozen buses; not one overtakes me back. I casually note that most of the traffic consists of single people sitting in cars, leavened with the occasional van.

At this rate I'm starting to think that the post office will have lost my parcel but no, they have it and it contains the correct books. Hurrah! Now all I have to do is get into work, which is slow but at least I get there.

On the way home in the evening the service is suspended because of a security alert aty Balham. Naturally London's superb bus service is available to take up the slack. As if. Very long wait, very crowded buses, very slow journey.

When I get home I install the schemas into my XE database. At least that works. I fire up Visio, click into reverse engineering mode and it shows me all the objects in my XE database. But when I tried to actually import a table it fails with fatal error. No clues but I'm guessing some kind of driver issue; I'll give it another go this evening.

But wasn't the twenty-first century supposed to be different? Where is my helicopter for commuting to the office? Where is my holiday on the moon? Where is the technology that works properly, first time, all the time?

Friday, November 11, 2005

Oracle Express Edition: Good things come to those who wait

I decided to give XE one last try on Windows before turning to VM Ware. So I uninstalled XE using the MSI program. This did a stand-up job of tidying up everthing which was a relief as it's not an experience I've always had with de-installing Oracle before.

Then I set about tweaking my configuration. About the only problem on the known issues list that I didn't have was an account name with spaces. Here's what I did do:

(1) Control Panel > System > Advanced > Environment
  • Remove ActiveState Perl from the PATH variable
  • Point TEMP and TMP variables at C:\temp instead of the default
  • Remove the ORACLE_HOME variable (not sure I have this, I think it might break an Ant script)

(2) Stop the Oracle 9i services
(3) Control Panel > Region and Language, change preference to English (US)
(4) Reboot

Then I re-ran the installer and it worked! I now have a nice 10gXE on my work machine. Just in time for the weekend, my wife will be pleased. And my 9i installation isn' t broken either so I'm a happy bunny once more.

Thursday, November 10, 2005

Oracle Express Edition: Security Patching Policy

Earlier this month Pete Finnegan wondered whether we will get security patches for XE. Mark Townsend has now posted on the OTN XE Forum that Oracle intends to release fully patched versions of XE. Users will just install the new XE software over their existing install. This approach is deemed to be "easier than patching".

Given the target demographics of XE this is probably true but it will be interesting to see how this works in practice. This will presumably create additional overhead for ISVs who wish to customise the XE download (for instance by replacing the default seed DB).

Still, at least it looks as though we will avoid Pete's nightmare version of thousands on unpatched Oracle databases taking over the web.

Wikipedia: the dumbness of crowds

A posting on the XE forum observes that "By far the best known Wiki is Wikipedia". Almost certainly true but how very depressing.

The problem with the Wikipedia is that entries are of highly variable reliability and quantity. Due to the sort of people who contibute to Wikipedia, the entries on (say) Star Wars or the Klingon language are broader, deeper, more detailed and accurate than (say) the entries on relational database theory. In practice most of the entries on computing and related disciplines are reasonably reliable, because there are anough web users with relevant knowledge to correct obvious errors in their own fields (if they can be bothered).

Even so, unless you already know a fair bit about the topic it can be hard to determine whether the entry has been written by a leading expert or some passing nimrod. And when it gets to things like Latvian mythology, who knows? Is this entry on Tanis Diena, the sacred pig holiday a spoof? How would you find out, except by going to some authoritative (but less exciting) source such as the Encyclopedia Britannica in your local library? Even the Wikipedia founder says that too many entries in the Wikipedia "are nearly unreadable crap".

I am reminded of the chapter in "Surely you're joking, Mr Feynman" when Richard Feynman was reviewing physics textbooks for schools.
The man who replaced me on the commission said, "That book [that I thought was bad] was approved by sixty-five engineers at the Such-and-such Aircraft Company." I didn't doubt that the company had some pretty good engineers, but to take sixty-five engineers is to take a wide range of ability - and to necessarily include some pretty poor guys...It would have been far better for the company to decide who their better engineers were, and have them look at the book. I couldn't claim I was smarter than sixty-five other guys - but the average of sixty-five other guys, certainly!

Of course, there are some very good uses for the wiki technology. A prime example is the Extreme Programming Roadmap. This site is hosted by Ward Cunningham, who invented the Wiki concept as well as being one of the founders of XP along with Kent Beck. This wiki works because it is a site for sharing and exploring ideas. It is a conversation, an exchange of opinions, not a source of facts. It is precisely not an encyclopedia of Extreme Programming (eXPedia? or has somebody already got that?).

Wikipedia is predicated on the assumption that knowledge works like some kind of pachinko machine: the channel where the most balls go must be the truth. But actually all you end up with is a lot of balls.

Tuesday, November 08, 2005

Oracle Express Edition: Third Strike

Mike Townsend on the XE forum said that the ORA-12557 error indicated an Oracle Home variable pointing at the wrong set of DLLs. After some bootless tweaking of registry settings (actually wuite a lot of booting was involved, I think fruitless is the word I'm after) I found that I had an ORACLE_HOME in my environment variables.

So I set that to the XE directory. And lo! the ORA-12557 error went away and the database build progressed a bit further. Not far enough to actually build the XE database you understand, but at least it was connecting to the instance. Unfortunately changing that variable to point to XE home breaks my 9i installation very badly. As I need 9i for my work right now and I don't need XE I think that just about wraps up my XE adventures for the time being.

In an unrelated item I note that the Register has a report on a survey finding that software problems cause people to swear, drink and throw things. Well I never! The things these surveys reveal!

Oracle Express Edition: two strikes, the pitcher steps up to the plate...

The world is divided into two groups of people: those for whom installing Oracle Express edition has been a piece of cake and those for whom it's been a flipping nightmare. Unfortunately I find myself in the latter group.

The first problem was the install spinning when it was trying to create the XE services. CPU meter up to 100% for as long as you like. This turned out to be an artefact of having NLS_LANG set to UK English. All that was required was settting to American_America.WE8ISO8859P1. Ooops! We might have thought that offshoring so much development and support work would have alerted Oracle to globalisation but apparently not.

Having got past that the second problem rears its ugly head. I now have an instance but no data files. Each time the scripts tried to connect to the database the failed with ORA-12557: TNS:protocol adapter not loadable. This is a rara avis; the only note on Metalink relates to Grid controllers, which doesn't seem to fit the case here, and Google likewise draws a blank. Let's hope Mike Townsend comes up with something.

Before you Linuxen start smirking this is not particularly a Windows problem: I was able to install XE on my home laptop first time. My home machine is lower spec but same operating system so it's something about the specific configuration of my work machine that's giving me grief. I am only persevering with this because if I ever need XE, I will need it on my work machine.

Although I must admit I am starting to get very tired with the process: it requires several manual steps - editing the registry, renaming files, two reboots - to clear down XE prior to re-installing. However, I have just discovered that if I re-run the MSI against an untouched install it asks if I want to uninstall XE. I wish I known this earlier: the Installation guide talks about using Add/Remove Programs in the Control Panel but that option only appears once the installation has passed the Services point. Of course, the MSI uninstall option may also only be triggered if the prior install got to that point. I'm afraid I lack the strength to de- and re-install just to find out.

So what have I learnt so far? Not a lot. I've spent hours, literally hours, trying to install XE on my work machine with no success. I certainly haven't had time to build an app on my home machine. I do know two things. One is that the MSDE team is not yet quaking in their boots. The other is that I don't think this blog is likely to appear in the 10XE User Experiences any time soon.

Thursday, November 03, 2005

UKOUG Annual Conference: A retrospective

Walking along the canals of Birmingham on Sunday I was struck by how not like San Francisco it was. Not just the colour of the sky but the whole attitude of the place. The canals of Birmingham have been reclaimed from their industrial past and re-branded as a tourist attraction. What this actually means is a lot of canal side bars with aspirational names like Panama, Ipanema and Santa Fe (not particularly famous for it's canals). One ristorante has an Venetian gondola moored outside. Meanwhile dead leaves float in the canal and people scurry past in their windcheaters and overcoats. Still, you can't get a decent pint of IPA in St Mark's Square so it cuts both ways.

Another difference between Open World and UKOUG, as Mark Rittman has also observed, is that us UKOUG committee members were there to do a job, so blogging in real time was difficult. Here are my personal highlights from the annual conference.

Best Presentation: Developing your career through system disasters by Martin Widlake

An irresistible title and a first class presentation. It wasn't just cynical laughing at the dumb things people do, it also gave tips on how to turn those dumb things to your professional advantage. Martin was full of useful insights, advice and aphorisms. "Disaster tolerant software isn't". Compressed time scales "move us into our stretch zones and develop our resilience skills". Interestingly enough the presentation turned, briefly, into a lecture on the value of certain RAD/Agile practices, specifically, developing systems in discrete chunks that take no longer than three months to deliver. As Martin said:
You don't understand your users. That's okay because they don't understand you either.

This is the situation he calls the Knowledge Curtain.

Most Brain Stretching Presentation: Null values: Nothing to worry about by Lex de Haan

It wasn't the SQL that fazed me it was the calculus. I'm a historian, get me out of here! Lex delivered a through exploration of how NULL works in SQL and the relationship between the empty set and NULL. The key fact is that a NULL in a arithmetic expression returns NULL whereas group functions ignore NULL. He gave us some good hints for writing queries to handle NULL without getting the wrong results. Definitely a presentation to download and work through the examples.

Most Interesting Factoid: How To Handle Missing Information Without Using Nulls by Hugh Darwen

I always thought that the reason the relational theory crowd didn't like NULL was because they objected to the absence of meaning. Hugh said that if SQL had implemented NULL=NULL that would have been okay. Well, okay-ish. The absence of meaning would still be a problem but it's the additional work necessary to handle NULL that really rankles (I supect Fabian Pascal may take a different stance). Anyway, Hugh started his presentation with the observation that everybody in the audience had a vested interested in the badness of SQL and ended it with an exhortation to us to pester Oracle for better SQL. Guilty as charged, but I'm afraid I'm more likely to pester Oracle for a more complete Type implementation than I am to ask for changes to the SQL standard. Although I do think being able to SELECT * EXCEPT comm FROM emp; would be nice to have.

Worst Start To A Presentation: Performance from a Different Perspective by Mogens Nørgaard

There's never a good time to hear the skirl of the bagpipes but 9.00am is really bad. (My father was Scottish so I'm allowed to say this.) At last year's conference Mogens presented without shoes. This year he presented without trousers1. It might be a good idea to skip next year's presentation ;)

Most Depressing Fact: Does ADF live up to the hype? by Paul Jeynes

In 2000 when I was working on a project using BC4J with JDeveloper3.0 we had real problems getting any kind of assistance from Oracle Support or finding relevant How To documentation. Of course, in those days Java was still supported by the Server Tech guys because Support thought it was only used in the database. Five years on, ADF is here, Java is primarily used in the J2EE web environment and the quality of support does not seem to have improved much.

Most Intriguing Business Move: The Launch of Oracle Express Edition by Tom Kyte

As Tom observed at the start of his presentation this has already been widely blogged even before the launch but he still managed to generate a buzz. Obviously giving away a free database was (with hindsight) almost inevitable in the current database market. People do like free as a price. I think the interesting thing about Oracle XE is its potential as a MySQL killer. With Oracle XE you are going to get a reliable database with stored procedures, triggers and relational integrity. Furthermore, you've got an easy migration path if you exceed the (generous) limits or need certain enterprise features. Probably the only people who aren't going to choose XE are zealots in the Open Source and the Microsoft communities. Who'd have thought they'd end up on the same side? So, taken with the purchase of InnoDB, I think Oracle really has MySQL AB by the short and curlies.

The only thing Oracle can do to muck this up is not issue patches, at least for show stopping bugs and security holes. There's no point in encouraging thousands of new people to join the Oracle community if means exposing them to Oracle-focused worms. Whilst stealing Microsoft's shtick on helping developers and learners Oracle do not also want to give themselves Redmond's reputation on security issues.

Best Meal: The Oracle Blogger's Dinner by Mark Rittman

Actually this is not a difficult call as catering for over two thousand people over short periods of time rarely generates fine cuisine. Still, thanks to Mark for organising it and thanks to James Haslam of the UKOUG for sponsoring it. It was nice to be able to put faces to some of the blogs I read. I think next time we should wear badges with the name of our blogs. By the way, what is it with Chinese restaurants? The set menus are always ridiculously over-specified. The third course had far too many dishes. As the sole troublesome veggie I ended up with three dishes all to myself plus rice, on top of the previous two courses. Thank goodness I had been unable to fill myself up on prawn crackers beforehand.

1. To be fair Mogens did wear a kilt.