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Primary keys only need to be unique; there's many characteristics they often have but don't need to have
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www.databasesandlife.com
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17 years ago
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eng
There is often a misunderstanding about primary keys in database tables. Primary keys identify rows uniquely, so the only property they have to obey is they must be unique . Primary keys don’t have to be numbers. But if they are, here are a few properties these numbers don’t have to have: Numerical PKs don't indicate ordering, i.e. which row was inserted first. Looking at the highest PK value doesn't indicate the number of ro..
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You know - most technologies change drastically over time. As a result, I got my hands on an old BlackBerry 950 model from 1998 (the 850/950 series were the original BlackBerry smartphones on the 800/900 MHz Mobitex networks, respectively). The problem is this: It really hasn’t changed that much. Aside from the color and graphics, the BlackBerry 950 running BlackBerry Device Software 2.5 had pretty much the same applications and functi..
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In the next few days, the last few 'Cubers are arriving on Station to help us with end-of-season commissioning of the new strings. Many more IceCube people are leaving, however… most of them drillers. It will be nice to be here when things are a bit quieter. The winter-overs are already talking about how great it will be when we summer folk are gone. Some people pay a fair chunk of change to fly here for an hour or two, look around, and ....
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The Beineke Rare Book & Manuscript Library at Yale is blogging a word a day from Samuel Johnson’s seminal A Dictionary of the English Language . Their selections are so far tending toward the obscure (i.e. bandog ), and include great photos of the book and many handwritten additions and corrections. I wonder how many of these words were actually in common usage in 1755, especially those where Shakespeare is given as the only reference..
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The Beineke Rare Book & Manuscript Library at Yale is blogging a word a day from Samuel Johnson’s seminal A Dictionary of the English Language . Their selections are so far tending toward the obscure (i.e. bandog ), and include great photos of the book and many handwritten additions and corrections. I wonder how many of these words were actually in common usage in 1755, especially those where Shakespeare is given as the only reference..
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In the next few days, the last few 'Cubers are arriving on Station to help us with end-of-season commissioning of the new strings. Many more IceCube people are leaving, however… most of them drillers. It will be nice to be here when things are a bit quieter. The winter-overs are already talking about how great it will be when we summer folk are gone. Some people pay a fair chunk of change to fly here for an hour or two, look around, and ....
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I think my previous excitement was unfounded … probably was just some guy playing around, not a real bot… But I’m patient.
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I think my previous excitement was unfounded … probably was just some guy playing around, not a real bot… But I’m patient.
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Thought I would set up a site to share things online. I don’t really know what exactly this will be other than a place to publish articles. Maybe some photos?
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It’s amazing that the following all works: Using my terminal program ( PuTTY on Windows, set to UTF-8) connected to a Linux computer (terminal settings set to UTF-8), created a file whose name had various Unicode characters The shell allowed me to type those characters (vi ) The standard programs such as "ls", "cat", "vi" seemed to be able to handle these file names I checked the file into the Subversion version control sy..
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The service went down because another service running on the same application server went down.” “You can’t use the improved version of your programming language because you’re running on the same application server as some old applications.” “We can’t help you deploy your application on the application server, because we’re busy with some other application.” If you’ve ever heard any of these statements, you’ve been victim to the accidental..
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Ok. Now we have the basic functionality of posting and reading from forms ready. I tried to keep the form very simple so any spambot should be able to submit into it. So far there are no ent...
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Ok. Now we have the basic functionality of posting and reading from forms ready. I tried to keep the form very simple so any spambot should be able to submit into it. So far there are no ent...
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I’m setting up the Tumblr blog. Will be using that for all blog posts and information about the website’s progress.
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I’m setting up the Tumblr blog. Will be using that for all blog posts and information about the website’s progress.
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There was a question about PRECOMPUTE_SUBQUERY hint in an Oracle Forums thread . Here I will post the answer I gave there and also elaborate it more as it explains a little known interesting fact about Oracle cursor management. Also it allows me to introduce few advanced Oracle troubleshooting scripts by example. This is a fairly long post, but if you are interested in some Oracle cursor management and SQL execution internals, keep on re....
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There was a question about PRECOMPUTE_SUBQUERY hint in an Oracle Forums thread . Here I will post the answer I gave there and also elaborate it more as it explains a little known interesting fact about Oracle cursor management. Also it allows me to introduce few advanced Oracle troubleshooting scripts by example. This is a fairly long post, but if you are interested in some Oracle cursor management and SQL execution internals, keep on re....
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An Email Address Field Should Be Called "email address" (Not "email")
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www.databasesandlife.com
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17 years ago
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eng
Naming is extremely important in software development. Any software that deals with emails probably also deals with email addresses. Emails and email addresses are two completely different types of objects, with a completely different set of attributes, and a completely different set of actions which one can perform on them. Even if your application only deals with the one or the other type, it would be unwise to confuse them.
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Lsof (list open files) is a really useful tool for troubleshooting open file decriptors which prevent a deleted file from being released or a shared memory segment from being removed. Here’s a little situation on Linux where an Oracle shared memory segment was not released as someone was still using it. $ ipcs -ma ------ Shared Memory Segments -------- key shmid owner perms bytes nattch status 0x00000000 393216 oracle 640 28940....
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Lsof (list open files) is a really useful tool for troubleshooting open file decriptors which prevent a deleted file from being released or a shared memory segment from being removed. Here’s a little situation on Linux where an Oracle shared memory segment was not released as someone was still using it. $ ipcs -ma ------ Shared Memory Segments -------- key shmid owner perms bytes nattch status 0x00000000 393216 oracle 640 28940....
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My room in the A4 wing of the Elevated Station Been here about 58 hours so far and the reason I am counting in hours instead of days is that my sense of days is pretty shot. I have a screwy sleep routine: 10 hours awake, 3 hours asleep. Lather, rinse repeat. I am trying to be up at night (we keep New Zealand time here) for the satellite hours but usually that entails a long nap in the middle, which curtails my sleep during the day. I’ll....
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My room in the A4 wing of the Elevated Station Been here about 58 hours so far and the reason I am counting in hours instead of days is that my sense of days is pretty shot. I have a screwy sleep routine: 10 hours awake, 3 hours asleep. Lather, rinse repeat. I am trying to be up at night (we keep New Zealand time here) for the satellite hours but usually that entails a long nap in the middle, which curtails my sleep during the day. I’ll....
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My room in the A4 wing of the Elevated Station Been here about 58 hours so far and the reason I am counting in hours instead of days is that my sense of days is pretty shot. I have a screwy sleep routine: 10 hours awake, 3 hours asleep. Lather, rinse repeat. I am trying to be up at night (we keep New Zealand time here) for the satellite hours but usually that entails a long nap in the middle, which curtails my sleep during the day. I’ll....
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Here’s a link to Alex Fatkulin’s blog if you haven’t seen it already: http://afatkulin.blogspot.com/ He has some good Oracle internals information in there, I also like his research style. Alex just blogged about a finding (on Oracle 11g on Linux) that when Oracle process doesn’t get a latch after spinning, it goes to sleep using semop() system call, which never wakes up unless this semaphore is posted by another process. From pas..
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Here’s a link to Alex Fatkulin’s blog if you haven’t seen it already: http://afatkulin.blogspot.com/ He has some good Oracle internals information in there, I also like his research style. Alex just blogged about a finding (on Oracle 11g on Linux) that when Oracle process doesn’t get a latch after spinning, it goes to sleep using semop() system call, which never wakes up unless this semaphore is posted by another process. From pas..
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10:07 PM New Zealand Daylight Time and I am well-socketed into my room in the station at the South Pole, watching videos, napping when I can, drinking as much water as I can stomach and waiting for my body’s chemistry to adjust to a physiological altitude of… let me check… 10,455 feet (the local air density here depends on the weather, and is displayed continuously on the monitors and the local Web site). To kill time while I acclimate, ....
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10:07 PM New Zealand Daylight Time and I am well-socketed into my room in the station at the South Pole, watching videos, napping when I can, drinking as much water as I can stomach and waiting for my body’s chemistry to adjust to a physiological altitude of… let me check… 10,455 feet (the local air density here depends on the weather, and is displayed continuously on the monitors and the local Web site). To kill time while I acclimate, ....
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10:07 PM New Zealand Daylight Time and I am well-socketed into my room in the station at the South Pole, watching videos, napping when I can, drinking as much water as I can stomach and waiting for my body’s chemistry to adjust to a physiological altitude of… let me check… 10,455 feet (the local air density here depends on the weather, and is displayed continuously on the monitors and the local Web site). To kill time while I acclimate, ....
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Last Friday, Andy Davidson , Jonathan Oddy, and I pushed out some research that has some quite worrying repercussions. Whilst I’ve heard from a lot of people privately about this matter, there’s a big flaw here, and as Andy posted on his blog (which is much more informative than mine, I think!), this is a big problem. The reason, I think, that we’re getting limited public discussion of this exploit (I hesitate to call it an exploit..
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Last Friday, Andy Davidson , Jonathan Oddy, and I pushed out some research that has some quite worrying repercussions. Whilst I’ve heard from a lot of people privately about this matter, there’s a big flaw here, and as Andy posted on his blog (which is much more informative than mine, I think!), this is a big problem. The reason, I think, that we’re getting limited public discussion of this exploit (I hesitate to call it an exploit..
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In the January/February 2009 edition of Books and Culture I read a review of Thomas Howard’s Dove Descending: A Journey into T.S. Eliot’s Four Quartets . (I would link to the review but it isn’t on the B&C web site yet. UPDATE: The article has been posted: Rest for the Weary .) This motivated me to dust off (literally) my copy of Eliot’s Selected Poems , which doesn’t contain “Four Quartets” but has the Ariel Poems, his first published..
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In the January/February 2009 edition of Books and Culture I read a review of Thomas Howard’s Dove Descending: A Journey into T.S. Eliot’s Four Quartets . (I would link to the review but it isn’t on the B&C web site yet. UPDATE: The article has been posted: Rest for the Weary .) This motivated me to dust off (literally) my copy of Eliot’s Selected Poems , which doesn’t contain “Four Quartets” but has the Ariel Poems, his first published..
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Occassional blogger-? That fits me... Have you ever thought of getting all the Andy's together on a blog or website and seeing what we can do-? Afterall... Being an Andy is rare and unusual and meybe even special-! When I worked in London it was the first time we had several "Andy's" in one office. Being a Yank I suggested we had designated "Andy''s: and even honorary "Andy's"... It was a fun time. Now we have the internet to show us how w..
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Have you ever looked at a list of compiler warnings the length of an essay on bad coding and thought to yourself: “You know, I really should do something about that… but I don’t have time just now”? On the other hand, have you ever looked at a lone warning that just appeared in a compilation and just fixed it? When I start a new project from scratch, there are no warnings, no clutter, no problems.
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When troubleshooting Oracle process memory issues like ORA-4030’s or just excessive memory usage, you may want to get a detailed breakdown of PGA, UGA and Call heaps to see which component in there is the largest one. The same goes for shared pool memory issues and ORA-4031’s – sometimes you need to dump the shared pool heap metadata for understanding what kind of allocations take most of space in there. The heap dumping can be done usi....
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When troubleshooting Oracle process memory issues like ORA-4030’s or just excessive memory usage, you may want to get a detailed breakdown of PGA, UGA and Call heaps to see which component in there is the largest one. The same goes for shared pool memory issues and ORA-4031’s – sometimes you need to dump the shared pool heap metadata for understanding what kind of allocations take most of space in there. The heap dumping can be done usi....
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Following getting my roadbike back out for the first time in a while (been really busy since moving to Ealing!) I figured I’d look at if there’s anything more about Di2 floating around. It seems the more I see of this system, the more I want it. Perhaps Orca with Di2 is something for 2009?
I've also started tracking my rides (mostly fixed, mostly to and from work at the moment) on this site , if there's any interest, I was pond..
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Following getting my roadbike back out for the first time in a while (been really busy since moving to Ealing!) I figured I’d look at if there’s anything more about Di2 floating around. It seems the more I see of this system, the more I want it. Perhaps Orca with Di2 is something for 2009?
I've also started tracking my rides (mostly fixed, mostly to and from work at the moment) on this site , if there's any interest, I was pond..
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Update: Luca Canali has written a newer version of Perfsheet (PerfSheet v4) and you can download it here . I am not updating/maintaining the old versions anymore (and Perfsheet v3 is only tested on up to Excel 2007) so I’d recommend to check out Luca’s PerfSheet v4. Hi all, I have been extremely busy over last couple of months, that’s why there haven’t been any blog entries (no, I haven’t ran out of good ideas ;-) I just managed to....
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Update: Luca Canali has written a newer version of Perfsheet (PerfSheet v4) and you can download it here . I am not updating/maintaining the old versions anymore (and Perfsheet v3 is only tested on up to Excel 2007) so I’d recommend to check out Luca’s PerfSheet v4. Hi all, I have been extremely busy over last couple of months, that’s why there haven’t been any blog entries (no, I haven’t ran out of good ideas ;-) I just managed to....
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C and I have been watching Battlestar Galactica. It’s something I’ve wanted to watch back in the U.S. on the Sci-Fi channel, but somehow always skipped over it because I couldn’t be bothered or couldn’t get into the storyline.
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