Materialized views are on the way, hopefully for
9.3.
The first pass at this is fairly limited, you have to refresh the matview yourself (i.e. it supports only the "snapshot" type of matview maintenance, per terminology here).
So I could get a T-72 tank [wikipedia.org] with a smoothbore 125mm gun [wikipedia.org], and it would be legal to keep armed?
No. See: http://en.wikipedia.org/wiki/Destructive_device for more information. The reason you can have a muzzle-loading smoothbore cannon (i.e. Civil War era) is mentioned at the end of the article. Your tank gun is not muzzle-loading.
Actually, you can sometimes buy functional tanks as a civilian, but they weld the barrels of the big guns shut:-(
I'm not sure what point you are trying to make, but alcohol is pretty darn cheap in the USA. Compare the cost of a can of cheap soda ($0.50, give or take) to a can of cheap beer ($0.80, give or take). Then factor in the alcohol taxes which go to the state and Federal government for the beer. In many states, revenue from alcohol/cigarette taxes are a major portion of the state's revenue.
I've donated my time/skills to charity (I've got ~20 years in IT). I received "payment" in value (tax write off). I get far less than what I'm worth (in the form of the write-off), but that's not why I'm doing it.
You can't deduct the value of your time or services spent on charitable work, but you can deduct mileage or vehicle expenses if you use your car for charitable purposes.
There is a serious problem with this patch on BSD kernels. All of the BSD sysv implementations have a shm_use_phys optimization which forces the kernel to wire up memory pages used to back SysV segments. This increases performance by not requiring the allocation of pv entries for these pages and also reduces memory pressure. Most serious users of PostgreSQL on BSD platforms use this well-documented optimization. After switching to 9.3, large and well optimized Pg installations that previously ran well in memory will be forced into swap because of the pv entry overhead.
I don't see your comment on the blog (maybe it has to be approved?), but the same issue was raised here during review of the patch. The concern was mostly blown off (most PG developers use Linux instead of BSD, that might well be part of it), but if you had some numbers to back up your post, the -hackers list would definitely be interested. Ideally, you could give numbers and a repeatable benchmark showing a deterioration of 9.3-post-patch vs. 9.3-pre-patch on a BSD. If that's too much work, just the numbers from a dumb C program reading/writing shared memory with mmap() vs. SysV would be a good discussion basis.
You do realize they still have to pay for that thing that syncs to your phone. You know the tower and its upkeep, and the lease for the land the tower is on, electricity to run the tower, and all the network to run to that tower, and permits, and taxes on that tower...Its not just the cost of the bandwidth...Why do people not get this...
So after all the towers have been put up, and the investment in infrastructure has been recouped, we should see prices go down. That's why the monthly prices for plans have plunged over the past few years, data allotments and minutes have become more generous, the price per text message has fallen to almost nothing, and you no longer have 2-year contract lock-ins. Right?
While disguising their individual faces was imperative, because of the illegality of their protest, dressing as Mohawk warriors was a very specific and symbolic choice.
Sure, let's make masks illegal... can't have people getting away with anything which might possibly be illegal without direct and immediate repercussions.
In my more entrepreneurial moments I've been thinking of setting up a GC exchange corporation where people could trade cards they don't want for a modest fee say 1% off the top. My wife for example would enjoy trading cash for your GC, assuming that store isn't the fat chick mall store (don't recall name sry).
Too bad your idea has already been done, and it works quite well: see plastic jungle.
always ask permission from authors and researchers, but no longer from publishers, as they just want to monetize and gouge.
Careful. Though you may have the permission from the authors to redistribute their works, they may not legally be able to give you such permission. See the rules for journal Cell, one of these Elsevier publications, under "Copyright" section:
Upon acceptance of an article, authors will be asked to transfer copyright. ..
They spell out further rules under Authors' Rights: the author does not retain the right to grant arbitrary redistribution rights to other individuals/corporations (i.e. to you). And these rules are actually some of the more lenient ones I've seen...
I recently did some research into a related topic -- I was looking for hosts for a decent sized (200 GB+) database with generous bandwidth, on a shoestring budget (under $50/month, for the 2-3 machines I need).
First, choose your provider wisely. Your choice of provider may seem like it doesn't matter except for the pricing, but as your post about "unlimited" providers hints, it can and will become very important very quickly once the shit hits the fan (i.e. provider thinks you are using too much disk I/O, or too much bandwidth, or too much space, or whatever -- and promptly kicks you off).
Second, Slashdot actually isn't the best place to ask this question. Hang out in webhostingtalk for a while (e.g. this thread).
Finally, my recommendation for hosting provider: honelive. Take a look at their offerings, and particularly their specials. I jumped on the dedicated Intel Atom dual core, with 250GB storage, when it was $39/month a few months back. Today they are offering a dedicated Core i7 Quad Core with 24 GB RAM, 1TB disk, 5TB bandwidth, for $100/month. Yes you read that right -- these are dedicated machines, and these guys are for real. I sleep easier at night knowing I'm not going to wake up to an email of "we disabled your server because your VPS was using too much I/O and loading down our horribly oversold machines". It's my machine, I run what I want. I know VPSs are all the rage now, cloud computing yadda yadda yadda. And sure, they're great for hosting your personal photo gallery or blog. But take it from me, once you start burning through TBs of monthly bandwidth, and the disk I/O of a 200 GB database, they start looking flimsy real fast, and hosting providers get anxious to see you and your piddly monthly payment gone.
BTW I'm just a happy honelive customer, I have no affiliation with them, no referral codes in this post, etc. I've been burned by a lot of shady VPS providers. Don't get me wrong, there are some great providers (Linode) out there, but you will have to shell out the $$ for them, and I haven't found ANY reputable VPS provider providing the bang for the buck and stability I'm getting with honelive.
Also, I do pay for 2 or 3 other VPSs affiliated with my site, but the needs for these are comparatively tiny, so I suggest just hanging out on lowendbox and grabbing one of the deals there, if you need a few small VPSs with decent bandwidth. You can easily find several providers who will give you a few TB of bandwidth per month for around $5/month. I've used 5ite for such purposes, though I can only give them a lukewarm recommendation. I have a $2/month VPS from Securedragon right now for a similar purpose, and it works well enough (for a 100% expendable machine).
I see you learned bash programming but never bothered to learn about exponents.
Hint: your entire "program" boils down to printing 2^(n-1) for various values of n.
Thought I was the only one who noticed this. The captcha can not be solved -- I tried three times, and each time I was pretty sure I had the captcha correct. Each time, it simply refreshed the page with a new captcha. Something about the site smells mighty fishy, like they really really want your Facebook account details for some reason...
Here's a serious question which has me totally baffled. As the parent says, it's pretty well agreed upon that neutrinos have some mass. Then how do they travel at light speed (let alone possibly faster)? I thought it would take infinite energy for a body with mass to get to light speed?
Oh, they still exist. You just have to look around. I've been using Lee County Bank & Trust's reward checking account for 2 or 3 years now. They started out paying 4.5% or so on balances up to $25K. Now they "only" pay 2.5%. (I do expect this deal, and others like it, to evaporate once the new restrictions on debit card fees go into effect, since the "catch" with these deals is you have to use your debit card at least 10 or so times per month, so that the banks can earn their $0.40 per transaction or whatever it is they earn).
Link: Lee County Bank (warning , terrible flash site). There are more such banks cataloged at sites like bankrate.com, I think.
Sigh, you've missed the entire point of the "Primary Keyvil" articles (Part 1, Part 2, Part 3), and many similar ones. Let's go through your drivel point by point.
"Student ID" is an acceptable primary key - you will be able to tell if two rows are duplicates based on this alone.
Wrong, wrong, wrong. A surrogate key, like "student ID", actually is an acceptable "primary key" for a table, but only if you have a real way to tell apart your users, something based on an understanding of an answer to the question "what defines a unique student, and how am I going to verify that?".
It's not automatically generated by the database, which is the primary keyvil syndrome.
VERY WRONG! From the database's point of view, and the "primary keyvil" syndrome, it doesn't matter if you fill in the "student ID" using, say, a database function called SYS_GUID(), or whether you generate this GUID on the client side. Read Part 1 of the Primary Keyvil syndrome articles for another example. But let's take our example of a table of students and run with it. You, the database application developer and schema designer, have created a table of students where the only unique key is a "student ID". Let's pretend you're smart, and you only assign new student IDs to new students coming through the gate on admission day. So far, so good, right?
Well, you're sitting in your office when a freshman comes in and says "Hey, I lost my ID. How do I get a new one". Now you're in a tough spot. You could say "what's your student ID number?", and if the student knows it, then you print off a new student ID for him, since you know who he is based on his ID number, right? Uh oh, you've just opened a door to students impersonating other students. But let's ignore that problem for now... what do you do if the poor kid doesn't know his ID number? Well, you ask him..... his name? Right? What if it's "Joe Smith", and you have fifty of those in your giant state school? Uh, I guess you ask him his name, and his street address, right? That's got to be unique, right? Or maybe his current SSN, those can never change, right? And how do you prove that the student in front of you is really who he says he is?
The frantic grasping around in the above paragraph is why you need to have a good answer to the question "what distinguishes a unique student?" before you go designing a table like this. There are several ways to answer this question: in practice, you might enforce unique constraints on (full name + home phone number), or maybe just a unique key on SSN if you're daring. But either way, relying solely on some arbitrary identifier like "Student ID" with no actual anchor in reality opens all sorts of paths to trouble. (Incidentally, the social security administration has the same problem, they've just thought through and been through the consequences. They have elaborate, formal answers to the question "how do we distinguish unique people, regardless of SSN", for scenarios like assigning new SSNs, changing SSNs, replacing lost social security cards to people who don't remember their SSN, etc etc.)
Another major problem I didn't even touch on, is how your model would prevent a user from getting two student IDs, either intentionally or accidentally. If you haven't answered these fundamental questions, you will have a database full of garbage. Kind of like the No Fly List.
It's as unique as it would be to include the students DNA in number form as the primary key.
Privacy concerns aside, DNA would actually be a totally reasonable way to distinguish unique students -- student comes in to your office, you take a cheek swab, and issue him his replacement ID card. (Hrm,
First, let me say that I really appreciate the work Stanford put into these online classes, especially the "free for everyone" aspect. They've done a great job pioneering free online classes _done well_, with lecture videos recorded well plus lecture notes plus banks of review questions plus exams. Really a great package overall.
I'm slowly going through the Machine Learning class, and the course is great. The instructor does a great job of easing the student into an otherwise math-heavy topic with graphing and hand-plotting, "Intuition", and simple examples.
However, I want to discourage anyone from investing a bunch of time in the "Introduction to Databases Course". Here's a slightly-edited explanation I sent to a friend, to whom I had at first recommended the course, before I had a chance to go through some of the videos (just a background note, I've worked with RDBMSs for several years, as an application developer, plus occassionally DBA, plus some work on an OSS RDBMS):
After watching two or three of that class's videos I've
decided to give up on it. The course seems to have a needless emphasis
on XML data storage, which turns out to be basically useless for
real-world big data problems. Plus, either the Professor's
presentation is unacceptably sloppy or she just doesn't know what
she's talking about: lecture video #2 (or #3, I forget) was particularly bad, with
imprecise terminology thrown around (row vs tuple) plus highly
questionable database design being presented matter-of-factly (table
of students flagrantly violates what's known as "Primary Keyvil"). She dove straight into the use of NULLs in this example table, presenting them as perfectly acceptable -- which would be OK for an "intro to MySQL"-type class, but not for a real course on the background of relational theory and RDBMSs (see "SQL and Relational Theory" and its treatment of NULLs).
Not
to dissuade you from taking it of course, there is probably some
useful information in there.
Seeing the professor present her table of students as a simple cut-and-dried example, with an explanation that "student ID" was an acceptable primary key, and no other unique keys on the table, really gives me a poor opinion of the professor's real-world subject matter knowledge.
Hrm, any radio astronomers out there? How hard would it be to rig up a poor man's directional radio antenna powerful enough to send a clear signal to that planet?
Let me introduce you to the wonderful world of pay-as-you-go data plans with an android phone.
Well, that's exactly what I use: T-Mobile pay by the minute, with an old G1 Android phone (the first android phone that came out, I think). The phone was about $100 used on ebay, and I pay about $5-10/month for 50-150 minutes of usage per month (the going rate for a 1000 minute, 1-year card is $90 on eBay). It sure is cheap, but dunno about "wonderful" - no 3G data, for one thing. And the phone is somehow designed to *require* a 3G-capable SIM card when you activate it with your Google account, otherwise it pretends it can't login to your google account via WiFi. So you really need to have a buddy with a T-Mobile SIM card and a 3G plan for this to work. I chose T-Mobile because the per-minute rate was the cheapest I could find that would give me a reasonable phone choice and coverage.
In summary: cheap: yes. good: yes. wonderful: not quite
Slashdot Mirror
Materialized views are on the way, hopefully for 9.3. The first pass at this is fairly limited, you have to refresh the matview yourself (i.e. it supports only the "snapshot" type of matview maintenance, per terminology here).
So I could get a T-72 tank [wikipedia.org] with a smoothbore 125mm gun [wikipedia.org], and it would be legal to keep armed?
No. See: http://en.wikipedia.org/wiki/Destructive_device for more information. The reason you can have a muzzle-loading smoothbore cannon (i.e. Civil War era) is mentioned at the end of the article. Your tank gun is not muzzle-loading.
Actually, you can sometimes buy functional tanks as a civilian, but they weld the barrels of the big guns shut :-(
Yes, like alcohol.
I'm not sure what point you are trying to make, but alcohol is pretty darn cheap in the USA. Compare the cost of a can of cheap soda ($0.50, give or take) to a can of cheap beer ($0.80, give or take). Then factor in the alcohol taxes which go to the state and Federal government for the beer. In many states, revenue from alcohol/cigarette taxes are a major portion of the state's revenue.
Uh, you do know that you're not allowed to claim volunteer time worked at a charity as a tax write-off, right? Source: http://www.hrblock.com/free-tax-tips-calculators/deductions-credits/charitable-giving.html#2
You can't deduct the value of your time or services spent on charitable work, but you can deduct mileage or vehicle expenses if you use your car for charitable purposes.
I don't see your comment on the blog (maybe it has to be approved?), but the same issue was raised here during review of the patch. The concern was mostly blown off (most PG developers use Linux instead of BSD, that might well be part of it), but if you had some numbers to back up your post, the -hackers list would definitely be interested. Ideally, you could give numbers and a repeatable benchmark showing a deterioration of 9.3-post-patch vs. 9.3-pre-patch on a BSD. If that's too much work, just the numbers from a dumb C program reading/writing shared memory with mmap() vs. SysV would be a good discussion basis.
So after all the towers have been put up, and the investment in infrastructure has been recouped, we should see prices go down. That's why the monthly prices for plans have plunged over the past few years, data allotments and minutes have become more generous, the price per text message has fallen to almost nothing, and you no longer have 2-year contract lock-ins. Right?
*SIGH* Need more caffeine before posting on /.
Yeah, a nice cold can of Mountain Dew sounds refreshing right about now :-)
While disguising their individual faces was imperative, because of the illegality of their protest, dressing as Mohawk warriors was a very specific and symbolic choice.
Sure, let's make masks illegal... can't have people getting away with anything which might possibly be illegal without direct and immediate repercussions.
In my more entrepreneurial moments I've been thinking of setting up a GC exchange corporation where people could trade cards they don't want for a modest fee say 1% off the top. My wife for example would enjoy trading cash for your GC, assuming that store isn't the fat chick mall store (don't recall name sry).
Too bad your idea has already been done, and it works quite well: see plastic jungle.
always ask permission from authors and researchers, but no longer from publishers, as they just want to monetize and gouge.
Careful. Though you may have the permission from the authors to redistribute their works, they may not legally be able to give you such permission. See the rules for journal Cell, one of these Elsevier publications, under "Copyright" section:
Upon acceptance of an article, authors will be asked to transfer copyright. . .
They spell out further rules under Authors' Rights: the author does not retain the right to grant arbitrary redistribution rights to other individuals/corporations (i.e. to you). And these rules are actually some of the more lenient ones I've seen...
I recently did some research into a related topic -- I was looking for hosts for a decent sized (200 GB+) database with generous bandwidth, on a shoestring budget (under $50/month, for the 2-3 machines I need).
First, choose your provider wisely. Your choice of provider may seem like it doesn't matter except for the pricing, but as your post about "unlimited" providers hints, it can and will become very important very quickly once the shit hits the fan (i.e. provider thinks you are using too much disk I/O, or too much bandwidth, or too much space, or whatever -- and promptly kicks you off).
Second, Slashdot actually isn't the best place to ask this question. Hang out in webhostingtalk for a while (e.g. this thread).
Finally, my recommendation for hosting provider: honelive. Take a look at their offerings, and particularly their specials. I jumped on the dedicated Intel Atom dual core, with 250GB storage, when it was $39/month a few months back. Today they are offering a dedicated Core i7 Quad Core with 24 GB RAM, 1TB disk, 5TB bandwidth, for $100/month. Yes you read that right -- these are dedicated machines, and these guys are for real. I sleep easier at night knowing I'm not going to wake up to an email of "we disabled your server because your VPS was using too much I/O and loading down our horribly oversold machines". It's my machine, I run what I want. I know VPSs are all the rage now, cloud computing yadda yadda yadda. And sure, they're great for hosting your personal photo gallery or blog. But take it from me, once you start burning through TBs of monthly bandwidth, and the disk I/O of a 200 GB database, they start looking flimsy real fast, and hosting providers get anxious to see you and your piddly monthly payment gone.
BTW I'm just a happy honelive customer, I have no affiliation with them, no referral codes in this post, etc. I've been burned by a lot of shady VPS providers. Don't get me wrong, there are some great providers (Linode) out there, but you will have to shell out the $$ for them, and I haven't found ANY reputable VPS provider providing the bang for the buck and stability I'm getting with honelive.
Also, I do pay for 2 or 3 other VPSs affiliated with my site, but the needs for these are comparatively tiny, so I suggest just hanging out on lowendbox and grabbing one of the deals there, if you need a few small VPSs with decent bandwidth. You can easily find several providers who will give you a few TB of bandwidth per month for around $5/month. I've used 5ite for such purposes, though I can only give them a lukewarm recommendation. I have a $2/month VPS from Securedragon right now for a similar purpose, and it works well enough (for a 100% expendable machine).
I see you learned bash programming but never bothered to learn about exponents. Hint: your entire "program" boils down to printing 2^(n-1) for various values of n.
True this. I try to give anonymously to deserving organization where possible, which helps cut down on the donations begging.
an impossible (!) captcha
Thought I was the only one who noticed this. The captcha can not be solved -- I tried three times, and each time I was pretty sure I had the captcha correct. Each time, it simply refreshed the page with a new captcha. Something about the site smells mighty fishy, like they really really want your Facebook account details for some reason...
Here's a serious question which has me totally baffled. As the parent says, it's pretty well agreed upon that neutrinos have some mass. Then how do they travel at light speed (let alone possibly faster)? I thought it would take infinite energy for a body with mass to get to light speed?
I remembered this anecdote from the great book "Expert C Programming" by Peter Van der Linden. See the bottom of page 61, and page 62: google books.
Oh, they still exist. You just have to look around. I've been using Lee County Bank & Trust's reward checking account for 2 or 3 years now. They started out paying 4.5% or so on balances up to $25K. Now they "only" pay 2.5%. (I do expect this deal, and others like it, to evaporate once the new restrictions on debit card fees go into effect, since the "catch" with these deals is you have to use your debit card at least 10 or so times per month, so that the banks can earn their $0.40 per transaction or whatever it is they earn).
Link: Lee County Bank (warning , terrible flash site). There are more such banks cataloged at sites like bankrate.com, I think.
Sigh, you've missed the entire point of the "Primary Keyvil" articles (Part 1, Part 2, Part 3), and many similar ones. Let's go through your drivel point by point.
"Student ID" is an acceptable primary key - you will be able to tell if two rows are duplicates based on this alone.
Wrong, wrong, wrong. A surrogate key, like "student ID", actually is an acceptable "primary key" for a table, but only if you have a real way to tell apart your users, something based on an understanding of an answer to the question "what defines a unique student, and how am I going to verify that?".
It's not automatically generated by the database, which is the primary keyvil syndrome.
VERY WRONG! From the database's point of view, and the "primary keyvil" syndrome, it doesn't matter if you fill in the "student ID" using, say, a database function called SYS_GUID(), or whether you generate this GUID on the client side. Read Part 1 of the Primary Keyvil syndrome articles for another example. But let's take our example of a table of students and run with it. You, the database application developer and schema designer, have created a table of students where the only unique key is a "student ID". Let's pretend you're smart, and you only assign new student IDs to new students coming through the gate on admission day. So far, so good, right?
Well, you're sitting in your office when a freshman comes in and says "Hey, I lost my ID. How do I get a new one". Now you're in a tough spot. You could say "what's your student ID number?", and if the student knows it, then you print off a new student ID for him, since you know who he is based on his ID number, right? Uh oh, you've just opened a door to students impersonating other students. But let's ignore that problem for now... what do you do if the poor kid doesn't know his ID number? Well, you ask him..... his name? Right? What if it's "Joe Smith", and you have fifty of those in your giant state school? Uh, I guess you ask him his name, and his street address, right? That's got to be unique, right? Or maybe his current SSN, those can never change, right? And how do you prove that the student in front of you is really who he says he is?
The frantic grasping around in the above paragraph is why you need to have a good answer to the question "what distinguishes a unique student?" before you go designing a table like this. There are several ways to answer this question: in practice, you might enforce unique constraints on (full name + home phone number), or maybe just a unique key on SSN if you're daring. But either way, relying solely on some arbitrary identifier like "Student ID" with no actual anchor in reality opens all sorts of paths to trouble. (Incidentally, the social security administration has the same problem, they've just thought through and been through the consequences. They have elaborate, formal answers to the question "how do we distinguish unique people, regardless of SSN", for scenarios like assigning new SSNs, changing SSNs, replacing lost social security cards to people who don't remember their SSN, etc etc.)
Another major problem I didn't even touch on, is how your model would prevent a user from getting two student IDs, either intentionally or accidentally. If you haven't answered these fundamental questions, you will have a database full of garbage. Kind of like the No Fly List.
It's as unique as it would be to include the students DNA in number form as the primary key.
Privacy concerns aside, DNA would actually be a totally reasonable way to distinguish unique students -- student comes in to your office, you take a cheek swab, and issue him his replacement ID card. (Hrm,
First, let me say that I really appreciate the work Stanford put into these online classes, especially the "free for everyone" aspect. They've done a great job pioneering free online classes _done well_, with lecture videos recorded well plus lecture notes plus banks of review questions plus exams. Really a great package overall.
I'm slowly going through the Machine Learning class, and the course is great. The instructor does a great job of easing the student into an otherwise math-heavy topic with graphing and hand-plotting, "Intuition", and simple examples.
However, I want to discourage anyone from investing a bunch of time in the "Introduction to Databases Course". Here's a slightly-edited explanation I sent to a friend, to whom I had at first recommended the course, before I had a chance to go through some of the videos (just a background note, I've worked with RDBMSs for several years, as an application developer, plus occassionally DBA, plus some work on an OSS RDBMS):
Seeing the professor present her table of students as a simple cut-and-dried example, with an explanation that "student ID" was an acceptable primary key, and no other unique keys on the table, really gives me a poor opinion of the professor's real-world subject matter knowledge.
It is difficult to get a man to understand something when his job depends on not understanding it. - Upton Sinclair
Couldn't Sun just write their JVM in Java, so that it could run on any platform without porting?
You either die a hero or you live long enough to see yourself become the villain.
The SQL standard itself doesn't allow for unsigned integers, that's why.
Hrm, any radio astronomers out there? How hard would it be to rig up a poor man's directional radio antenna powerful enough to send a clear signal to that planet?
Let me introduce you to the wonderful world of pay-as-you-go data plans with an android phone.
Well, that's exactly what I use: T-Mobile pay by the minute, with an old G1 Android phone (the first android phone that came out, I think). The phone was about $100 used on ebay, and I pay about $5-10/month for 50-150 minutes of usage per month (the going rate for a 1000 minute, 1-year card is $90 on eBay). It sure is cheap, but dunno about "wonderful" - no 3G data, for one thing. And the phone is somehow designed to *require* a 3G-capable SIM card when you activate it with your Google account, otherwise it pretends it can't login to your google account via WiFi. So you really need to have a buddy with a T-Mobile SIM card and a 3G plan for this to work. I chose T-Mobile because the per-minute rate was the cheapest I could find that would give me a reasonable phone choice and coverage.
In summary: cheap: yes. good: yes. wonderful: not quite