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• unbuffered I/O in Linux

  - by stuck

  I'm writing lots and lots of data that will not be read again for weeks - as my program runs the amount of free memory on the machine (displayed with 'free' or 'top') drops very quickly, the amount of memory my app uses does not increase - neither does the amount of memory used by other processes. This leads me to believe the memory is being consumed by the filesystems cache - since I do not intend to read this data for a long time I'm hoping to bypass the systems buffers, such that my data is written directly to disk. I dont have dreams of improving perf or being a super ninja, my hope is to give a hint to the filesystem that I'm not going to be coming back for this memory any time soon, so dont spend time optimizing for those cases. On Windows I've faced similar problems and fixed the problem using FILE_FLAG_NO_BUFFERING|FILE_FLAG_WRITE_THROUGH - the machines memory was not consumed by my app and the machine was more usable in general. I'm hoping to duplicate the improvements I've seen but on Linux. On Windows there is the restriction of writing in sector sized pieces, I'm happy with this restriction for the amount of gain I've measured. is there a similar way to do this in Linux?

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• How do I become better in math, after being a programmer for several years.

  - by loxs

  I've had quite a weird career till now. First I graduated from a medical school. Then I went into marketing (pharmaceuticals). And then umm, after some time, I decided to go for my (till then) hobby and became a "professional" programmer. I've been quite successful at this ever since. I have quite some languages "under my belt". I earn not bad and I have been involved in the opensource community quite heavily. The thing is that I suck at math :). Well, not totally of course, as I get my work done. But I don't know how much I suck. And I don't know how to find out. Math has never really been of any priority during my middle/high school years. I only picked as little as I could afford, because I was always getting ready to go for Medicine. Of course I know the basics of algebra. Things like "normal" and square equations. Also the basics of geometry. But well, there are things that I have missed. And lately I am being fascinated by things like probability theory, infinity, chaos/order etc. But every time I try to learn something about these topics, I hit a wall of terminology, special symbols, and some special kind of thinking, that is quite like mine (a programmer), but also a lot different (and appears weird to me). So, what kinds of books would you recommend me? It's very hard to find something suitable. All that I find are either too easy (and boring) or totally impenetrable.

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• I have data about deadlocks, but I can't understand why they occur

  - by Alex

  I am receiving a lot of deadlocks in my big web application. http://stackoverflow.com/questions/2941233/how-to-automatically-re-run-deadlocked-transaction-asp-net-mvc-sql-server Here I wanted to re-run deadlocked transactions, but I was told to get rid of the deadlocks - it's much better, than trying to catch the deadlocks. So I spent the whole day with SQL Profiler, setting the tracing keys etc. And this is what I got. There's a Users table. I have a very high usable page with the following query (it's not the only query, but it's the one that causes troubles) UPDATE Users SET views = views + 1 WHERE ID IN (SELECT AuthorID FROM Articles WHERE ArticleID = @ArticleID) And then there's the following query in ALL pages: User = DB.Users.SingleOrDefault(u => u.Password == password && u.Name == username); That's where I get User from cookies. Very often a deadlock occurs and this second Linq-to-SQL query is chosen as a victim, so it's not run, and users of my site see an error screen. I read a lot about deadlocks... And I don't understand why this is causing a deadlock. So obviously both of this queries run very often. At least once a second. Maybe even more often (300-400 users online). So they can be run at the same time very easily, but why does it cause a deadlock? Please help. Thank you

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• File size monitoring in C#

  - by manemawanna

  Hello, I work in the Systems & admin team and have been given the task of creating a quota management application to try and encourage users to better manage there resources as we currently have issues with disc space and don't enforce hard quotas. At the moment I'm using the code below to go through all the files in a users homespace to retrieve the overall amount of space they are using. As from what I've seen else where theres no other way to do this in C#, the issue with it is theirs quite a high overhead while it retireves the size of each file then creates a total. try { long dirSize = 0; FileInfo[] FI = new DirectoryInfo("I:\\").GetFiles("*.*", SearchOption.AllDirectories); foreach (FileInfo F1 in FI) { dirSize += F1.Length; } return dirSize; } So I'm looking for a quicker way to do this or a quick way to monitor changes in the size of files while using the options avaliable through FileSystemWatcher. At the moment the only thing I can think of is creating a hashtable containing the file location and size of each file, so when a size changed event occurs I can compare the old size against the new one and update the total. Any suggestions would be greatly appreciated.

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• System Calls in windows & Native API?

  - by claws

  Recently I've been using lot of Assembly language in *NIX operating systems. I was wondering about the windows domain. Calling convention in linux: mov $SYS_Call_NUM, %eax mov $param1 , %ebx mov $param2 , %ecx int $0x80 Thats it. That is how we should make a system call in linux. Reference of all system calls in linux: Regarding which $SYS_Call_NUM & which parameters we can use this reference : http://docs.cs.up.ac.za/programming/asm/derick_tut/syscalls.html OFFICIAL Reference : http://kernel.org/doc/man-pages/online/dir_section_2.html Calling convention in Windows: ??? Reference of all system calls in Windows: ??? Unofficial : http://www.metasploit.com/users/opcode/syscalls.html , but how do I use these in assembly unless I know the calling convention. OFFICIAL : ??? If you say, they didn't documented it. Then how is one going to write libc for windows without knowing system calls? How is one gonna do Windows Assembly programming? Atleast in the driver programming one needs to know these. right? Now, whats up with the so called Native API? Is Native API & System calls for windows both are different terms referring to same thing? In order to confirm I compared these from two UNOFFICIAL Sources System Calls: http://www.metasploit.com/users/opcode/syscalls.html Native API: http://undocumented.ntinternals.net/aindex.html My observations: All system calls are beginning with letters Nt where as Native API is consisting of lot of functions which are not beginning with letters Nt. System Call of windows are subset of Native API. System calls are just part of Native API. Can any one confirm this and explain.

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• My project is no longer used - how should I feel?

  - by flybywire

  For the last two years I have been developing and supporting an important project for a big customer. The project included mining data from the customer's existing systems, processing, and displaying and updating in the customer's public home page. The project was defined as crucial by the customer and I was payed good money and flown at the customer's expense to meet key employees. Some months ago, when the project was finished and in maintainance mode, I informed the customer that I am no longer interested in doing it as I had a new opportunity that would not be compatible with my existing customer. I was payed to train one of their employees, flown to meet him, make sure everything works and that he can be safely left in charge of the project. We finished in good terms after I complied with all my obligations and they payed me all they owed me. Some days ago, just out of curiosity, I entered to their website to see how the data continues to be updated and much to my dismay I discovered that the day after my contract was finished my system was "turned off" and it ceased to feed data to the public website. Let's put it clear, there is no issue of money or broken contract here. They are in they full right to do whatever they want with my software. But it is an issue of broken "programmer's ego". Should I feel bad about it (I do). Should I care and check out with my customer if they need some help? Or is it none of my matters?

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• Void* array casting to float, int32, int16, etc.

  - by Griffin

  Hey guys, I've got an array of PCM data, it could be 16 bit, 24 bit packed, 32 bit, etc.. It could be signed, or unsigned, and it could be 32 or 64 bit floating point. It is currently stored as a "void**" matrix, indexed by channel, then by frame. The goal is to allow my library to take in any PCM format and buffer it, without requiring manipulation of the data to fit a designated structure. If the A/D converter spits out 24 bit packed arrays of interleaved PCM, I need to accept it gracefully. I also need to support 16 bit non interleaved, as well as any permutation of the above formats. I know the bit depth and other information at runtime, and I'm trying to code efficiently while not duplicating code. What I need is an effective way to cast the matrix, put PCM data into the matrix, and then pull it out later. I can cast the matrix to int32_t, or int16_t for the 32 and 16 bit signed PCM respectively, I'll probably have to store the 24 bit PCM in an int32_t for 32 bit, 8 bit byte systems as well. Can anyone recommend a good way to put data into this array, and pull it out later? I'd like to avoid large sections of code which look like: switch( mFormat ) { case 1: // unsigned 8 bit for( int i = 0; i < mChannels; i++ ) framesArray = (uint8_t*)pcm[i]; break; case 2: // signed 8 bit for( int i = 0; i < mChannels; i++ ) framesArray = (int8_t*)pcm[i]; break; case 3: // unsigned 16 bit ... Limitations: I'm working in C/C++, no templates, no RTTI, no STL. Think embedded. Things get trickier when I have to port this to a DSP with 16 bit bytes. Does anybody have any useful macros they might be willing to share? Thanks, -Griff

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• sIFR 3 randomly placing text on a single line in FF3.6

  - by bigsweater

  Hello, sIFR 3 is behaving strangely in Firefox. The actual sIFR flash element is set within a box that is 412px wide. In IE, Chrome, Safari, etc., the with of the Flash element is a consistent 412px; however, in Firefox, the Flash element is briefly as wide as the Body element, before correcting itself. When the page finishes loading, sometimes the Flash element remains that wide, breaking the layout (the Flash text flows underneath the sidebar to the right). Setting a width in the CSS for the .sIFR-flash element causes it to remain the proper 412px wide, but the text doesn't wrap at all--it just cuts off at the right edge, and the height of the flash element remains one line high. The markup is simple; it's just an h2 within a div. My sIFR code: var clerkenwell = { src: '/flash/sifr.swf' }; sIFR.activate(clerkenwell); sIFR.replace(clerkenwell, { selector: '.post h2', css: '.sIFR-root { color: #1899c4; text-transform:uppercase; font-size:30px; }', transparent: 'true', }); Setting forceWidth: 'true', just causes the same problem as using a CSS width on the .sIFR-flash element. So: how can I get the sIFR text to remain as wide as its containing element while allowing for line breaks in Firefox? Thanks for any and all help!

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• Better language or checking tool?

  - by rwallace

  This is primarily aimed at programmers who use unmanaged languages like C and C++ in preference to managed languages, forgoing some forms of error checking to obtain benefits like the ability to work in extremely resource constrained systems or the last increment of performance, though I would also be interested in answers from those who use managed languages. Which of the following would be of most value? A language that would optionally compile to CLR byte code or to machine code via C, and would provide things like optional array bounds checking, more support for memory management in environments where you can't use garbage collection, and faster compile times than typical C++ projects. (Think e.g. Ada or Eiffel with Python syntax.) A tool that would take existing C code and perform static analysis to look for things like potential null pointer dereferences and array overflows. (Think e.g. an open source equivalent to Coverity.) Something else I haven't thought of. Or put another way, when you're using C family languages, is the top of your wish list more expressiveness, better error checking or something else? The reason I'm asking is that I have a design and prototype parser for #1, and an outline design for #2, and I'm wondering which would be the better use of resources to work on after my current project is up and running; but I think the answers may be useful for other tools programmers also. (As usual with questions of this nature, if the answer you would give is already there, please upvote it.)

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• SQL Server 2008 R2

  - by kevchadders

  Hi all, I heard on the grapevine that Microsoft will be releasing SQL Server 2008 R2 within a year. Though I initially thought this was a patch for the just released 2008 version, I realised that it’s actually a completely different version that you would have to pay for. (Am I correct, if you had SQL Server 2008, would you have to pay again if you wanted to upgrade to 2008 R2?) If you’re already running SQL Server 2008, would you say it’s still worth the upgrade? Or does it depend on the size of your company and current setup. For what I’ve initially read, I do get the impression that this version would be more useful for the very high end hardware setup where you want to have very good scalability. With regard to programming, is there any extra enhancements/support in there which you’re aware of that will significantly help .NET Products/Web Development? Initially found a couple of links on it, but I was wondering if anyone had anymore info to share on subject as I couldn’t find nothing on SO about it? Thanks. New SQL Server R2 Microsoft Link on it. Microsoft SQL 2008 R2 EDIT: More information based on the Express Edition One very interesting thing about SQL Server 2008 R2 concerns the Express edition. Previous express versions of SQL Server Express had a database size limit of 4GB. With SQL Server Express 2008 R2, this has now been increased to 10GB !! This now makes the FREE express edition a much more viable option for small & medium sized applications that are relatively light on database requirements. Bear in mind, that this limit is per database, so if you coded your application cleverly enough to use a separate database for historical/archived data, you could squeeze even more out of it! For more information, see here: http://blogs.msdn.com/sqlexpress/archive/2010/04/21/database-size-limit-increased-to-10gb-in-sql-server-2008-r2-express.aspx

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• firefox does not load large size images

  - by Pradeep

  I am stuck with a kind of bug in FF, wherein it’s unable to load images of big size (I have 8 MB size of image) from the server. The loading of image is all fine on IE. I am still looking out for ways to get rid of this problem. I changed server(IIS) settings to allow bigger file sizes. Also, I used “load” event on image using JQuery and tried all sort of options listed here http://api.jquery.com/load-event/, but nothing worked so far. If anyone of you has come across any such similar problem, and a way to resolve it, it would be nice to hear from you Please note: high resolution images are part of the requirement. Code : <style> img { background-color: #FFFFFF; background-image: url(http://eremurus.hyd:8080/QMS/plugin/imagepanner/loader.gif); background-repeat: no-repeat; background-position: center center; } </style> <script src="../plugin/jquery-ui-1.8.7.custom/js/jquery-1.4.4.min.js" type="text/javascript"></script> <script> jQuery(document).ready(function($){ ///var _url = "http://eremurus.hyd:8080/QMS/plugin/imagepanner/floorPlan.jpg"; // set up the node / element _im =$("#main"); //_im.bind("load",function(){ $(this).fadeIn(); }); // set the src attribute now, after insertion to the DOM //_im.attr('src',_url); $("#main").one("load",function(){ alert('loaded'); }) .each(function(){ if(this.complete){ $(this).trigger("load"); } }); }); </script> </head> <body> <div id="target"><img id='main' src="http://eremurus.hyd:8080/QMS/plugin/imagepanner/floorPlan.jpg"> </img></div> </body> </html>

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• Error while sending mail (attachment file)

  - by Surya sasidhar

  hi, in my application i am using to send mail with attachments i write the code like this Using System.Net.Mail; MailMessage mail = new MailMessage(); mail.Body = "<html><body><b> Name Of The Job Seeker: " + txtName.Text + "<br><br>" + "The Mail ID:" + txtEmail.Text + "<br><br>" + " The Mobile Number: " + txtmobile.Text + "<br><br>" + "Position For Applied: " + txtPostionAppl.Text + "<br><br>" + "Description " + txtdescript.Text + "<br><br></b></body></html>"; mail.From = new MailAddress ( txtEmail.Text); mail.To .Add (new MailAddress ( mailid)); mail.Priority = MailPriority.High; FileUpload1.PostedFile.SaveAs("~/Resume/" + FileUpload1.FileName); mail.Attachments.Add(filenme); SmtpMail sm = new SmtpMail(); sm.Send(mail); it is giving error at attachment like mail.Attachemts.Add(filena) like this 'System.Collections.ObjectModel.Collection.Add(System.Net.Mail.Attachment)' has some invalid arguments.

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• complex regular expression task

  - by Don Don

  Hi, What regular expressions do I need to extract section title(s) in a text file? So, in the following sample text, I'd like to extract "Communication and Leadership" "1.Self-Knowledge" "2. Humility" "(3) Clear Thinking". Many thanks. Communication and Leadership True leaders understand that, rather than forcing their followers into a preconceived mold, their job is to motivate and organize followers to collectively accomplish goals that are in everyone's interests. The ability to communicate this to co-workers and followers is critical to the effectiveness of leadership. 1.Self-Knowledge Superior leaders are able to devote their skills and energies to leadership of a group because they have worked through personal issues to the point where they know themselves thoroughly. A high level of self-knowledge is a prerequisite to effective communication skills, because the things that you communicate as a leader are coming from within. 2. Humility This subversion of personal preference requires a certain level of humility. Although popular definitions of leaders do not always see them as humble, the most effective leaders actually are. This humility may not be expressed in self-effacement, but in a total commitment to the goals of the organization. Humility requires an understanding of one's own relative unimportance in comparison to larger systems. (3) Clear Thinking Clarity of thinking translates into clarity of communication. A leader whose goals or personal analysis is muddled will tend to deliver unclear or ambiguous directions to followers, leading to confusion and dissatisfaction. A leader with a clear mind who is not ambivalent about her purposes will communicate what needs to be done in a s traightforward and unmistakable manner.

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• iPhone OpenGLES: Textures are consuming too much memory and the program crashes with signal "0"

  - by CustomAppsMan

  I am not sure what the problem is. My app is running fine on the simulator but when I try to run it on the iPhone it crashes during debugging or without debugging with signal "0". I am using the Texture2D.m and OpenGLES2DView.m from the examples provided by Apple. I profiled the app on the iPhone with Instruments using the Memory tracer from the Library and when the app died the final memory consumed was about 60Mb real and 90+Mb virtual. Is there some other problem or is the iPhone just killing the application because it has consumed too much memory? If you need any information please state it and I will try to provide it. I am creating thousands of textures at load time which is why the memory consumption is so high. Really cant do anything about reducing the number of pics being loaded. I was running before on just UIImage but it was giving me really low frame rates. I read on this site that I should use OpenGLES for higher frame rates. Also sub question is there any way not to use UIImage to load the png file and then use the Texture class provided to create the texture for OpenGLES functions to use it for drawing? Is there some function in OpenGLES which will create a texture straight from a png file?

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• Can the Visual Studio (2010) Command Window handle "external tools" with project/solution relative p

  - by ee

  I have been playing with the Command Window in Visual Studio (View-Other Windows-Command Window). It is great for several mouse-free scenarios. (The autocompleting file "Open" command rocks in a non-trivial solution.) That success got me thinking and experimenting: Possibility 1.1: You can use the Alias commands to create custom commands Possibility 1.2: You can use the Shell command to run arbitrary executables and specify parameters (and pipe the result to the output or command windows) Possibility 2: A previously setup external tool definition (with project-relative path variables) could be run from the command window What I am stuck on is: There doesn't appear to be a way to send parameters to an aliased command (and thus the underlying Shell call) There doesn't appear to be a way to use project/solution relative paths ($SolutionDir/$ProjectDir) on a Shell call Using absolute paths in Shell works, but is fragile and high-maintenance (one alias for each needed use case). Typically you want the command to run against a file relative to your project/solution. It seems you can't run the traditional external tools (Tools-External Tools...) in the command window Ultimately I want the external tool functionality in the command window in some way. Can anyone see a way to do this? Or am I barking up the wrong tree? So my questions: Can an "external tool" of some sort (using relative project/solution path parameters) be used in the Command Window? If yes, How? If no, what might be a suitable alternative?

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• What can cause a spontaneous EPIPE error without either end calling close() or crashing?

  - by Hongli

  I have an application that consists of two processes (let's call them A and B), connected to each other through Unix domain sockets. Most of the time it works fine, but some users report the following behavior: A sends a request to B. This works. A now starts reading the reply from B. B sends a reply to A. The corresponding write() call returns an EPIPE error, and as a result B close() the socket. However, A did not close() the socket, nor did it crash. A's read() call returns 0, indicating end-of-file. A thinks that B prematurely closed the connection. Users have also reported variations of this behavior, e.g.: A sends a request to B. This works partially, but before the entire request is sent A's write() call returns EPIPE, and as a result A close() the socket. However B did not close() the socket, nor did it crash. B reads a partial request and then suddenly gets an EOF. The problem is I cannot reproduce this behavior locally at all. I've tried OS X and Linux. The users are on a variety of systems, mostly OS X and Linux. Things that I've already tried and considered: Double close() bugs (close() is called twice on the same file descriptor): probably not as that would result in EBADF errors, but I haven't seen them. Increasing the maximum file descriptor limit. One user reported that this worked for him, the rest reported that it did not. What else can possibly cause behavior like this? I know for certain that neither A nor B close() the socket prematurely, and I know for certain that neither of them have crashed because both A and B were able to report the error. It is as if the kernel suddenly decided to pull the plug from the socket for some reason.

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• Quickly accessing files in a 'project'

  - by bbbscarter

  Hi all. I'm looking for a way to quickly open files in my project's source tree. What I've been doing so far is adding files to the file-name-cache like so: (file-cache-add-directory-recursively (concat project-root "some/sub/folder") ".*\\.\\(py\\)$") after which I can use anything-for-files to access any file in the source tree with about 4 keystrokes. Unfortunately, this solution started falling over today. I've added another folder to the cache and emacs has started running out of memory. What's weird is that this folder contains less than 25% of files I'm adding, and yet emacs memory use goes up from 20mb to 400mb on adding just this folder. The total number of files is around 2000, so this memory use seems very high. Presumably I'm abusing the file cache. Anyway, what do other people do for this? I like this solution for its simplicity and speed; I've looked at some of the many, many project management packages for emacs and none of them really grabbed me... Thanks in advance! Simon

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• C++ RPC library suggestions

  - by Oxsnarder

  I'm looking for suggestions regarding RPC libraries implemented in C++, for C++ developers. Some requirements constraints: Should work on both linux/unix and win32 systems Be able to execute free function and class methods Hopefully written in modern C++ not 90's/java-esque C++ Be able to function over networks and hetrogenous architectures Not too slow or inefficient Hopefully provide interfaces for TR1 style std::function's et al. My example usage is to invoke the free function foo on a remote machine. ---snip--- // foo translation unit int foo(int i, int j) { return i + j; } ---snip--- ---snip--- // client side main int main() { //register foo on client and server //setup necassary connections and states int result; if (RPCmechanism.invoke("foo",4,9,result)) std::cout << "foo(4,9) = " result << std::endl; else std::cout << "failed to invoke foo(4,9)!" << std::endl; return 0; } ---snip--- Something that can achieve the above or similar would be great.

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• A generic C++ library that provides QtConcurrent functionality?

  - by Lucas

  QtConcurrent is awesome. I'll let the Qt docs speak for themselves: QtConcurrent includes functional programming style APIs for parallel list processing, including a MapReduce and FilterReduce implementation for shared-memory (non-distributed) systems, and classes for managing asynchronous computations in GUI applications. For instance, you give QtConcurrent::map() an iterable sequence and a function that accepts items of the type stored in the sequence, and that function is applied to all the items in the collection. This is done in a multi-threaded manner, with a thread pool equal to the number of logical CPU's on the system. There are plenty of other function in QtConcurrent, like filter(), filteredReduced() etc. The standard CompSci map/reduce functions and the like. I'm totally in love with this, but I'm starting work on an OSS project that will not be using the Qt framework. It's a library, and I don't want to force others to depend on such a large framework like Qt. I'm trying to keep external dependencies to a minimum (it's the decent thing to do). I'm looking for a generic C++ framework that provides me with the same/similar high-level primitives that QtConcurrent does. AFAIK boost has nothing like this (I may be wrong though). boost::thread is very low-level compared to what I'm looking for. I know C# has something very similar with their Parallel Extensions so I know this isn't a Qt-only idea. What do you suggest I use?

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• Timestamps and Intervals: NUMTOYMINTERVAL SYSTDATE CALCULATION SQL QUERY

  - by MeachamRob

  I am working on a homework problem, I'm close but need some help with a data conversion I think. Or sysdate - start_date calculation The question is: Using the EX schema, write a SELECT statement that retrieves the date_id and start_date from the Date_Sample table (format below), followed by a column named Years_and_Months_Since_Start that uses an interval function to retrieve the number of years and months that have elapsed between the start_date and the sysdate. (Your values will vary based on the date you do this lab.) Display only the records with start dates having the month and day equal to Feb 28 (of any year). DATE_ID START_DATE YEARS_AND_MONTHS_SINCE_START 2 Sunday , February 28, 1999 13-8 4 Monday , February 28, 2005 7-8 5 Tuesday , February 28, 2006 6-8 Our EX schema that refers to this question is simply a Date_Sample Table with two columns: DATE_ID NUMBER NOT Null START_DATE DATE I Have written this code: SELECT date_id, TO_CHAR(start_date, 'Day, MONTH DD, YYYY') AS start_date , NUMTOYMINTERVAL((SYSDATE - start_date), 'YEAR') AS years_and_months_since_start FROM date_sample WHERE TO_CHAR(start_date, 'MM/DD') = '02/28'; But my Years and months since start column is not working properly. It's getting very high numbers for years and months when the date calculated is from 1999-ish. ie, it should be 13-8 and I'm getting 5027-2 so I know it's not correct. I used NUMTOYMINTERVAL, which should be correct, but don't think the sysdate-start_date is working. Data Type for start_date is simply date. I tried ROUND but maybe need some help to get it right. Something is wrong with my calculation and trying to figure out how to get the correct interval there. Not sure if I have provided enough information to everyone but I will let you know if I figure it out before you do. It's a question from Murach's Oracle and SQL/PL book, chapter 17 if anyone else is trying to learn that chapter. Page 559.

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• Suggestion on Database structure for relational data

  - by miccet

  Hi there. I've been wrestling with this problem for quite a while now and the automatic mails with 'Slow Query' warnings are still popping in. Basically, I have Blogs with a corresponding table as well as a table that keeps track of how many times each Blog has been viewed. This last table has a huge amount of records since this page is relatively high traffic and it logs every hit as an individual row. I have tried with indexes on the fields that are included in the WHERE clause, but it doesn't seem to help. I have also tried to clean the table each week by removing old ( 1.weeks) records. SO, I'm asking you guys, how would you solve this? The query that I know is causing the slowness is generated by Rails and looks like this: SELECT count(*) AS count_all FROM blog_views WHERE (created_at >= '2010-01-01 00:00:01' AND blog_id = 1); The tables have the following structures: CREATE TABLE IF NOT EXISTS 'blogs' ( 'id' int(11) NOT NULL auto_increment, 'name' varchar(255) default NULL, 'perma_name' varchar(255) default NULL, 'author_id' int(11) default NULL, 'created_at' datetime default NULL, 'updated_at' datetime default NULL, 'blog_picture_id' int(11) default NULL, 'blog_picture2_id' int(11) default NULL, 'page_id' int(11) default NULL, 'blog_picture3_id' int(11) default NULL, 'active' tinyint(1) default '1', PRIMARY KEY ('id'), KEY 'index_blogs_on_author_id' ('author_id') ) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=1 ; And CREATE TABLE IF NOT EXISTS 'blog_views' ( 'id' int(11) NOT NULL auto_increment, 'blog_id' int(11) default NULL, 'ip' varchar(255) default NULL, 'created_at' datetime default NULL, 'updated_at' datetime default NULL, PRIMARY KEY ('id'), KEY 'index_blog_views_on_blog_id' ('blog_id'), KEY 'created_at' ('created_at') ) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=1 ;

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• data ownership and performance

  - by Ami

  We're designing a new application and we ran into some architectural question when thinking about data ownership. we broke down the system into components, for example Customer and Order. each of this component/module is responsible for a specific business domain, i.e. Customer deals with CRUD of customers and business process centered around customers (Register a n new customer, block customer account, etc.). each module is the owner of a set of database tables, and only that module may access them. if another module needs data that is owned by another module, it retrieves it by requesting it from that module. so far so good, the question is how to deal with scenarios such as a report that needs to show all the customers and for each customer all his orders? in such a case we need to get all the customers from the Customer module, iterate over them and for each one get all the data from the Order module. performance won't be good...obviously it would be much better to have a stored proc join customers table and orders table, but that would also mean direct access to the data that is owned by another module, creating coupling and dependencies that we wish to avoid. this is a simplified example, we're dealing with an enterprise application with a lot of business entities and relationships, and my goal is to keep it clean and as loosely coupled as possible. I foresee in the future many changes to the data scheme, and possibly splitting the system into several completely separate systems. I wish to have a design that would allow this to be done in a relatively easy way. Thanks!

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• How can I make "month" columns in Sql?

  - by Beska

  I've got a set of data that looks something like this (VERY simplified): productId Qty dateOrdered --------- --- ----------- 1 2 10/10/2008 1 1 11/10/2008 1 2 10/10/2009 2 3 10/12/2009 1 1 10/15/2009 2 2 11/15/2009 Out of this, we're trying to create a query to get something like: productId Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec --------- ---- --- --- --- --- --- --- --- --- --- --- --- --- 1 2008 0 0 0 0 0 0 0 0 0 2 1 0 1 2009 0 0 0 0 0 0 0 0 0 3 0 0 2 2009 0 0 0 0 0 0 0 0 0 3 2 0 The way I'm doing this now, I'm doing 12 selects, one for each month, and putting those in temp tables. I then do a giant join. Everything works, but this guy is dog slow. I know this isn't much to go on, but knowing that I barely qualify as a tyro in the db world, I'm wondering if there is a better high level approach to this that I might try. (I'm guessing there is.) (I'm using MS Sql Server, so answers that are specific to that DB are fine.) (I'm just starting to look at "PIVOT" as a possible help, but I don't know anything about it yet, so if someone wants to comment about that, that might be helpful as well.)

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• How can multiple variables be passed to a function cleanly in C?

  - by aquanar

  I am working on an embedded system that has different output capabilities (digital out, serial, analog, etc). I am trying to figure out a clean way to pass many of the variables that will control those functions. I don't need to pass ALL of them too often, but I was hoping to have a function that would read the input data (in this case from a TCP network), and then parse the data (IE, the 3rd byte contains the states of 8 of the digital outputs (according to which bit in that byte is high or low)), and put that into a variable where I can then use elsewhere in the program. I wanted that function to be separate from the main() function, but to do so would require passing pointers to some 20 or so variables that it would be writing to. I know I could make the variables global, but I am trying to make it easier to debug by making it obvious when a function is allowed to edit that variable, by passing it to the function. My best idea was a struct, and just pass a pointer to it, but wasn't sure if there was a more efficient way, especially since there is only really 1 function that would need to access all of them at once, while most others only require parts of the information that will be stored in this bunch of state variables. So anyway, is there a clean way to send many variables between functions at once that need to be edited?

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• Parsing localized date strings in PHP

  - by Mikeage

  Hi, I have some code (it's part of a wordpress plugin) which takes a text string, and the format specifier given to date(), and attempts to parse it into an array containing hour, minute, second, day, month, year. Currently, I use the following code (note that strtotime is horribly unreliable with things like 01/02/03) // $format contains the string originally given to date(), and $content is the rendered string if (function_exists('date_parse_from_format')) { $content_parsed = date_parse_from_format($format, $content); } else { $content = preg_replace("([0-9]st|nd|rd|th)","\\1",$content); $content_parsed = strptime($content, dateFormatToStrftime($format)); $content_parsed['hour']=$content_parsed['tm_hour']; $content_parsed['minute']=$content_parsed['tm_min']; $content_parsed['day']=$content_parsed['tm_mday']; $content_parsed['month']=$content_parsed['tm_mon'] + 1; $content_parsed['year']=$content_parsed['tm_year'] + 1900; } This actually works fairly well, and seems to handle every combination I've thrown at it. However, recently someone gave me 24 ??????, 2010. This is Russian for November 24, 2010 [the date format was j F, Y], and it is parsed as year = 2010, month = null, day = 24. Are there any functions that I can use that know how to translate both November and ?????? into 11? EDIT: Running print_r(setlocale(LC_ALL, 0)); returns C. Switching back to strptime() seems to fix the problem, but the docs warn: Internally, this function calls the strptime() function provided by the system's C library. This function can exhibit noticeably different behaviour across different operating systems. The use of date_parse_from_format(), which does not suffer from these issues, is recommended on PHP 5.3.0 and later. Is date_parse_from_format() the correct API, and if so, how do I get it to recognize the language?

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