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• Are Fortran control characters (carriage control) still implemented in compilers?

  - by CmdrGuard

  In the book Fortran 95/2003 for Scientists and Engineers, there is much talk given to the importance of recognizing that the first column in a format statement is reserved for control characters. I've also seen control characters referred to as carriage control on the internet. To avoid confusion, by control characters, I refer to the characters "1, a blank (i.e. \s), 0, and +" as having an effect on the vertical spacing of output when placed in the first column (character) of a FORMAT statement. Also, see this text-only web page written entirely in fixed-width typeface : Fortran carriage-control (because nothing screams accuracy and antiquity better than prose in monospaced font). I found this page and others like it to be not quite clear. According to Fortran 95/2003 for Scientists and Engineers, failure to recall that the first column is reserved for carriage control can lead to horrible unintended output. Paraphrasing Dave Barry, type the wrong character, and nuclear missiles get fired at Norway. However, when I attempt to adhere to this stern warning, I find that gfortran has no idea what I'm talking about. Allow me to illustrate my point with some example code. I am trying to print out the number Pi: PROGRAM test_format IMPLICIT NONE REAL :: PI = 2 * ACOS(0.0) WRITE (*, 100) PI WRITE (*, 200) PI WRITE (*, 300) PI 100 FORMAT ('1', "New page: ", F11.9) 200 FORMAT (' ', "Single Space: ", F11.9) 300 FORMAT ('0', "Double Space: ", F11.9) END PROGRAM test_format This is the output: 1New page: 3.141592741 Single Space: 3.141592741 0Double Space: 3.141592741 The "1" and "0" are not typos. It appears that gfortran is completely ignoring the control character column. My question, then, is this: Are control characters still implemented in standards compliant compilers or is gfortran simply not standards compliant? For clarity, here is the output of my gfortran -v Using built-in specs. Target: powerpc-apple-darwin9 Configured with: ../gcc-4.4.0/configure --prefix=/sw --prefix=/sw/lib/gcc4.4 --mandir=/sw/share/man --infodir=/sw/share/info --enable-languages=c,c++,fortran,objc,java --with-gmp=/sw --with-libiconv-prefix=/sw --with-ppl=/sw --with-cloog=/sw --with-system-zlib --x-includes=/usr/X11R6/include --x-libraries=/usr/X11R6/lib --disable-libjava-multilib --build=powerpc-apple-darwin9 --host=powerpc-apple-darwin9 --target=powerpc-apple-darwin9 Thread model: posix gcc version 4.4.0 (GCC)

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• Capistrano fails for multiple host deployments

  - by morris082

  I be at a loss here, and after scouring the seas (read: internet) for solutions I am left with none other than to hit up the stack. any help appreciated. I have capistrano running locally for deployments onto several different environments. (I'm on windows 7, fwiw). All was well until I needed to deploy to multiple :app servers during a single deployment. Usually I'm prompted for my ssh passphrase once when I call 'cap deploy'. I have ssh-agent running (git never pesters for my pass) but despite this Capistrano has always bugged me once each deployment. Regardless, it always worked when deploying to ONE host. Now, when I attempt to deploy to multiple servers at once, it asks for my passphrase what appears to be multiple times: (ips removed by ME) servers: ["redacted", "redacted"]<br /> Enter passphrase for ~/.ssh/id_rsa: Enter passphrase for ~/.ssh/id_rsa: So with the above I enter my passphrase but this doesn't work. It waits as little while, then spits out this error: connection failed for: <one of the server ips> (NoMethodError: undefined method `overwrite' for nil:NilClass) And that's the end of that. I can "passwordless" ssh into the servers I'm deploying on just fine. I'm pretty certain the ssh-agent is running since I can hit Git w/out entering my passphrase every time Using 'forward_agent' setting in cap deploy did not work. This is my role: role :app, "ip 1 removed", "ip 2 removed" If i set default_run_options[:max_hosts] = 1, it works OK but it asks for my passphrase for every single connection to each host I'm deploying to.. which ends up being a lot. Essentially I'm looking for any of the below (but not limited to): - "You're never going to fix that on windows" - "This is how you get REAL passwordless deployment in capistrano" - "Have you overlooked this setting/feature?" - "I have a rock that can fix anything, you may borrow it" Thanks!

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• Use of Syntactic Sugar / Built in Functionality

  - by Kyle Rozendo

  I was busy looking deeper into things like multi-threading and deadlocking etc. The book is aimed at both pseudo-code and C code and I was busy looking at implementations for things such as Mutex locks and Monitors. This brought to mind the following; in C# and in fact .NET we have a lot of syntactic sugar for doing things. For instance (.NET 3.5): lock(obj) { body } Is identical to: var temp = obj; Monitor.Enter(temp); try { body } finally { Monitor.Exit(temp); } There are other examples of course, such as the using() {} construct etc. My question is when is it more applicable to "go it alone" and literally code things oneself than to use the "syntactic sugar" in the language? Should one ever use their own ways rather than those of people who are more experienced in the language you're coding in? I recall having to not use a Process object in a using block to help with some multi-threaded issues and infinite looping before. I still feel dirty for not having the using construct in there. Thanks, Kyle

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• What is difference between my atoi() calls?

  - by Lucas

  I have a big number stored in a string and try to extract a single digit. But what are the differences between those calls? #include <iostream> #include <string> int main(){ std::string bigNumber = "93485720394857230"; char tmp = bigNumber.at(5); int digit = atoi(&tmp); int digit2 = atoi(&bigNumber.at(5)) int digit3 = atoi(&bigNumber.at(12)); std::cout << "digit: " << digit << std::endl; std::cout << "digit2: " << digit2 << std::endl; std::cout << "digit3: " << digit3 << std::endl; } This will produce the following output. digit: 7 digit2: 2147483647 digit3: 57230 The first one is the desired result. The second one seems to me to be a random number, which I cannot find in the string. The third one is the end of the string, but not just a single digit as I expected, but up from the 12th index to the end of the string. Can somebody explain the different outputs to me? EDIT: Would this be an acceptable solution? char tmp[2] = {bigNumber.at(5), '\0'}; int digit = atoi(tmp); std::cout << "digit: " << digit << std::endl;

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• Pros/cons of reading connection string from physical file vs Application object (ASP.NET)?

  - by HaterTot

  my ASP.NET application reads an xml file to determine which environment it's currently in (e.g. local, development, production). It checks this file every single time it opens a connection to the database, in order to know which connection string to grab from the Application Settings. I'm entering a phase of development where efficiency is becoming a concern. I don't think it's a good idea to have to read a file on a physical disk ever single time I wish to access the database (very often). I was considering storing the connection string in Application["ConnectionString"]. So the code would be public static string GetConnectionString { if (Application["ConnectionString"] == null) { XmlDocument doc = new XmlDocument(); doc.Load(HttpContext.Current.Request.PhysicalApplicationPath + "bin/ServerEnvironment.xml"); XmlElement xe = (XmlElement) xnl[0]; switch (xe.InnerText.ToString().ToLower()) { case "local": connString = Settings.Default.ConnectionStringLocal; break; case "development": connString = Settings.Default.ConnectionStringDevelopment; break; case "production": connString = Settings.Default.ConnectionStringProduction; break; default: throw new Exception("no connection string defined"); } Application["ConnectionString"] = connString; } return Application["ConnectionString"].ToString(); } I didn't design the application so I figure there must have been a reason for reading the xml file every time (to change settings while the application runs?) I have very little concept of the inner workings here. What are the pros and cons? Do you think I'd see a small performance gain by implementing the function above? THANKS

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• Would this method work to scale out SQL queries?

  - by David

  I have a database containing a single huge table. At the moment a query can take anything from 10 to 20 minutes and I need that to go down to 10 seconds. I have spent months trying different products like GridSQL. GridSQL works fine, but is using its own parser which does not have all the needed features. I have also optimized my database in various ways without getting the speedup I need. I have a theory on how one could scale out queries, meaning that I utilize several nodes to run a single query in parallel. The idea is to take an incoming SQL query and simply run it exactly like it is on all the nodes. When the results are returned to a coordinator node, the same query is run on the union of the resultsets. I realize that an aggregate function like average need to be rewritten into a count and sum to the nodes and that the coordinator divides the sum of the sums with the sum of the counts to get the average. What kinds of problems could not easily be solved using this model. I believe one issue would be the count distinct function. Edit: I am getting so many nice suggestions, but none have addressed the method.

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• Web page database query optimization

  - by morpheous

  I am putting together a web page which is quite 'expensive' in terms of database hits. I don't want to start optimizing at this stage - though with me trying to hit a deadline, I may end up not optimizing at all. Currently the page requires 18 (that's right eighteen) hits to the db. I am already using joins, and some of the queries are UNIONed to minimize the trips to the db. My local dev machine can handle this (page is not slow) however, I feel if I release this into the wild, the number of queries will quickly overwhelm my database (MySQL). I could always use memcache or something similar, but I would much rather continue with my other dev work that needs to be completed before the deadline - at least retrieving the page works - its simply a matter of optimization now (if required). My question therefore is - is 18 db queries for a single page retrieval completely outrageous - (i.e. I should put everything on hold and optimize the hell of the retrieval logic), or shall I continue as normal, meet the deadline and release on schedule and see what happens? [Edit] Just to clarify, I have already done the 'obvious' things like using (single and composite) indexes for fields used in the queries. What I haven't yet done is to run a query analyzer to see if my indexes etc are optimal.

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• hint and textview with right gravity and a singleline

  - by codeScriber

  I've opened a bug but i was wondering if anyone encountered this issue and knows a workaround. If you define a text view with a hint inside it, give it right gravity (android:gravity="right") then if you define android:singleLine=true or android:maxLines="1" or android:scrollHorizonatally="true" you don't see the hint. removing the right gravity returns the hint to the left side, removing all the tree params i mentioned above puts the hint on the right side. i want my hint on the right, but i need a single horizontal line... here's the sample layout that doesn't show the hint: <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="wrap_content" android:padding="5dp"> <EditText android:layout_width="fill_parent" android:layout_gravity="center_vertical|right" android:layout_height="wrap_content" android:layout_margin="6dp" android:textSize="16sp" android:paddingRight="5dp" android:id="@+id/c" android:gravity="right" android:hint="hello!!!" android:scrollHorizontally="true" android:maxLines="1" android:singleLine="true"/> </LinearLayout> i checked on 1.6 and 2.1 emulators and it reproduces 100%, i'm prettysure it's a bug, i don't see the connection between single line and the hint.... what's more the hint got it's own layout in the TextView (mLayout and mHintLayout both exists, in onDraw if the text length is 0 mHintLayout if mHint is not null is used).

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• Why is my PHP string being converted to 1?

  - by animuson

  Ok, so here's the quick rundown. I have a function to generate the page numbers. This: <?php die($ani->e->tmpl->pages("/archive", 1, 15, 1, true)); ?> will output Single Page like expected. But this: <?php $page_numbers = $ani->e->tmpl->pages("/archive", 1, 15, 1, true); ?> <?= $page_numbers ?> will output a simple 1 to the page. Why is it getting converted to a 1? I would expect it to store the 'Single Page' string to the page_numbers variable and then output it (like an echo) exactly the same. EDIT: Running a var_dump($page_numbers) returns int(1)... Here is the entire function in context: <?php // other functions... function show_list() { global $ani; $page_numbers = $ani->e->tmpl->pages("/archive", 1, 15, 1, true); ob_start(); ?> <!-- content:start --> <?php $archive_result = $ani->e->db->build(array("select" => "*", "from" => "animuson_archive", "orderby" => "0-time", "limit" => 15)); while ($archive = $ani->e->db->fetch($archive_result)) { ?> <h2><a href="/archive/article/<?= $archive['aid'] ?>/<?= $archive['title_nice'] ?>"><?= $archive['title'] ?></a></h2> <!-- breaker --> <?php } ?> <?= var_dump($page_numbers) ?> <!-- content:stop --> <?php $ani->e->tmpl->process("box", ob_get_clean()); } // other functions... ?>

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• Choose a XML node in SQL Server based on max value of a child element

  - by Jay

  I am trying to select from SQL Server 2005 XML datatype some values based on the max data that is located in a child node. I have multiple rows with XML similar to the following stored in a field in SQL Server: <user> <name>Joe</name> <token> <id>ABC123</id> <endDate>2013-06-16 18:48:50.111</endDate> </token> <token> <id>XYX456</id> <endDate>2014-01-01 18:48:50.111</endDate> </token> </user> I want to perform a select from this XML column where it determines the max date within the token element and would return the datarows similar to the result below for each record: Joe XYZ456 2014-01-01 18:48:50.111 I have tried to find a max function for xpath that would all me to select the correct token element but I couldn't find one that would work. I also tried to use the SQL MAX function but I wasn't able to get it working with that method either. If I only have a single token it of course works fine but when I have more than one I get a NULL, most likely because the query doesn't know which date to pull. I was hoping there would be a way to specify a where clause [max(endDate)] on the token element but haven't found a way to do that. Here is an example of the one that works when I only have a single token: SELECT XMLCOL.query('user/name').value('.','NVARCHAR(20)') as name XMLCOL.query('user/token/id').value('.','NVARCHAR(20)') as id XMLCOL.query('user/token/endDate').value(,'xs:datetime(.)','DATETIME') as endDate FROM MYTABLE

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• What does the Excel VBA range.Rows property really do?

  - by RBarryYoung

  OK, I am finishing up an add-on project for a legacy Excel-VBA application, and I have once again run up against the conundrum of the mysterious range.Rows(?) and worksheet.Rows properties. Does anyone know what these properties really do and what they are supposed to provide to me? (note: all of this probably applies to the corresponding *.Columns properties also). What I would really like to be able to use it for is to return a range of rows, like this: SET rng = wks.Rows(iStartRow, iEndRow) But I have never been able to get it to do that, even though the Intellisense shows two arguments for it. Instead I have to use one of the two or three other (very kludgy) techniques. The help is very unhelpful (typically so for Office VBA), and googling for "Rows" is not very useful, no matter how many other terms I add to it. The only things that I have been able to use it for are 1) return a single row as a range ( rng.Rows(i) ) and 2) return a count of the rows in a range ( rng.Rows.Count ). Is that it? Is there really nothing else that it's good for? Clarification: I know that it returns a range and that there are other ways to get a range of rows. What I am asking for is specifically what do we get from .Rows() that we do not already get from .Cells() and .Range()? The two things that I know are 1) an easier way to return a range of a single row and 2) a way to count the number of rows in a range. Is there anything else?

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• Is there a standard for storing normalized phone numbers in a database?

  - by Eric Z Beard

  What is a good data structure for storing phone numbers in database fields? I'm looking for something that is flexible enough to handle international numbers, and also something that allows the various parts of the number to be queried efficiently. [Edit] Just to clarify the use case here: I currently store numbers in a single varchar field, and I leave them just as the customer entered them. Then, when the number is needed by code, I normalize it. The problem is that if I want to query a few million rows to find matching phone numbers, it involves a function, like where dbo.f_normalizenum(num1) = dbo.f_normalizenum(num2) which is terribly inefficient. Also queries that are looking for things like the area code become extremely tricky when it's just a single varchar field. [Edit] People have made lots of good suggestions here, thanks! As an update, here is what I'm doing now: I still store numbers exactly as they were entered, in a varchar field, but instead of normalizing things at query time, I have a trigger that does all that work as records are inserted or updated. So I have ints or bigints for any parts that I need to query, and those fields are indexed to make queries run faster.

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• Mix Audio tracks with offset in SOX

  - by Laramie

  From ASP.Net, I am using FFMPEG to convert flv files on a Flash Media Server to wavs that I need to mix into a single MP3 file. I originally attempted this entirely with FFMPEG but eventually gave up on the mixing step because I don't believe it it possible to combine audio only tracks into a single result file. I would love to be wrong. I am now using FFMPEG to access the FLV files and extract the audio track to wav so that SOX can mix them. The problem is that I must offset one of the audio tracks by a few seconds so that they are synchronized. Each file is one half of a conversation between a student and a teacher. For example teacher.wav might need to begin 3.3 seconds after student.wav. I can only figure out how to mix the files with SOX where both tracks begin at the same time. My best attempt at this point is: ffmpeg -y -i rtmp://server/appName/instance/student.flv -ac 1 student.wav ffmpeg -y -i rtmp://server/appName/instance/teacher.flv -ac 1 teacher.wav sox -m student.wav teacher.wav combined.mp3 splice 3.3 These tools (FFMEG/SoX) were chosen based on my best research, but are not required. Any working solution would allow an ASP.Net service to input the two FMS flvs and create a combined MP3 using open-source or free tools.

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• How to hold payment in paygate for a while?

  - by Fero

  HI all, I have a query regarding holding the payment in PAYGATE PAYMENT GATEWAY. Here is the problem in brief. I am doing a website where the payment should be made only a certain members buy the product. For Example if there is an iPhone in my site, then that particular phone must be buy by certain quantities which given by admin. It may be done one by one user or a single user can buy all the quantities at a single time. In this case as a developer how can i able to hold the payment which received by user? Because i don't want to receive the payments until the certain quantities bought. Because if certain quantities were not buy i need to refund the money to their account. We don't like to do this process. That's why we are looking for holding the payment. Is it possible or what is the best way to solve this problem? Please let me know what is you professional opinion? thanks in advance... Please let me know what is you professional opinion?

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• Simple description of worker and I/O threads in .NET

  - by Konstantin

  It's very hard to find detailed but simple description of worker and I/O threads in .NET What's clear to me regarding this topic (but may not be technically precise): Worker threads are threads that should employ CPU for their work; I/O threads (also called "completion port threads") should employ device drivers for their work and essentially "do nothing", only monitor the completion of non-CPU operations. What is not clear: Although method ThreadPool.GetAvailableThreads returns number of available threads of both types, it seems there is no public API to schedule work for I/O thread. You can only manually create worker thread in .NET? It seems that single I/O thread can monitor multiple I/O operations. Is it true? If so, why ThreadPool has so many available I/O threads by default? In some texts I read that callback, triggered after I/O operation completion is performed by I/O thread. Is it true? Isn’t this a job for worker thread, considering that this callback is CPU operation? To be more specific – do ASP.NET asynchronous pages user I/O threads? What exactly is performance benefit in switching I/O work to separate thread instead of increasing maximum number of worker threads? Is it because single I/O thread does monitor multiple operations? Or Windows does more efficient context switching when using I/O threads?

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• WM_NOTIFY and superclass chaining issue in Win32

  - by DasMonkeyman

  For reference I'm using the window superclass method outlined in this article. The specific issue occurs if I want to handle WM_NOTIFY messages (i.e. for custom drawing) from the base control in the superclass I either need to reflect them back from the parent window or set my own window as the parent (passed inside CREATESTRUCT for WM_(NC)CREATE to the base class). This method works fine if I have a single superclass. If I superclass my superclass then I run into a problem. Now 3 WindowProcs are operating in the same HWND, and when I reflect WM_NOTIFY messages (or have them sent to myself from the parent trick above) they always go to the outermost (most derived) WindowProc. I have no way to tell if they're messages intended for the inner superclass (base messages are supposed to go to the first superclass) or messages intended for the outer superclass (messages from the inner superclass are intended for the outer superclass). These messages are indistinguishable because they all come from the same HWND with the same control ID. Is there any way to resolve this without creating a new window to encapsulate each level of inheritance? Sorry about the wall of text. It's a difficult concept to explain. Here's a diagram. single superclass: SuperA::WindowProc() - Base::WindowProc()---\ ^--------WM_NOTIFY(Base)--------/ superclass of a superclass: SuperB::WindowProc() - SuperA::WindowProc() - Base::WindowProc()---\ ^--------WM_NOTIFY(Base)--------+-----------------------/ ^--------WM_NOTIFY(A)-----------/ The WM_NOTIFY messages in the second case all come from the same HWND and control ID, so I cannot distinguish between the messages intended for SuperA (from Base) and messages intended for SuperB (from SuperA). Any ideas?

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• Modelling deterministic and nondeterministic data separately

  - by Superstringcheese

  I'm working with the Microsoft ADO.NET Entity Framework for a game project. Following the advice of other posters on SO, I'm considering modelling deterministic and nondeterministic data separately. The idea for this came from a discussion on multiplayer games, but it seemed to make sense in a single-player scenario as well. Deterministic (things that aren't going to change during gameplay) Attributes (Strength, Agility, etc.) and their descriptions Skills and their descriptions and requirements Races, Factions, Equipment, etc. Base Attribute/Skill/Equipment loadouts for monsters Nondeterministic (things that will change a lot during gameplay) Beings' current AttributeModifers (Potion of Might = +10 Strength), current health and mana, etc. Player inventory, cash, experience, level Player quests states Player FactionRelationships ...and so on. My deterministic model would serve as a set of constants. My nondeterministic model would provide my on-the-fly operable data and would be serialized to a savegame file to maintain game state between play sessions. The data store will be an embedded SQL Compact database. So I might want to create relations between my Attributes table (deterministic model) and my BeingAttributeModifiers table (nondeterministic model), but how do I set that up across models? Det model/db Nondet model/db ____________ ________________________ |Attributes | |PlayerAttributeModifiers| |------------| |------------------------| |Id | |Id | |Name | |AttributeId | |Description | |SourceId | ------------ |Value | ------------------------ Should I use two separate models (edmx) that transact with a single database containing both deterministic-type and nondeterministic-type tables? Or should/can I use two separate databases in one model? Or two models each with their own database? With distinct models/dbs it seems like this will get really complicated and I'll end up fighting EF a lot, rolling my own transaction code, and generally losing out on a lot of the advantages of the framework. I know these are vague questions, I'm just looking for a sanity check before I forge ahead any further.

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• What information should a SVN/Versioned file commit comment contain?

  - by RenderIn

  I'm curious what kind of content should be in a versioned file commit comment. Should it describe generally what changed (e.g. "The widget screen was changed to display only active widgets") or should it be more specific (e.g. "A new condition was added to the where clause of the fetchWidget query to retrieve only active widgets by default") How atomic should a single commit be? Just the file containing the updated query in a single commit (e.g. "Updated the widget screen to display only active widgets by default"), or should that and several other changes + interface changes to a screen share the same commit with a more general description like ("Updated the widget screen: A) display only active widgets by default B) added button to toggle showing inactive widgets") I see subversion commit comments being used very differently and was wondering what others have had success with. Some comments are as brief as "updated files", while others are many paragraphs long, and others are formatted in a way that they can be queried and associated with some external system such as JIRA. I used to be extremely descriptive of the reason for the change as well as the specific technical changes. Lately I've been scaling back and just giving a general "This is what I changed on this page" kind of comment.

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• oracle query with inconsistent results

  - by Spencer Stejskal

  Im having a very strange problem, i have a complicated view that returns incorrect data when i query on a particular column. heres an example: select empname, has_garnishment from timecard_v2 where empname = 'Testerson, Testy'; this returns the single result 'Testerson, Testy', 'N' however, if i use the query: select empname, has_garnishment from timecard_v2 where empname = 'Testerson, Testy' and has_garnishment = 'Y'; this returns the single result 'Testerson, Testy', 'Y' The second query should return a subset of the first query, but it returns a different answer. I have dissected the view and determined that this section of the view definition is where the problem arises(Note, I removed all of the select clause except the parts of interests for clarity, in the full query all joined tables are required): SELECT e.fullname empname , NVL2(ded.has_garn, 'Y', 'N') has_garnishment FROM timecard tc , orderdetail od , orderassign oa , employee e , employee3 e3 , customer10 c10 , order_misc om, (SELECT COUNT(*) has_garn, v_ssn FROM deductions WHERE yymmdd_stop = 0 OR (LENGTH(yymmdd_stop) = 7 AND to_date(SUBSTR(yymmdd_stop, 2), 'YYMMDD') sysdate) GROUP BY v_ssn ) ded WHERE oa.lrn(+) = tc.lrn_order AND om.lrn(+) = od.lrn AND od.orderno = oa.orderno AND e.ssn = tc.ssn AND c10.custno = tc.custno AND e.lrn = e3.lrn AND e.ssn = ded.v_ssn(+) One thing of note about the definition of the 'ded' subquery. The v_ssn field is a virtual field on the deductions table. I am not a DBA im a software developer but we recently lost our DBA and the new one is still getting up to speed so im trying to debug this issue. That being said, please explain things a little more thoroughly then you would for a fellow oracle expert. thanks

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• Constructor Overloading

  - by Mark Baker

  Normally when I want to create a class constructor that accepts different types of parameters, I'll use a kludgy overloading principle of not defining any args in the constructor definition: e.g. for an ECEF coordinate class constructor, I want it to accept either $x, $y and $z arguments, or to accept a single array argument containg x, y and z values, or to accept a single LatLong object I'd create a constructor looking something like: function __construct() { // Identify if any arguments have been passed to the constructor if (func_num_args() > 0) { $args = func_get_args(); // Identify the overload constructor required, based on the datatype of the first argument $argType = gettype($args[0]); switch($argType) { case 'array' : // Array of Cartesian co-ordinate values $overloadConstructor = 'setCoordinatesFromArray'; break; case 'object' : // A LatLong object that needs converting to Cartesian co-ordinate values $overloadConstructor = 'setCoordinatesFromLatLong'; break; default : // Individual Cartesian co-ordinate values $overloadConstructor = 'setCoordinatesFromXYZ'; break; } // Call the appropriate overload constructor call_user_func_array(array($this,$overloadConstructor),$args); } } // function __construct() I'm looking at an alternative: to provide a straight constructor with $x, $y and $z as defined arguments, and to provide static methods of createECEFfromArray() and createECEFfromLatLong() that handle all the necessary extraction of x, y and z; then create a new ECEF object using the standard constructor, and return that Which option is cleaner from an OO purists perspective?

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• DB2 Driver Connection Hanging in Glassfish Connection Pool

  - by Ant

  We have an intermittent issue around the DB2 used from a Glassfish connection pool. What happens is this: Under situations where the database (DB2 on ZOS) is under stress, our application (which is a multi-threaded application using connections to DB2 via a Glassfish connection pool) stops doing anything. The following are observed: 1) Looking at the server using JConsole, we can see a thread waiting indefinitely in the DB2 driver's getConnection() method. We can also see that it has gained a lock on a Vector within the driver. Several other threads are also calling the getConnection() method in the driver, and are hanging waiting for the lock on the Vector to be released. 2) Looking at the database itself, we can see that there are connections from the Glassfish server open and waiting to be used. It seems that there is some sort of mismatch between the connection pool on Glassfish and the connections actually open to DB2. Has anyone come across this issue before? Or something similar? If you need any more information that I haven't provided, then please let me know!

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• asyncore callbacks launching threads... ok to do?

  - by sbartell

  I'm unfamiliar with asyncore, and have very limited knowledge of asynchronous programming except for a few intro to twisted tutorials. I am most familiar with threads and use them in all my apps. One particular app uses a couchdb database as its interface. This involves longpolling the db looking for changes and updates. The module I use for couchdb is couchdbkit. It uses an asyncore loop to watch for these changes and send them to a callback. So, I figure from this callback is where I launch my worker threads. It seems a bit crude to mix asynchronous and threaded programming. I really like couchdbkit, but would rather not introduce issues into my program. So, my question is, is it safe to fire threads from an async callback? Here's some code... {{{ def dispatch(change): global jobs, db_url # jobs is my queue db = Database(db_url) work_order = db.get(change['id']) # change is an id to the document that changed. # i need to get the actual document (workorder) worker = Worker(work_order, db) # fire the thread jobs.append[worker] worker.start() return main() . . . consumer.wait(cb=dispatch, since=update_seq, timeout=10000) #wait constains the asyncloop. }}}

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• Project Euler Problem #11

  - by SoulBeaver

  Source: http://projecteuler.net/index.php?section=problems&id=11 Quick overview: Take a 20x20 grid of numbers and compute the largest product of 4 pairs of numbers in either horizontal, vertical, or diagonal. My current approach is to divide the 20x20 grid up into single rows and single columns and go from there with a much more manageable grid. The code I'm using to divide the rows into rows is void fillRows ( string::const_iterator& fieldIter, list<int>& rowElements, vector<list<int>>& rows ) { int count(0); for( ; fieldIter < field.end(); ++fieldIter ) { if(isdigit(field[*fieldIter])) { rowElements.push_back(toInt(field[*fieldIter])); ++count; } if(count == 40) { rows.push_back(rowElements); count = 0; rowElements.clear(); } } } Short explanation: I have the field set as static const std::string field and I am filling a vector with lists of rows. Why a list? Because the queue doesn't have a clear function. Also practice using STL container lists and not ones I write myself. However, this thing isn't working. Oftentimes I see it omitting a character( function toInt parses the const char as int ) and I end up with 18 rows, two rows short of the 20x20 grid. The length of the rows seem good. Rows: 18 RowElements[0]: 40 (instead of pairs I saved each number individually. Will fix that later) What am I doing wrong?

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• Representing complex scheduled reoccurance in a database

  - by David Pfeffer

  I have the interesting problem of representing complex schedule data in a database. As a guideline, I need to be able to represent the entirety of what the iCalendar -- ics -- format can represent, but in a database. I'm not actually implementing anything relating to ics, but it gives a good scope of the type of rules I need to be able to model. I need to allow allow representation of a single event or a reoccurring event based on multiple times per day, days of the week, week of a month, month, year, or some combination of those. For example, the third Thursday in November annually, or the 25th of December annually, or every two weeks starting November 2 and continuing until September 8 the following year. I don't care about insertion efficiency but query efficiency is critical. The operation I will be doing most often is providing either a single date/time or a date/time range, and trying to determine if the defined schedule matches any part of the date/time range. Other operations can be slower. For example, given January 15, 2010 at 10:00 AM through January 15, 2010 at 11:00 AM, find all schedules that match at least part of that time. (i.e. a schedule that covers 10:30 - 11:00 still matches.) Any suggestions? I looked at http://stackoverflow.com/questions/1016170/how-would-one-represent-scheduled-events-in-an-rdbms but it doesn't cover the scope of the type of reoccurance rules I'd like to model.

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• Parsing a JSON feed from YQL using jQuery

  - by Keith

  I am using YQL's query.multi to grab multiple feeds so I can parse a single JSON feed with jQuery and reduce the number of connections I'm making. In order to parse a single feed, I need to be able to check the type of result (photo, item, entry, etc) so I can pull out items in specific ways. Because of the way the items are nested within the JSON feed, I'm not sure the best way to loop through the results and check the type and then loop through the items to display them. Here is a YQL (http://developer.yahoo.com/yql/console/) query.multi example and you can see three different result types (entry, photo, and item) and then the items nested within them: select * from query.multi where queries= "select * from twitter.user.timeline where id='twitter'; select * from flickr.photos.search where has_geo='true' and text='san francisco'; select * from delicious.feeds.popular" or here is the JSON feed itself: http://query.yahooapis.com/v1/public/yql?q=select%20*%20from%20query.multi%20where%20queries%3D%22select%20*%20from%20flickr.photos.search%20where%20user_id%3D'23433895%40N00'%3Bselect%20*%20from%20delicious.feeds%20where%20username%3D'keith.muth'%3Bselect%20*%20from%20twitter.user.timeline%20where%20id%3D'keithmuth'%22&format=json&env=store%3A%2F%2Fdatatables.org%2Falltableswithkeys&callback=

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