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• My app crashes after multiple rotates

  - by Ian Rae

  My app is crashing when I try and rotate it more than a couple of times. I first thought it was just the iPhone Simulator, so I loaded the app onto an iPod touch, and it crashed after fewer rotates in a row. I suspect it's a memory leak in one of my rotate methods. The only place I can think that the crash is being caused is in willRotateToInterfaceOrientation:duration:. The only two methods related to rotate that I've added/extended are shouldAutorotateToInterfaceOrientation: and willRotateToInterfaceOrientation:duration and I don't think it's the first because it only contains the two words: return YES;. Here is my willRotateToInterfaceOrientation:duration: method so you can review it and see where the possible memory leak is. -(void)willRotateToInterfaceOrientation:(UIInterfaceOrientation)orientation duration:(NSTimeInterval)duration { UIFont *theFont; if ((orientation == UIInterfaceOrientationLandscapeLeft) || (orientation == UIInterfaceOrientationLandscapeRight)) { theFont = [yearByYear.font fontWithSize:16.0]; yearByYear.font = theFont; [theview setContentSize:CGSizeMake(460.0f, 635.0f)]; } else { theFont = [yearByYear.font fontWithSize:10.0]; yearByYear.font = theFont; [theview setContentSize:CGSizeMake(300.0f, 460.0f)]; } [theFont release]; } yearByYear is a UITextView theview is a UIScrollView if anyone has any idea of why my app is crashing, I would be greatly appreciative.

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• Unable to run .exe application using C# code

  - by bjh Hans

  I have an exe that i need to call from my C# Program with two arguments(PracticeId,ClaimId) for example Suppose if i have an application "test.exe" , whose functionality is to make claim acording to given two argument On cmd i would normally give the following command as: test.exe 1 2 and it works fine and performs its job of conversion. but what if i want to execute the same thing using my c# code. i am using the following sample code: Process compiler = new Process(); compiler.StartInfo.FileName = "test.exe" ; compiler.StartInfo.Arguments = "1 2" ; compiler.StartInfo.UseShellExecute = true; compiler.StartInfo.RedirectStandardOutput = true; compiler.Start(); when i try to invoke the test.exe using the above code , it fails to perform its operation of making claim txt file what is the issue in this i don' know pls help me regarding this whether the problem of threding or not i don't know. Can anyone tell me if i need to add anything more to the above code It would be great if somebody could provide some help on the above topic.

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• Do [sprite stopActionByTag: kTag]; working differently for different CCActions ?

  - by srikanth rongali

  //prog 1 -(void)gameLogic:(ccTime)dt { id actionMove = [CCMoveTo actionWithDuration:1.0 position:ccp(windowSize.width/2-400, actualY)]; [actionMove setTag:6]; [self schedule:@selector(update:)]; [hitBullet runAction:actionMove]; } -(void)update:(ccTime)dt { if ( (CGRectIntersectsRect(hitRect, playerRect)) ) { [[[self getActionByTag:6] retain] autorelease]; [hitBullet stopActionByTag: 6]; } } //prog 2 -(void)gameLogic:(ccTime)dt { id actionMove = [CCMoveTo actionWithDuration:1.0 position:ccp(windowSize.width/2-400, actualY)]; id hitBulletAction = [CCSequence actionWithDuration:(intervalforEnemyshoot)]; id hitBulletSeq = [CCSequence actions: hitBulletAction, actionMove, nil]; [hitBulletSeq setTag:5]; [self schedule:@selector(update:)]; [hitBullet runAction:hitBulletSeq]; } -(void)update:(ccTime)dt { if ( (CGRectIntersectsRect(hitRect, playerRect)) ) { [[[self getActionByTag:5] retain] autorelease]; [hitBullet stopActionByTag: 5]; } } While prog1 is working prog2 is not working ? I think the both are same. But why the two stopActions are working differently in two prog1 and prog2 ? I mean the actions are stopped in prog1 but the actions are not stopping in prog2 ? thank You.

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• Templates, and C++ operator for logic: B contained by set A

  - by James Morris

  In C++, I'm looking to implement an operator for selecting items in a list (of type B) based upon B being contained entirely within A. In the book "the logical design of digital computers" by Montgomery Phister jr (published 1958), p54, it says: F11 = A + ~B has two interesting and useful associations, neither of them having much to do with computer design. The first is the logical notation of implication... The second is notation of inclusion... This may be expressed by a familiar looking relation, B < A; or by the statement "B is included in A"; or by the boolean equation F11= A + ~B = 1. My initial implementation was in C. Callbacks were given to the list to use for such operations. An example being a list of ints, and a struct containting two ints, min and max, for selection purposes. There, selection would be based upon B = A-min && B <= A-max. Using C++ and templates, how would you approach this after having implemented a generic list in C using void pointers and callbacks? Is using < as an over-ridden operator for such purposes... <ugh> evil? </ugh> (or by using a class B for the selection criteria, implementing the comparison by overloading ?)

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• Examples of monoids/semigroups in programming

  - by jkff

  It is well-known that monoids are stunningly ubiquitous in programing. They are so ubiquitous and so useful that I, as a 'hobby project', am working on a system that is completely based on their properties (distributed data aggregation). To make the system useful I need useful monoids :) I already know of these: Numeric or matrix sum Numeric or matrix product Minimum or maximum under a total order with a top or bottom element (more generally, join or meet in a bounded lattice, or even more generally, product or coproduct in a category) Set union Map union where conflicting values are joined using a monoid Intersection of subsets of a finite set (or just set intersection if we speak about semigroups) Intersection of maps with a bounded key domain (same here) Merge of sorted sequences, perhaps with joining key-equal values in a different monoid/semigroup Bounded merge of sorted lists (same as above, but we take the top N of the result) Cartesian product of two monoids or semigroups List concatenation Endomorphism composition. Now, let us define a quasi-property of an operation as a property that holds up to an equivalence relation. For example, list concatenation is quasi-commutative if we consider lists of equal length or with identical contents up to permutation to be equivalent. Here are some quasi-monoids and quasi-commutative monoids and semigroups: Any (a+b = a or b, if we consider all elements of the carrier set to be equivalent) Any satisfying predicate (a+b = the one of a and b that is non-null and satisfies some predicate P, if none does then null; if we consider all elements satisfying P equivalent) Bounded mixture of random samples (xs+ys = a random sample of size N from the concatenation of xs and ys; if we consider any two samples with the same distribution as the whole dataset to be equivalent) Bounded mixture of weighted random samples Which others do exist?

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• Confused about definition of a 'median' when constructing a kd-Tree

  - by user352636

  Hi there. Im trying to build a kd-tree for searching through a set of points, but am getting confused about the use of 'median' in the wikipedia article. For ease of use, the wikipedia article states the pseudo-code of kd-tree construction as: function kdtree (list of points pointList, int depth) { if pointList is empty return nil; else { // Select axis based on depth so that axis cycles through all valid values var int axis := depth mod k; // Sort point list and choose median as pivot element select median by axis from pointList; // Create node and construct subtrees var tree_node node; node.location := median; node.leftChild := kdtree(points in pointList before median, depth+1); node.rightChild := kdtree(points in pointList after median, depth+1); return node; } } I'm getting confused about the "select median..." line, simply because I'm not quite sure what is the 'right' way to apply a median here. As far as I know, the median of an odd-sized (sorted) list of numbers is the middle element (aka, for a list of 5 things, element number 3, or index 2 in a standard zero-based array), and the median of an even-sized array is the sum of the two 'middle' elements divided by two (aka, for a list of 6 things, the median is the sum of elements 3 and 4 - or 2 and 3, if zero-indexed - divided by 2.). However, surely that definition does not work here as we are working with a distinct set of points? How then does one choose the correct median for an even-sized list of numbers, especially for a length 2 list? I appreciate any and all help, thanks! -Stephen

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• Problem with duplicates in a SQL Join

  - by Chris Ballance

  I have the following result set from a join of three tables, an articles table, a products table, an articles to products mapping table. I would like to have the results with duplicates removed similar to a select distinct on content id. Current result set: [ContendId] [Title] [productId] 1 article one 2 1 article one 3 1 article one 9 4 article four 1 4 article four 10 4 article four 14 5 article five 1 6 article six 8 6 article six 10 6 article six 11 6 article six 13 7 article seven 14 Desired result set: [ContendId] [Title] [productId] 1 article one * 4 article four * 5 article five * 6 article six * 7 article seven * Here is condensed example of the relevant SQL: IF EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'tempdb.dbo.products') AND type = (N'U')) drop table tempdb.dbo.products go CREATE TABLE tempdb.dbo.products ( productid int, productname varchar(255) ) go IF EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'articles') AND type = (N'U')) drop table tempdb.dbo.articles go create table tempdb.dbo.articles ( contentid int, title varchar(255) ) IF EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'articles') AND type = (N'U')) drop table tempdb.dbo.articles go create table tempdb.dbo.articles ( contentid int, title varchar(255) ) IF EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'articleproducts') AND type = (N'U')) drop table tempdb.dbo.articleproducts go create table tempdb.dbo.articleproducts ( contentid int, productid int ) insert into tempdb.dbo.products values (1,'product one'), (2,'product two'), (3,'product three'), (4,'product four'), (5,'product five'), (6,'product six'), (7,'product seven'), (8,'product eigth'), (9,'product nine'), (10,'product ten'), (11,'product eleven'), (12,'product twelve'), (13,'product thirteen'), (14,'product fourteen') insert into tempdb.dbo.articles VALUES (1,'article one'), (2, 'article two'), (3, 'article three'), (4, 'article four'), (5, 'article five'), (6, 'article six'), (7, 'article seven'), (8, 'article eight'), (9, 'article nine'), (10, 'article ten') INSERT INTO tempdb.dbo.articleproducts VALUES (1,2), (1,3), (1,9), (4,1), (4,10), (4,14), (5,1), (6,8), (6,10), (6,11), (6,13), (7,14) GO select DISTINCT(a.contentid), a.title, p.productid from articles a JOIN articleproducts ap ON a.contentid = ap.contentid JOIN products p ON a.contentid = ap.contentid AND p.productid = ap.productid ORDER BY a.contentid

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• Where should you put 3rd party .NET dlls when using git submodules to avoid duplication

  - by Tim Abell

  I have two .NET library projects in Visual Studio 2008 that both make use of the MySql Connector for .NET (MySql.Data.dll). These libraries are then in turn both used by a .NET command line application which also uses the Connector. The library projects are pulled in to the application's solution as git submodules and referenced by project in Visual Studio. I'm looking for the most effective strategy for storing and referencing the MySql Connector library. I have tried having the MySql.Data.dll checked in to all three projects (in their root folder), this was problematic when one project changed to a newer version of the connector dll. Although each project had its own version of the dll, only one was packaged into the resultant application leading to an API mismatch which was hard to pin down. This has put me off this approach. I have tried having the command line application reference the connector dll that is held in a submodule, however this only removes the possibility of version mismatches when there is only one submodule rather than two as in this case. I am contemplating putting the dll in the global assembly cache (GAC) of all machines that need to build or use the application, but I'm wary of not having all dependencies for an application available in source control.

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• Can Haskell's Parsec library be used to implement a recursive descent parser with backup?

  - by Thor Thurn

  I've been considering using Haskell's Parsec parsing library to parse a subset of Java as a recursive descent parser as an alternative to more traditional parser-generator solutions like Happy. Parsec seems very easy to use, and parse speed is definitely not a factor for me. I'm wondering, though, if it's possible to implement "backup" with Parsec, a technique which finds the correct production to use by trying each one in turn. For a simple example, consider the very start of the JLS Java grammar: Literal: IntegerLiteral FloatingPointLiteral I'd like a way to not have to figure out how I should order these two rules to get the parse to succeed. As it stands, a naive implementation like this: literal = do { x <- try (do { v <- integer; return (IntLiteral v)}) <|> (do { v <- float; return (FPLiteral v)}); return(Literal x) } Will not work... inputs like "15.2" will cause the integer parser to succeed first, and then the whole thing will choke on the "." symbol. In this case, of course, it's obvious that you can solve the problem by re-ordering the two productions. In the general case, though, finding things like this is going to be a nightmare, and it's very likely that I'll miss some cases. Ideally, I'd like a way to have Parsec figure out stuff like this for me. Is this possible, or am I simply trying to do too much with the library? The Parsec documentation claims that it can "parse context-sensitive, infinite look-ahead grammars", so it seems like something like I should be able to do something here.

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• transactions and delete using fluent nhibernate

  - by Will I Am

  I am starting to play with (Fluent) nHibernate and I am wondering if someone can help with the following. I'm sure it's a total noob question. I want to do: delete from TABX where name = 'abc' where table TABX is defined as: ID int name varchar(32) ... I build the code based on internet samples: using (ITransaction transaction = session.BeginTransaction()) { IQuery query = session.CreateQuery("FROM TABX WHERE name = :uid") .SetString("uid", "abc"); session.Delete(query.List<Person>()[0]); transaction.Commit(); } but alas, it's generating two queries (one select and one delete). I want to do this in a single statement, as in my original SQL. What is the correct way of doing this? Also, I noticed that in most samples on the internet, people tend to always wrap all queries in transactions. Why is that? If I'm only running a single statement, that seems an overkill. Do people tend to just mindlessly cut and paste, or is there a reason beyond that? For example, in my query above, if I do manage it to get it from two queries down to one, i should be able to remove the begin/commit transaction, no? if it matters, I'm using PostgreSQL for experimenting.

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• Invalid method declaration, return type required

  - by Brett Steen

  I am getting an error at public Rectangle(double width, double height){ saying that it's an invalid method declaration, return type required. I'm not sure how to fix it. These are also my instructions for my assignment: Write a super class encapsulating a rectangle. A rectangle has two attributes representing the width and the height of the rectangle. It has methods returning the perimeter and the area of the rectangle. This class has a subclass, encapsulating a parallelepiped, or box. A parallelepiped has a rectangle as its base, and another attribute, its length. It has two methods that calculate and return its area and volume. `public class Rectangle1 { private double width; private double height; public Rectangle1(){ } public Rectangle(double width, double height){ this.width = width; this.height = height; } public double getWidth(){ return width; } public void setWidth(double width) { this.width = width; } public double getHeight(){ return height; } public void setHeight(double height){ this.height = height; } public double getArea(){ return width * height; } public double getPerimeter(){ return 2 * (width + height); } } public class TestRectangle { public static void main(String[] args) { Rectangle1 rectangle = new Rectangle1(2,4); System.out.println("\nA rectangle " + rectangle.toString()); System.out.println("The area is " + rectangle.getArea()); System.out.println("The perimeter is " + rectangle.getPerimeter()); } }`

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• How do I left join tables in unidirectional many-to-one in Hibernate?

  - by jbarz

  I'm piggy-backing off of http://stackoverflow.com/questions/2368195/how-to-join-tables-in-unidirectional-many-to-one-condition. If you have two classes: class A { @Id public Long id; } class B { @Id public Long id; @ManyToOne @JoinColumn(name = "parent_id", referencedColumnName = "id") public A parent; } B - A is a many to one relationship. I understand that I could add a Collection of Bs to A however I do not want that association. So my actual question is, Is there an HQL or Criteria way of creating the SQL query: select * from A left join B on (b.parent_id = a.id) This will retrieve all A records with a Cartesian product of each B record that references A and will include A records that have no B referencing them. If you use: from A a, B b where b.a = a then it is an inner join and you do not receive the A records that do not have a B referencing them. I have not found a good way of doing this without two queries so anything less than that would be great. Thanks.

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• tabBarController and navigationControllers in landscape mode, episode II

  - by unforgiven

  I have a UITabBarController, and each tab handles a different UIViewController that pushes on the stack new controllers as needed. In two of these tabs I need, when a specific controller is reached, the ability to rotate the iPhone and visualize a view in landscape mode. After struggling a lot I have found that it is mandatory subclassing UITabBarController to override shouldAutorotateToInterfaceOrientation. However, if i simply return YES in the implementation, the following undesirable side effect arises: every controller in every tab is automatically put in landscape mode when rotating the iPhone. Even overriding shouldAutorotateToInterfaceOrientation in each controller to return NO does not work: when the iPhone is rotated, the controller is put in landscape mode. I implemented shouldAutorotateToInterfaceOrientation as follows in the subclassed UITabBarController: (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation { if([self selectedIndex] == 0 || [self selectedIndex] == 3) return YES; return NO; } So that only the two tabs I am interested in actually get support for landscape mode. Is there a way to support landscape mode for a specific controller on the stack of a particular tab? I tried, without success, something like (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation { if([self selectedIndex] == 0 || [self selectedIndex] == 3) { if ([[self selectedViewController] isKindOfClass: [landscapeModeViewController class]]) return YES; } return NO; } Also, I tried using the delegate method didSelectViewController, without success. Any help is greatly appreciated. Thank you.

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• How to join a table in symfony (Propel) and retrieve object from both table with one query

  - by Jean-Philippe

  Hi, I'm trying to get an easy way to fetch data from two joined Mysql table using Propel (inside Symfony) but in one query. Let's say I do this simple thing: $comment = CommentPeer::RetrieveByPk(1); print $comment->getArticle()->getTitle(); //Assuming the Article table is joined to the Comment table Symfony will call 2 queries to get that done. The first one to get the Comment row and the next one to get the Article row linked to the comment one. Now, I am trying to find a way to make all that within one query. I've tried to join them using $c = new Criteria(); $c->addJoin(CommentPeer::ARTICLE_ID, ArticlePeer::ID); $c->add(CommentPeer::ID, 1); $comment = CommentPeer::doSelectOne($c); But when I try to get the Article object using $comment->getArticle() It will still issue the query to get the Article row. I could easily clear all the selected columns and select the columns I need but that would not give me the Propel object I'd like, just an array of the query's raw result. So how can I get a populated propel object of two (or more) joined table with only one query? Thanks, JP

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• What is the basic pattern for using (N)Hibernate?

  - by Vilx-

  I'm creating a simple Windows Forms application with NHibernate and I'm a bit confused about how I'm supposed to use it. To quote the manual: ISession (NHibernate.ISession) A single-threaded, short-lived object representing a conversation between the application and the persistent store. Wraps an ADO.NET connection. Factory for ITransaction. Holds a mandatory (first-level) cache of persistent objects, used when navigating the object graph or looking up objects by identifier. Now, suppose I have the following scenario: I have a simple classifier which is a MSSQL table with two columns - ID (auto_increment) and Name (nvarchar). To edit this classifier I create a form which contains a single gridview and two buttons - OK and Cancel. The user can nearly directly edit the table in the gridview, and when he hits OK the changes he made are persisted to the DB (or if he hits cancel, nothing happens). Now, I have several questions about how to organize this: What should the lifetime of my ISession be? Should I create a single ISession for my whole application; an ISession for each of my forms (the application is single-threaded MDI); or an ISession for every DB operation/transaction? Does NHibernate offer some kind of built-in dirty tracking or must I do this myself? The manual mentions something like it here and there but does not go into details. How is this done? Is there not a huge overhead? Is it somehow tied with the cache(s) that NHibernate has? What are these caches for? Are they not specific to a single ISession? That is, if I use a seperate ISession for every transaction, won't it break the dirty tracking? How does the built-in dirty tracking detect deleted objects?

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• Oracle why does creating trigger fail when there is a field called timestamp?

  - by Omar Kooheji

  I've just wasted the past two hours of my life trying to create a table with an auto incrementing primary key bases on this tutorial, The tutorial is great the issue I've been encountering is that the Create Target fails if I have a column which is a timestamp and a table that is called timestamp in the same table... Why doesn't oracle flag this as being an issue when I create the table? Here is the Sequence of commands I enter: Creating the Table: CREATE TABLE myTable (id NUMBER PRIMARY KEY, field1 TIMESTAMP(6), timeStamp NUMBER, ); Creating the Sequence: CREATE SEQUENCE test_sequence START WITH 1 INCREMENT BY 1; Creating the trigger: CREATE OR REPLACE TRIGGER test_trigger BEFORE INSERT ON myTable REFERENCING NEW AS NEW FOR EACH ROW BEGIN SELECT test_sequence.nextval INTO :NEW.ID FROM dual; END; / Here is the error message I get: ORA-06552: PL/SQL: Compilation unit analysis terminated ORA-06553: PLS-320: the declaration of the type of this expression is incomplete or malformed Any combination that does not have the two lines with a the word "timestamp" in them works fine. I would have thought the syntax would be enough to differentiate between the keyword and a column name. As I've said I don't understand why the table is created fine but oracle falls over when I try to create the trigger... CLARIFICATION I know that the issue is that there is a column called timestamp which may or may not be a keyword. MY issue is why it barfed when I tried to create a trigger and not when I created the table, I would have at least expected a warning. That said having used Oracle for a few hours, it seems a lot less verbose in it's error reporting, Maybe just because I'm using the express version though. If this is a bug in Oracle how would one who doesn't have a support contract go about reporting it? I'm just playing around with the express version because I have to migrate some code from MySQL to Oracle.

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• Netbeans GUI building on pre-defined code

  - by deliriumtremens

  I am supposed edit some code for an assignment, and he gave us the framework and wants us to implement code for it. I load the project into netbeans and can't figure out how I'm supposed to edit the swing components. I don't see how to edit source vs. design. import javax.swing.*; import java.util.*; import java.io.*; public class CurrencyConverterGUI extends javax.swing.JFrame { /************************************************************************************************************** insert your code here - most of this will be generated by NetBeans, however, you must write code for the event listeners and handlers for the two ComboBoxes, the two TextBoxes, and the Button. Please note you must also poulate the ComboBoxes withe currency symbols (which are contained in the KeyList attribute of CurrencyConverter CC) ***************************************************************************************************************/ private CurrencyConverter CC; private javax.swing.JTextField Currency1Field; private javax.swing.JComboBox Currency1List; private javax.swing.JTextField Currency2Field; private javax.swing.JComboBox Currency2List; private javax.swing.JButton jButton1; private javax.swing.JPanel jPanel1; } class CurrencyConverter{ private HashMap HM; // contains the Currency symbols and conversion rates private ArrayList KeyList; // contains the list of currency symbols public CurrencyConverter() { /************************************************** Instantiate HM and KeyList and load data into them. Do this by reading the data from the Rates.txt file ***************************************************/ } public double convert(String FromCurrency, String ToCurrency, double amount){ /*************************************************************************** Will return the converted currency value. For example, to convert 100 USD to GBP, FromCurrency is USD, ToCurrency is GBP and amount is 100. The rate specified in the file represent the amount of each currency which is equivalent to one Euro (EUR). Therefore, 1 Euro is equivalent to 1.35 USD Use the rate specified for USD to convert to equivalent GBP: amount / USD_rate * GBP_rate ****************************************************************************/ } public ArrayList getKeys(){ // return KeyList } } This is what we were given, but I can't do anything with it inside the GUI editor. (Can't even get to the GUI editor). I have been staring at this for about an hour. Any ideas?

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• question about MySQL database migration

  - by WilliamLou

  Hi there: If I have a MySQL database with several tables on a live server, now I would like to migrate this database to another server. Of course, the migration I mean here involves some database tables, for example: add some new columns to several tables, add some new tables etc.. Now, the only method I can think of is to use some php/python(two scripts I know) script, connect two databases, dump the data from the old database, and then write into the new database. However, this method is not efficient at all. For example: in old database, table A has 28 columns; in new database, table A has 29 columns, but the extra column will have default value 0 for all the old rows. My script still needs to dump the data row by row and insert each row into the new database. Is there any tools or a better method than writing a script yourself? Here, I dont need to worry about multithread writing problems etc.., I mean the old database will be down (not open to public usage etc.., only for upgrade ) for a while. Thanks!!

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• What is optimal hardware configuration for heavy load LAMP application

  - by Piotr Kochanski

  I need to run Linux-Apache-PHP-MySQL application (Moodle e-learning platform) for a large number of concurrent users - I am aiming 5000 users. By concurrent I mean that 5000 people should be able to work with the application at the same time. "Work" means not only do database reads but writes as well. The application is not very typical, since it is doing a lot of inserts/updates on the database, so caching techniques are not helping to much. We are using InnoDB storage engine. In addition application is not written with performance in mind. For instance one Apache thread usually occupies about 30-50 MB of RAM. I would be greatful for information what hardware is needed to build scalable configuration that is able to handle this kind of load. We are using right now two HP DLG 380 with two 4 core processors which are able to handle much lower load (typically 300-500 concurrent users). Is it reasonable to invest in this kind of boxes and build cluster using them or is it better to go with some more high-end hardware? I am particularly curious how many and how powerful servers are needed (number of processors/cores, size of RAM) what network equipment should be used (what kind of switches, network cards) any other hardware, like particular disc storage solutions, etc, that are needed Another thing is how to put together everything, that is what is the most optimal architecture. Clustering with MySQL is rather hard (people are complaining about MySQL Cluster, even here on Stackoverflow).

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• Merging sql queries to get different results by date

  - by pedalpete

  I am trying to build a 'recent events' feed and can't seem to get either my query correct, or figure out how to possible merge the results from two queries to sort them by date. One table holds games/, and another table holds the actions of these games/. I am trying to get the recent events to show users 1) the actions taken on games that are publicly visible (published) 2) when a new game is created and published. So, my actions table has actionId, gameid, userid, actiontype, lastupdate My games table has gameid, startDate, createdby, published, lastupdate I currently have a query like this (simplified for easy understanding I hope). SELECT actionId, actions.gameid, userid, actiontype, actions.lastupdate FROM actions JOIN ( SELECT games.gameid, startDate, createdby, published, games.lastupdate FROM games WHERE published=1 AND lastupdate>today-2 ) publishedGames on actions.gameid=games.gameid WHERE actions.type IN (0,4,5,6,7) AND actions.lastupdate>games.lastupdate and published=1 OR games.lastupdate>today-2 AND published=1 This query is looking for actions from published games where the action took place after the game was published. That pretty much takes care of the first thing that needs to be shown. However, I also need to get the results of the SELECT games.gameid, startDate, createdby, published, games.lastupdate FROM games WHERE published=1 AND startDate>today-2 so I can include in the actions list, when a new game has been published. When I run the query as I've got it written, I get all the actionids, and their gameids, but I don't get a row which shows the gameid when it was published. I understand that it may be possible that I need to run two seperate queries, and then somehow merge the results afterword with php, but I'm completely lost on where to start with that as well.

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• When do you tag your software project?

  - by WilhelmTell of Purple-Magenta

  I realize there are various kinds of software projects: commercial (for John Doe) industrial (for Mr. Montgomery Burns) successful open-source (with audience larger than, say, 10 people) personal projects (with audience size in the vicinity of 1). each of which release a new version of their product on difference conditions. I'm particularly interested in the case of personal projects and open-source projects. When, or under what conditions, do you make a new release of any kind? Do you subscribe to a fixed recurring deadline such as every two weeks? Do you commit to a release of at least 10 minor fixes, or one major fix? Do you combine the two conditions such as at least one condition must hold, or both must hold? I reckon this is a subjective question. I ask this question in light of searching for tricks to keep my projects alive and kicking. Sometimes my projects are active but look as if they aren't because I don't have the confidence to make a release or a tag of any sort for a long time -- in the order of months.

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• Accessing previous activity instances in a sequence activity

  - by Dan Revell

  This has a rather SharePoint spin to it but the problem is straight workflow. I've got a parallel replication activity which contains a sequence activity. The sequence activity contains a CreateTask activity, a CodeActivity, a OnTaskChanged activity and finally a CompleteTask activity. The idea is to create a task for each username passed into the ReplicatorActivity.InitialChildData property. Typically in workflow I bind a field to the CreateTask.TaskId and CreateTask.TaskProperties and inside the CreateTask.MethodInvoking I set these through the local bound fields. This works and my tasks all get created properly. However in the CodeActivity that follows, I want to then access the TaskProperties. The problem I am encountering is that this field holds the values of the final task to be created as the CreateTask runs for all the replications before the CodeActivity gets to runs. From the CodeActivity, here are two ways I've tried to access the CreateTask activity instance from the same context or instance or whatever the terminology is for the replicated sequence. CreateTask task = ((CreateTask)sender.Parent.GetActivityByName("createSoftwareRequestTask", true)); CreateTask createTask = (CreateTask)sender.Parent.Activities[0]; Unfortunately the CreateTask activities both refer back to the last task to be created and not the task from the context that the CodeActivity is executing within. Two reasons why this might be that I can think of. I'm not accessing the correct instance with my code. I am accessing the correct instance, but as the properties I require were bound to and set through local fields then their previous data was overwritten. I'm hitting a brick wall with my understanding of workflow with this and would very much appreciate some assistance here.

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• Finding the right terminology for a dictionary table

  - by Karl Forner

  My concern is about what I currently call "dictionary tables", that are database tables containing a list of controlled vocabulary. Let's use an example: Suppose you have a table User containing fields: user_id : primary key first_name last_name user_type_id : foreign key to the UserType table and another table UserType with just two fields: user_type_id : primary key name : the name/value of a particular type of user. For instance, the UserType table may contain (1, Administrator), (2, PowerUser), (3, Normal)... My question is: what is the canonical term for a table like UserType, that only contains a list of (dictinct) words. I want to publish some code that help managing this kind of tables, but first I have to name them ! Thanks for your help. Current state of thought: For now I feel Lookup Tables is a good term. It is also used with the same meaning in these posts: http://dbix-class.35028.n2.nabble.com/RFC-Component-for-Lookup-tables-td3504085.html http://tonyandrews.blogspot.de/2004/10/otlt-and-eav-two-big-design-mistakes.html Lookup Tables Best Practices: DB Tables... or Enumerations The only problem is that lookup table is also sometimes used to name a junction table.

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• How can I make an even more random number in ActionScript 2.0

  - by Theo

  I write a piece of software that runs inside banner ads which generates millions of session IDs every day. For a long time I've known that the random number generator in Flash is't random enough to generate sufficiently unique IDs, so I've employed a number of tricks to get even more random numbers. However, in ActionScript 2.0 it's not easy, and I'm seeing more and more collisions, so I wonder if there is something I've overlooked. As far as I can tell the problem with Math.random() is that it's seeded by the system time, and when you have sufficient numbers of simultaneous attempts you're bound to see collisions. In ActionScript 3.0 I use the System.totalMemory, but there's no equivalent in ActionScript 2.0. AS3 also has Font.enumerateFonts, and a few other things that are different from system to system. On the server side I also add the IP address to the session ID, but even that isn't enough (for example, many large companies use a single proxy server and that means that thousands of people all have the same IP -- and since they tend to look at the same sites, with the same ads, roughly at the same time, there are many session ID collisions). What I need isn't something perfectly random, just something that is random enough to dilute the randomness I get from Math.random(). Think of it this way: there is a certain chance that two people will generate the same random number sequence using only Math.random(), but the chance of two people generating the same sequence and having, say, the exact same list of fonts is significantly lower. I cannot rely on having sufficient script access to use ExternalInterface to get hold of things like the user agent, or the URL of the page. I don't need suggestions of how to do it in AS3, or any other system, only AS2 -- using only what's available in the standard APIs. The best I've come up with so far is to use the list of microphones (Microphone.names), but I've also tried to make some fingerprinting using some of the properties in System.capabilities, I'm not sure how much randomness I can get out of that though so I'm not using that at the moment. I hope I've overlooked something.

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• Ignore case in Python strings

  - by Paul Oyster

  What is the easiest way to compare strings in Python, ignoring case? Of course one can do (str1.lower() <= str2.lower()), etc., but this created two additional temporary strings (with the obvious alloc/g-c overheads). I guess I'm looking for an equivalent to C's stricmp(). [Some more context requested, so I'll demonstrate with a trivial example:] Suppose you want to sort a looong list of strings. You simply do theList.sort(). This is O(n * log(n)) string comparisons and no memory management (since all strings and list elements are some sort of smart pointers). You are happy. Now, you want to do the same, but ignore the case (let's simplify and say all strings are ascii, so locale issues can be ignored). You can do theList.sort(key=lambda s: s.lower()), but then you cause two new allocations per comparison, plus burden the garbage-collector with the duplicated (lowered) strings. Each such memory-management noise is orders-of-magnitude slower than simple string comparison. Now, with an in-place stricmp()-like function, you do: theList.sort(cmp=stricmp) and it is as fast and as memory-friendly as theList.sort(). You are happy again. The problem is any Python-based case-insensitive comparison involves implicit string duplications, so I was expecting to find a C-based comparisons (maybe in module string). Could not find anything like that, hence the question here. (Hope this clarifies the question).

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