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  • Database triggers / referential integrity and in-memory caching

    - by Ran Biron
    Do you see database triggers / referential integrity rules being used in a way that changes actual data in the database (changing row w in table x causes a change in row y in table z)? If yes, How does this tie-in with the increasing popularity of in-memory caching (memcache and friends)? After all, these actions occur inside the database but the caching system must be aware of them in order to reflect to correct state (or at least invalidate the possibly changed state). I find it hard to believe that callbacks are implemented for such cases. Does anyone have real-world experience with such a setup / real-world experience with considering such a setup and abandoning it (which way did you go? if caching, how do you enforce integrity?)

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  • (NOT) NULL for NVARCHAR columns

    - by Anders Abel
    Allowing NULL values on a column is normally done to allow the absense of a value to be represented. When using NVARCHAR there is aldready a possibility to have an empty string, without setting the column to NULL. In most cases I cannot see a semantical difference between an NVARCHAR with an empty string and a NULL value for such a column. Setting the column as NOT NULL saves me from having to deal with the possibility of NULL values in the code and it feels better to not have to different representations of "no value" (NULL or an empty string). Will I run into any other problems by setting my NVARCHAR columns to NOT NULL. Performance? Storage size? Anything I've overlooked on the usage of the values in the client code?

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  • Structuremap and creating objects with initial state

    - by Simon
    I have an object which needs a dependency injected into it public class FootballLadder { public FootballLadder(IMatchRepository matchRepository, int round) { // set initial state this.matchRepo = matchRepository; this.round = round; } public IEnumerable<LadderEntry> GetLadderEntries() { // calculate the ladder based on matches retrieved from the match repository // return the calculated ladder } private IMatchRepository matchRepo; private int round; } For arguments sake, lets assume that I can't pass the round parameter into the GetLadderEntries call itself. Using StructureMap, how can I inject the dependency on the IMatchRepository and set the initial state? Or is this one of those cases where struggling against the framework is a sign the code should be refactored?

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  • Common causes of slow performing jQuery and how to optimize the code?

    - by Polaris878
    Hello, This might be a bit of a vague or general question, but I figure it might be able to serve as a good resource for other jQuery-ers. I'm interested in common causes of slow running jQuery and how to optimize these cases. We have a good amount of jQuery/JavaScript performing actions on our page... and performance can really suffer with a large number off elements. What are some obvious performance pitfalls you know of with jQuery? What are some general optimizations a jQuery-er can do to squeeze every last bit of performance out of his/her scripts? One example: a developer may use a selector to access an element that is slower than some other way. Thanks

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  • Need some explanation about MS Ajax using PageMethods

    - by Ahmed Said
    I have a project that uses PageMethods to call functions on the server. The server functions (written in C#) return the values as array of strings, without doing any kind of serialization and in the client side (from Js) the accessing of the return values is by using static variable called arguments. I found that sometimes for some users (cases are not repro) sometimes an exception occured "WebServiceFailedException the server method 'Foo' returned invalid data. the 'd' property is missing from JSON." Some searching on google I found that people are serializing the return values using DataContractJsonSerializer class and in js accessing the return value using one of the callback function Example: function OnRequestComplete(result, userContext, methodName) { var Person = eval('(' + result + ')'); alert(Person.Forename); alert(Person.Surname); } So is the first technique is correct? or what?

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  • Having a fork match the original repo when the original master branch can't be merged in?

    - by a2h
    The related questions that SO offer me only answer simple cases that can be solved with a pull - however, that won't work for my case. There's a repository I've forked, with just a master branch, and I've forked it, and I've worked in both my master, and a new branch of my own, rw-style. The owner of the forked repository's committed some of my changes but not others; the black dots on the top right below represent commits from both my master and rw-style branches. I'm aware using the fork queue is not a good idea, so I'm staying away from it. Using git pull does work, but it creates a conflict that I would then need to resolve, and it also results in duplicate history for my master branch, and that doesn't look particularly pretty. I don't know any other solutions right now, so I'm currently considering just creating a patch from two commits that I haven't yet pushed, deleting my fork, creating it again from the original, and then applying my patches on top of it. Is that the only solution?

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  • What do you enjoy about programming?

    - by Earlz
    Some of us here(or is it just me?) enjoy programming. Even if we're not being paid for it, and in some cases, even though the end result will not do anything for us. For example, many people do the Project Euler problems just for fun, and in the end nothing was really "accomplished" materially. What is it that makes us enjoy programming? How is programming different from another job? You don't see an accountant going home to do some accounting on their own time just for the pure joy of it. How are we different? (also, if anyone has some ideas on how to tag this, then please do correct it for me.. )

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  • ASP.NET web services leak memory when (de)serializing disposable objects?

    - by Serilla
    In the following two cases, if Customer is disposable (implementing IDisposable), I believe it will not be disposed by ASP.NET, potentially being the cause of a memory leak: [WebMethod] public Customer FetchCustomer(int id) { return new Customer(id); } [WebMethod] public void SaveCustomer(Customer value) { // save it } This flaw applies to any IDisposable object. So returning a DataSet from a ASP.NET web service, for example, will also result in a memory leak - the DataSet will not be disposed. In my case, Customer opened a database connection which was cleaned up in Dispose - except Dispose was never called resulting in loads of unclosed database connections. I realise there a whole bunch of bad practices being followed here (its only an example anyway), but the point is that ASP.NET - the (de)serializer - is responsible for disposing these objects, so why doesn't it? This is an issue I was aware of for a while, but never got to the bottom of. I'm hoping somebody can confirm what I have found, and perhaps explain if there is a way of dealing with it.

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  • Modifying object in AfterInsert / AfterUpdate

    - by Jean Barmash
    I have a domain object that holds results of a calculation based on parameters that are properties of the same domain object. I'd like to make sure that any time parameters get changed by the user, it recalculates and gets saved properly into the database. I am trying to do that with afterInsert (to make sure calculation is correct in the first place), and afterUpdate. However, since my calculation is trying to modify the object itself, it's not working - throwing various hibernate exceptions. I tried to put the afterUpdate code into a transaction, but that didn't help. I am afraid I am getting into a circular dependency issues here. The exception I am getting right now is: org.hibernate.StaleObjectStateException: Row was updated or deleted by another transaction (or unsaved-value mapping was incorrect): [esc.scorecard.PropertyScorecard#27] Are the GORM events designed for simpler use cases? I am tempted to conclude that modifying the object you are in the middle of saving is not the way to go.

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  • How to avoid StaleObjectStateException when transaction updates thousands of entities?

    - by ThinkFloyd
    We are using Hibernate 3.6.0.Final with JPA 2 and Spring 3.0.5 for a large scale enterprise application running on tomcat 7 and MySQL 5.5. Most of the transactions in application, lives for less than a second and update 5-10 entities but in some use cases we need to update more than 10-20K entities in single transaction, which takes few minutes and hence more than 70% of times such transaction fails with StaleObjectStateException because some of those entities got updated by some other transaction. We generally maintain version column in all tables and in case of StaleObjectStateException we generally retry but since these longs transactions are anyways very long so if we keep on retrying then also I am not very sure that we'll be able to escape StaleObjectStateException. Also lot of activities keep updating these entities in busy hours so we cannot go with pessimistic approach because it can potentially halt many activities in system. Please suggest how to fix such long transaction issue because we cannot spawn thousands of independent and small transactions because we cannot afford messed up data in case of some failed & some successful transactions.

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  • FMS: Stream.play on server side makes video choppy

    - by Tinelise
    I have an *.flv file on a FMS. When I play it on the client side the video plays just fine, but when I call Stream.play(filename, 0, -1, false) on the server side the video turns out really choppy. I both cases I use NetConnection to connect to an rtmp and NetStream to play the stream, but in one case I connect to a stream and request the server to play my file on that stream. Apparently that doesn't work with files? It works just fine for live streams. I really don't get why this should differ at all. Any suggestions?

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  • Grammatically correct double-noun identifiers, plural versions

    - by Michal Czardybon
    Consider compounds of two nouns, which in natural English would most often appear in the form "noun of noun", e.g. "direction of light", "output of a filter". When programming we usually write "LightDirection" and "FilterOutput". Now, I have a problem with plural nouns. There are two cases: 1) singular of plural e.g. "union of (two) sets", "intersection of (two) segments" Which is correct, SetUnion and SegmentIntersection or SetsUnion and SegmentsIntersection? 2) plural of plural There are two subcases: (a) Many elements, each having many related elements, e.g. "outputs of filters" (b) Many elements, each having single related element, e.g. "directions of vectors" Shell I use FilterOutputs and VectorDirections or FiltersOutputs and VectorsDirections? I suspect correct is the first version (FilterOutupts, VectorDirections), but I think it may lead to ambiguities, e.g. FilterOutputs - many outputs of a single filter or many outputs of many filters? LineSegmentProjections - projections of many segments or many projections of a single segment?

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  • Better name needed for applying a function on elements of a container

    - by stefaanv
    I have a container class (containing a multi-index container) for which I have a public "foreach" member-function, so users can pass a functor to apply on all elements. While implementing, I had a case where the functor should only be applied to some elements of a range in the container, so I overloaded the foreach, to pass some valid range. Now, in some cases, it was worthwhile to stop on a certain condition, so practically, I let the foreach stop based on the return-value of the function. I'm pleased with how the system works, but I have one concern: How should a "foreach" on a range, with stop conditions be called? Anyone knows a generic, clear and concise name?

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  • How should I migrate DDL changes from one environment to the next?

    - by Rl
    I make DDL changes using SQL Developer's GUI. Problem is, I need to apply those same changes to the test environment. I'm wondering how others handle this issue. Currently I'm having to manually write ALTER statements to bring the test environment into alignment with the development environment, but this is prone to error (doing the same thing twice). In cases where there's no important data in the test environment I usually just blow everything away, export the DDL scripts from dev and run them from scratch in test. I know there are triggers that can store each DDL change, but this is a heavily shared environment and I would like to avoid that if possible. Maybe I should just write the DDL stuff manually rather than using the GUI?

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  • When to use Hibernate?

    - by Ramo
    Hi All, I was asked in an interview this question so I answered with the following: -Better Performance: - Efficient queries. - 1st and 2nd level caching. - Good caching gives better scalability. - Good Database Portability: - Changing the DB is as easy as changing the dialect configuration. - Increased Developer Productivity: - Think only in object terms not in query language terms. But I also feel that systems fall in one of the below categories, and Hibernate may not be suited for all these cases, I'm interested in your thoughts about this, do you agree with me? please let me know when would use HB in the following case and why. Write Only Systems: Read Only Systems: Write Mostly Systems: Read Mostly Systems: Regards Ramo

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  • PC reboots spontaenously: debugging tips [closed]

    - by aaron
    I swapped my core 2 duo for a quad core recently, and generally things run fine, but every now and then my computer just restarts. I don't even get a blue screen (Vista 32). Core temp isn't a problem. My thinking is that my power supply is inadequate, but I haven't been able to test that (one idea was to under clock the cpu to see if that helped, but going up in speed was the only simple thing to do in the BIOS) Two cases where I semi-consistanly get problems: - Borderlands windowed after some period of time (and some other games, but Borderlands does it pretty regularly) - watching a video (e.g. quicktime/vlc) and having another video running Another thought is non-cpu heat? Maybe the graphics card? Any thoughts on how to track this down appreciated. Thanks!

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  • Android: how to update UI dynamically?

    - by pandre
    I have an Android app and I need to change UI dynamically: ex: when user presses a button, I want to change the current activity's views and, as in some cases there are a lot of views involved, I need to display a ProgressDialog. I have been using an AsyncTask, but I think that it is not the best solution, because AsyncTask's doInBackground runs a different thread, so I can't update UI from there - I have to use runOnUiThread, which runs the code in the UI Thread, but freezes the progress dialog that is shown. I guess there should be more people with similar issues, as updating UI while displaying a ProgressDialog seems to be something done regularly by applications. So does anyone have a solution to this?

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  • How do you handle options that can't be used together with OptionParser?

    - by Joel
    My Python script (for todo lists) is started from the command line like this: todo [options] <command> [command-options] Some options can not be used together, for example todo add --pos=3 --end "Ask Stackoverflow" would specify both the third position and the end of the list. Likewise todo list --brief --informative would confuse my program about being brief or informative. Since I want to have quite a powerful option control, cases like these will be a bunch, and new ones will surely arise in the future. If a users passes a bad combination of options, I want to give an informative message, preferably along with the usage help provided by optparse. Currently I handle this with an if-else statement that I find really ugly and poor. My dream is to have something like this in my code: parser.set_not_allowed(combination=["--pos", "--end"], message="--pos and --end can not be used together") and the OptionParser would use this when parsing the options. Since this doesn't exist as far as I know, I ask the SO community: How do you handle this?

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  • Implementation Details as a "Document" ( In generic terms) - Python, C++

    - by mgj
    Hi..:) For documentation and presentation purposes, we often find professionals/students creating SRS, coding guidelines etc. for these things there is some kind of a checklist which one could use to appropriately match what could relate to a specific case and accordingly one does a documentation for each. On those grounds could you please give me some sort of a checklist( any points/guidelines) one could use for going about Implementation( in the form of Implementation Details) in Python and C++ . Although this might sound specific as the query is "Implementation Details" and is different for different cases as one goes about the REAL implementation, I just want a SET of guidelines one should follow ( Preferably In Python, C++ specific, even for any other language is Welcome) if this( Implementation Details ) has to also be documented or presented. Hope the question is clear, I am sorry if it still sounds ambiguous, I guess this is the best I could do to frame my query. Thank you for your time...:)

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  • Proper thread termination in multi-threaded C# application

    - by Brian
    I have what I think is a rather complex problem. I have a C# application that utilizes a plug-in architecture using reflection. The application loads plug-in dlls and the user is able to enable/disable them. When a plug-in is enabled, the main app starts a thread to run the plug-in in. In many cases the plug-in may have multiple threads of its own. When I want to disable a plug-in I am calling Thread.Abort(). This seems to kill the initial thread that was created for the plug-in, but any additional threads that the plug-in created continue running. Is there a better way to stop all of the associated plug-in's threads along with the main thread? Thanks.

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  • Windows Azure:broken logging after migration to the new SDK 1.3

    - by cloud.dev
    Hi, pls, help. I've migrated to new SDK 1. (Full-IIS mode) I use the following logging: case TraceLevel.Error: Trace.TraceError(message); break; case TraceLevel.Warning: Trace.TraceWarning(message); break; case TraceLevel.Info: Trace.TraceInformation(message); break; case TraceLevel.Verbose: Trace.WriteLine(message); break; it worked fine until I migrated to the new SDK. now, logging works only for Worker Roles. Web-Role can log only inside OnStart-method of WebRole.cs in other cases: logged nothing I understand that Full-IIS means different domains. so, I must call someway WaIIS.exe from w3wp.exe or ...?

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  • Rails nested attributes with a join model, where one of the models being joined is a new record

    - by gzuki
    I'm trying to build a grid, in rails, for entering data. It has rows and columns, and rows and columns are joined by cells. In my view, I need for the grid to be able to handle having 'new' rows and columns on the edge, so that if you type in them and then submit, they are automatically generated, and their shared cells are connected to them correctly. I want to be able to do this without JS. Rails nested attributes fail to handle being mapped to both a new record and a new column, they can only do one or the other. The reason is that they are a nested specifically in one of the two models, and whichever one they aren't nested in will have no id (since it doesn't exist yet), and when pushed through accepts_nested_attributes_for on the top level Grid model, they will only be bound to the new object created for whatever they were nested in. How can I handle this? Do I have to override rails handling of nested attributes? My models look like this, btw: class Grid < ActiveRecord::Base has_many :rows has_many :columns has_many :cells, :through => :rows accepts_nested_attributes_for :rows, :allow_destroy => true, :reject_if => lambda {|a| a[:description].blank? } accepts_nested_attributes_for :columns, :allow_destroy => true, :reject_if => lambda {|a| a[:description].blank? } end class Column < ActiveRecord::Base belongs_to :grid has_many :cells, :dependent => :destroy has_many :rows, :through => :grid end class Row < ActiveRecord::Base belongs_to :grid has_many :cells, :dependent => :destroy has_many :columns, :through => :grid accepts_nested_attributes_for :cells end class Cell < ActiveRecord::Base belongs_to :row belongs_to :column has_one :grid, :through => :row end

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  • Obtain all keys of a Neo4j index

    - by MattiSG
    I have a Neo4j database whose content is generated dynamically from a big dataset. All “entry points” nodes are indexed on a named index (IndexManager.forNodes(…)). I can therefore look up a particular “entry point” node. However, I would now like to enumerate all those specific nodes, but I can't know on which key they were indexed. Is there any way to enumerate all keys of a Neo4j Index? If not, what would be the best way to store those keys, a data type that is eminently non-graph-oriented? UPDATE (thanks for asking details :) ): the list would be more than 2 million entries. The main use case would be to never update it after an initialization step, but other use cases might need it, so it has to be somewhat scalable. Also, I would really prefer avoiding killing my current resilience abilities, so storing all keys at once, as opposed to adding them incrementally, would be a last-resort solution.

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  • How to configure .NET test assembly to use website web.config?

    - by Morten Christiansen
    I've run into a problem setting up Selenium tests for an ASP.NET MVC project in cases where I need the settings provided in the web.config of the site under test. The problem is that I want to create a dummy user before running the test and this causes an error saying that the password-answer supplied is invalid. This is due to the test assembly not using the web.config, instead using default values for membership configuration. I've tried to copy the relevant section (membership configuration) into the app.config of the assembly without luck, but I admit I'm just grasping at straws here.

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  • Qt/C++ event loop exception handling

    - by Georg
    I am having an application heavily based on QT and on a lot of third party libs. THese happen to throw some exceptions in several cases. In a native Qt App this causes the application to abort or terminate. Often the main data model is still intact as I am keeping it in pure Qt with no external data. So I am thinking that I could also just recover by telling the user that there has occured an error in this an that process and he should save now or even decide to continue working on the main model. Currently the program jsut silently exits without even telling a story. Please help.

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