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  • SQLVDI error - attempt to release mutex not owned by caller

    - by Chris W
    I've started getting some errors in the App event log of one of our database servers (Windows 2003 & SQL Server 2005). The nightly full database backups are completing successfully however immediately after the job success is written to the event log there is a run of entries that say: SQLVDI: Loc=CVDS. Desc=Release(ClientAliveMutex). ErrorCode=(288)Attempt to release mutex not owned by caller. There's five of these logged - the server itself has more than 20 databases on it which are all backed up successfully. The server is backed up by Bacula using a VSS backup. Has anyone got any ideas what would be causing the errors? They seem to have started after a re-boot on Friday to install some patches which included KB960089. Edit: After getting the errors for a few days they've now stopped without any action on my part other than letting the backups continue as they were. It may be a coincidence but they stopped after Bacula completed its weekly full rather than the daily incremental backup.

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  • Dataflow Programming - Patterns and Frameworks

    - by Styrac
    I just came across the proposed Boost::Dataflow library. It seems like an interesting approach and I was wondering if there are other such alternative frameworks for C++, and if there are any related design patterns. I have not ruled out Boost::Dataflow, I am just looking into any available alternatives so I can understand the domain and my options better (or roll my own if necessary).

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  • SQL Server 2005 standard filegroups / files for performance on SAN

    - by Blootac
    I submitted this to stack overflow (here) but realised it should really be on serverfault. so apologies for the incorrect and duplicate posting: Ok so I've just been on a SQL Server course and we discussed the usage scenarios of multiple filegroups and files when in use over local RAID and local disks but we didn't touch SAN scenarios so my question is as follows; I currently have a 250 gig database running on SQL Server 2005 where some tables have a huge number of writes and others are fairly static. The database and all objects reside in a single file group with a single data file. The log file is also on the same volume. My interpretation is that separate data files should be used across different disks to lessen disk contention and that file groups should be used for partitioning of data. However, with a SAN you obviously don't really have the same issue of disk contention that you do with a small RAID setup (or at least we don't at the moment), and standard edition doesn't support partitioning. So in order to improve parallelism what should I do? My understanding of various Microsoft publications is that if I increase the number of data files, separate threads can act across each file separately. Which leads me to the question how many files should I have. One per core? Should I be putting tables and indexes with high levels of activity in separate file groups, each with the same number of data files as we have cores? Thank you

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  • Proper way to set class variables

    - by ensnare
    I'm writing a class to insert users into a database, and before I get too far in, I just want to make sure that my OO approach is clean: class User(object): def setName(self,name): #Do sanity checks on name self._name = name def setPassword(self,password): #Check password length > 6 characters #Encrypt to md5 self._password = password def commit(self): #Commit to database >>u = User() >>u.setName('Jason Martinez') >>u.setPassword('linebreak') >>u.commit() Is this the right approach? Should I declare class variables up top? Should I use a _ in front of all the class variables to make them private? Thanks for helping out.

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  • Mindmapping as a Documentation Tool

    - by mcass20
    My team has recently begun using XMind to organize development projects. It seems to be a pretty powerful brainstorming software. I'm just wondering if other developers have employed similar techniques to aid in documenting software design.

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  • Looking for efficient scaling patterns for Silverlight application with distributed text-file data s

    - by Edward Tanguay
    I'm designing a Silverlight software solution for students and teachers to record flashcards, e.g. words and phrases that students find while reading and errors that teachers notice while teaching. Requirements are: each person publishes his own flashcards in a file on a web server, e.g. http://:www.mywebserver.com/flashcards.txt other people subscribe to that person's flashcards by using a Silverlight flashcard reader that I have developed and entering the URLs of flashcard files they want to subscribe to, URLs and imported flashcards being saved in IsolatedStorage the flashcards.txt file has the following simple format: title, then blocks of question/answers: Jim Smith's flashcards from English class 53-222, winter semester 2009 ==fla Das kann nicht sein. That can't be. ==fla Es sei denn, er kommt nicht. Unless he doesn't come. The user then makes public the URL to his flashcard file and other readers begin reading in his flashcards. In order to lower the bar for non-technical users to contribute, it will even be possible for them to save this text in a Google Document, which they publish and distribute the URL. The flashcard readers will then recognize it is a google document and perform the necessary screen scraping to get at the raw text. I have two technical questions about this approach: What is a best way to plan now for scalability issues: e.g. if your reader is subscribed to 10 flashcard files that are each 200K, it will have to download 2MB of text just to find out if any new flashcards are available. Or can I somehow accurately and consistently get at the last update date/time of text files on servers and published google docs? Each reader will have the ability to allow the person to test himself on imported flashcards and add meta information to them, e.g. categorize them, edit them, etc. This information will be stored in IsolatedStorage along with the important flashcards themselves. What is a good pattern to allow these readers to share and synchronize this meta data, e.g. so when you are looking at a flashcard you can see that 5 other people have made corrections to it. The best solution I can think of now is that the Silverlight readers will have to republish their data to a central database, but then there is the problem of uniquely identifying each flashcard, the best approach seems to be URL + position-in-file, or even better URL + original text of both question and answer fields, but both of these have their obvious drawbacks. The main requirement is that the bar for participation is kept as low as possible, i.e. type text in a google document, publish it, distribute the URL, and you're publishing within the flashcard community. So I want to come up with the most efficient technical solutions in order to compensate for the lack of database, lack of unique ids, etc. For those who have designed or developed similar non-traditional, distributed database projects like this, what advice, experience or best-practice tips you can share on the above two points?

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  • Factory Pattern - when do you say you need a specialised factory

    - by dbones
    Hi, I am having a little design crisis, I am making a Plane class, which is made of an engine 2 wings and N seats The engine takes in a engine size, and the wings have a span. would this still be feasible to have a PlaneFactory, when the factory may have to take in multiple parameters to setup the plane (wings, engine, no of seats) thanks in advance bones

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  • Best UI to be shown to User while his request is still in process behind the scenes ?

    - by Rachel
    I am currently involved with an Application where I need to design the UI part of the Application and current I am in the process of implementation of UI which would be displayed to end user while his or her request is being processed behind the scenes. So my question is that: What is the best UI approach/symbol/suggestions to be displayed to end User while his or her request is still being processed behind the scenes ? Thanks.

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  • What is a 'thunk'?

    - by fbrereto
    I've seen it used in programming (specifically in the C++ domain) and have no idea what it is. Presumably it is a design pattern, but I could be wrong. Can anyone give a good example of a thunk?

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  • CSV engine on MySQL server

    - by Jeff
    I don't think that this is a programming question so I am going to ask it here - Reading the book high performance mysql, I read about the CSV engine. The paragraph says: The CSV engine can treat comma-separated values (CSV) files as table, but it does not support indexes on them. This engine lets you copy files in and out of the database while the server is running. If you export a CSV file from a spreadsheet and save it in the MySQL server's data directory, the server can read it immediately. Similary, if you write data to a CSV table, an external program can read it right away. CSV tables are especially useful as a data interchange format and for certain kinds of logging. What I get from this paragraph is that I can copy a .CSV file into the data directory of database, and it should show as a table that is able to be read from. However, whenever I copy a test .csv file into the directory, it does not appear as a table. I can't access it. I am using MySQL 5.5 also Does anyone know why this is not working, or what I am doing wrong? Thanks

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  • Have you been stuck with the math in a Flash project?

    - by VideoDnd
    Have you been stuck with the math in a Flash project? It's a loose design pattern my director formulated. My goal is to keep the project object oriented, and get 'non Flash obstacles' off my plate. XML values going to AS3, updating a changing acceleration formula. I don't hate math, but it just doesn't seem OOP or good project planning to have the math stuck in Flash. Your comments are welcome.

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  • Can one Python project use both 2.x and 3.x code?

    - by Begbie00
    Hi all - I'm going to start on a long (~1-year) programming project in Python. I want to use wxPython for my GUI (supports 2.6), but I also want to use 3.1 for the rest of the project (to start using the 3.x syntax). Is there any way for me to design a project that mixes 2.x and 3.x modules? Or should I just bite the bullet and use either 2.x (preferred, since I really want to learn wxPython) or 3.x throughout? Thanks, Mike

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  • Why did Matz choose to make Strings mutable by default in Ruby?

    - by Seth Tisue
    It's the reverse of this question: http://stackoverflow.com/questions/93091/why-cant-strings-be-mutable-in-java-and-net Was this choice made in Ruby only because operations (appends and such) are efficient on mutable strings, or was there some other reason? (If it's only efficiency, that would seem peculiar, since the design of Ruby seems otherwise to not put a high premium on faciliating efficient implementation.)

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  • How to change easily between ajax-based website and basic HTML website?

    - by A.S al-shammari
    Hi, I have a website ( based on JSP/Servlets ,using MVC pattern), and I want to support AJAX-based website and basic HTML-based website. website visitors should be able to change the surfing mode from Ajax to basic HTML and vise versa, - as it applies in Google-mail. The Questions : What is the best way to achieve this goal easily? Should I design two views for each page? I use JQuery and JSON as the result of this answer.

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  • AWS document on number of databases allowed on an Amazon RDS instance

    - by user35042
    At the Amazon RDS FAQ there is the question "What is a database instance (DB Instance)?". The entire answer (as of mid-June 2012) is: You can think of a DB Instance as a database environment in the cloud with the compute and storage resources you specify. You can create and delete DB Instances, define/refine infrastructure attributes of your DB Instance(s), and control access and security via the AWS Management Console, Amazon RDS APIs, and Command Line Tools. Multiple MySQL databases or SQL Server databases (up to 30) or Oracle database schemas can be created on a given DB Instance. The last part of that quote, "Multiple MySQL databases or SQL Server databases (up to 30) Oracle database schemas" I interpret to mean that you can have an "unlimited" number of databases on an RDS MySQL or Oracle instance but only 30 databases on an MS SQL Server instance ("unlimited" meaning not limited by the RDS infrastructure itself). This was asked in the Stackoverflow question Does Amazon RDS support multiple databases per instance?. The answer quoted an older version of the FAQ. What I am looking for is an Amazon document that clarifies this question, or else someone who has experience using Amazon RDS who can attest what the situation actually is.

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  • Schemas and tables versus user-ids in a single table using PostgreSQL

    - by gvkv
    I'm developing a web app and I've come to a fork in the road with respect to database structure and I don't know which direction to take. I have a database with user information that I can structure one of two ways. The first is to create a schema and a set of tables for each user (duplicating the structure for each user) and the second is to create a single set of tables and query information based on user-id. Suppose 100000 users. Here are my questions: Considering security, performance, scalability and administration where does each choice lie? Would the answers change for 1000000 or 10000? Is there a set of best practices that lead to one choice or the other? It seems to me that multiple schemas are more secure since it's trivial to restrict user privileges but what about performance and scalability? Administration seems like a wash since dumping (and restoring) lots of schemas isn't any more difficult than dumping a few.

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  • PhpMyAdmin Missing parameter:

    - by Ali
    Everything was working fine until this moment I want to create a new database and I'm receiving this error db_create.php: Missing parameter: new_db (FAQ 2.8) Also when I was trying to export my database I also receive the following error export.php: Missing parameter: what (FAQ 2.8) export.php: Missing parameter: export_type (FAQ 2.8) When I looked it FAQ 2.8 from the suggested link in PHPMYADMIN 2.8 I get "Missing parameters" errors, what can I do? Here are a few points to check: In config.inc.php, try to leave the $cfg['PmaAbsoluteUri'] directive empty. See also FAQ 4.7. Maybe you have a broken PHP installation or you need to upgrade your Zend Optimizer. See http://bugs.php.net/bug.php?id=31134. If you are using Hardened PHP with the ini directive varfilter.max_request_variables set to the default (200) or another low value, you could get this error if your table has a high number of columns. Adjust this setting accordingly. (Thanks to Klaus Dorninger for the hint). In the php.ini directive arg_separator.input, a value of ";" will cause this error. Replace it with "&;". If you are using Hardened-PHP, you might want to increase request limits. The directory specified in the php.ini directive session.save_path does not exist or is read-only. I did tried with php.ini to make sure that I've session.save_path = "/tmp" I'm using Mac Xserver and running with MAMP I did tried everything to restart my server and nothing help. Please if anyone help me to give me some suggestion. Apologize if I post in a wrong place.

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  • JFace Providers and MVC/MVP/etc.

    - by Alexey Romanov
    Where do the JFace providers belong in an MVP or MVC architecture? Or should Provider pattern be treated as a different way of View-Model separation? If so, is it the same as the ASP.NET Provider pattern? Is there an article on a proper design of JFace applications using Providers?

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  • Proper way to set object instance variables

    - by ensnare
    I'm writing a class to insert users into a database, and before I get too far in, I just want to make sure that my OO approach is clean: class User(object): def setName(self,name): #Do sanity checks on name self._name = name def setPassword(self,password): #Check password length > 6 characters #Encrypt to md5 self._password = password def commit(self): #Commit to database >>u = User() >>u.setName('Jason Martinez') >>u.setPassword('linebreak') >>u.commit() Is this the right approach? Should I declare class variables up top? Should I use a _ in front of all the class variables to make them private? Thanks for helping out.

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  • Silverlight open source font replacement for Segoe

    - by Rus
    I'm currently building a LOB application in Silverlight 4. I've been considering the question of typography for the application. After some experimentation on the design side the font that people like is Segoe UI. Now I can embed this font and although the font is freely available in Windows we don’t have distribution rights for this font. I am looking for an open source font visually equivalent of the Segoe family that can be freely distributed. Does such a font exist?

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  • Observer pattern used with decorator pattern

    - by icelated
    I want to make a program that does an order entry system for beverages. ( i will probably do description, cost) I want to use the Decorator pattern and the observer pattern. I made a UML drawing and saved it as a pic for easy viewing. This site wont let me upload as a word doc so i have to upload a pic - i hope its easily viewable.... I need to know if i am doing the UML / design patterns correctly before moving on to the coding part. Beverage is my abstract component class. Espresso, houseblend, darkroast are my concrete subject classes.. I also have a condiment decorator class milk,mocha,soy,whip. would be my observer? because they would be interested in data changes to cost? Now, would the espresso,houseblend etc, be my SUBJECT and the condiments be my observer? My theory is that Cost is a changes and that the condiments need to know the changes? So, subject = esspresso,houseblend,darkroast,etc.. // they hold cost() Observer = milk,mocha,soy,whip? // they hold cost() would be the concrete components and the milk,mocha,soy,whip? would be the decorator! So, following good software engineering practices "design to an interface and not implementation" or "identify things that change from those that dont" would i need a costbehavior interface? If you look at the UML you will see where i am going with this and see if i am implementing observer + Decorator pattern correctly? I think the decorator is correct. since, the pic is not very viewable i will detail the classes here: Beverage class(register observer, remove observer, notify observer, description) these classes are the concrete beverage classes espresso, houseblend,darkroast, decaf(cost,getdescription,setcost,costchanged) interface observer class(update) // cost? interface costbehavior class(cost) // since this changes? condiment decorator class( getdescription) concrete classes that are linked to the 2 interface s and decorator are: milk,mocha,soy,whip(cost,getdescription,update) these are my decorator/ wrapper classes. Thank you.. Is there a way to make this picture bigger?

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  • Learning to write organized and modular programs

    - by Peter
    I'm a computer science student, and I'm just starting to write relatively larger programs for my coursework (between 750 - 1500 lines). Up until now, it's been possible to get by with any reasonable level of modularization and object oriented design. However, now that I'm writing more complex code for my assignments I'd like to learn to write better code. Can anyone point me in the direction of some resources for learning about what sort of things to look for when designing your program's architecture so that you can make it as modularized as possible?

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