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  • Essential management tools for a small/medium software development shop

    - by mikera
    I've recently started work with an organisation that is rapidly expanding and is recruiting or growing several development teams (including two web-based products and a data warehouse/BI team). They are basically working to agile methodologies but haven't formalised a standard way of working yet. Despite the fact that it is early days, I've been surprised by the lack of tools being used to manage the development processes (e.g. no issue tracker, no tool to manage the product backlog etc.) Although it's not my primary responsibility, I'd like to help them out with some recommendations on the most important tools they should get in place. What are the 3-5 top priority tools to establish for management of a good development shop? Why are they necessary? How do they improve the software development process, and how do I justify them to my bosses?

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  • Cannot connect to google talk using empathy/pidgin after upgrading

    - by levesque
    I can't seem to be able to connect to google talk using either pidgin or empathy after upgrading to Ubuntu 10.10 (fresh install). I do not know why... empathy just writes "Connecting ..." forever and never connects. What can I do from there? Google talk's web interface works just fine for me so I doubt it is a firewall issue. EDIT: In fact sometimes it's able to connect (empathy), it just takes a LOOONG time (I'd say about 5 mins), longer than I am willing to wait. On the other hand, the web interface is able to connect in seconds.

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  • Developer Training – Difficult Questions and Alternative Perspective – Part 3

    - by pinaldave
    Developer Training - Importance and Significance - Part 1 Developer Training – Employee Morals and Ethics – Part 2 Developer Training – Difficult Questions and Alternative Perspective - Part 3 Developer Training – Various Options for Developer Training – Part 4 Developer Training – A Conclusive Summary- Part 5 Congratulations!  You are now a fully trained developer!  You spent hours in a classroom, watching webinars, and reading materials.  You are now more educated and more prepared than ever before.  Now what? Stay or Quit The simple answer is that you now have two options – stay where you are or move on to a new job.  Even though you might now be smarter than you have ever felt before, this can still be a tough decision to make.  You feel extra trained and ready for a promotion or a raise, but you and your employer might not see eye to eye on this issue.  The logical conclusion is to go on a job hunt, but that might not be the most ethical thing to do. Click Image to Enlarge Manager’s Perspective Click Image to Enlarge Try to see the issue from your manager’s perspective.  You feel that you have just spent a lot of time and energy getting trained, and you should be rewarded.  But they have invested their time and energy in you.  They might see the training as a way to help you complete the goals they require from you, or as a way to help you complete tasks that will ultimately end in a reward or promotion. Moral Compass As in most cases, honesty is the best policy.  Be open with your manager about your expectations, and ask them to explain their goals.  When there is open and honest communication, everyone can walk away happy.  If you’re unable to discuss with your manager for one reason or another, just try to keep the company policy in mind and follow your own moral compass.  If all else fails, and your company is unwilling to make allowances for your new value, offer to pay the company back for the training before moving on your way. Whether you stay at your old job or move on to a new one, you are still faced with the question of what you’re going to do with all your new knowledge.  If you feel comfortable, offer to train others around you who are interested in the same subject.  This can look very good on your resume, and if you are working in a team environment it is sure to help you in the long run! What Next? You can even offer to train other trainers at the company – managers, those above you, or even report back to your original trainer about how your education is helping you in the work place.  Obviously this should be completely voluntary on the trainer’s part.  Taking advice from a “newbie” may not be their favorite idea, but it could also show the company that you are open to expanding your horizons and being helpful to everyone around you. Last in Line for Opportunity Click Image to Enlarge At this time, let us address a subject related to training and what to do with it – what if you are always overlooked for training?  This can as thorny a problem as receiving training in the first place.  The best advice is to let your supervisors know that you are always open to training and very interested in certain topics.  If you are consistently passed over, be patient.  Your turn will probably come, but the company as a whole has to focus on other problems at the moment.  If you feel that there are more personal issues at play, be sure to bring this up with your supervisor in a calm and professional manager so that everything can be worked out best for both parties. You, Yourself and Your Future! If all else fails, offer to pay for training yourself.  Perhaps money problems are at the root of being passed over.  Even if there are other reasons, offering to pay your own way shows your dedication and could work out well for you in the long run.  Always remember – in life you have to go out and make your own way, you cannot always sit and wait for things to land in your lap. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Developer Training, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • Silverlight Cream for January 01, 2011 -- #1020

    - by Dave Campbell
    In this short New Year's Day 2011 Issue, 3 Mikes: Mike Taulty, Mike Snow, and Mike Ormond. Above the Fold: Silverlight: "Native Extensions for Silverlight (NESL)?" Mike Taulty WP7: "Monitoring Memory Usage on Windows Phone 7" Mike Ormond From SilverlightCream.com: Native Extensions for Silverlight (NESL)? Mike Taulty has a really good write-up on Native Extensions for Silverlight... he describes what that project is about and gives guidance on best practices. Win7 Mobile: Uniquely Identifying a Device or User Mike Snow has a post up describing how to uniquely identify the phone or device your app is running on using the Microsoft.Phone.Info.DeviceExtendedProperties namespace Monitoring Memory Usage on Windows Phone 7 Mike Ormond has a post up showing how to turn on and make use of the framerate counters in WP7 Stay in the 'Light! Twitter SilverlightNews | Twitter WynApse | WynApse.com | Tagged Posts | SilverlightCream Join me @ SilverlightCream | Phoenix Silverlight User Group Technorati Tags: Silverlight    Silverlight 3    Silverlight 4    Windows Phone MIX10

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  • Wireless driver - how to load manufacturer's STA file (Ralink 3290)

    - by Matt
    Caution: I'm a newb. Hardware: Giada i35G, cedar trail atom with nvidia gf119, railtek ethernet and Ralink 3290 for wireless. Already accomplished: Installed Ubuntu 12.10, loaded GPU drivers and redirected sound out through GPU card to HDMI. Ethernet works like a charm. Issue: Can't get my wireless up and running. There seems to be no package to which I can simply run a sudo get-aspt install ... I found the corresponding Linux driver from the manufacturer's site, but I have not managed to find out what to with the file. Here's the manufacturers site: http://www.ralinktech.com/en/04_support/support.php?sn=501 I get a file with the following name: \2012_0508_RT3290_Linux_STA_v2.6.0.0.bz2 I hope somebody might be able to tell me what to do next. Thanks for reading and apologies for potentially asking a trivial question. Best regards, Matt

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  • Java Transaction Service without the application server

    - by johnny
    Is it possible to have a Java standalone application (no application server attached) that exposes some operations that a client can call and be the one to manage the transactions? I was thinking this application to expose JNDI resources and get a hold of a java:comp/UserTransaction from there, get also a bean from there and call methods A, B and C on it and coordinate the transaction from the client? The application I'm writing isn't complex enough so that I need a big application server around it so I'm thinking to have a standalone JTS inside it that the client could interact with from a transactions point of view. I don't have much experience with distributed transactions and don't really know how to tackle the issue. Is it even possible? Am I getting myself into something beyond what a mere mortal (programmer) can handle? How can I approach this?

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  • Acer 7551g - hibernation and suspending don't work

    - by gonzunio
    Issue is quite the same like here, I've tried everything I found and nothing happens. If I use uswsusp, suspending works good, but graphics doesn't wake up, when I want to hibernate system, it tells me "Looking for splash system... none s2disk:snapshotting system" and nothing happens. I'm using ATI drivers, i've tried to disable kms, unload usb3 and network drivers, still nothing. Please help me, I don't want to come back to Windows after my 2-year-relationship with Linux. I can share all files I have with you, just help me.

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  • How to test a 3D rendering engine?

    - by YoYo
    Me and some friends developing simple 3D rendering engine as practice for the university. We used Ogre 3d as prototype and now we are developing it from base The engine is wrapped up in simple game that asks the user to select shape (circle, triangle, square...), color and dimensions and renders the image to the screen. It also enables to move and rotate the shape on screen using mouse. We would like to test automate the view rendering. I could not find any test framework for this issue and I would like to know how 3D test is done in non manual matter

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  • rsyslog channels change ownership from root

    - by Paul Whelan
    Hello all I am using rsyslog on ubuntu 10.4 64bit LTS. the following is the relevant config in /etc/rsyslog.d/60-mylogger.conf $template Paul,"%msg%\n" $outchannel log_rotation_paul,/var/log/paul/events.log,2000,/opt/scripts/log_rotation_script.sh local0.* $log_rotation_paul;Paul This should rotate every 2000 bytes My problem is the the channel directive here causes the ownership defined in /etc/rsyslog.conf to be completely ignored and when my log rotate script is called I don't have the root permissions required to move my log file as its the script runs as rsyslog and the file I am moving requires root permissions. Any ideas I found this link but unfortunately it does not fix my issue.

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  • Importing data from text file to specific columns using BULK INSERT

    - by Dinesh Asanka
    Bulk insert is much faster than using other techniques such as  SSIS. However, when you are using bulk insert you can’t insert to specific columns. If, for example, there are five columns in a table you should have five values for each record in the text file you are importing from. This is an issue when you are expecting default values to be inserted into tables. Let us say you have table as below: In this table, you are expecting ID, Status and CreatedDate to be updated automatically, so your text file may only have   FirstName  LastName  values as below: Dinesh,Asanka Saman,Liyanage Ruwan,Silva Susantha,Bathige Jude,Peires Sanjeewa,Jayawickrama If you use bulk insert to this table like follows, You will be returned an error: Bulk load data conversion error (type mismatch or invalid character for the specified codepage) for row 1, column 1 (ID). To avoid this you will need to create a view with the columns you are expecting to fill and use bulk insert against it. If you check the table now, you will see table with values in the text file and the default values.

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  • how to do database updates in each release

    - by Manoj R
    Our application uses database (mostly Oracle), and database is at the core. Each customer has its own database, with its own copy of application. Now with each new release of our product, we also need to update the database schema. These changes are adding new tables, removing columns, manipulating data etc. How do the people handle this? Are there any standard processes for this? EDIT:- The main issue is the databases are huge with many tables and more of huge amount of data. We provide the scripts and some utilities to manipulate the data. How to handle the failures and false negatives? More of looking for this kind articles. http://thedailywtf.com/Articles/Database-Changes-Done-Right.aspx

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  • NTFS Signature is missing

    - by LuckyBearing
    So I got a new secondary hard drive caddy and formatted it to NTFS. I forgot to partition the drive after formatting, I rebooted and now I can't access the drive that has around 400gb of data because the NTFS Signature is missing. "Error mounting...NTFS signature is missing. Failed to mount '/dev/sdb2': Invalid argument The device '/dev/sdb2' doesn't seem to have a valid NTFS. Maybe the wrong device is used? Or the whole disk instead of a partition (e.g. /dev/sda, not /dev/sda1)? Or the other way around?" Says the same thing for sdb1. But I think the sdb2 has most, if not all of the copied data. How do I retrieve my data back? I read somewhere I can install ntfs-progs and it will fix the issue. here

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  • Migrating SQL Server Databases – The DBA’s Checklist (Part 2)

    - by Sadequl Hussain
    Continuing from Part 1  , our Migration Checklist continues: Step 5: Update statistics It is always a good idea to update the statistics of the database that you have just installed or migrated. To do this, run the following command against the target database: sp_updatestats The sp_updatestats system stored procedure runs the UPDATE STATISTICS command against every user and system table in the database.  However, a word of caution: running the sp_updatestats against a database with a compatibility level below 90 (SQL Server 2005) will reset the automatic UPDATE STATISTICS settings for every index and statistics of every table in the database. You may therefore want to change the compatibility mode before you run the command. Another thing you should remember to do is to ensure the new database has its AUTO_CREATE_STATISTICS and AUTO_UPDATE_STATISTICS properties set to ON. You can do so using the ALTER DATABASE command or from the SSMS. Step 6: Set database options You may have to change the state of a database after it has been restored. If the database was changed to single-user or read-only mode before backup, the restored copy will also retain these settings. This may not be an issue when you are manually restoring from Enterprise Manager or the Management Studio since you can change the properties. However, this is something to be mindful of if the restore process is invoked by an automated job or script and the database needs to be written to immediately after restore. You may want to check the database’s status programmatically in such cases. Another important option you may want to set for the newly restored / attached database is PAGE_VERIFY. This option specifies how you want SQL Server to ensure the physical integrity of the data. It is a new option from SQL Server 2005 and can have three values: CHECKSUM (default for SQL Server 2005 and latter databases), TORN_PAGE_DETECTION (default when restoring a pre-SQL Server 2005 database) or NONE. Torn page detection was itself an option for SQL Server 2000 databases. From SQL Server 2005, when PAGE_VERIFY is set to CHECKSUM, the database engine calculates the checksum for a page’s contents and writes it to the page header before storing it in disk. When the page is read from the disk, the checksum is computed again and compared with the checksum stored in the header.  Torn page detection works much like the same way in that it stores a bit in the page header for every 512 byte sector. When data is read from the page, the torn page bits stored in the header is compared with the respective sector contents. When PAGE_VERIFY is set to NONE, SQL Server does not perform any checking, even if torn page data or checksums are present in the page header.  This may not be something you would want to set unless there is a very specific reason.  Microsoft suggests using the CHECKSUM page verify option as this offers more protection. Step 7: Map database users to logins A common database migration issue is related to user access. Windows and SQL Server native logins that existed in the source instance and had access to the database may not be present in the destination. Even if the logins exist in the destination, the mapping between the user accounts and the logins will not be automatic. You can use a special system stored procedure called sp_change_users_login to address these situations. The procedure needs to be run against the newly attached or restored database and can accept four parameters. Depending on what you want to do, you may be using less than four though. The first parameter, @Action, can take three values. When you specify @Action = ‘Report’, the system will provide you with a list of database users which are not mapped to any login. If you want to map a database user to an existing SQL Server login, the value for @Action will be ‘Update_One’. In this case, you will only need to provide the database user name and the login it will map to. So if your newly restored database has a user account called “bob” and there is already a SQL Server login with the same name and you want to map the user to the login, you will execute a query like the following: sp_change_users_login         @Action = ‘Update_One’,         @UserNamePattern = ‘bob’,         @LoginName = ‘bob’ If the login does not exist, you can instruct SQL Server to create the login with the same name. In this case you will need to provide a password for the login and the value of the @Action parameter will be ‘Auto_Fix’. If the login already exists, it will be automatically mapped to the user account. Unfortunately sp_change_users_login system stored procedure cannot be used to map database users to trusted logins (Windows accounts) in SQL Server. You will need to follow a manual process to re-map the database user accounts.  Continues…

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  • Online games programming basics

    - by Renkon
    I am writing with regard to an issue I am having nowadays. I have come up with an interesting idea of making an online game in C#, yet I do not have the knowledge to work with more than a player. Basic games like a TIC-TAC-TOE or a SNAKE were done already, and I would like to do a simple, but online, game. Would you mind giving me some tutorials or guides related to that? I would really like to learn how to work online with the client/server structure (though, I do know the basics about that structure). I look forward to reading from you. Yours faithfully, Renkon.

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  • which graphics driver will solve my laptop screen display problem?

    - by vi.su.
    which graphics driver will solve my laptop screen display problem? Recently installed Ubuntu 10.04.4 LTS on my laptop and upgraded it to 12.10, through 12.04.1 LTS. I am not able to get the display right, from the beginning. During boot laptop screen is all green, and images / videos are not getting displayed properly when logged in. Actual problem started last week, when this laptop was with Windows Vista (preloaded), and I tried to update Nvidia graphics drivers. something went wrong and I couldn't find a way to fix, so decided to install Ubuntu. Over last week, installed / re-installed Ubuntu many times with various drivers with no success. Laptop : Dell Inspiron 1420 Installed OS : ubuntu 10.04 LTS (Current, Ubuntu 12.10) Nvidia driver : GeForce 8400M GS (tried in previous installations; not installed now) Print-screen was not able to catch this issue as mentioned in the comment, so I am posting screen photos.

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  • How to make Rect of irregular shape sprite?

    - by Anil gupta
    I used masking for breaking an image as the below mention pattern now its breaking in different pieces but now i have one issue to make the Rect of each pieces, i need to drag the broken pieces and to adjust at correct position so that i can make again actual images. To drag and put at right positing i need to make Rect but i am not getting idea how to make Rect of this irregular shape, I will be very thankful to you, any idea or code to make rect . My previous Question is: How do I break an image into 6 or 8 pieces of different shapes? Thanks.

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  • Configure EnableTransaction and IsolationLevel property in Business Rules for Dynamic Send Port

    - by Vishal
    Why do you want to add these properties to the BRE..??                 There is a lot of performance issue when using WCF adapters with Dynamic Send Port. Please check the below link for more info.   http://blogs.msdn.com/mdoctor/archive/2009/12/18/performance-tip-when-using-wcf-custom-with-dynamic-send-ports-and-custom-bindings-on-biztalk-server-2009.aspx?CommentPosted=true#commentmessage     So if you are using ESB Toolkit 2.0 in your solution and you do not want to move towards static adapte then you can add the below line in your SetEndpointConfig value for BRE.                 BindingType=xyzAdapterBinding&EnableTransaction=true&IsolationLevel=ReadCommited&BindingConfiguration=<bindingname=”xyzAdapterBinding" />   The IsolationLevel values can be: Serializable RepeatableRead ReadCommited ReadUncommited Snapshot Chaos   Below are few Business Rules Composer Screenshots.

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  • In Scrum, should tasks such as development environment set-up and capability development be managed as subtasks within actual user stories?

    - by Asim Ghaffar
    Sometimes in projects we need to spend time on tasks such as: exploring alternate frameworks and tools learning the framework and tools selected for the project setting up the servers and project infrastructure (version control, build environments, databases, etc) If we are using User Stories, where should all this work go? One option is to make them all part of first user story (e.g. make the homepage for application). Another option is to do a spike for these tasks. A third option is to make task part of an Issue/Impediment (e.g. development environment not selected yet) rather than a user Story.

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  • libgdx spite position relative to body

    - by While-E
    Apologies if this is a reiteration, as I couldn't find another discussion of this over the past couple days. Issue: I'm using libgdx and box2d, and I'm currently updating the sprite's position to the body's current position every render call. Using a debugRenderer to see the bodies, I see that there is fairly noticeable lag between the movement/position of the body and the sprite that is being moved relative to it. Question: Is this lag normal, possibly to perform collisions ahead of time? If not, should I be manipulating/relating the positions differently? Thanks in advance! [Solution] This was a coding error on my part. Pointed out by a good reply below, I was updating the position of the sprite relative to the body and then stepping the physics. Thus never actually setting the sprite to the body's CURRENT position. Thanks!

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  • Songs bought from the Ubuntu One Music store showing Unknown Album/Artist in streaming app

    - by rotard
    I've been using Ubuntu one for several years and have purchased several albums from the Ubuntu One music store. All was well while I was playing them from Rhythmbox or Banshee. However, I recently started using the U.O. streaming android app and streaming section of the one.ubuntu.com website and most of my music appears to be untagged. What is going on? Before this question is dismissed as a duplicate, let me reiterate the crucial differences: ALL of the music in my U.O. account was bought in the Ubuntu One music store. This is NOT music that I ripped or bought elsewhere The mp3s that end up on my hard drive DO appear to be tagged correctly The issue affects the U.O. Streaming Music Android app AND the website (viewed in Chrome on my Win7 work PC) Is this some problem with the streaming service? Is there anything I can do?

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  • SQL SERVER – Replace a Column Name in Multiple Stored Procedure all together

    - by pinaldave
    I receive a lot of emails every day. I try to answer each and every email and comments on Facebook and Twitter. I prefer communication on social media as this gives opportunities to others to read the questions and participate along with me. There is always some question which everyone likes to read and remember. Here is one of the questions which I received in email. I believe the same question will be there any many developers who are beginning with SQL Server. I decided to blog about it so everyone can read it and participate. “I am beginner in SQL Server. I have a very interesting situation and need your help. I am beginner to SQL Server and that is why I do not have access to the production server and I work entirely on the development server. The project I am working on is also in the infant stage as well. In product I had to create a multiple tables and every table had few columns. Later on I have written Stored Procedures using those tables. During a code review my manager has requested to change one of the column which I have used in the table. As per him the naming convention was not accurate. Now changing the columname in the table is not a big issue. I figured out that I can do it very quickly either using T-SQL script or SQL Server Management Studio. The real problem is that I have used this column in nearly 50+ stored procedure. This looks like a very mechanical task. I believe I can go and change it in nearly 50+ stored procedure but is there a better solution I can use. Someone suggested that I should just go ahead and find the text in system table and update it there. Is that safe solution? If not, what is your solution. In simple words, How to replace a column name in multiple stored procedure efficiently and quickly? Please help me here with keeping my experience and non-production server in mind.” Well, I found this question very interesting. Honestly I would have preferred if this question was asked on my social media handles (Facebook and Twitter) as I am very active there and quite often before I reach there other experts have already answered this question. Anyway I am now answering the same question on the blog so all of us can participate here and come up with an appropriate answer. Here is my answer - “My Friend, I do not advice to touch system table. Please do not go that route. It can be dangerous and not appropriate. The issue which you faced today is what I used to face in early career as well I still face it often. There are two sets of argument I have observed – there are people who see no value in the name of the object and name objects like obj1, obj2 etc. There are sets of people who carefully chose the name of the object where object name is self-explanatory and almost tells a story. I am not here to take any side in this blog post – so let me go to a quick solution for your problem. Note: Following should not be directly practiced on Production Server. It should be properly tested on development server and once it is validated they should be pushed to your production server with your existing deployment practice. The answer is here assuming you have regular stored procedures and you are working on the Development NON Production Server. Go to Server Note >> Databases >> DatabaseName >> Programmability >> Stored Procedure Now make sure that Object Explorer Details are open (if not open it by clicking F7). You will see the list of all the stored procedures there. Now you will see a list of all the stored procedures on the right side list. Select either all of them or the one which you believe are relevant to your query. Now… Right click on the stored procedures >> SELECT DROP and CREATE to >> Now select New Query Editor Window or Clipboard. Paste the complete script to a new window if you have selected Clipboard option. Now press Control+H which will bring up the Find and Replace Screen. In this screen insert the column to be replaced in the “Find What”box and new column name into “Replace With” box. Now execute the whole script. As we have selected DROP and CREATE to, it will created drop the old procedure and create the new one. Another method would do all the same procedure but instead of DROP and CREATE manually replace the CREATE word with ALTER world. There is a small advantage in doing this is that if due to any reason the error comes up which prevents the new stored procedure to be created you will have your old stored procedure in the system as it is. “ Well, this was my answer to the question which I have received. Do you see any other workaround or solution? Reference : Pinal Dave (http://blog.SQLAuthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Server Management Studio, SQL Stored Procedure, SQL Tips and Tricks, T SQL, Technology

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  • Issues with ganglia and upstart in 13.04

    - by theist
    I'm having an issue with ganglia-monitor and upstart. Just after installing it starts and it cannot be stopped. I tried to solve it following http://upstart.ubuntu.com/cookbook/#expect but I can achieve upstart to track the actual pid of gmond. Assuming the configuration of the init config is wrong i followed direcetions in http://upstart.ubuntu.com/cookbook/#how-to-establish-fork-count in order to try to fix it. As it states a count of 1 means "exec fork" stanza and 2 means "exec daemon" .... gmond gives a count of 8... And of course I can get it to track the actual PID. I haven't found a bug report or something like that. Is there something I missed ? Upstart seems to be failing and the worst thing is that upstart hangs on start/stop and I cannot even uninstall or reconfigure packages.

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  • SQL SERVER – BI Quiz – Troubleshooting Cube Performance

    - by pinaldave
    My friend Jacob Sebastian runs SQL BI Quiz competition. Where there are 30 different questions on each day of the month. Winners get opportunity to participate in this Quiz, learn something new and win great awards. Working with huge data is very common when it is about Data Warehousing. It is necessary to create Cubes on the data to make it meaningful and consumable. There are cases when retrieving the data from cube takes lots of the time. Let us assume that your cube is returning you data very quickly. Suddenly on one day it is returning the data very slowly. What are the three things will you in order to diagnose this. After diagnose what you will do to resolve performance issue. Participate in my question over here Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Business Intelligence, Pinal Dave, PostADay, Readers Question, SQL, SQL Authority, SQL Performance, SQL Puzzle, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • Solving Null Entity Problems with JPA Data Controls in PS1

    - by shay.shmeltzer
    Turns out there is a slight bug that seems to prevent you from doing interactions (update, scroll) with the results of a JPA named query that you dropped on a page using ADF Binding. People are running into this when they are doing the EJB tutorial on OTN for example. The problem is that the way the binding is set up for you automatically doesn't allow you to actually access the iterator set of records to do follow up operations. When I last checked this was solved in the next release of JDeveloper, but in the meantime there is a quick simple way to resolve the issue by changing the refresh condition of the oiterator in your page binding. Here is a little demo that shows the problem and the solution:

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  • Do Not Optimize Without Measuring

    - by Alois Kraus
    Recently I had to do some performance work which included reading a lot of code. It is fascinating with what ideas people come up to solve a problem. Especially when there is no problem. When you look at other peoples code you will not be able to tell if it is well performing or not by reading it. You need to execute it with some sort of tracing or even better under a profiler. The first rule of the performance club is not to think and then to optimize but to measure, think and then optimize. The second rule is to do this do this in a loop to prevent slipping in bad things for too long into your code base. If you skip for some reason the measure step and optimize directly it is like changing the wave function in quantum mechanics. This has no observable effect in our world since it does represent only a probability distribution of all possible values. In quantum mechanics you need to let the wave function collapse to a single value. A collapsed wave function has therefore not many but one distinct value. This is what we physicists call a measurement. If you optimize your application without measuring it you are just changing the probability distribution of your potential performance values. Which performance your application actually has is still unknown. You only know that it will be within a specific range with a certain probability. As usual there are unlikely values within your distribution like a startup time of 20 minutes which should only happen once in 100 000 years. 100 000 years are a very short time when the first customer tries your heavily distributed networking application to run over a slow WIFI network… What is the point of this? Every programmer/architect has a mental performance model in his head. A model has always a set of explicit preconditions and a lot more implicit assumptions baked into it. When the model is good it will help you to think of good designs but it can also be the source of problems. In real world systems not all assumptions of your performance model (implicit or explicit) hold true any longer. The only way to connect your performance model and the real world is to measure it. In the WIFI example the model did assume a low latency high bandwidth LAN connection. If this assumption becomes wrong the system did have a drastic change in startup time. Lets look at a example. Lets assume we want to cache some expensive UI resource like fonts objects. For this undertaking we do create a Cache class with the UI themes we want to support. Since Fonts are expensive objects we do create it on demand the first time the theme is requested. A simple example of a Theme cache might look like this: using System; using System.Collections.Generic; using System.Drawing; struct Theme { public Color Color; public Font Font; } static class ThemeCache { static Dictionary<string, Theme> _Cache = new Dictionary<string, Theme> { {"Default", new Theme { Color = Color.AliceBlue }}, {"Theme12", new Theme { Color = Color.Aqua }}, }; public static Theme Get(string theme) { Theme cached = _Cache[theme]; if (cached.Font == null) { Console.WriteLine("Creating new font"); cached.Font = new Font("Arial", 8); } return cached; } } class Program { static void Main(string[] args) { Theme item = ThemeCache.Get("Theme12"); item = ThemeCache.Get("Theme12"); } } This cache does create font objects only once since on first retrieve of the Theme object the font is added to the Theme object. When we let the application run it should print “Creating new font” only once. Right? Wrong! The vigilant readers have spotted the issue already. The creator of this cache class wanted to get maximum performance. So he decided that the Theme object should be a value type (struct) to not put too much pressure on the garbage collector. The code Theme cached = _Cache[theme]; if (cached.Font == null) { Console.WriteLine("Creating new font"); cached.Font = new Font("Arial", 8); } does work with a copy of the value stored in the dictionary. This means we do mutate a copy of the Theme object and return it to our caller. But the original Theme object in the dictionary will have always null for the Font field! The solution is to change the declaration of struct Theme to class Theme or to update the theme object in the dictionary. Our cache as it is currently is actually a non caching cache. The funny thing was that I found out with a profiler by looking at which objects where finalized. I found way too many font objects to be finalized. After a bit debugging I found the allocation source for Font objects was this cache. Since this cache was there for years it means that the cache was never needed since I found no perf issue due to the creation of font objects. the cache was never profiled if it did bring any performance gain. to make the cache beneficial it needs to be accessed much more often. That was the story of the non caching cache. Next time I will write something something about measuring.

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