Search Results

Search found 89481 results on 3580 pages for 'new technology'.

Page 30/3580 | < Previous Page | 26 27 28 29 30 31 32 33 34 35 36 37  | Next Page >

  • New Features in DNM 01.20.00 for DotNetNuke

    In this tutorial we look at the new features of DNM RAD and walk you through how to create a new data source, creating a linked table, creating a direct query and we preview the new color coded editor in DNM RAD 1.2 for DotNetNuke.Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

    Read the article

  • New MAF Episode on Listeners and Events.

    - by Grant Ronald
    We've sneaked in an extra episode into the UI Development playlist of the MAF online training.  You can access the new episode on Listeners and Events here. Note, that we've renumbered all of the subsequent episodes (just incase you were referring back to the episodes by number.  This is a new episode 16). If you have any other ideas for new episodes, please let me know via a comment.

    Read the article

  • New MAF Episode on Listeners and Events.

    - by Grant Ronald
    We've sneaked in an extra episode into the UI Development playlist of the MAF online training.  You can access the new episode on Listeners and Events here. Note, that we're renumbered all of the subsequent episodes (just incase you were referring back to the episodes by number.  This is a new episode 16). If you have any other ideas for new episodes, please let me know via a comment.

    Read the article

  • A Brand-new Automated Testing Tool is the Result of Telerik and ArtOfTest Merger

    Im sure youve already heard the great news about Telerik expansion and the new Telerik Automated Testing Tools division. I am excited to share what we worked on and produced for the last couple of months. New Release The latest Telerik release that went live this week added a completely new tool to Teleriks automated testing product line. The new QA Edition is tailored for QA Professionals. The QA Edition is a standalone tool that allows QAs to freely create, execute and maintain their tests without having to install Visual Studio. If you are a developer and you want something much faster and lightweight than VS, then the Standalone tool is worth trying. New IDE The QA Edition is a WPF application with interface built on top of the latest and greatest RadControls for WPF. This allowed us to configure and build intuitive and easy-to-use UI. Additionally, the rich ...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

    Read the article

  • [Silverlight 4] New PathListBox Control

    - by FernandoCortes
    One of the new features of Silverlight 4 is the new PathListBox Control. This control is basically a Listbox control witch takes the layout of a shape that you want, so we can represent our data as we want without limits.   So we are ready to open the new Microsoft Blend 4 Beta. First, we going to create a new Silverlight Data Driven Application (MVVM) project.   Open the main view (MainView.xaml), you can find it in Views folder, i look for the new control.   Once you add the PathListbox Control to the main layout of the MainView.xaml, we will add a Line Shape. Now, we are in the main step. Set the LayoutPaths property of the PathListbox control with the line shape that is just created.   The final step is set the ItemsSource property of the PathListbox control. We are going to use a mock object collection from the main view model. I have created the object collection on the main view model created by the Silverlight MVVM project template.   This is the result that we can improve with some animations. This a basic basic use of the PathListbox but using your imagination you can do very cool things.

    Read the article

  • Repainting a window with a new scene with winapi (beginner question)

    - by user90760
    I'm following theForger's win32 API tutorial in order to create a GUI for a project. I've successfully made simple, one window applications, but I can't figure out how to repaint an entire window with new information. As an example: I have five buttons corresponding to five colors on the main application window. When a user clicks a color button, the entire window is repainted such that: 1. all five buttons are removed and a new "back" button is replaced, 2. the background is colored the color that was picked. I'm able to change the background color by trapping the button pressed message in my wndproc, but I can't figure out how to change the entire window with a new "scene" (removing the color buttons and adding a back button). This seems like a trivial task, but I can't find a solution in tutorials. Do I need to declare a new windows class with the back button and then have my button trap create a window of this class?

    Read the article

  • What's New in Oracle Supply Chain Management: Key highlights of R12.1 and new solutions (PART 2 of 2

    The latest EBS 12.1 release provides significant new capabilities in supply chain management that companies can deploy immediately to drive rapid ROI.  In addition, new solutions such as Advanced Planning Command Center, Spare Parts Planning, Demand Signal Repository and Manufacturing Operations Center enable companies to achieve operational excellence, while reducing costs and improving margins. This webcast will discuss the latest release, highlighting new capabilities and how companies can benefit from them.

    Read the article

  • What's New in Oracle Supply Chain Management: Key highlights of R12.1 and new solutions (PART 1 of 2

    The latest EBS 12.1 release provides significant new capabilities in supply chain management that companies can deploy immediately to drive rapid ROI.  In addition, new solutions such as Advanced Planning Command Center, Spare Parts Planning, Demand Signal Repository and Manufacturing Operations Center enable companies to achieve operational excellence, while reducing costs and improving margins. This webcast will discuss the latest release, highlighting new capabilities and how companies can benefit from them.

    Read the article

  • create new subdomain or buy new domain? seo costs [closed]

    - by greek_no_money
    If I am targeting the same audience, but the new sub-site has different concept from the existing site, should I create a new sub-domain or create a new domain? What are the seo advantages and disadvantages of creating a new sub-domain? For example Stack Exchange with Alexa rank 1.474 right now, has sub-domains such as programmers.stackexchange.com and other domains such us serverfault.com with rank 3.515 and stackoverflow.com with rank 109. So why didn't Stack Exchange put, for example, Stack Overflow in a sub-domain to create a better ranking?

    Read the article

  • Intel Rapid Storage Technology (pre-OS) driver installation

    - by Nero theZero
    My desktop machine is built on Gigabyte GA-Z87-UD3H and Gigabyte provides the latest driver for Intel Rapid Storage Technology (IRST), which I installed after installing the OS. Same goes for my Lenovo Thinkpad-T420. And for both machine, checking the controller device under the IDE ATA/ATAPI Controllers section in Device Manager I see the driver has been updated to the latest version. I set the SATA controller to AHCI from BIOS On the desktop machine I have one WD 2TB BLACK & one WD 3TB Green I don’t use RAID, & no chance of using in near future, but according to Intel IRST improves performance in single disk scenario too. Now I have the following questions – What is the actual purpose of IRST (pre-OS install) driver that doesn’t get served with a post-OS driver that I installed? There must be some difference, otherwise there wouldn’t be a pre-OS version of the driver. Right? In the pre-OS procedure (loading the drivers at OS-installation time) after successfully completing the OS installation, do I need that post-OS driver? Because after installing from that one I got a quick launch icon that runs the IRST configuration application. Where do get that after installing the pre-OS driver? As it is “pre-OS”, when I load it at OS-installation time, does it updates anything at BIOS level or anywhere other than HDD? That’s because I’m going to dual boot Windows 7 with Windows 8.1, and after installing Windows 7 when I install Windows 8.1 & load the IRST driver for that, is there any chance of any “overwriting” or OS-incompatibility? In short, is there anything specific to follow while installing the second OS?

    Read the article

  • Drobo FS vs Lime Technology unRAID vs FreeNAS

    - by elluca
    I already decided to by a drobo fs until I just found these two tests: http://www.digitalversus.com/data-robotics-drobo-fs-p889_9543_487.html http://www.digitalversus.com/lime-technology-unraid-p889_8992_473.html The two cons agains drobo for me: loudness price What disadvantages has the unraid stuff against the drobo fs? Has it also got that ease of use like swapping drives on the go, simply extend capacity by plugging in new drives, notify me of drive errors, disk failure protection, dynamic space of "partitions", better/worse effective capacity, etc. Which is more secure? Am I able to simply replace a bad drive with a new one on unraid? What happens if my pc fails? Lets say the cpu overheats. Since I have a complete pc which is going to be replaced, I only have to pay the software to use unraid. I am going to use my nas for: music library (how well does it integrate with iTunes? ) picture library movie library development (i need to be able to be to use time machine) I am going to use this nas with a MacBook pro. My current disks: 2x 500Gb 1x 1.5Tb 1x 2Tb On a drobo fs I would have 2.26 Tb of space. What would it be on unraid? Is FreeNAS also an alternative?

    Read the article

  • 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

    Read the article

  • Best available technology for layered disk cache in linux

    - by SpliFF
    I've just bought a 6-core Phenom with 16G of RAM. I use it primarily for compiling and video encoding (and occassional web/db). I'm finding all activities get disk-bound and I just can't keep all 6 cores fed. I'm buying an SSD raid to sit between the HDD and tmpfs. I want to setup a "layered" filesystem where reads are cached on tmpfs but writes safely go through to the SSD. I want files (or blocks) that haven't been read lately on the SSD to then be written back to a HDD using a compressed FS or block layer. So basically reads: - Check tmpfs - Check SSD - Check HD And writes: - Straight to SSD (for safety), then tmpfs (for speed) And periodically, or when space gets low: - Move least frequently accessed files down one layer. I've seen a few projects of interest. CacheFS, cachefsd, bcache seem pretty close but I'm having trouble determining which are practical. bcache seems a little risky (early adoption), cachefs seems tied to specific network filesystems. There are "union" projects unionfs and aufs that let you mount filesystems over each other (USB device over a DVD usually) but both are distributed as a patch and I get the impression this sort of "transparent" mounting was going to become a kernel feature rather than a FS. I know the kernel has a built-in disk cache but it doesn't seem to work well with compiling. I see a 20x speed improvement when I move my source files to tmpfs. I think it's because the standard buffers are dedicated to a specific process and compiling creates and destroys thousands of processes during a build (just guessing there). It looks like I really want those files precached. I've read tmpfs can use virtual memory. In that case is it practical to create a giant tmpfs with swap on the SSD? I don't need to boot off the resulting layered filesystem. I can load grub, kernel and initrd from elsewhere if needed. So that's the background. The question has several components I guess: Recommended FS and/or block layer for the SSD and compressed HDD. Recommended mkfs parameters (block size, options etc...) Recommended cache/mount technology to bind the layers transparently Required mount parameters Required kernel options / patches, etc..

    Read the article

  • Technology behind twilio

    - by John Stewart
    I wanted to discuss the technology behind Twilio. I have been playing around with the service for a few days now and it is simply mind-blowing. While I don't have a direct need for it right now, I am curious to find the back-end of the technology. So can anyone shed some thoughts on how does Twilio do its magic?

    Read the article

  • how to keep same header on starting of next page in pdf

    - by Santosh Singh
    Here is My Code. private void getActionItems(Document document, Chapter chapter, Section section, Paragraph pas) { List drbRefList = null; try { _actionService = new ActionItemImpl(); _aiBean = new ActionItemData(); if (_aiBean != null) { _actionList = new ArrayList(); LOG.info("business passed here is" + _business); _actionList = _actionService.getActionItemsForPDF(_userSSOID, _business, _reviewID, _connection); } LOG.info(" after calling getActionItemsForPDF"); LOG.info("_actionList" + _actionList); Table tablesh1 = new Table(1, 1); float[] widthsh1 = new float[1]; widthsh1[0] = ReviewConstants.MAGIC_DOTTWELVE; tablesh1.setTableFitsPage(true); tablesh1.setPadding(2); tablesh1.setSpacing(0); tablesh1.setWidth(ReviewConstants.MAGIC_ONEZEROZERO); tablesh1.setWidths(widthsh1); tablesh1.setBorderColor(Color.WHITE); Cell hcell = new Cell(new Paragraph(ReviewConstants.S_ACTIONHEADING, new Font(Font.HELVETICA, fontSize, Font.BOLD, Color.BLUE))); hcell.setHeader(true); tablesh1.addCell(hcell); section.add(tablesh1); Table actionTable = null; String businessUnit = reviewData.getBusinessUnit(); float[] widthac = null; //Updated for Nuclear Energy Engineering Business Unit Requirement by Naveen if(!"Nuclear Energy Engineering".equalsIgnoreCase(businessUnit)){ actionTable = new Table(ReviewConstants.NINE,ReviewConstants.THREE); widthac = new float[ReviewConstants.NINE]; widthac[0] = ReviewConstants.MAGIC_DOTONE; widthac[1] = ReviewConstants.MAGIC_DOTONEZERO; widthac[2] = ReviewConstants.MAGIC_DOTTWOZERO; widthac[ReviewConstants.THREE] = ReviewConstants.MAGIC_DOTTWOZERO; widthac[ReviewConstants.FOUR] = ReviewConstants.MAGIC_DOTONEZERO; widthac[ReviewConstants.FIVE] = ReviewConstants.MAGIC_DOTONEZERO; widthac[ReviewConstants.SIX] = ReviewConstants.MAGIC_DOTONEZERO; widthac[ReviewConstants.SEVEN] = ReviewConstants.MAGIC_DOTONEZERO; widthac[ReviewConstants.EIGHT] = ReviewConstants.MAGIC_DOTONEZERO; }else{ actionTable = new Table(ReviewConstants.SIX,ReviewConstants.THREE); widthac = new float[ReviewConstants.SIX]; widthac[0] = ReviewConstants.MAGIC_DOTONE; widthac[1] = ReviewConstants.MAGIC_THREEZERO; widthac[2] = ReviewConstants.MAGIC_THREEZERO; widthac[ReviewConstants.THREE] = ReviewConstants.MAGIC_THREEZERO; widthac[ReviewConstants.FOUR] = ReviewConstants.MAGIC_DOTONEZERO; widthac[ReviewConstants.FIVE] = ReviewConstants.MAGIC_DOTONEZERO; } actionTable.setTableFitsPage(true); actionTable.setPadding(2); actionTable.setSpacing(0); actionTable.setWidth(ReviewConstants.MAGIC_ONEZEROZERO); actionTable.setWidths(widthac); actionTable.setBorderWidth(1); Cell accell = new Cell(new Paragraph(ReviewConstants.S_ACTIONID, new Font(Font.HELVETICA, fontSize, Font.BOLD))); accell.setHeader(true); actionTable.addCell(accell); if(!"Nuclear Energy Engineering".equalsIgnoreCase(businessUnit)){ accell = new Cell(new Paragraph(ReviewConstants.PDF_RT, new Font(Font.HELVETICA, fontSize, Font.BOLD))); accell.setHeader(true); actionTable.addCell(accell); } accell = new Cell(new Paragraph(ReviewConstants.S_REQA, new Font(Font.HELVETICA, fontSize, Font.BOLD))); accell.setHeader(true); actionTable.addCell(accell); accell = new Cell(new Paragraph(ReviewConstants.S_CLOSURE, new Font(Font.HELVETICA, fontSize, Font.BOLD))); accell.setHeader(true); actionTable.addCell(accell); accell = new Cell(new Paragraph(ReviewConstants.S_DISPOSITION, new Font(Font.HELVETICA, fontSize, Font.BOLD))); accell.setHeader(true); actionTable.addCell(accell); //added by santosh on 18 june actionTable.endHeaders(); document.add(actionTable); if(!"Nuclear Energy Engineering".equalsIgnoreCase(businessUnit)){ accell = new Cell(new Paragraph(ReviewConstants.S_DRB_REFERENCE, new Font( Font.HELVETICA, fontSize, Font.BOLD))); accell.setHeader(true); actionTable.addCell(accell); accell = new Cell(new Paragraph(ReviewConstants.S_DEADLINE, new Font( Font.HELVETICA, fontSize, Font.BOLD))); accell.setHeader(true); actionTable.addCell(accell); } accell = new Cell(new Paragraph(ReviewConstants.S_OWNER, new Font( Font.HELVETICA, fontSize, Font.BOLD))); accell.setHeader(true); actionTable.addCell(accell); accell = new Cell(new Paragraph(ReviewConstants.S_STATE, new Font( Font.HELVETICA, fontSize, Font.BOLD))); accell.setHeader(true); actionTable.addCell(accell); int acSize = 0; if (_actionList != null) { acSize = _actionList.size(); } for (int i = 0; i < acSize; i++) { _aiBean = (ActionItemData) _actionList.get(i); Cell adCell = new Cell(new Paragraph(_aiBean.getActionID(), new Font( Font.HELVETICA, ReviewConstants.MAGIC_EIGHT))); adCell.setHeader(false); actionTable.addCell(adCell); if(!"Nuclear Energy Engineering".equalsIgnoreCase(businessUnit)){ if (_aiBean.getActionItemType().equals("0")) { adCell = new Cell(new Paragraph("Normal", new Font(Font.HELVETICA, fontSize))); } else { adCell = new Cell(new Paragraph("Critical", new Font(Font.HELVETICA, fontSize))); } adCell.setHeader(false); actionTable.addCell(adCell); } adCell = new Cell(new Paragraph(_aiBean.getRequiredAction(), new Font(Font.HELVETICA, fontSize))); adCell.setHeader(false); actionTable.addCell(adCell); adCell = new Cell(new Paragraph(_aiBean.getClosureCriteria(), new Font(Font.HELVETICA, fontSize))); adCell.setHeader(false); actionTable.addCell(adCell); String drbLink = ReviewConstants.EMPTY; drbRefList = new ArrayList(); if (!DRUtils.isEmpty(_aiBean.getState()) && ((_aiBean.getState() .equalsIgnoreCase(ReviewConstants.DRAFT_BEGUN_STATE)) || (_aiBean.getState() .equalsIgnoreCase(ReviewConstants.SCOPE_PROPOSED)) || (_aiBean .getState() .equalsIgnoreCase(ReviewConstants.RES_PROPOSED)))) { drbLink = ReviewConstants.EMPTY; _aiBean.setDisposition(ReviewConstants.EMPTY); } else { drbRefList = _actionService.getDrbRefForPDF(_aiBean.getActionSeqID(), _connection); int drbRefCnt = 0; if (drbRefList != null) { drbRefCnt = drbRefList.size(); int j = 0; for (j = 0; j < drbRefCnt; j++) { LOG.info("drbRefList.get(j)" + drbRefList.get(j).toString()); if (j < (drbRefCnt - 1)) { drbLink += drbRefList.get(j).toString() + ReviewConstants.COMMA_SPACE; } else { drbLink += drbRefList.get(j).toString(); } } } } LOG.info("drbLink" + drbLink); adCell = new Cell(new Paragraph(_aiBean.getDisposition(), new Font(Font.HELVETICA, fontSize))); adCell.setHeader(false); actionTable.addCell(adCell); //Updated for Nuclear Energy Engineering Business Unit Requirement by Naveen if(!"Nuclear Energy Engineering".equalsIgnoreCase(businessUnit)){ adCell = new Cell(new Paragraph(drbLink, new Font( Font.HELVETICA, fontSize))); adCell.setHeader(false); actionTable.addCell(adCell); adCell = new Cell(new Paragraph(_aiBean.getDeadline(), new Font(Font.HELVETICA, fontSize))); adCell.setHeader(false); actionTable.addCell(adCell); } adCell = new Cell(new Paragraph(_aiBean.getActionItemOwnerName(), new Font(Font.HELVETICA, fontSize))); adCell.setHeader(false); actionTable.addCell(adCell); adCell = new Cell(new Paragraph(_aiBean.getState(), new Font(Font.HELVETICA, fontSize))); adCell.setHeader(false); actionTable.addCell(adCell); //added by santosh actionTable.endHeaders(); document.add(actionTable); // added by santosh end } /*Phrase headerPhrase = new Phrase(); Table headTab = (Table)actionTable.getElement(0, 5); headerPhrase.add(headTab); HeaderFooter printHeader = new HeaderFooter(headerPhrase,false); System.out.println("addHeader"); document.setHeader(printHeader); actionTable.setLastHeaderRow(1); actionTable.endHeaders(); document.add(actionTable);*/ // added by santosh actionTable.endHeaders(); document.add(actionTable); // added by santosh end section.add(actionTable); } catch (Exception e) { LOG.error("General Exception occured", e); } }

    Read the article

  • SQL SERVER – Concurrency Basics – Guest Post by Vinod Kumar

    - by pinaldave
    This guest post is by Vinod Kumar. Vinod Kumar has worked with SQL Server extensively since joining the industry over a decade ago. Working on various versions from SQL Server 7.0, Oracle 7.3 and other database technologies – he now works with the Microsoft Technology Center (MTC) as a Technology Architect. Let us read the blog post in Vinod’s own voice. Learning is always fun when it comes to SQL Server and learning the basics again can be more fun. I did write about Transaction Logs and recovery over my blogs and the concept of simplifying the basics is a challenge. In the real world we always see checks and queues for a process – say railway reservation, banks, customer supports etc there is a process of line and queue to facilitate everyone. Shorter the queue higher is the efficiency of system (a.k.a higher is the concurrency). Every database does implement this using checks like locking, blocking mechanisms and they implement the standards in a way to facilitate higher concurrency. In this post, let us talk about the topic of Concurrency and what are the various aspects that one needs to know about concurrency inside SQL Server. Let us learn the concepts as one-liners: Concurrency can be defined as the ability of multiple processes to access or change shared data at the same time. The greater the number of concurrent user processes that can be active without interfering with each other, the greater the concurrency of the database system. Concurrency is reduced when a process that is changing data prevents other processes from reading that data or when a process that is reading data prevents other processes from changing that data. Concurrency is also affected when multiple processes are attempting to change the same data simultaneously. Two approaches to managing concurrent data access: Optimistic Concurrency Model Pessimistic Concurrency Model Concurrency Models Pessimistic Concurrency Default behavior: acquire locks to block access to data that another process is using. Assumes that enough data modification operations are in the system that any given read operation is likely affected by a data modification made by another user (assumes conflicts will occur). Avoids conflicts by acquiring a lock on data being read so no other processes can modify that data. Also acquires locks on data being modified so no other processes can access the data for either reading or modifying. Readers block writer, writers block readers and writers. Optimistic Concurrency Assumes that there are sufficiently few conflicting data modification operations in the system that any single transaction is unlikely to modify data that another transaction is modifying. Default behavior of optimistic concurrency is to use row versioning to allow data readers to see the state of the data before the modification occurs. Older versions of the data are saved so a process reading data can see the data as it was when the process started reading and not affected by any changes being made to that data. Processes modifying the data is unaffected by processes reading the data because the reader is accessing a saved version of the data rows. Readers do not block writers and writers do not block readers, but, writers can and will block writers. Transaction Processing A transaction is the basic unit of work in SQL Server. Transaction consists of SQL commands that read and update the database but the update is not considered final until a COMMIT command is issued (at least for an explicit transaction: marked with a BEGIN TRAN and the end is marked by a COMMIT TRAN or ROLLBACK TRAN). Transactions must exhibit all the ACID properties of a transaction. ACID Properties Transaction processing must guarantee the consistency and recoverability of SQL Server databases. Ensures all transactions are performed as a single unit of work regardless of hardware or system failure. A – Atomicity C – Consistency I – Isolation D- Durability Atomicity: Each transaction is treated as all or nothing – it either commits or aborts. Consistency: ensures that a transaction won’t allow the system to arrive at an incorrect logical state – the data must always be logically correct.  Consistency is honored even in the event of a system failure. Isolation: separates concurrent transactions from the updates of other incomplete transactions. SQL Server accomplishes isolation among transactions by locking data or creating row versions. Durability: After a transaction commits, the durability property ensures that the effects of the transaction persist even if a system failure occurs. If a system failure occurs while a transaction is in progress, the transaction is completely undone, leaving no partial effects on data. Transaction Dependencies In addition to supporting all four ACID properties, a transaction might exhibit few other behaviors (known as dependency problems or consistency problems). Lost Updates: Occur when two processes read the same data and both manipulate the data, changing its value and then both try to update the original data to the new value. The second process might overwrite the first update completely. Dirty Reads: Occurs when a process reads uncommitted data. If one process has changed data but not yet committed the change, another process reading the data will read it in an inconsistent state. Non-repeatable Reads: A read is non-repeatable if a process might get different values when reading the same data in two reads within the same transaction. This can happen when another process changes the data in between the reads that the first process is doing. Phantoms: Occurs when membership in a set changes. It occurs if two SELECT operations using the same predicate in the same transaction return a different number of rows. Isolation Levels SQL Server supports 5 isolation levels that control the behavior of read operations. Read Uncommitted All behaviors except for lost updates are possible. Implemented by allowing the read operations to not take any locks, and because of this, it won’t be blocked by conflicting locks acquired by other processes. The process can read data that another process has modified but not yet committed. When using the read uncommitted isolation level and scanning an entire table, SQL Server can decide to do an allocation order scan (in page-number order) instead of a logical order scan (following page pointers). If another process doing concurrent operations changes data and move rows to a new location in the table, the allocation order scan can end up reading the same row twice. Also can happen if you have read a row before it is updated and then an update moves the row to a higher page number than your scan encounters later. Performing an allocation order scan under Read Uncommitted can cause you to miss a row completely – can happen when a row on a high page number that hasn’t been read yet is updated and moved to a lower page number that has already been read. Read Committed Two varieties of read committed isolation: optimistic and pessimistic (default). Ensures that a read never reads data that another application hasn’t committed. If another transaction is updating data and has exclusive locks on data, your transaction will have to wait for the locks to be released. Your transaction must put share locks on data that are visited, which means that data might be unavailable for others to use. A share lock doesn’t prevent others from reading but prevents them from updating. Read committed (snapshot) ensures that an operation never reads uncommitted data, but not by forcing other processes to wait. SQL Server generates a version of the changed row with its previous committed values. Data being changed is still locked but other processes can see the previous versions of the data as it was before the update operation began. Repeatable Read This is a Pessimistic isolation level. Ensures that if a transaction revisits data or a query is reissued the data doesn’t change. That is, issuing the same query twice within a transaction cannot pickup any changes to data values made by another user’s transaction because no changes can be made by other transactions. However, this does allow phantom rows to appear. Preventing non-repeatable read is a desirable safeguard but cost is that all shared locks in a transaction must be held until the completion of the transaction. Snapshot Snapshot Isolation (SI) is an optimistic isolation level. Allows for processes to read older versions of committed data if the current version is locked. Difference between snapshot and read committed has to do with how old the older versions have to be. It’s possible to have two transactions executing simultaneously that give us a result that is not possible in any serial execution. Serializable This is the strongest of the pessimistic isolation level. Adds to repeatable read isolation level by ensuring that if a query is reissued rows were not added in the interim, i.e, phantoms do not appear. Preventing phantoms is another desirable safeguard, but cost of this extra safeguard is similar to that of repeatable read – all shared locks in a transaction must be held until the transaction completes. In addition serializable isolation level requires that you lock data that has been read but also data that doesn’t exist. Ex: if a SELECT returned no rows, you want it to return no. rows when the query is reissued. This is implemented in SQL Server by a special kind of lock called the key-range lock. Key-range locks require that there be an index on the column that defines the range of values. If there is no index on the column, serializable isolation requires a table lock. Gets its name from the fact that running multiple serializable transactions at the same time is equivalent of running them one at a time. Now that we understand the basics of what concurrency is, the subsequent blog posts will try to bring out the basics around locking, blocking, deadlocks because they are the fundamental blocks that make concurrency possible. Now if you are with me – let us continue learning for SQL Server Locking Basics. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: Concurrency

    Read the article

  • SQL SERVER – Puzzle to Win Print Book – Write T-SQL Self Join Without Using FIRST _VALUE and LAST_VALUE

    - by pinaldave
    Last week we asked a puzzle SQL SERVER – Puzzle to Win Print Book – Functions FIRST_VALUE and LAST_VALUE with OVER clause and ORDER BY . This puzzle got very interesting participation. The details of the winner is listed here. In this puzzle we received two very important feedback. This puzzle cleared the concepts of First_Value and Last_Value to the participants. As this was based on SQL Server 2012 many could not participate it as they have yet not installed SQL Server 2012. I really appreciate the feedback of user and decided to come up something as fun and helps learn new feature of SQL Server 2012. Please read yesterday’s blog post SQL SERVER – Introduction to LEAD and LAG – Analytic Functions Introduced in SQL Server 2012 before continuing this puzzle as it is based on yesterday’s post. Yesterday I ran following query which uses functions LEAD and LAG. USE AdventureWorks GO SELECT s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty, FIRST_VALUE(SalesOrderDetailID) OVER (ORDER BY SalesOrderDetailID) FstValue, LAST_VALUE(SalesOrderDetailID) OVER (ORDER BY SalesOrderDetailID) LstValue FROM Sales.SalesOrderDetail s WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty GO The above query will give us the following result: Puzzle: Now use T-SQL Self Join where same table is joined to itself and get the same result without using LEAD or LAG functions. Hint: Introduction to JOINs – Basic of JOINs Self Join A new analytic functions in SQL Server Denali CTP3 – LEAD() and LAG() Rules Leave a comment with your detailed answer by Nov 21's blog post. Open world-wide (where Amazon ships books) If you blog about puzzle’s solution and if you win, you win additional surprise gift as well. Prizes Print copy of my new book SQL Server Interview Questions Amazon|Flipkart If you already have this book, you can opt for any of my other books SQL Wait Stats [Amazon|Flipkart|Kindle] and SQL Programming [Amazon|Flipkart|Kindle]. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Function, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

    Read the article

  • SQLAuthority News – Microsoft SQL Server 2012 Service Pack 1 Released (SP1)

    - by pinaldave
    Last week, I was attending SQLPASS 2012 and I had great fun attending the event. During the event long awaited SQL Serer 2012 Service Pack 1 was released. I am pretty excited with SP1 as new service packs are cumulative updates and upgrade all editions and service levels of SQL Server 2012 to SP1. This service pack contains SQL Server 2012 Cumulative Update 1 (CU1) and Cumulative Update 2 (CU2). The latest SP1 has many new and enhanced features. Here are a few for example: Cross-Cluster Migration of AlwaysOn Availability Groups for OS Upgrade Selective XML Index DBCC SHOW_STATISTICS works with SELECT permission New function returns statistics properties – sys.dm_db_stats_properties SSMS Complete in Express SlipStream Full Installation Business Intelligence highlights with Office and SharePoint Server 2013 Management Object Support Added for Resource Governor DDL Please note that the size of the service pack is near 1 GB. Here is the link to SQL Server 2012 Service Pack 1. SQL Server Express is the free and feature rich edition of the SQL Server. It is used with lightweight website and desktop applications. Here is the link to SQL Server 2012 EXPRESS Service Pack 1. Here is the question for you – how long have you been using SQL Server 2012? Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Documentation, SQL Download, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: Service Pack

    Read the article

< Previous Page | 26 27 28 29 30 31 32 33 34 35 36 37  | Next Page >