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• Basket Analysis with #dax in #powerpivot and #ssas #tabular

  - by Marco Russo (SQLBI)

  A few days ago I published a new article on DAX Patterns web site describing how to implement Basket Analysis in DAX. This topic is a very classical one and is also covered in the many-to-many revolution white paper. It has been also discussed in several blog posts, listed here in historical order: Simple Basket Analysis in DAX by Chris Webb PowerPivot, basket analysis and the hidden many to many by Alberto Ferrari Applied Basket Analysis in Power Pivot using DAX by Gerhard Brueckl As usual, in DAX Patterns we try to present the required DAX formulas in a way that is easy to adapt to specific models. We also try to show a good implementation from a performance point of view. Further optimizations are always possible in DAX. However, in order to keep the model simple to adapt in different scenarios, we avoid presenting optimizations that would require particular assumptions or restrictions on the data model. I hope you will find the Basket Analysis pattern useful. Even if you do not need it today, reading the DAX formula is a good exercise to check your knowledge of evaluation contexts in DAX. For example, describing how does it work the following expression is not a trivial task! [Orders with Both Products] := CALCULATE (     DISTINCTCOUNT ( Sales[SalesOrderNumber] ),     CALCULATETABLE (         SUMMARIZE ( Sales, Sales[SalesOrderNumber] ),         ALL ( Product ),         USERELATIONSHIP ( Sales[ProductCode], 'Filter Product'[Filter ProductCode] )     ) ) The good news is that you can use the patterns even if you do not really understand all the details of the DAX formulas you are using! Any feedback on this new pattern is very welcome.

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• Presenting at Roanoke Code Camp Saturday!

  - by andyleonard

  Introduction I am honored to once again be selected to present at Roanoke Code Camp ! An Introductory Topic One of my presentations is titled "I See a Control Flow Tab. Now What?" It's a Level 100 talk for those wishing to learn how to build their very first SSIS package. This highly-interactive, demo-intense presentation is for beginners and developers just getting started with SSIS. Attend and learn how to build SSIS packages from the ground up . Designing an SSIS Framework I'm also presenting...(read more)

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• Experiences with learning Chinese

  - by Greg Low

  I've had a few friends asking me about learning Chinese and what I've found works and doesn't work. I was answering a question on a mailing list today and I thought I should post this info where it might be useful to many. The question that was initially asked was whether Rosetta Stone was useful but I've provided much more info on learning the language here. I’ve used Rosetta Stone with Chinese but it’s really hard to know whether to recommend it or not. Rosetta Stone works the same way in all languages. They show you photos and then let you both see and hear the target language and get you to work out what they’re talking about. The thinking is that that’s how children learn. However, at first, I found it very frustrating. I’d be staring at photos trying to work out what they were really trying to get at. Sometimes it’s far from obvious. I could not have survived without Google Translate open at the same time. The other weird thing is that the photos are from a mixture of countries. While that’s good in a way, it also means that they are endlessly showing pictures of something that would never happen in the target language and culture. For any language, constant interaction with a speaker of the target language is needed. Rosetta Stone has a “Studio” option. That’s the best part of the program. In my case, it lets me connect around twice a week to a live online class from Beijing. Classes usually have the teacher plus two to four students. You get some Studio access with the initial packages but need to purchase it for ongoing use. I find it very inexpensive. It seems to work out to about $70 (AUD/USD) for six months. That’s a real bargain. The other downside to Rosetta Stone is that they tend to teach very formal language, but as with other languages, that’s not how the locals speak. It might have been correct at one point but no-one actually says that. As an example, Rosetta Stone teach Gonggòng qìche (pronounced roughly like “gong gong chee chure” for bus. Most of my friends from areas like Taiwan would just say Gongche. Google Translate says Zongxiàn (pronounced somewhat like “dzong sheean”) instead. Mind you, the Rosetta Stone option isn't really as bad as "omnibus"; it's more like saying "public bus". If you say the option they provide, people would understand you. I also listen to ChinesePod in the car. They also have SpanishPod. Each podcast is about five minutes of spoken conversation. It is very good for providing current language. Another resource I use is local Meetup groups. Most cities have these and for a variety of languages. It’s way less structured (just standard conversation) but good for getting interaction. The obvious challenge for Asian languages is reading/writing. The input editors for Chinese that are part of Windows are excellent. Many of my Chinese friends speak fluently but cannot read or write. I was determined to learn to do both. For writing, I’m talking about on a computer, not with a pen. (Mind you, I can barely write English with a pen nowadays). When using Rosetta Stone, you can choose to have the Chinese words displayed in pinyin (Wo xihuan xuéxí zhongguó) or in Chinese characters (???????) or both. This year, I’ve been forcing myself to just use the Chinese characters. I use a pinyin input editor in Windows though, as it’s very fast.  (The character recognition input in the iPad is also amazing). Notice from the example that I provided above that the pronunciation of the pinyin isn’t that obvious to us at first either.  Since changing to only using characters, I find I can now read many more Chinese characters fluently. It’s a major challenge though. I can read about 300 now and yet you need around 2,500 to be able to read a newspaper fairly well. Tones are a major issue for some Asian languages. Mandarin has four tones (plus a neutral tone) and there is a major difference in meaning between two words that are spelled the same in pinyin but with different tones. For example, Ma (3rd tone?) is a horse, Ma (1st tone?) is like “mom”, and ma (neutral tone?) is a question mark and so on. Clearly you don’t want to mix these up. As in English, they also have words that do sound the same but mean different things in different contexts. What’s interesting is that even though we see two words that differ only by tone as very similar, to a native speaker, if you say the right words with the wrong tone, you might as well have said a completely different word. My wife’s dialect of Chinese has eight tones. It’s much worse. The reason I’m so keen to learn to read/write Chinese is that even though the different dialects are pronounced so differently that speakers of one dialect often cannot understand another dialect, the writing is generally the same. The only difference is that many years ago, the Chinese government created a simplified set of characters for some of the most commonly used ones. Older Chinese and most Cantonese speakers often struggle with the simplified characters. This is the simplified form of “three apples”: ????   This is the traditional form of the same words: ????  Note that two of the characters are the same but the middle two are quite different. For most languages, the best thing is to watch current movies in the target language but to watch them with the target language as subtitles, not your native language. You want to know what they actually said, not what it roughly means (which is what the English subtitle would give you). The difficulty with Asian languages like Chinese is that you have the added challenge of understanding the subtitles when they are written in the target language. I wish there were Mandarin Chinese movies with pinyin subtitles. For learning to read characters, I also recommend HanCard on the iPad. It is targeted at the HSK language proficiency levels. (I’m intending to take the first HSK exam as soon as I’m ready). Hope that info helps someone get started.  

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• Live from the #summit13 keynote : 2013-10-17

  - by AaronBertrand

  Douglas McDowell (EVP Finance) takes the stage (no kilt), and talks numbers. PASS has an impressive $1MM in reserves as a "rainy day" fund. Last fiscal year they spent $7.6MM on community; 30% of that internationally. Bill Graziano comes on (no kilt) to say goodbye and thanks to the outgoing board members, Douglas McDowell, Rob Farley and Rushabh Mehta. Thomas LaRock comes on. No kilt , but he did tuck his shirt in . He introduces the incoming executive team. The 2014 PASS Business Analytics Conference...(read more)

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• A Review of From Zero To SSIS Training

  - by andyleonard

  I recently (5-9 Mar 2012) delivered my five-day SSIS training course – From Zero To SSIS! – in London. The class was delivered in collaboration with TechniTrain . I must commend Chris Webb ( blog | @Technitrain ) and Helen Lau on their leadership, professionalism, and attention to detail. They made the course a breeze for the students and the instructor! It was a pleasure and privilege to work with them. In addition to people just learning data integration, this class contained several experienced...(read more)

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• 24 Hours of PASS: 15 Powerful Dynamic Management Objects - Deck and Demos

  - by Adam Machanic

  Thank you to everyone who attended today's 24 Hours of PASS webcast on Dynamic Management Objects! I was shocked, awed, and somewhat scared when I saw the attendee number peak at over 800. I really appreciate your taking time out of your day to listen to me talk. It's always interesting presenting to people I can't see or hear, so I relied on Twitter for a form of nearly real-time feedback. I would like to especially thank everyone who left me tweets both during and after the presentation. Your feedback...(read more)

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• Fixing SSMS Tabs

  - by Tara Kizer

  It never occurred to me that the way SSMS handles tabs could be changed, and it’s just that the default settings suck.  In this blog post, Brent Ozar shows us how to fix SSMS so that the tabs are actually usable and not annoying anymore. I can’t love his post enough.  It has really helped me become more efficient.  I’m always flipping between tabs and can’t quickly find the one I need at some critical time, but now I can easily find it!

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• Differences in documentation for sys.dm_exec_requests

  - by AaronBertrand

  I've already complained about this on Connect ( see #641790 ), but I just wanted to point out that if you're trying to make sense of the sys.dm_exec_requests document and what it lists as the commands supported by the percent_complete column, you should check which version of the documentation you're reading. I noticed the following discrepancies. I can't explain why certain operations are missing, except that the Denali topic was generated from the 2008 topic (or maybe from the 2008 R2 topic before...(read more)

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• CodePlex Daily Summary for Monday, July 29, 2013

  CodePlex Daily Summary for Monday, July 29, 2013Popular ReleasesGIS Raster Tile Normalizer for GeoServer: V110 Extended to tile DEMs: 1) Now imports large DEM datasets. They are stored as 3.25 degree tiles in GeoTIFF 32 bit single band tiles ready to be used by GeoServer. Also, parallel colorized hillshade tiles are optionally created for easy visualization in GeoServer. 2) No longer uses FWTools, but the more recent 32 bit Windows 1.9 GDAL installation from Tamas at http://www.gisinternals.com/sdk/. Also required is Python 2.7, the GDAL Python Bindings from Tamas, and the Numpy python libraries. This is because we use th...R.NET: R.NET 1.5: The major changes in v1.5 are: Initialize method must be called before using R. Settings should be passed to the method. EagerEvaluate method renamed to Evaluate (use Defer method when you want old version of Evaluate).TX264: 0.9.7: --0.9.7 -Added: Encoding time will be shown in the log -Added: 64bit FLAC.exe -Added: Tx264 will now write version info file to its own folder -Added: Option to set encoder priorties (thx to XanaMuui&Ruriko) -Fixed: A possible error where source files were deleted -Updated: x264 to rev2345 -Updated: MediaInfo to 0.7.64 -Updated: MkvToolNix to 6.3.0 -Updated: FLAC to 1.3.0 -Updated: AlphaControls to 8.42 Stable -Updated: QAAC to 2.19 -Updated: SoX build with unicode by Lord_MulderMedia Companion: Media Companion MC3.574b: Some good bug fixes been going on with the new XBMC-Link function. Thanks to all who were able to do testing and gave feedback. New:* Added some adhoc extra General movie filters, one of which is Plot = Outline (see fixes above). To see the filters, add the following line to your config.xml: <ShowExtraMovieFilters>True</ShowExtraMovieFilters>. The others are: Imdb in folder name, Imdb in not folder name & Imdb not in folder name & year mismatch. * Movie - display <tag> list on browser tab ...OfflineBrowser: Preview Release with Search: I've added search to this release.VG-Ripper & PG-Ripper: VG-Ripper 2.9.46: changes FIXED LoginMath.NET Numerics: Math.NET Numerics v2.6.0: What's New in Math.NET Numerics 2.6 - Announcement, Explanations and Sample Code. New: Linear Curve Fitting Linear least-squares fitting (regression) to lines, polynomials and linear combinations of arbitrary functions. Multi-dimensional fitting. Also works well in F# with the F# extensions. New: Root Finding Brent's method. ~Candy Chiu, Alexander Täschner Bisection method. ~Scott Stephens, Alexander Täschner Broyden's method, for multi-dimensional functions. ~Alexander Täschner ...AJAX Control Toolkit: July 2013 Release: AJAX Control Toolkit Release Notes - July 2013 Release Version 7.0725July 2013 release of the AJAX Control Toolkit. AJAX Control Toolkit .NET 4.5 – AJAX Control Toolkit for .NET 4.5 and sample site (Recommended). AJAX Control Toolkit .NET 4 – AJAX Control Toolkit for .NET 4 and sample site (Recommended). AJAX Control Toolkit .NET 3.5 – AJAX Control Toolkit for .NET 3.5 and sample site (Recommended). Notes: - Instructions for using the AJAX Control Toolkit with ASP.NET 4.5 can be found at...MJP's DirectX 11 Samples: Specular Antialiasing Sample: Sample code to complement my presentation that's part of the Physically Based Shading in Theory and Practice course at SIGGRAPH 2013, entitled "Crafting a Next-Gen Material Pipeline for The Order: 1886". Demonstrates various methods of preventing aliasing from specular BRDF's when using high-frequency normal maps. The zip file contains source code as well as a pre-compiled x64 binary.English Practice Helper: English Practice Helper Demo v1.1: Fix some bug in sentences compareKartris E-commerce: Kartris v2.5003: This fixes an issue where search engines appear to identify as IE and so trigger the noIE page if there is not a non-responsive skin specified.Blue Mercs Data Gateway: Blue Mercs Data Gateway 2.0: Changes made for major release v2.0 build in support for Microsoft Access Database build in logging support (with optional stopwatch duration) implemented thread DbContext that can be referenced to share context accross layers implented 'having' sql keyword implemented 'top(n)' and 'first' sql keywords implemented 'distinct' sql keyword implemented sql column expressions implemented CTE (common table expressions) joins are refactored allow auto join on keys when using entiti...Wix Test: WIX Test Bootstrapper (Burn): WIX Test Bootstrapper and MSI setup files. Alfa versions.ScriptZilla: ScriptZilla 1.2.5.1: New Programming Languages(C++ too !) and An Better Editor.SSISConnectionBuilder: Alpha 2: Removed SSIS SDK dependencies.VBDownloader: VBDownloader 1.0: VBDownloader v1.0 The open source solution for downloads First releasemysqllib: mysqllib 1.5: La nuova versione 1.5 vede espandersi questa libreria con nuovi metodi e nuove caratteristiche interessanti. Ecco i cambiamenti: (NEW) Aggiunta classe MySqlTable per visualizzare tutti i dettagli della tabella, tra cui una lista di dettagli delle colonne (NEW) Aggiunta classe MySqlColumn per visualizzare tutti i dettagli della colonna, tra cui una lista dei valori della colonna (NEW) Nuovi metodi GetTable(...) e GetColumn(...) per risultati dettagliati di tabelle e colonne (NEW) Nuovi met...GoAgent GUI: GoAgent GUI 1.3.5 Alpha (20130723): ????????Alpha?，???????????，?????????????。 ??????????GoAgent???（???phus lu?GitHub??????GoAgent??????，??????????????????） ????????????????????????Bug ?????????。??????????????。 ????issue????，????????，????????????????。LogicCircuit: LogicCircuit 2.13.07.22: Logic Circuit - is educational software for designing and simulating logic circuits. Intuitive graphical user interface, allows you to create unrestricted circuit hierarchy with multi bit buses, debug circuits behavior with oscilloscope, and navigate running circuits hierarchy. Changes of this versionYou can make visual elements of the circuit been visible on its symbols. This way you can build composite displays, keyboards and reuse them. Please read about displays for more details http://ww...LINQ to Twitter: LINQ to Twitter v2.1.08: Supports .NET 3.5, .NET 4.0, .NET 4.5, Silverlight 4.0, Windows Phone 7.1, Windows Phone 8, Client Profile, Windows 8, and Windows Azure. 100% Twitter API coverage. Also supports Twitter API v1.1! Also on NuGet.New Projects#Zyan Drench, a game for Android: Zyan Drench is a simple yet very entertaining game for Android phones developed using Zyan Communication Framework: http://zyan.com.de Crzy Game Launcher: All in one game launcher and updater. Keep your game up-to-date with this simple to use launcher.Ecobee API: This project is a portable .NET Library wrapping the Ecobee Thermostat API.Fire-Fighting Kinect Game: Fire-Fighting Kinect Game A fire-fighting game that uses Vizard virtual reality software and the Microsoft Kinect to allow the player to put out virtual fires.Fish Atlantis: This is our homework.FreeBee 900 Pro - Open Source XBee® Pro Alternative: https://hg.codeplex.com/freebee900proFuelRex: FuelRex foi feito pra lhe ajudar em seu dia a dia. Facilite seus cálculos e obtenha números reais sobre o gasto de combustíveis, em um aplicativo totalmente.KbdPlayground: A collection of .NET helpers and experimentsMailChimpNET: MailChimpNET provides a .NET PCL based wrapper around the mailchimp.com web API.MVC Generator: Addin for Visual Studio that generates MVC from Entity Framework files. A Rapid Scaffolder with options.One More ENgine project: OMEN projet (One More ENgine) main objective is to provide a simple application container.Orchard Podcasts: The Orchard Podcasting module allows users to create and publish a podcast feed (Yahoo Media RSS) for consumption by users using Orchard v1.6+.Outlook 2013 Backup Add-In: Automatically backups psd-files after closing Outlook. This plugin is compatible with Outlook 2013 32/64 Bit Version. Project Emilie: A little help to make your WinRT XAML projects truly fast and fluid, based on work from two of the top Windows 8 applications.Search WPF: A small utility to browse the WPF classes and interfaces.sGaming: Silverlight 3D EngineTelerik Connect: Simple ASP.NET Project aiming to build a copy of the LinkedIn website functionality.Testing The Unittesting Tools in Visual Studio: This project is a collection of testprograms for verifying the different test adapters available for Visual Studio. TvLinks Torrent Searcher: Easy way to search Torrents for TV Series.xnaGaming: XNA game engine

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• London: SQLFAQ 2010 Festive Soirée (Buffet & Dance) - 17th December

  - by NeilHambly

  On the 17th December (Friday Evening) I'm holding a Xmas Soirée (Buffet & Dance) @ Central London club, so dress to impress & join us for this festive Soirée, Enjoy a Fabulous buffet, along with reserved seating for the evening, fee also includes cover charge to club areas which ahs multiple different dance floors & music Cost Per Person is £25 (Includes finger buffet & first drink, resevred seating & club access) Please notify me if you wish to be included in this as bookings...(read more)

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• Restore database to the point of disaster

  - by TiborKaraszi

  This is really basic, but so often overlooked and misunderstood. Basically, we have a database, and something goes south. Can we restore all the way up to that point? I.e., even if the last backup (db or log) is earlier than the disaster? Yes, of course we can (unless for more extreme cases, read on), but many don't realize/do that, for some strange reason. This blog post was inspired from a thread in the MSDN forums, which exposed just this misunderstanding. Basically the scenario was that they...(read more)

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• Register now for the UK Windows Azure Self-paced Interactive Learning Course starting May 10th

  - by Eric Nelson

  [Suggested twitter tag #selfpacedazure] We (myself and David Gristwood) have been working in the UK to create a fantastic opportunity to get yourself up to speed on the Windows Azure Platform over a 6 week period starting May 10th – without ever needing to leave the comfort of your home/office.  The course is derived from the internal training Microsoft gives on Azure which is both fun and challenging in equal parts – and we felt was just too good to keep to ourselves! We will be releasing more details nearer the date but hopefully the following is enough to convince you to register and … recommend it to a colleague or three :-) What we have produced is the “Microsoft Azure Self-paced Learning Course”. This is a free, interactive, self-paced, technical training course covering the Windows Azure platform – Windows Azure, SQL Azure and the Azure AppFabric. The course takes place over a six week period finishing on June 18th. During the course you will work from your own home or workplace, and get involved via interactive Live Meetings session, watch on-line videos, work through hands-on labs and research and complete weekly coursework assignments. The mentors and other attendees on the course will help you in your research and learning, and there are weekly Live Meetings where you can raise questions and interact with them. This is a technical course, aimed at programmers, system designers, and architects who want a solid understanding of the Microsoft Windows Azure platform, hence a prerequisite for this course is at least six months programming in the .NET framework and Visual Studio. Check out the full details of the event or go straight to registration.   The course outline is: Week 1 - Windows Azure Platform Week 2 - Windows Azure Storage Week 3 - Windows Azure Deep Dive and Codename "Dallas" Week 4 - SQL Azure Week 5 - Windows Azure Platform AppFabric Access Control Week 6 - Windows Azure Platform AppFabric Service Bus If you have any questions about the course and its suitability, please email [email protected].

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• HTML Maps for DataViz

  - by jamiet

  I don’t talk about data visualisation (#dataviz) much on this blog because, well, because its not something I can claim to be particularly knowledgeable about – that doesn’t stop me from having an opinion about it though. I just stumbled upon an article that compares the media ecosystems of four various technology companies entitled Mapping The Entertainment Ecosystems of Apple, Microsoft, Google & Amazon and apart from being a well-researched and well-written article (not something that the tech press excels in, in my opinion) I was struck by how well the author uses maps to tell a story to the reader. Take the map in this screenshot: Clicking on one of the four icons at the bottom of the map dynamically changes the shaded areas of the map to indicate which countries that company offers their services. Its aesthetically pleasing but moreover it instantly coveys useful information to me. What I love about it most of all though is that its all pure HTML – I don’t need any poxy Silverlight or Flash plugin to view the maps and interact with them – all I need is an up to date web browser (I use Chrome v22 although I tested using IE9 and it worked fine there too). This is how I believe data visualisation should be - conveying useful info in a friction-free way. Maps are a great way of achieving that – I just wish more people agreed with me about calendars as a mechanism for doing the same! @Jamiet

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• Presenting at PASS Summit 2011!

  - by andyleonard

  Introduction I am honored to be presenting at the PASS Summit 2011 11-14 Oct 2011 in Seattle! This year, I was selected to present a regular session and a pre-conference session. The pre-con is going to be fun. It’s a team effort with Tim Mitchell ( Blog | @Tim_Mitchell | SQLPeople ) and – even though he isn’t listed as a presenter – Matt Masson ( Blog | @mattmasson ). Like me, Tim’s been using SSIS since it was released; and Matt’s on the SSIS developer team at Microsoft – he helps build SSIS! Our...(read more)

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• SQL2K8R2: StreamInsight changes at RTM: Hopping Windows

  - by Greg Low

  We've been working on updating our demos and samples for the RTM changes of StreamInsight. I'll detail these as I come across them. The first is that there is a change to the HoppingWindow. The first two parameters are the same in the constructor but the third parameter is now required. It is the HoppingWindowOutputPolicy. Currently, there is only a single option for this which is ClipToWindowEnd. So you can create a HoppingWindow like this: var queryOutput = from w in input.HoppingWindow ( TimeSpan...(read more)

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• Where is a good place to start to learn about custom caching in .Net

  - by John

  I'm looking to make some performance enhancements to our site, but I'm not sure exactly where to begin. We have some custom object caching, but I think that we can do better. Our Business We aggregate news stories on a news type of web site. We get approximately 500-1000 new stories per week. We have index pages that show various lists of the items and details pages that show the individual stories. Our Current Use case: Getting an Individual Story User makes a request The Data Access Layer(DAL) checks to see if the item is in cache and if item is fresh (15 minutes). If the item is not in cache or is not fresh, retrieve the item from SQL Server, save to cache and return to user. Problems with this approach The pull nature of caching means that users have to pay the waiting cost every time that the cache is refreshed. Once a story is published, it changes infrequently and I think that we should replace the pull model with something better. My initial thoughts My initial thought is that stories should ALL be stored locally in some type of dictionary. (Cache or is there another, better way?). If the story is not found, then make a trip to the database, update the local dictionary and send the item back. Since there may be occasional updates to stories, this should be an entirely process from the user. I watched a video by Brent Ozar, How StackOverflow Scales SQL Server, in which Brent states "the fastest database query is the one that you don't make". Where do I start? At this point, I don't know exactly what the solution is. Is it caching? Is there a better way of using local storage? Do I use a Dictionary, OrderedDictionary, List ? It seems daunting and I'm just looking for some good starting points to learn more about how to do this type of optimization.

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• Clustered Index

  - by Derek Dieter

  The clustered index on a table can be defined as: the sort order for how the data for the table is actually stored. Being that the clustered index is the actual data itself, you cannot have two clustered indexes. You can however have many non clustered indexes. These non clustered indexes are [...]

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• Speaking at SQLSaturday #44 in Huntington Beach, CA (Los Angeles Area)

  - by Ben Nevarez

    I'll be presenting a session at SQLSaturday #44 in Huntington Beach, the first SQLSaturday on Southern California. The event takes place on Saturday, April 24 at the Golden West College on 15744 Goldenwest St, Huntington Beach, CA 92647.. For more information visit the following link   http://sqlsaturday.com/44/eventhome.aspx   My session is “How the Query Optimizer Works”. I hope to see you there. Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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• Indexed view deadlocking

  - by Dave Ballantyne

  Deadlocks can be a really tricky thing to track down the root cause of.  There are lots of articles on the subject of tracking down deadlocks, but seldom do I find that in a production system that the cause is as straightforward.  That being said,  deadlocks are always caused by process A needs a resource that process B has locked and process B has a resource that process A needs.  There may be a longer chain of processes involved, but that is the basic premise. Here is one such (much simplified) scenario that was at first non-obvious to its cause: The system has two tables,  Products and Stock.  The Products table holds the description and prices of a product whilst Stock records the current stock level. USE tempdb GO CREATE TABLE Product ( ProductID INTEGER IDENTITY PRIMARY KEY, ProductName VARCHAR(255) NOT NULL, Price MONEY NOT NULL ) GO CREATE TABLE Stock ( ProductId INTEGER PRIMARY KEY, StockLevel INTEGER NOT NULL ) GO INSERT INTO Product SELECT TOP(1000) CAST(NEWID() AS VARCHAR(255)), ABS(CAST(CAST(NEWID() AS VARBINARY(255)) AS INTEGER))%100 FROM sys.columns a CROSS JOIN sys.columns b GO INSERT INTO Stock SELECT ProductID,ABS(CAST(CAST(NEWID() AS VARBINARY(255)) AS INTEGER))%100 FROM Product There is a single stored procedure of GetStock: Create Procedure GetStock as SELECT Product.ProductID,Product.ProductName FROM dbo.Product join dbo.Stock on Stock.ProductId = Product.ProductID where Stock.StockLevel <> 0 Analysis of the system showed that this procedure was causing a performance overhead and as reads of this data was many times more than writes,  an indexed view was created to lower the overhead. CREATE VIEW vwActiveStock With schemabinding AS SELECT Product.ProductID,Product.ProductName FROM dbo.Product join dbo.Stock on Stock.ProductId = Product.ProductID where Stock.StockLevel <> 0 go CREATE UNIQUE CLUSTERED INDEX PKvwActiveStock on vwActiveStock(ProductID) This worked perfectly, performance was improved, the team name was cheered to the rafters and beers all round.  Then, after a while, something else happened… The system updating the data changed,  The update pattern of both the Stock update and the Product update used to be: BEGIN TRAN UPDATE... COMMIT BEGIN TRAN UPDATE... COMMIT BEGIN TRAN UPDATE... COMMIT It changed to: BEGIN TRAN UPDATE... UPDATE... UPDATE... COMMIT Nothing that would raise an eyebrow in even the closest of code reviews.  But after this change we saw deadlocks occuring. You can reproduce this by opening two sessions. In session 1 begin transaction Update Product set ProductName ='Test' where ProductID = 998 Then in session 2 begin transaction Update Stock set Stocklevel = 5 where ProductID = 999 Update Stock set Stocklevel = 5 where ProductID = 998 Hop back to session 1 and.. Update Product set ProductName ='Test' where ProductID = 999 Looking at the deadlock graphs we could see the contention was between two processes, one updating stock and the other updating product, but we knew that all the processes do to the tables is update them.  Period.  There are separate processes that handle the update of stock and product and never the twain shall meet, no reason why one should be requiring data from the other.  Then it struck us,  AH the indexed view. Naturally, when you make an update to any table involved in a indexed view, the view has to be updated.  When this happens, the data in all the tables have to be read, so that explains our deadlocks.  The data from stock is read when you update product and vice-versa. The fix, once you understand the problem fully, is pretty simple, the apps did not guarantee the order in which data was updated.  Luckily it was a relatively simple fix to order the updates and deadlocks went away.  Note, that there is still a *slight* risk of a deadlock occurring, if both a stock update and product update occur at *exactly* the same time.

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• Presenting the Cloud in a Different Way

  - by BuckWoody

  I had the honor of presenting the Developers at the Portland PASS chapter, and decided to go a different way than just using PowerPoint Slides…. (click on any picture to enlarge) The point is that when you need to get a point across, it’s OK to change tactics to make sure the information sticks. In this case, I decided to make the audience the PowerPoint. I used a few props to show the various paradigms we use to describe what the industry uses for the word “cloud” First, we talked about Infrastructure as a Service. I picked a gentleman who didn’t quite fit the hard hat and safety vest I picked out for him. Notice our “user” as she accesses our “Server” (complete with tray and glass) which has been virtualized.    Software as a service comes next. In this case, the user and potentially even customers just access software (represented here as a Windows ME box…) remotely – everything is virtualized. Finally, Platform as a Service – Yup, Platform shoes as a necklace, and a tie-dye shirt to represent the 70’s – a decade when mainframes used stateless programming as well. Notice also the components of Windows Azure – Compute (Keyboard) Application Fabric (Toy Bus) and Storage (Bucket).   And at the end of the day, it’s all about serving those customers…

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• Two BULK INSERT issues I worked around recently

  - by AaronBertrand

  Since I am still afraid of SSIS, and because I am dealing mostly with CSV files and table structures that are relatively simple and require only one of the three letters in the acronym "ETL," I find myself using BULK INSERT a lot. I have been meaning to switch to using CLR, since I am doing a lot of file system querying using xp_cmdshell, but I haven't had the chance to really explore it yet. I know, a lot of you are probably thinking, wow, look at all those bad habits. But for every person thinking...(read more)

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• SQLBits 6 Registration Now Open

  - by MartinBell

  SQLBits VI registations opened on 17 March 2010 at 12:00 ...(read more)

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• The Excel Connection Manager is not supported in the 64-bit version of SSIS

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• 24 Hours of PASS - Today!

  - by andyleonard

  24 Hours of PASS (2010) starts this morning! Tune in! :{> Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!...(read more)

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• Dovecot not working pop3 with postfix

  - by samer na

  $ telnet localhost pop3 Trying ::1... Trying 127.0.0.1... telnet: Unable to connect to remote host: Connection refused $ netstat -l tcp 0 0 *:www : LISTEN tcp 0 0 localhost.localdoma:ipp : LISTEN tcp 0 0 *:smtp : LISTEN tcp 0 0 localhost.localdo:mysql : LISTEN and nothing about dovecot in mail.log or mail.err when I run this service dovecot start I got start: Rejected send message, 1 matched rules; type="method_call", sender=":1.553" (uid=1000 pid=26250 comm="start) interface="com.ubuntu.Upstart0_6.Job" member="Start" error name="(unset)" requested_reply=0 destination="com.ubuntu.Upstart" (uid=0 pid=1 comm="/sbin/init")) in dovecot.conf protocols = imap imaps pop3 pop3s disable_plaintext_auth = no log_timestamp = "%Y-%m-%d %H:%M:%S " mail_location = maildir:/var/spool/mail/%d/%n mail_access_groups = mail first_valid_uid = 106 first_valid_gid = 106 protocol imap { } protocol pop3 { listen=*:110 pop3_uidl_format = %08Xu%08Xv } protocol lda { postmaster_address = [email protected] mail_plugins = quota log_path = /var/log/dovecot-deliver.log info_log_path = /var/log/dovecot-deliver.log } auth default { mechanisms = digest-md5 plain passdb sql { args = /etc/dovecot/dovecot-mysql.conf } userdb sql { args = /etc/dovecot/dovecot-mysql.conf } user = root }

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