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• Microsoft SQL Server 2012 Analysis Services – The BISM Tabular Model #ssas #tabular #bism

  - by Marco Russo (SQLBI)

  I, Alberto and Chris spent many months (many nights, holidays and also working days of the last months) writing the book we would have liked to read when we started working with Analysis Services Tabular. A book that explains how to use Tabular, how to model data with Tabular, how Tabular internally works and how to optimize a Tabular model. All those things you need to start on a real project in order to make an happy customer. You know, we’re all consultants after all, so customer satisfaction is really important to be paid for our job! Now the book writing is finished, we’re in the final stage of editing and reviews and we look forward to get our print copy. Its title is very long: Microsoft SQL Server 2012 Analysis Services – The BISM Tabular Model. But the important thing is that you can already (pre)order it. This is the list of chapters: 01. BISM Architecture 02. Guided Tour on Tabular 03. Loading Data Inside Tabular 04. DAX Basics 05. Understanding Evaluation Contexts 06. Querying Tabular 07. DAX Advanced 08. Understanding Time Intelligence in DAX 09. Vertipaq Engine 10. Using Tabular Hierarchies 11. Data modeling in Tabular 12. Using Advanced Tabular Relationships 13. Tabular Presentation Layer 14. Tabular and PowerPivot for Excel 15. Tabular Security 16. Interfacing with Tabular 17. Tabular Deployment 18. Optimization and Monitoring And this is the book cover – have a good read!

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• Analysis Services Tabular books #ssas #tabular

  - by Marco Russo (SQLBI)

  Many people are looking for books about Analysis Services Tabular. Today there are two books available and they complement each other: Microsoft SQL Server 2012 Analysis Services: The BISM Tabular Model by Marco Russo, Alberto Ferrari and Chris Webb Applied Microsoft SQL Server 2012 Analysis Services: Tabular Modeling by Teo Lachev The book I wrote with Alberto and Chris is a complete guide to create tabular models and has a good coverage about DAX, including how to use it for enriching a semantic model with calculated columns and measures and how to use it for querying a Tabular model. In my experience, DAX as a query language is a very interesting option for custom analytical applications that requires a fast calculation engine, or simply for standard reports running in Reporting Services and accessing a Tabular model. You can freely preview the table of content and read some excerpts from the book on Safari Books Online. The book is in printing and should be shipped within mid-July, so finally it will be very soon on the shelf of all the people already preordered it! The Teo Lachev’s book, covers the full spectrum of Tabular models provided by Microsoft: starting with self-service BI, you have users creating a model with PowerPivot for Excel, publishing it to PowerPivot for SharePoint and exploring data by using Power View; then, the PowerPivot for Excel model can be imported in a Tabular model and published in Analysis Services, adding more control on the model through row-level security and partitioning, for example. Teo’s book follows a step-by-step approach describing each feature that is very good for a beginner that is new to PowerPivot and/or to BISM Tabular. If you need to get the big picture and to start using the products that are part of the new Microsoft wave of BI products, the Teo’s book is for you. After you read the book from Teo, or if you already have a certain confidence with PowerPivot or BISM Tabular and you want to go deeper about internals, best practices, design patterns in just BISM Tabular, then our book is a suggested read: it contains several chapters about DAX, includes discussions about new opportunities in data model design offered by Tabular models, and also provides examples of optimizations you can obtain in DAX and best practices in data modeling and queries. It might seem strange that an author write a review of a book that might seem to compete with his one, but in reality these two books complement each other and are not alternatives. If you have any doubt, buy both: you will be not disappointed! Moreover, Amazon usually offers you a deal to buy three books, including the Visualizing Data with Microsoft Power View, another good choice for getting all the details about Power View.

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• White Paper on Analysis Services Tabular Large-scale Solution #ssas #tabular

  - by Marco Russo (SQLBI)

  Since the first beta of Analysis Services 2012, I worked with many companies designing and implementing solutions based on Analysis Services Tabular. I am glad that Microsoft published a white paper about a case-study using one of these scenarios: An Analysis Services Case Study: Using Tabular Models in a Large-scale Commercial Solution. Alberto Ferrari is the author of the white paper and many people contributed to it. The final result is a very technical document based on a case study, which provides a level of detail that I don’t see often in other case studies (which are usually more marketing-oriented). This white paper has the following structure: Requirements (data model, capacity planning, client tool) Options considered (SQL Server Columnstore Indexes, SSAS Multidimensional, SSAS Tabular) Data Model optimizations (memory compression, query performance, scalability) Partitioning and Processing strategy for near real-time latency Hardware selection (NUMA analysis, Azure VM tests) Scalability tests (estimation of maximum users per node) If you are in charge of evaluating Tabular as analytical engine, or if you have to design your solution based on Tabular, this white paper is a must read. But if you just want to increase your knowledge of Analysis Services, you will find a lot of useful technical information. That said, my favorite quote of the document is the following one, funny but true: […] After several trials, the clear winner was a video gaming machine that one guy on the team used at home. That computer outperformed any available server, running twice as fast as the server-class machines we had in house. At that point, it was clear that the criteria for choosing the server would have to be expanded a bit, simply because it would have been impossible to convince the boss to build a cluster of gaming machines and trust it to serve our customers.  But, honestly, if a business has the flexibility to buy gaming machines (assuming the machines can handle capacity) – do this. Owen Graupman, inContact I want to write a longer discussion about how companies are adopting Tabular in scenarios where it is the hidden engine of a more complex solution (and not the classical “BI system”), because it is more frequent than you might expect (and has several advantages over many alternative approaches).

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• The updated Survey pattern for Power Pivot and Tabular #powerpivot #tabular #ssas #dax

  - by Marco Russo (SQLBI)

  One of the first models I created for the many-to-many revolution white paper was the Survey one. At the time, it was in Analysis Services Multidimensional, and then we implemented it in Analysis Services Tabular and in Power Pivot, using the DAX language. I recently reviewed the data model and published it in the Survey article on DAX Patterns site. The Survey pattern is the foundation for others, such as the Basket Analysis, and it is widely used in many different business scenario. I was particularly happy to know it has been using to perform data analysis for cancer research! In this article I did some maintenance on the DAX formulas, checking that the proper error handling is part of the formulas, and highlighting some differences in slicers behavior between Excel 2010 and Excel 2013, which could be particularly important for the Survey scenario. As usual, we provide sample workbooks for both Excel 2010 and Excel 2013, and we use DAX Formatter to make the DAX code easier to read. Any feedback will be appreciated!

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• Parallelize incremental processing in Tabular #ssas #tabular

  - by Marco Russo (SQLBI)

  I recently came in a problem trying to improve the parallelism of Tabular processing. As you know, multiple tables can be processed in parallel, whereas the processing of several partitions within the same table cannot be parallelized. When you perform an incremental update by adding only new rows to existing table, what you really do is adding rows to a partition, so adding rows to many tables means adding rows to several partitions. The particular condition you have in this case is that every partition in which you add rows belongs to a different table. Adding rows implies using the ProcessAdd command; its QueryBinding parameter specifies a SQL syntax to read new rows, otherwise the original query specified for the partition will be used, and it could generate duplicated data if you don’t have a dynamic behavior on the SQL side. If you create the required XMLA code manually, you will find that the QueryBinding node that should be part of the ProcessAdd command has to be moved out from ProcessAdd in case you are using a Batch command with more than one Process command (which is the reason why you want to use a single batch: run multiple process operations in parallel!). If you use AMO (Analysis Management Objects) you will find that this combination is not supported, even if you don’t have a syntax error compiling the code, but you might obtain this error at execution time: The syntax for the 'Process' command is incorrect. The 'Bindings' keyword cannot appear under a 'Process' command if the 'Process' command is a part of a 'Batch' command and there are more than one 'Process' commands in the 'Batch' or the 'Batch' command contains any out of line related information. In this case, the 'Bindings' keyword should be a part of the 'Batch' command only. If this is happening to you, the best solution I’ve found is manipulating the XMLA code generated by AMO moving the Binding nodes in the right place. A more detailed description of the issue and the code required to send a correct XMLA batch to Analysis Services is available in my article Parallelize ProcessAdd with AMO. By the way, the same technique (and code) can be used also if you have the same problem in a Multidimensional model.

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• Implement Budget Allocation in DAX for Power Pivot and Tabular #powerpivot #tabular #ssas #dax

  - by Marco Russo (SQLBI)

  Comparing sales and budget, or costs and budget, is a very common operation. However, it is often the case that you have different granularities for different tables containing budget and the data to compare with. There are two ways to do that: you can limit the comparison to the granularity that is common to the two tables, or you can allocate the budget where it’s not defined. For example, if you have a budget defined by quarter and category, you might want to allocate it by month and product. In this way, you will do the comparison as you had a more granular definition of the budget, without actually having to do the manual job of allocating data (usually in an Excel worksheet!). If you want to do budget allocation in DAX, you can use the Budget Patterns we published on DAX Patterns. If you come from and MDX/OLAP background, at first you might find it hard to solve the problem of not having attribute hierarchies that helps you in propagating the budget values to lower hierarchical levels. However, I think that once you get used to DAX, you will find the behavior very predictable and easy to “debug” also for more complex allocation formula. You just have to be careful in writing the DAX formula, but probably the pattern we wrote should help you designing the right data model, without creating physical relationships to the budget table! This pattern is also based on the Handling Different Granularities scenario I discussed a couple of weeks ago.

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• Implement Budget Allocation in DAX for Power Pivot and Tabular #powerpivot #tabular #ssas #dax

  - by Marco Russo (SQLBI)

  Comparing sales and budget, or costs and budget, is a very common operation. However, it is often the case that you have different granularities for different tables containing budget and the data to compare with. There are two ways to do that: you can limit the comparison to the granularity that is common to the two tables, or you can allocate the budget where it’s not defined. For example, if you have a budget defined by quarter and category, you might want to allocate it by month and product. In this way, you will do the comparison as you had a more granular definition of the budget, without actually having to do the manual job of allocating data (usually in an Excel worksheet!). If you want to do budget allocation in DAX, you can use the Budget Patterns we published on DAX Patterns. If you come from and MDX/OLAP background, at first you might find it hard to solve the problem of not having attribute hierarchies that helps you in propagating the budget values to lower hierarchical levels. However, I think that once you get used to DAX, you will find the behavior very predictable and easy to “debug” also for more complex allocation formula. You just have to be careful in writing the DAX formula, but probably the pattern we wrote should help you designing the right data model, without creating physical relationships to the budget table! This pattern is also based on the Handling Different Granularities scenario I discussed a couple of weeks ago.

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• Updates about Multidimensional vs Tabular #ssas #msbi

  - by Marco Russo (SQLBI)

  I recently read the blog post from James Serra Tabular model: Not ready for prime time? (read also the comments because there are discussions about a few points raised by James) and the following post from Christian Wade Multidimensional or Tabular. In the last 2 years I worked with many companies adopting Tabular in different scenarios and I agree with some of the points expressed by James in his post (especially about missing features in Tabular if compared to Multidimensional), but I strongly disagree in others. In general, Tabular is a good choice for a new project when: the development team does not have a good knowledge of Multidimensional and MDX (DAX is faster to learn, not so easy as it is sold by MS, but definitely easier than MDX) you don’t need calculations based on hierarchies (common in certain financial applications, but not so common as it could seem) there are important calculations based on distinct count measures there are complex calculations based on many-to-many relationships Until now, I never suggested to migrate an existing Multidimensional model to a Tabular one. There should be very important reasons for that, such as performance issues in distinct count and many-to-many relationships that cannot be easily solved by optimizing the Multidimensional model, but I still never encountered this scenario. I would say that in 80% of the new projects, you might use either Multidimensional or Tabular and the real difference is the time-to-market depending on the skills of the development team. So it’s not strange that who is used to Multidimensional is not moving to Tabular, not getting a particular benefit from the new model unless specific requirements exist. The recent DAXMD feature that allows using SharePoint Power View on Multidimensional is a really important one, even if I’d like having also Excel Power View enabled for this scenario (this should be just a question of time). Another scenario in which I’m seeing a growing adoption of Tabular is in companies that creates models for their product/service and do that by using XMLA or Tabular AMO 2012. I am used to call them ISVs, even if those providing services cannot be really defined in this way. These companies are facing the multitenancy challenge with Tabular and even if this is a niche market, I see some potential here, because adopting Tabular seems a much more natural choice than Multidimensional in those scenario where an analytical engine has to be embedded to deliver one of the features of a larger product/service delivered to customers. I’d like to see other feedbacks in the comments: tell your story of choosing between Tabular and Multidimensional in a BI project you started with SQL Server 2012, thanks!

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• SSAS Tabular Workshop online and other upcoming dates (and updates!) #ssas #tabular

  - by Marco Russo (SQLBI)

  After many conferences and travels, this summer I had some time to write and prepare new sessions for the next wave of conferences. In reality I am just doing that, even if I already restarted traveling for consulting and training. So expect new content about DAX and Tabular coming in the next months! Starting to see real customer adopting Tabular is showing many new challenges and there is still a lot to learn and to create. If you still didn’t started working on Tabular, well, you should. As I always say, as a BI developer you should be able to choose between Tabular and Multidimensional, and in order to do that you should know both of them! One thing that I don’t like very much about marketing is that “Tabular is simpler”, because it’s often translated in “Tabular is for simple projects” when this last statement is not true. Actually, I see a lot of good reasons to adopt Tabular in complex data models, especially in non-traditional scenarios. I know, this is because I love to understand what are the actual limits of a technology, and I’m learning that there is simple a lot of space of improvement also for Tabular. It’s already fast, but it could be faster! How can you start? Well, first of all, by reading our book. Then, by attending to our SSAS Tabular workshop. There is an online edition of the workshop on September 3-4, 2012 (hurry up if you want to register), and there are already several dates planned for the next months (and others will be added soon!). And, of course, by installing SQL Server 2012 and trying to create models over your databases. If you are too lazy, just start with PowerPivot. As soon as you start working with Tabular or PowerPivot, you will see that there is one important skill you need: learning DAX. In the next few days I should publish an article that I’m finishing these days about best practices using SUMMARIZE and ADDCOLUMNS. If only someone published this article one year ago, I would have saved many hours of my life. But, you know, flight manuals are written in blood… and someone has to write! Stay tuned.

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• Common request: export #Tabular model and data to #PowerPivot

  - by Marco Russo (SQLBI)

  I received this request in many courses, messages and also forum discussions: having an Analysis Services Tabular model, it would be nice being able to extract a correspondent PowerPivot data model. In order of priority, here are the specific feature people (including me) would like to see: Create an empty PowerPivot workbook with the same data model of a Tabular model Change the connections of the tables in the PowerPivot workbook extracting data from the Tabular data model Every table should have an EVALUATE ‘TableName’ query in DAX Apply a filter to data extracted from every table For example, you might want to extract all data for a single country or year or customer group Using the same technique of applying filter used for role based security would be nice Expose an API to automate the process of creating a PowerPivot workbook Use case: prepare one workbook for every employee containing only its data, that he can use offline Common request for salespeople who want a mini-BI tool to use in front of the customer/lead/supplier, regardless of a connection available This feature would increase the adoption of PowerPivot and Tabular (and, therefore, Business Intelligence licenses instead of Standard), and would probably raise the sales of Office 2013 / Office 365 driven by ISV, who are the companies who requests this feature more. If Microsoft would do this, it would be acceptable it only works on Office 2013. But if a third-party will do that, it will make sense (for their revenues) to cover both Excel 2010 and Excel 2013. Another important reason for this feature is that the “Offline cube” feature that you have in Excel is not available when your PivotTable is connected to a Tabular model, but it can only be used when you connect to Analysis Services Multidimensional. If you think this is an important features, you can vote this Connect item.

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• #SSAS #Tabular Workshop and Community Events in Netherlands and Denmark

  - by Marco Russo (SQLBI)

  Next week I will finally start the roadshow of the SSAS Tabular Workshop, a 2-day seminar about the new BISM Tabular model for Analysis Services that has been introduced in SQL Server 2012. During these roadshows, we always try to arrange some speeches at local community events in the evening - we already defined for Copenhagen, we have some logistic issue in Amsterdam that we're trying to solve. Here is the timetable: Netherlands SSAS Workshop in Amsterdam, NL – April 16-17, 2012 2-day seminar, I and Alberto will be the trainers for this event, register here We're trying to manage a Community event but we still don't have a confirmation, stay tuned        Denmark SSAS Workshop in Copenhagen, DK – April 26-27, 2012 2-day seminar, I and Alberto will be the trainers for this event, register here Community event on April 26, 2012 This event will run in Hellerup, at Microsoft venue All details available here: http://msbip.dk/events/26/msbip-mode-nr-5/ People from Sweden are welcome! Just register to this private group on LinkedIn in order to announce your presence, so we’ll know how many people will attend In community events we’ll deliver two speeches – here are the descriptions: Inside xVelocity (VertiPaq) PowerPivot and BISM Tabular models in Analysis Services share a great columnar-based database engine called xVelocity in-memory analytics engine (VertiPaq). If you want to improve performance and optimize memory used, you have to understand some basic principles about how this engine works, how data is compressed, and how you can design a data model for better optimization. Prepare yourself to change your mind. xVelocity optimization techniques might seem counterintuitive and are absolutely different than OLAP and SQL ones! Choosing between Tabular and Multidimensional You have a new project and you have to make an important decision upfront. Should you use Tabular or Multidimensional? It is not easy to answer, because sometime there is a clear choice, but most of the times both decisions might be correct, at least at the beginning. In this session we’ll help you making an informed decision, correctly evaluating pros and cons of each one according to common scenarios, considering both short-term and long-term consequences of your choice. I hope to meet many people in this first dates. We have many other events coming in May and June, including an online event (for US time zones), and you can also attend our PreCon Day at TechEd US in Orland (PRC06) or TechEd Europe in Amsterdam. I’ll be a good customer for airline companies in the next three months! I’m just sorry that I hadn’t time to write other articles in the last month, but I’m accumulating material that I will need to write down during some flight – stay tuned…

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• Community Events in Köln (October) and Copenhagen November #ssas #tabular #powerpivot

  - by Marco Russo (SQLBI)

  Short update about community events in Europe where I will speak.On October 11 I will present DAX in Action in Köln - all details in the PASS local chapter here: http://www.sqlpass.de/Regionen/Deutschland/K%C3%B6lnBonnD%C3%BCsseldorf.aspxI will be speaking at a community event in Copenhagen on November 21, 2012. The session will be Excel 2013 PowerPivot in Action and details about time and location are available here: http://msbip.dk/events/30/msbip-mode-nr-9/I will be in Köln and Copenhagen to teach the SSAS Tabular Workshop. The workshop in Köln is the first in Germany and I look forward to meet new BI developers there.Copenhagen is the second edition after another we delivered this spring. It is a convenient location also for people coming from Malmoe and Göteborg in Sweden. Last event in Copenhagen were conflicting with a large event in Sweden, maybe this time I'll meet more people coming from the other side of the Øresund Bridge!Many other dates and location are available on the SSAS Tabular Workshop website.

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• xVelocity engines compared: VertiPaq vs ColumnStore #ssas #vertipaq #xvelocity #sql #tabular

  - by Marco Russo (SQLBI)

  During the last months I and Alberto worked in several projects using Analysis Services Tabular and we had to face real world issues, such as complex queries, large data volume, frequent data updates and so on. Sometime we faced the challenge of comparing Tabular performance with SQL Server. It seemed a non-sense, because even if the same core xVelocity technology is implemented in both products (SQL Server 2012 uses ColumnStore indexes, whereas Analysis Services 2012 uses VertiPaq), we initially assumed that the better optimization for the in-memory engine used by Analysis Services would have been always better than SQL Server. However, we discovered several important things: Processing time might be different and having data on SQL Server could make ColumnStore way faster for processing. Partitioning in SQL Server might be much more effective for query performance than Analysis Services. A single query can scale easily on more processor on SQL Server, whereas in Analysis Services the formula engine is single-threaded and could be a bottleneck for certain queries. In case of a large workload with many concurrent users, storage engine cache in Analysis Services could be a big advantage over SQL Server, especially for scalability As you can see, these considerations are not always obvious and you might be tempted to make other assumptions based on these information. Well, don’t do that. Before anything else, read the whitepaper VertiPaq vs ColumnStore Comparison written by Alberto Ferrari. Then, measure your workload. Finally, make some conclusion. But don’t make too many assumptions. You might be wrong, as we did at the beginning of this journey.

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• Write DAX queries in Report Builder #ssrs #dax #ssas #tabular

  - by Marco Russo (SQLBI)

  If you use Report Builder with Reporting Services, you can use DAX queries even if the editor for Analysis Services provider does not support DAX syntax. In fact, the DMX editor that you can use in Visual Studio editor of Reporting Services (see a previous post on that), is not available in Report Builder. However, as Sagar Salvi commented in this Microsoft Connect entry, you can use the DAX query text in the query of a Dataset by using the OLE DB provider instead of the Analysis Services one. I think it’s a good idea to show the steps required. First, create a DataSet using the OLE DB connection type, and provide the connection string the provider (Provider), the server name (Data Source) and the database name (Initial Catalog), such as: Provider=MSOLAP;Data Source=SERVERNAME\\TABULAR;Initial Catalog=AdventureWorks Tabular Model SQL 2012 Then, create a Dataset using the data source previously defined, select the Text query type, and write the DAX code in the Query pane: You can also use the Query Designer window, that doesn’t provide any particular help in writing the DAX query, but at least can show a preview of the result of the query execution. I hope DAX will get better editors in the future… in the meantime, remember you can use DAX Studio to write and test your DAX queries, and DAX Formatter to improve their readability!If you want to learn the DAX Query Language, I suggest you watching my video Data Analysis Expressions as a Query Language on Project Botticelli!

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• Write DAX queries in Report Builder #ssrs #dax #ssas #tabular

  - by Marco Russo (SQLBI)

  If you use Report Builder with Reporting Services, you can use DAX queries even if the editor for Analysis Services provider does not support DAX syntax. In fact, the DMX editor that you can use in Visual Studio editor of Reporting Services (see a previous post on that), is not available in Report Builder. However, as Sagar Salvi commented in this Microsoft Connect entry, you can use the DAX query text in the query of a Dataset by using the OLE DB provider instead of the Analysis Services one. I think it’s a good idea to show the steps required. First, create a DataSet using the OLE DB connection type, and provide the connection string the provider (Provider), the server name (Data Source) and the database name (Initial Catalog), such as: Provider=MSOLAP;Data Source=SERVERNAME\\TABULAR;Initial Catalog=AdventureWorks Tabular Model SQL 2012 Then, create a Dataset using the data source previously defined, select the Text query type, and write the DAX code in the Query pane: You can also use the Query Designer window, that doesn’t provide any particular help in writing the DAX query, but at least can show a preview of the result of the query execution. I hope DAX will get better editors in the future… in the meantime, remember you can use DAX Studio to write and test your DAX queries, and DAX Formatter to improve their readability!If you want to learn the DAX Query Language, I suggest you watching my video Data Analysis Expressions as a Query Language on Project Botticelli!

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• LASTDATE dates arguments and upcoming events #dax #tabular #powerpivot

  - by Marco Russo (SQLBI)

  Recently I had to write a DAX formula containing a LASTDATE within the logical condition of a FILTER: I found that its behavior was not the one I expected and I further investigated. At the end, I wrote my findings in this article on SQLBI, which can be applied to any Time Intelligence function with a <dates> argument.The key point is that when you write LASTDATE( table[column] )in reality you obtain something like LASTDATE( CALCULATETABLE( VALUES( table[column] ) ) )which converts an existing row context into a filter context.Thus, if you have something like FILTER( table, table[column] = LASTDATE( table[column] ) the FILTER will return all the rows of table, whereas you probably want to use FILTER( table, table[column] = LASTDATE( VALUES( table[column] ) ) )so that the existing filter context before executing FILTER is used to get the result from VALUES( table[column] ), avoiding the automatic expansion that would include a CALCULATETABLE that would hide the existing filter context.If after reading the article you want to get more insights, read the Jeffrey Wang's post here.In these days I'm speaking at SQLRally Nordic 2012 in Copenhagen and I will be in Cologne (Germany) next week for a SSAS Tabular Workshop, whereas Alberto will teach the same workshop in Amsterdam one week later. Both workshops still have seats available and the Amsterdam's one is still in early bird discount until October 3rd!Then, in November I expect to meet many blog readers at PASS Summit 2012 in Seattle and I hope to find the time to write other article on interesting things on Tabular and PowerPivot. Stay tuned!

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• #DAX Query Plan in SQL Server 2012 #Tabular

  - by Marco Russo (SQLBI)

  The SQL Server Profiler provides you many information regarding the internal behavior of DAX queries sent to a BISM Tabular model. Similar to MDX, also in DAX there is a Formula Engine (FE) and a Storage Engine (SE). The SE is usually handled by Vertipaq (unless you are using DirectQuery mode) and Vertipaq SE Query classes of events gives you a SQL-like syntax that represents the query sent to the storage engine. Another interesting class of events is the DAX Query Plan , which contains a couple...(read more)

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• Optimize SUMMARIZE with ADDCOLUMNS in Dax #ssas #tabular #dax #powerpivot

  - by Marco Russo (SQLBI)

  If you started using DAX as a query language, you might have encountered some performance issues by using SUMMARIZE. The problem is related to the calculation you put in the SUMMARIZE, by adding what are called extension columns, which compute their value within a filter context defined by the rows considered in the group that the SUMMARIZE uses to produce each row in the output. Most of the time, for simple table expressions used in the first parameter of SUMMARIZE, you can optimize performance by removing the extended columns from the SUMMARIZE and adding them by using an ADDCOLUMNS function. In practice, instead of writing SUMMARIZE( <table>, <group_by_column>, <column_name>, <expression> ) you can write: ADDCOLUMNS(     SUMMARIZE( <table>, <group by column> ),     <column_name>, CALCULATE( <expression> ) ) The performance difference might be huge (orders of magnitude) but this optimization might produce a different semantic and in these cases it should not be used. A longer discussion of this topic is included in my Best Practices Using SUMMARIZE and ADDCOLUMNS article on SQLBI, which also include several details about the DAX syntax with extended columns. For example, did you know that you can create an extended column in SUMMARIZE and ADDCOLUMNS with the same name of existing measures? It is *not* a good thing to do, and by reading the article you will discover why. Enjoy DAX!

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• DATE function does not support all the dates in DAX by design #powerpivot #tabular #dax

  - by Marco Russo (SQLBI)

  The DATE function in DAX has this simple syntax: DATE( <year>, <month>, <day> ) If you are like me, you never read the BOL notes that says in a clear way that it supports dates beginning with March 1, 1900. In fact, I was wrongly assuming that it would have supported any date that can be represented in a Date data type in Data Models, so all the dates beginning with January 1, 1900. The funny thing is that in some of the BOL documentation you will find that Date data type supports dates after March 1, 1900 (which seems not including that date, but this is a detail…). But we should not digress. The real issue is that if you try to call the DATE function passing values between January 1 and February 28, 1900, you will see a different day as a result. evaluate row ( "x", DATE( 1900, 1, 1 ) ) -- return WRONG result -- [x] 12/31/1899 12:00:00 AM   evaluate row ( "x", DATE( 1901, 2, 29 ) ) -- return WRONG result -- [x] 2/28/1900 12:00:00 AM   evaluate row ( "x", DATE( 1900, 3, 1 ) ) -- return CORRECT result -- [x] 3/1/1900 12:00:00 AM As usual, this is not a bug. It is “by design”. The DATE function works in this way in Excel. And also in Excel it was “by design”. In this case the design is having the same bug of Lotus 1-2-3 that handled 1900 a leap year, even though it isn’t. The first release of Lotus 1-2-3 is dated 1983. I hope many of my readers are younger than that. I tried to open a bug in Connect. Please vote it. I would like if Microsoft changed this type of items from “by design” (as we can expect) to “by genetic disease”. Or by “historical respect”, in order to be more politically correct.

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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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• A proposal for #DAX Code Formatting #ssas #powerpivot #tabular

  - by Marco Russo (SQLBI)

  I recently published a set of rules for DAX code formatting. The following is an example of what I obtain: CALCULATE (     SUMX (         Orders,         Orders[Amount]     ),     FILTER (         ALL ( Customers ),         CALCULATE (             COUNTROWS ( Sales ),             ALL ( Calendar[Date] )         ) > 42 + 8 – 25 * ( 3 - 1 )             + 2 – 1 + 2 – 1             + CALCULATE (                   2 + 2 – 2                   + 2 - 2               )             – CALCULATE ( 4 )     ) ) The goal is to improve code readability and I look forward to implement a code formatting feature in DAX Studio. The DAX Editor already supports the rules described in the article. I am also considering whether to add a rule specific for ADDCOLUMNS / SUMMARIZE because I would like to see the “pairs” of arguments to define a column in the same row or with a special indentation rule (DAX expression for a column is indented in the line following the column name). EVALUATE CALCULATETABLE (        CALCULATETABLE (         SUMMARIZE (             Audience,             'Date'[Year],             Individuals[Gender],             Individuals[AgeRange],             "Num of Rows", FORMAT (COUNTROWS (Audience), "#,#"),             "Weighted Mean Age",                 SUMX (Audience, Audience[Weight] * Audience[Age]) / SUM (Audience[Weight])         ),         SUMMARIZE (             BridgeIndividualsTargets,             Individuals[ID_Individual]         ),         Audience[Weight] > 0        ),        Targets[Target] = "Maschi",     'Date'[Year] = 2010,     'Date'[MonthName] = "January" ) I would like to get feedback for that – you can use comments here or comments in original article. Thanks!

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• Understanding #DAX Query Plans for #powerpivot and #tabular

  - by Marco Russo (SQLBI)

  Alberto Ferrari wrote a very interesting white paper about DAX query plans. We published it on a page where we'll gather articles and tools about DAX query plans: http://www.sqlbi.com/topics/query-plans/I reviewed the paper and this is the result of many months of study - we know that we just scratched the surface of this topic, also because we still don't have enough information about internal behavior of many of the operators contained in a query plan. However, by reading the paper you will start reading a query plan and you will understand how it works the optimization found by Chris Webb one month ago to the events-in-progress scenario. The white paper also contains a more optimized query (10 time faster), even if the performance depends on data distribution and the best choice really depends on the data you have. Now you should be curious enough to read the paper until the end, because the more optimized query is the last example in the paper!

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• latex tabular vertical alignment to top?

  - by shoosh

  I'm trying to create a simple tabular with two cells of text and two images below them like so: \begin{tabular}[h]{ c | c} \emph{Normal} & \emph{Cone} \\ \includegraphics[width=0.39\textwidth]{images/pipe1} & \includegraphics[width=0.61\textwidth]{images/pipe2} \end{tabular} The first image is shorter than the second and I want it to be aligned at the top of the cell but for some reason it gets aligned to the bottom of the cell instead. I've tried using the array package and do this: \begin{tabular}[h]{ p{0.39\textwidth} | p{0.61\textwidth} } \emph{Normal} & \emph{Cone} \\ \includegraphics[width=0.39\textwidth]{images/pipe1} & \includegraphics[width=0.61\textwidth]{images/pipe2} \end{tabular} But this doesn't change anything. The first image is still aligned to the bottom. Why is that? Could there be something else going on which forces the alignment to stick to the bottom?

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• Watch @marcorus and @ferrarialberto sessions online #teched #msteched #tee2012

  - by Marco Russo (SQLBI)

  In June I participated to two TechEd editions (North America and Europe). I and Alberto delivered a Pre Conference and two sessions about Tabular. Both conferences provides recorded sessions freely available on Channel 9 so that you can compare which one has been delivered in the best way! If you have to choose between the two versions, consider that in North America we receive more questions during and after the session (still recording), increasing the interaction, whereas in Europe questions usually comes after the session finished (so no recording available). If you’re curious, watch both and let me know which version you prefer, especially for Multidimensional vs Tabular! BISM: Multidimensional vs. Tabular (TechEd North America 2012) BISM: Multidimensional vs. Tabular (TechEd Europe 2012) Many-to-Many Relationships in BISM Tabular (TechEd North America 2012) Many-to-Many Relationships in BISM Tabular (TechEd Europe 2012) If you are interested to learn SSAS Tabular, don’t miss the next SSAS Tabular Workshop online on September 3-4, 2012. We are also planning dates for another roadshow in Europe this fall and I’m happy to announce we’ll have two dates in Germany, too. More updates in the coming weeks.

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• Watch @marcorus and @ferrarialberto sessions online #teched #msteched #tee2012

  - by Marco Russo (SQLBI)

  In June I participated to two TechEd editions (North America and Europe). I and Alberto delivered a Pre Conference and two sessions about Tabular. Both conferences provides recorded sessions freely available on Channel 9 so that you can compare which one has been delivered in the best way! If you have to choose between the two versions, consider that in North America we receive more questions during and after the session (still recording), increasing the interaction, whereas in Europe questions usually comes after the session finished (so no recording available). If you’re curious, watch both and let me know which version you prefer, especially for Multidimensional vs Tabular! BISM: Multidimensional vs. Tabular (TechEd North America 2012) BISM: Multidimensional vs. Tabular (TechEd Europe 2012) Many-to-Many Relationships in BISM Tabular (TechEd North America 2012) Many-to-Many Relationships in BISM Tabular (TechEd Europe 2012) If you are interested to learn SSAS Tabular, don’t miss the next SSAS Tabular Workshop online on September 3-4, 2012. We are also planning dates for another roadshow in Europe this fall and I’m happy to announce we’ll have two dates in Germany, too. More updates in the coming weeks.

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