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• SQL Saturday #44 Huntington Beach Recap

  What a great day. It was long and tiring, but rewarding in so many ways. On Sunday morning, I was driving home and I decided to take the Pacific Coast Highway from Huntington Beach.  It was a great chance to exhale and just enjoy the sun and smells of the beach (I really love SoCal sometimes). And for future reference for all you speakers, the beach and ocean are only 5 minutes from the SQL Saturday location.  I just could help noticing also the shocking number of high priced cars on the road (4 Bentleys, 3 Ferraris, 1 Aston Martins, 3 Maserati, 1 Rolls Royce, and 2 Lamborghinis).  It made me think about this: Price of all those cars: $ 150,000+.  Impacting the ability of people to learn: Priceless.  We have positively impacted the education, knowledge, capabilities of not only our attendees, but also all of their companies and people they might help as well.  That is just staggering and something to be immensely proud of. To all of my fellow community leaders, I salute you. So lets talk about the event Overall We had over 220 people register for the event and had 180+ people attend the event. I was shooting for the magical 200 number, but I guess it just gives us more motivation to make it even bigger and better next time. We had a few snags along the way, but what event doesnt, but I think everything turned out great. I did not hear any negative comments and heard lots of positive comments along with people asking when the next one is going to be (More on that later). Location- Golden West College We could not have asked for a better partner for the event. Herb Cohen from Golden West College was the wizard behind the curtains. From the beginning, he was our advocate to the GWC Board and was instrumental in getting our event approved. The day off, Herb was a HUGE help getting any and all logistics that we needed taken care of. In the craziness of the early morning registration crush it was a big help knowing that he and Bret Stateham (Blog | Twitter) were taking care of testing projectors in all the rooms. Anything we needed he was there and was even proactive in getting some things that I had not even thought of (i.e. a dumpster for all of our garbage). I cannot thank Herb enough along with other members of the GWC staff including Minnie Higgins of the Career and Technical Education Division office, Jack Taylor, public safety, and Ron Pryor, Tech Services Support. And last, but not least, the Wireless on campus was absolutely FANTASTIC! Some lessons learned Unless you are a glutton for punishment, as I no doubt am, you most certainly want to give yourself more than six weeks to plan the event. I am lucky that I have a very understanding wife and had a wonderful set of co-coordinators helping me out. A big thanks goes out to Phil, Marlon (Blog | Twitter), Nitin (Twitter), Thomas (Blog | Twitter), Bret (Blog | Twitter), Ben, and Laurie. Thankfully, the sponsor and speaker community was hugely supportive and we were able to fill out the entire event with speakers and sponsors. I have to say that there is not a lot that I would change after this years event. There are obviously going to be some things that we can do better or differently next time, but overall I think it was a great event and I was more than happy with the response we received from the community. Sponsors We obviously could not have put together our event without our sponsors. So certainly have to show them some love. Platinum Sponsors Quest Software http://www.quest.com My Space http://www.myspace.com/ Gold Strategy Companion http://www.strategycompanion.com Silver Fusion-IO http://www.fusionio.com Bronze WestClinTech http://westclintech.com Professional Association For SQL Server http://www.sqlpass.org Attunity http://www.attunity.com Sharepoint 360 http://www.sharepoint360.com Some additional Thanks Andy Warren (Blog | Twitter) Always there to answer my question and help out when I had some issues or questions with the website. The amount of work that he and everyone else put into SQL Saturday is very amazing. What a great gift to the community! Einstein Bros. Bagels They were our Breakfast Vendor and arrived perfectly on time with yummy bagels, sweets and most importantly coffee. Luccis Deli (http://www.luccisdeli.com) Luccis was out Lunch Vendor. They were great to work with and the food was excellent. They worked with us to give us a great price. Heard lots of great comments about the lunches. Definitely not your ordinary box lunch. Moving Forward Unfortunately, the work does not end after the event. We have a few things to clear up such as surveys, sponsor stuff, presentations uploaded to the website, expense reimbursement, stuff like that. Hopefully, all that should be cleared up within the next couple weeks. After that as a group we are going to get together and decide what our next steps are. We definitely want to keep some of the momentum that we are building as a SQL Community and channel that into future SQL Saturdays and other types of community events. In the meantime, for additional training be sure to check out your local User Group and PASS. San Diego SQL Server Users Group ( http://www.sdsqlug.org/home/index.cfm ) Orange County SQL Server Users Group ( http://www.sqloc.com/ ) L.A. SQL Server Users Group ( http://www.sql.la/ ) SQL PASS ( http://www.sqlpass.org/ ) 24 Hours of PASS ( http://www.sqlpass.org/24hours/2010/ ) So stay tuned, there will be more events to come in SoCal!!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.

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• Gene Hunt Says:

  - by BizTalk Visionary

  "She's as nervous as a very small nun at a penguin shoot"   "He's got fingers in more pies than a leper on a cookery course" "You so much as belch out of line and I'll have your scrotum on a barbed wire plate" "Let's go play slappyface" "your surrounded by armed barstewards" “Right, get out and find this murdering scum right now!” [pause] “Scratch that, we start 9am sharp tomorrow, it's beer-o-clock.” "So then Cartwright, you're such a good Detective.... Go and Detect me a packet of Garibaldies" "You're not the one who is going to have to knit himself a new arsehole after 25 years of aggressive male love in prison" “A dream for me is Diana Dors and a bottle of chip fat." “A dream for me is Diana Dors and a bottle of chip fat." “They reckon you've got concussion - but personally, I couldn't give a tart's furry cup if half your brains are falling out. Don't ever waltz into my kingdom playing king of the jungle.” “You great... soft... sissy... girlie... nancy... french... bender... Man-United supporting POOF!!” “Drugs eh? What's the point. They make you forget, make you talk funny, make you see things that aren't there. My old grandma got all of that for free when she had a stroke.” “He's Dead! It's quite serious!” “Fanny in the flat...Nice Work” “SoopaDoopa” “Tits in a Jumper!” “Drop your weapons! You are surrounded by armed bastards!” “It's 1973, almost dinnertime. I'm 'avin 'oops!” “Trust the Gene Genie!” “I wanna hump Britt Ekland...What're we gonna do...!” “Was that 'E' and you don't know the rest?! or you going 'Eeee, I Dunno'” “Good Girl! Prostate probe and no jelly. “ “Give over, it's nothing like Spain!” “I'll come over your houses and stamp on all your toys!” “The Wizard will sort it out. It's cos of the wonderful things he does” “Cartwright can jump up and down on his knackers!” “It's not a windup love, he really thinks like this!” “Women! You can't say two words to them” “I was thinking, maybe, a Berni Inn!” “If I wanted a bollocking for drinking too much...!” “Shhhh...hear that...that's the sound of this case being closed! “Chicken!? In a basket!?” “Seems a large quantity of cocaine...” “You probably thought he kept his cock in his keks!” “The tail-end of Rays demotion speech!” “Stephen Warren is gay!?” “You're a smart boy, use your initiative!” “Don't be such a Jessie!” “I find the idea of a bird brushing her teeth...!” “Never been tempted to the Magic talcum powder?” “Make sure she's got nice tits!” “You're more likely to find an ostrich with a plum up it's arse!” “Drink this lot under the table and have a pint on the way home!” “Never be a female Prime Minister!” “Pub? Pub! pub!.....Pub!” “Thou shalt not suck off rent boys!” “The number for the special clinic is on the notice board!” “If me uncle had tits, would he be me auntie!” “Got your vicars in a twist!” “We Done?!” “Your mates got balls...If they were any bigger he'd need a wheelbarrow!” “The Ending - from 'I want to go home' to the end music.”

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• Checksum Transformation

  The Checksum Transformation computes a hash value, the checksum, across one or more columns, returning the result in the Checksum output column. The transformation provides functionality similar to the T-SQL CHECKSUM function, but is encapsulated within SQL Server Integration Services, for use within the pipeline without code or a SQL Server connection. As featured in The Microsoft Data Warehouse Toolkit by Joy Mundy and Warren Thornthwaite from the Kimbal Group. Have a look at the book samples especially Sample package for custom SCD handling. All input columns are passed through the transformation unaltered, those selected are used to generate the checksum which is passed out through a single output column, Checksum. This does not restrict the number of columns available downstream from the transformation, as columns will always flow through a transformation. The Checksum output column is in addition to all existing columns within the pipeline buffer. The Checksum Transformation uses an algorithm based on the .Net framework GetHashCode method, it is not consistent with the T-SQL CHECKSUM() or BINARY_CHECKSUM() functions. The transformation does not support the following Integration Services data types, DT_NTEXT, DT_IMAGE and DT_BYTES. ChecksumAlgorithm Property There ChecksumAlgorithm property is defined with an enumeration. It was first added in v1.3.0, when the FrameworkChecksum was added. All previous algorithms are still supported for backward compatibility as ChecksumAlgorithm.Original (0). Original - Orginal checksum function, with known issues around column separators and null columns. This was deprecated in the first SQL Server 2005 RTM release. FrameworkChecksum - The hash function is based on the .NET Framework GetHash method for object types. This is based on the .NET Object.GetHashCode() method, which unfortunately differs between x86 and x64 systems. For that reason we now default to the CRC32 option. CRC32 - Using a standard 32-bit cyclic redundancy check (CRC), this provides a more open implementation. The component is provided as an MSI file, however to complete the installation, you will have to add the transformation to the Visual Studio toolbox by hand. This process has been described in detail in the related FAQ entry for How do I install a task or transform component?, just select Checksum from the SSIS Data Flow Items list in the Choose Toolbox Items window. Downloads The Checksum Transformation is available for SQL Server 2005, SQL Server 2008 (includes R2) and SQL Server 2012. Please choose the version to match your SQL Server version, or you can install multiple versions and use them side by side if you have more than one version of SQL Server installed. Checksum Transformation for SQL Server 2005 Checksum Transformation for SQL Server 2008 Checksum Transformation for SQL Server 2012 Version History SQL Server 2012 Version 3.0.0.27 – SQL Server 2012 release. Includes upgrade support for both 2005 and 2008 packages to 2012. (5 Jun 2010) SQL Server 2008 Version 2.0.0.27 – Fix for CRC-32 algorithm that inadvertently made it sort dependent. Fix for race condition which sometimes lead to the error Item has already been added. Key in dictionary: '79764919' . Fix for upgrade mappings between 2005 and 2008. (19 Oct 2010) Version 2.0.0.24 - SQL Server 2008 release. Introduces the new CRC-32 algorithm, which is consistent across x86 and x64.. The default algorithm is now CRC32. (29 Oct 2008) Version 2.0.0.6 - SQL Server 2008 pre-release. This version was released by mistake as part of the site migration, and had known issues. (20 Oct 2008) SQL Server 2005 Version 1.5.0.43 – Fix for CRC-32 algorithm that inadvertently made it sort dependent. Fix for race condition which sometimes lead to the error Item has already been added. Key in dictionary: '79764919' . (19 Oct 2010) Version 1.5.0.16 - Introduces the new CRC-32 algorithm, which is consistent across x86 and x64. The default algorithm is now CRC32. (20 Oct 2008) Version 1.4.0.0 - Installer refresh only. (22 Dec 2007) Version 1.4.0.0 - Refresh for minor UI enhancements. (5 Mar 2006) Version 1.3.0.0 - SQL Server 2005 RTM. The checksum algorithm has changed to improve cardinality when calculating multiple column checksums. The original algorithm is still available for backward compatibility. Fixed custom UI bug with Output column name not persisting. (10 Nov 2005) Version 1.2.0.1 - SQL Server 2005 IDW 15 June CTP. A user interface is provided, as well as the ability to change the checksum output column name. (29 Aug 2005) Version 1.0.0 - Public Release (Beta). (30 Oct 2004) Screenshot

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• PASS: Election Changes for 2011

  - by Bill Graziano

  Last year after the election, the PASS Board created an Election Review Committee.  This group was charged with reviewing our election procedures and making suggestions to improve the process.  You can read about the formation of the group and review some of the intermediate work on the site – especially in the forums. I was one of the members of the group along with Joe Webb (Chair), Lori Edwards, Brian Kelley, Wendy Pastrick, Andy Warren and Allen White.  This group worked from October to April on our election process.  Along the way we: Interviewed interested parties including former NomCom members, Board candidates and anyone else that came forward. Held a session at the Summit to allow interested parties to discuss the issues Had numerous conference calls and worked through the various topics I can’t thank these people enough for the work they did.  They invested a tremendous number of hours thinking, talking and writing about our elections.  I’m proud to say I was a member of this group and thoroughly enjoyed working with everyone (even if I did finally get tired of all the calls.) The ERC delivered their recommendations to the PASS Board prior to our May Board meeting.  We reviewed those and made a few modifications.  I took their recommendations and rewrote them as procedures while incorporating those changes.  Their original recommendations as well as our final document are posted at the ERC documents page.  Please take a second and read them BEFORE we start the elections.  If you have any questions please post them in the forums on the ERC site. (My final document includes a change log at the end that I decided to leave in.  If you want to know which areas to pay special attention to that’s a good start.) Many of those recommendations were already posted in the forums or in the blogs of individual ERC members.  Hopefully nothing in the ERC document is too surprising. In this post I’m going to walk through some of the key changes and talk about what I remember from both ERC and Board discussions.  I’ll pay a little extra attention to things the Board changed from the ERC.  I’d also encourage any of the Board or ERC members to blog their thoughts on this. The Nominating Committee will continue to exist.  Personally, I was curious to see what the non-Board ERC members would think about the NomCom.  There was broad agreement that a group to vet candidates had value to the organization. The NomCom will be composed of five members.  Two will be Board members and three will be from the membership at large.  The only requirement for the three community members is that you’ve volunteered in some way (and volunteering is defined very broadly).  We expect potential at-large NomCom members to participate in a forum on the PASS site to answer questions from the other PASS members. We’re going to hold an election to determine the three community members.  It will be closer to voting for Summit sessions than voting for Board members.  That means there won’t be multiple dedicated emails.  If you’re at all paying attention it will be easy to participate.  Personally I wanted it easy for those that cared to participate but not overwhelm those that didn’t care.  I think this strikes a good balance. There’s also a clause that in order to be considered a winner in this NomCom election, you must receive 10 votes.  This is something I suggested.  I have no idea how popular the NomCom election is going to be.  I just wanted a fallback that if no one participated and some random person got in with one or two votes.  Any open slots will be filled by the NomCom chair (usually the PASS Immediate Past President).  My assumption is that they would probably take the next highest vote getters unless they were throwing flames in the forums or clearly unqualified.  As a final check, the Board still approves the final NomCom. The NomCom is going to rank candidates instead of rating them.  This has interesting implications.  This was championed by another ERC member and I’m hoping they write something about it.  This will really force the NomCom to make decisions between candidates.  You can’t just rate everyone a 3 and be done with it.  It may also make candidates appear further apart than they actually are.  I’m looking forward talking with the NomCom after this election and getting their feedback on this. The PASS Board added an option to remove a candidate with a unanimous vote of the NomCom.  This was primarily put in place to handle people that lied on their application or had a criminal background or some other unusual situation and we figured it out. We list an explicit goal of three candidate per open slot. We also wanted an easy way to find the NomCom candidate rankings from the ballot.  Hopefully this will satisfy those that want a broad candidate pool and those that want the NomCom to identify the most qualified candidates. The primary spokesperson for the NomCom is the committee chair.  After the issues around the election last year we didn’t have a good communication plan in place.  We should have and that was a failure on the part of the Board.  If there is criticism of the election this year I hope that falls squarely on the Board.  The community members of the NomCom shouldn’t be fielding complaints over the election process.  That said, the NomCom is ranking candidates and we are forcing them to rank some lower than others.  I’m sure you’ll each find someone that you think should have been ranked differently.  I also want to highlight one other change to the process that we started last year and isn’t included in these documents.  I think the candidate forums on the PASS site were tremendously helpful last year in helping people to find out more about candidates.  That gives our members a way to ask hard questions of the candidates and publicly see their answers. This year we have two important groups to fill.  The first is the NomCom.  We need three people from our membership to step up and fill this role.  It won’t be easy.  You will have to make subjective rankings of your fellow community members.  Your actions will be important in deciding who the future leaders of PASS will be.  There’s a 50/50 chance that one of the people you interview will be the President of PASS someday.  This is not a responsibility to be taken lightly. The second is the slate of candidates.  If you’ve ever thought about running for the Board this is the year.  We’ve never had nine candidates on the ballot before.  Your chance of making it through the NomCom are higher than in any previous year.  Unfortunately the more of you that run, the more of you that will lose in the election.  And hopefully that competition will mean more community involvement and better Board members for PASS. Is this the end of changes to the election process?  It isn’t.  Every year that I’ve been on the Board the election process has changed.  Some years there have been small changes and some years there have been large changes.  After this election we’ll look at how the process worked and decide what steps to take – just like we do every year.

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• PASS: SQLRally Thoughts

  - by Bill Graziano

  The PASS Board recently decided that we wouldn’t put another US-based SQLRally on the calendar until we had a chance to review the program. I wanted to provide some of my thinking around this. Keep in mind that this is the opinion of one Board member. The Board committed to complete two SQLRally events to determine if an event modeled between SQL Saturday and the Summit was viable. We’ve completed the two events and now it’s time to step back and review the program. This is my seventh year on the PASS Board. Over that time people have asked me why PASS does certain things. Many, many times my answer has been “Because that’s the way we did it last year”. And I am tired of giving that answer. We need to take a step back and review the US-based SQLRally before we schedule another one. It would be irresponsible for me as a Board member to commit resources to this without validating that what we’re doing makes sense for the organization and our members. I have no doubt that this was a great event for the attendees. We just need to validate it’s the best use of our resources. Please keep in mind that we haven’t cancelled the event. We’ve just said we need to review it before scheduling another one. My opinion is that some fairly serious changes are needed to the model before we consider it again – IF we do it again. I’ve come to that conclusion after speaking with the Dallas organizers, our HQ team, our Marketing team, other Board members (including one of the Orlando organizers), attendees in Orlando and Dallas and visiting other similar events. I should point out that their views aren’t unanimous on nearly any part of this event -- which is one of the reasons I want to take some time and think about this before continuing. I think it’s helpful to look at the original goals of what we were trying to accomplish. Andy Warren wrote these up in August of 2010. My summary of these goals and some thoughts on each one is below. Many of these thoughts revolve around the growth of SQL Saturdays. In the two years since that document was written these events have grown significantly. The largest SQL Saturdays are now over 500 people which mean they are nearly the same size as our recent SQLRally. Our goals included: Geographic diversity. We wanted an event in an area of the country that was away from any given Summit location. I think that’s still a valid goal. But we also have SQL Saturdays all over the country. What does SQLRally bring to this that SQLSaturday doesn’t? Speaker growth. One of the stated goals was to build a “farm club” for speakers. This gives us a way for speakers to work up to speaking at Summit by speaking in front of larger crowds. What does SQLRally bring to this that the larger SQL Saturdays aren’t providing? Pre-Conference speakers is one obvious answer here. Lower price. On a per-day basis, SQLRally is roughly 1/4th the price of the Summit. We wanted a way for people to experience something Summit-like at a lower price point. The challenge is that we are very budget constrained at that lower price point. International Event Model.  (I need to write more about this but I’m out of time.  I’ll cover it in the next installment.) There are a number of things I really like about SQLRally. I love the smaller conferences. They give me a chance to meet more people than at something the size of Summit. I like the two day format. That gives you two evenings to be at social events with people. Seeing someone a second day is a great way to build a bond with that person. That’s more difficult to do at a SQL Saturday. We also need to talk about the financial aspects of the event. Last year generated a small $17,000 profit on revenues of $200,000. Percentage-wise that’s reasonable but on an absolute basis it’s not a huge amount in our budget. We think this year will lose between $30,000 and $50,000 and take roughly 1,000 hours of HQ time. We don’t have detailed financials back yet but that’s our best guess at this point. Part of that was driven by using a convention center instead of a hotel. Until we get detailed financials back we won’t have the full picture around the financial impact. This event also takes time and mindshare from our Marketing team. This may sound like a small thing but please don’t underestimate it. Our original vision for this was something that would take very little time from our Marketing team and just a few mentions in the Connector. It turned out to need more than that. And all those mentions and emails take up space we could use to talk about other events and other programs. Last I wanted to talk about some of the things I’m thinking about. I don’t think it’s as simple as saying if we just fix “X” it all gets better. Is this that much better of an event than SQL Saturdays? What if we gave a few SQL Saturdays some extra resources? When SQL Saturdays were around 250 people that wasn’t as viable. With some of those events over 500 we need to reconsider this. We need to get back to a hotel venue. That will help with cost and networking. Is this the best use of the 1,000 HQ hours that we invested in the event? Is our price-point correct? I’m leaning toward raising our price closer to Summit on a per-day basis. I think this will let us put on a higher quality event and alleviate much of the budget pressure. Should growing speakers be a focus? Having top-line pre-conference speakers helps market the event. It will also have an impact on pricing and overall profit. We should also ask if it actually does grow speakers. How many of these people will eventually register for Summit? Attend chapters? Is SQLRally a driver into PASS or is it something that chapters, etc. drive people to? Should we have one paid day and one free instead of two paid days? This is a very interesting model that is used by SQLBits in the UK. This gives you the two day aspect as well as offering options for paid and free attendees. I’m very intrigued by this. Should we focus on a topic? Buried in the minutes is a discussion of whether PASS should have a Business Analytics conference separate from Summit. This is an interesting question to consider. Would making SQLRally be focused on a particular topic make it more attractive? Would that even be a SQLRally? Can PASS effectively manage the two events? (FYI - Probably not.) Would it help differentiate it from Summit and SQL Saturday? These are all questions that I think should be asked and answered before we do this event again. And we can’t do that if we don’t take time to have the discussion. I wanted to get this published before I take off for a few days of vacation. When I get back I’d like to write more about why the international events are different and talk about where we go from here.

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• StreamInsight 2.1, meet LINQ

  - by Roman Schindlauer

  Someone recently called LINQ “magic” in my hearing. I leapt to LINQ’s defense immediately. Turns out some people don’t realize “magic” is can be a pejorative term. I thought LINQ needed demystification. Here’s your best demystification resource: http://blogs.msdn.com/b/mattwar/archive/2008/11/18/linq-links.aspx. I won’t repeat much of what Matt Warren says in his excellent series, but will talk about some core ideas and how they affect the 2.1 release of StreamInsight. Let’s tell the story of a LINQ query. Compile time It begins with some code: IQueryable<Product> products = ...; var query = from p in products             where p.Name == "Widget"             select p.ProductID; foreach (int id in query) {     ... When the code is compiled, the C# compiler (among other things) de-sugars the query expression (see C# spec section 7.16): ... var query = products.Where(p => p.Name == "Widget").Select(p => p.ProductID); ... Overload resolution subsequently binds the Queryable.Where<Product> and Queryable.Select<Product, int> extension methods (see C# spec sections 7.5 and 7.6.5). After overload resolution, the compiler knows something interesting about the anonymous functions (lambda syntax) in the de-sugared code: they must be converted to expression trees, i.e.,“an object structure that represents the structure of the anonymous function itself” (see C# spec section 6.5). The conversion is equivalent to the following rewrite: ... var prm1 = Expression.Parameter(typeof(Product), "p"); var prm2 = Expression.Parameter(typeof(Product), "p"); var query = Queryable.Select<Product, int>(     Queryable.Where<Product>(         products,         Expression.Lambda<Func<Product, bool>>(Expression.Property(prm1, "Name"), prm1)),         Expression.Lambda<Func<Product, int>>(Expression.Property(prm2, "ProductID"), prm2)); ... If the “products” expression had type IEnumerable<Product>, the compiler would have chosen the Enumerable.Where and Enumerable.Select extension methods instead, in which case the anonymous functions would have been converted to delegates. At this point, we’ve reduced the LINQ query to familiar code that will compile in C# 2.0. (Note that I’m using C# snippets to illustrate transformations that occur in the compiler, not to suggest a viable compiler design!) Runtime When the above program is executed, the Queryable.Where method is invoked. It takes two arguments. The first is an IQueryable<> instance that exposes an Expression property and a Provider property. The second is an expression tree. The Queryable.Where method implementation looks something like this: public static IQueryable<T> Where<T>(this IQueryable<T> source, Expression<Func<T, bool>> predicate) {     return source.Provider.CreateQuery<T>(     Expression.Call(this method, source.Expression, Expression.Quote(predicate))); } Notice that the method is really just composing a new expression tree that calls itself with arguments derived from the source and predicate arguments. Also notice that the query object returned from the method is associated with the same provider as the source query. By invoking operator methods, we’re constructing an expression tree that describes a query. Interestingly, the compiler and operator methods are colluding to construct a query expression tree. The important takeaway is that expression trees are built in one of two ways: (1) by the compiler when it sees an anonymous function that needs to be converted to an expression tree, and; (2) by a query operator method that constructs a new queryable object with an expression tree rooted in a call to the operator method (self-referential). Next we hit the foreach block. At this point, the power of LINQ queries becomes apparent. The provider is able to determine how the query expression tree is evaluated! The code that began our story was intentionally vague about the definition of the “products” collection. Maybe it is a queryable in-memory collection of products: var products = new[]     { new Product { Name = "Widget", ProductID = 1 } }.AsQueryable(); The in-memory LINQ provider works by rewriting Queryable method calls to Enumerable method calls in the query expression tree. It then compiles the expression tree and evaluates it. It should be mentioned that the provider does not blindly rewrite all Queryable calls. It only rewrites a call when its arguments have been rewritten in a way that introduces a type mismatch, e.g. the first argument to Queryable.Where<Product> being rewritten as an expression of type IEnumerable<Product> from IQueryable<Product>. The type mismatch is triggered initially by a “leaf” expression like the one associated with the AsQueryable query: when the provider recognizes one of its own leaf expressions, it replaces the expression with the original IEnumerable<> constant expression. I like to think of this rewrite process as “type irritation” because the rewritten leaf expression is like a foreign body that triggers an immune response (further rewrites) in the tree. The technique ensures that only those portions of the expression tree constructed by a particular provider are rewritten by that provider: no type irritation, no rewrite. Let’s consider the behavior of an alternative LINQ provider. If “products” is a collection created by a LINQ to SQL provider: var products = new NorthwindDataContext().Products; the provider rewrites the expression tree as a SQL query that is then evaluated by your favorite RDBMS. The predicate may ultimately be evaluated using an index! In this example, the expression associated with the Products property is the “leaf” expression. StreamInsight 2.1 For the in-memory LINQ to Objects provider, a leaf is an in-memory collection. For LINQ to SQL, a leaf is a table or view. When defining a “process” in StreamInsight 2.1, what is a leaf? To StreamInsight a leaf is logic: an adapter, a sequence, or even a query targeting an entirely different LINQ provider! How do we represent the logic? Remember that a standing query may outlive the client that provisioned it. A reference to a sequence object in the client application is therefore not terribly useful. But if we instead represent the code constructing the sequence as an expression, we can host the sequence in the server: using (var server = Server.Connect(...)) {     var app = server.Applications["my application"];     var source = app.DefineObservable(() => Observable.Range(0, 10, Scheduler.NewThread));     var query = from i in source where i % 2 == 0 select i; } Example 1: defining a source and composing a query Let’s look in more detail at what’s happening in example 1. We first connect to the remote server and retrieve an existing app. Next, we define a simple Reactive sequence using the Observable.Range method. Notice that the call to the Range method is in the body of an anonymous function. This is important because it means the source sequence definition is in the form of an expression, rather than simply an opaque reference to an IObservable<int> object. The variation in Example 2 fails. Although it looks similar, the sequence is now a reference to an in-memory observable collection: var local = Observable.Range(0, 10, Scheduler.NewThread); var source = app.DefineObservable(() => local); // can’t serialize ‘local’! Example 2: error referencing unserializable local object The Define* methods support definitions of operator tree leaves that target the StreamInsight server. These methods all have the same basic structure. The definition argument is a lambda expression taking between 0 and 16 arguments and returning a source or sink. The method returns a proxy for the source or sink that can then be used for the usual style of LINQ query composition. The “define” methods exploit the compile-time C# feature that converts anonymous functions into translatable expression trees! Query composition exploits the runtime pattern that allows expression trees to be constructed by operators taking queryable and expression (Expression<>) arguments. The practical upshot: once you’ve Defined a source, you can compose LINQ queries in the familiar way using query expressions and operator combinators. Notably, queries can be composed using pull-sequences (LINQ to Objects IQueryable<> inputs), push sequences (Reactive IQbservable<> inputs), and temporal sequences (StreamInsight IQStreamable<> inputs). You can even construct processes that span these three domains using “bridge” method overloads (ToEnumerable, ToObservable and To*Streamable). Finally, the targeted rewrite via type irritation pattern is used to ensure that StreamInsight computations can leverage other LINQ providers as well. Consider the following example (this example depends on Interactive Extensions): var source = app.DefineEnumerable((int id) =>     EnumerableEx.Using(() =>         new NorthwindDataContext(), context =>             from p in context.Products             where p.ProductID == id             select p.ProductName)); Within the definition, StreamInsight has no reason to suspect that it ‘owns’ the Queryable.Where and Queryable.Select calls, and it can therefore defer to LINQ to SQL! Let’s use this source in the context of a StreamInsight process: var sink = app.DefineObserver(() => Observer.Create<string>(Console.WriteLine)); var query = from name in source(1).ToObservable()             where name == "Widget"             select name; using (query.Bind(sink).Run("process")) {     ... } When we run the binding, the source portion which filters on product ID and projects the product name is evaluated by SQL Server. Outside of the definition, responsibility for evaluation shifts to the StreamInsight server where we create a bridge to the Reactive Framework (using ToObservable) and evaluate an additional predicate. It’s incredibly easy to define computations that span multiple domains using these new features in StreamInsight 2.1! Regards, The StreamInsight Team

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