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  • Thou shalt not put code on a piedestal - Code is a tool, no more, no less

    - by Ralf Westphal
    “Write great code and everything else becomes easier” is what Paul Pagel believes in. That´s his version of an adage by Brian Marick he cites: “treat code as an end, not just a means.” And he concludes: “My post-Agile world is software craftsmanship.” I wonder, if that´s really the way to go. Will “simply” writing great code lead the software industry into the light? He´s alluding to the philosopher Kant who proposed, a human beings should never be treated as a means, but always as an end. But should we transfer this ethical statement into the world of software? I doubt it.   Reason #1: Human beings are categorially different from code. They are autonomous entities who need to find a way of living happily together. To Kant it seemed this goal could only be reached if nobody (ab)used a human being for his/her purposes. Because using a human being, i.e. treating it as a means, would contradict the fundamental autonomy and freedom of human beings. People should hold up a symmetric view of their relationships: Since nobody wants to be (ab)used, nobody should (ab)use anybody else. If you want to be treated decently, with respect, in accordance with your own free will - which means as an end - then do the same to other people. Code is dead, it´s a product, it´s a tool for people to reach their goals. No company spends any money on code other than to save money or earn money in the long run. Code is not a puppy. Enterprises do not commission software development to just feel good in its company. Code is not a buddy. Code is a slave, if you will. A mechanical slave, a non-tangible robot. Code is a tool, is a tool. And if we start to treat it differently, if we elevate its status unduely… I guess that will contort our relationship in a contraproductive way. Please get me right: Just because something is “just a tool”, “just a product” does not mean we should not be careful while designing, building, using it. Right to the contrary. We should be very careful when writing code – but not for the code´s sake! We should be careful because we respect our customers who are fellow human beings who should be treated as an end. If we are careless, neglectful, ignorant when producing code on their behalf, then we´re using them. Being sloppy means you´re caring more for yourself that for your customer. You´re then treating the customer as a means to fulfill some of your own needs. That´s plain unethical behavior.   Reason #2: The focus should always be on your purpose, not on any tool. But if code is treated as an end, then the focus is on the code. That might sound right, because where else should be your focus as a software developer? But, well, I´d say, your focus should be on delivering value to your customer. Because in the end your customer does not care if you write a single line of code. She just wants her problem to be solved. Solving problems is the purpose of any contractor. Code must be treated just as a means, a tool we know how to handle very well. But if we´re really trying to be craftsmen then we should be conscious about exactly that and act ethically. That means we must never be so focused on our tool as to be unable to suggest better solutions to the problems of our customers than code.   I´m all with Paul when he urges us to “Write great code”. Sure, if you need to write code, then by all means do so. Write the best code you can think of – and then try to improve it. Paul has all the best intentions when he signs Brians “treat code as an end” - but as we all know: “The road to hell is paved with best intentions” ;-) Yes, I can imagine a “hell of code focus”. In fact, I don´t need to imagine it, I´m seeing it quite often. Because code hell is whereever two developers stand together and are so immersed in talking about all sorts of coding tricks, design patterns, code smells, technologies, platforms, tools that they lose sight of the big picture. Talking about TDD or SOLID or refactoring is a sign of consciousness – relative to the “cowboy coders” view of the world. But from yet another point of view TDD, SOLID, and refactoring are just cures for ailments within a system. And I fear, if “Writing great code” is the only focus or the main focus of software development, then we as an industry lose the ability to see that. Focus draws a line around something, it defines a horizon for perceptions and thinking. So if we focus on code our horizon ends where “the land of code” ends. I don´t think that should be our professional attitude.   So what about Software Craftsmanship as the next big thing after Agility? I think Software Craftsmanship has an important message for all software developers and beyond. But to make it the successor of the Agility movement seems to miss a point. Agility never claimed to solve all software development problems, I´d say. So to blame it for having missed out on certain aspects of it is wrong. If I had to summarize Agility in one word I´d say “Value”. Agility put value for the customer back in software development. Focus on delivering value early and often – that´s Agility´s mantra. All else follows from that. And I ask you: Is that obsolete? Is delivering value not hip anymore? No, sure not. That´s our very purpose as software developers. So how can Agility become obsolete and need to be replaced? We need to do away with this “either/or”-thinking. It´s either Agility or Lean or Software Craftsmanship or whatnot. Instead we should start integrating concepts and movements. Think “both/and”. Think Agility plus Software Craftsmanship plus Lean plus whatnot. We don´t neet to tear down anything from a piedestal and replace it with a new idol. Instead we should do away with piedestals and arrange whatever is helpful is a circle. Then we can turn to concepts, movements for whatever they are best. After 10 years of Agility we should be able to identify what it was good at – and keep that. Keep Agility around and add whatever Agility was lacking or never concerned with. Add whatever is at the core of Software Craftsmanship. Add whatever is at the core of Lean etc. But don´t call out the age of Post-Agility. Because it better never will end. Because once we start to lose Agility´s core we´re losing focus of the customer.

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  • What is the least intrusive way to display WPF tooltip on focus?

    - by Andrey Shchekin
    What is the minimum number of steps required to display a tooltip when the following control gets focus? <TextBox ToolTip="Hello there!" ... /> I tried the following in GotFocus private void ..._GotFocus(object sender, RoutedEventArgs e) { var element = (FrameworkElement)sender; var tooltip = element.ToolTip; if (!(tooltip is ToolTip)) { tooltip = new ToolTip { Content = tooltip }; element.ToolTip = tooltip; } ((ToolTip)tooltip).IsOpen = true; } However, it seems to ignore the ToolTipService.Placement for this control and SystemParameters.ToolTipPopupAnimationKey set up level higher. How can I make it work and honor all settings that generally work for tooltips (except the timing, obviously)?

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  • What technologies should I focus on to work as a developer in Japan?

    - by Atomiton
    I'm thinking of one day moving to Japan and I was wondering if anyone here has any experience working there. I'm curious as to what languages/technology are popular there for web development and software development. I have heard Ruby is/was strong there due to its founder being Japanese. What would you recommend someone focus on if they wanted to work as a developer in Japan? I have heard Microsoft has a strong base in Japan, but my guess is that whatever platform has supported unicode or Shift-JIS the best would be the strongest.

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  • How to use JQuery to focus on a specific DIV tag?

    - by kwokwai
    Hi all, Say I got a few DIV tags in a HTML page like: <DIV ID="div1"> <Input type="radio" name="data['site1']['user']" VALUE="1">user1<br/> </DIV> <DIV ID="div2"> <Input type="radio" name="data['site1']['user']" VALUE="2">user2<br/> </DIV> <DIV ID="div3"> <Input type="radio" name="data['site1']['user']" VALUE="3">user3<br/> </DIV> <DIV ID="div4"> <Input type="radio" name="data['site1']['user']" VALUE="4">user4<br/> </DIV> Is it possible to do the same effect in JQuery like this: Document.getElementByID('div2').focus();

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  • How to retain focus on an editable html after deleting an element.

    - by Lukasz
    Hello, I have a website with design mode on (aka. content editable = true) with some basic text on it. To that site I hooked up a shortcut so that at any point in the text I can insert an input box that serves me as an autocomplete. For that input however I want it to disappear right after I hit ENTER so that I can continue typing. It is an easy task to just make the input box disappear but I always loose focus from my document. I would greatly appreciate any suggestions on how to make this work?

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  • How do I have my apps dialog box pop up and take focus from the current running app?

    - by simba
    I know this type of thing is looked negatively upon but I write software for people with disabilities and sometimes good gui practices don't make sense. In this case, the user interacts with a assistive interface and under certain conditions, my control app needs to prompt the user with a question. My background process creates a dialog (I'm using wxwidgets wxDialog class) and calls Show(). The dialog box appears but it does not have focus (the application that the user was previously using keeps it). Since my users can't use mice, they can't simply click on the window. I've tried calling show and then followed by SetFocus(HWND) but that doesn't do it. What's the problem? Is this even possible? Window7. I'm thinking that it might have something to do with it being a dialog and not a full window (wxFrame). Any help is greatly appreciated.

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  • C# How to disable the right-click menu about embedded applications and Focus embedded app's textbox?

    - by liqingChen
    I used such API to embed other app in my control. SetParent(app.MainWindowHandle, control.Handle); SetWindowLong(new HandleRef(this, app.MainWindowHandle), GWL_STYLE, (WS_VISIBLE | WS_CHILD) & ~WS_BORDER); MoveWindow(app.MainWindowHandle, 0, 0, control.Width, control.Height, true); 1?How to diaable the right-click menu about embeded app? 2?Used such API, I can click anyButton in embed APP,But cant focus other APP to input text. Change SetWindowLong param like this,can ipnut text ,but embed app's menubar will exist. SetWindowLong(new HandleRef(this, app.MainWindowHandle), GWL_STYLE, WS_VISIBLE & ~WS_BORDER);

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  • html open a url on new target and focus.

    - by richard
    I am trying to fix a web site. It opens a help page in a new window/tab via <a href="..." target="help"> (no other frame has this name) This works well the first time opening a new window/tab, for the help. But on subsequent clicks the window/tab is loaded but remains hidden. I tryed this: <script> function OpenAndFocusHelp() { win=window.open('help/1000CH00017.htm','help'); win.focus(); } </script> <a href="help.html" target="help" onclick="OpenAndFocusHelp()">Help</a> It did not work!

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  • Heaps of Trouble?

    - by Paul White NZ
    If you’re not already a regular reader of Brad Schulz’s blog, you’re missing out on some great material.  In his latest entry, he is tasked with optimizing a query run against tables that have no indexes at all.  The problem is, predictably, that performance is not very good.  The catch is that we are not allowed to create any indexes (or even new statistics) as part of our optimization efforts. In this post, I’m going to look at the problem from a slightly different angle, and present an alternative solution to the one Brad found.  Inevitably, there’s going to be some overlap between our entries, and while you don’t necessarily need to read Brad’s post before this one, I do strongly recommend that you read it at some stage; he covers some important points that I won’t cover again here. The Example We’ll use data from the AdventureWorks database, copied to temporary unindexed tables.  A script to create these structures is shown below: CREATE TABLE #Custs ( CustomerID INTEGER NOT NULL, TerritoryID INTEGER NULL, CustomerType NCHAR(1) COLLATE SQL_Latin1_General_CP1_CI_AI NOT NULL, ); GO CREATE TABLE #Prods ( ProductMainID INTEGER NOT NULL, ProductSubID INTEGER NOT NULL, ProductSubSubID INTEGER NOT NULL, Name NVARCHAR(50) COLLATE SQL_Latin1_General_CP1_CI_AI NOT NULL, ); GO CREATE TABLE #OrdHeader ( SalesOrderID INTEGER NOT NULL, OrderDate DATETIME NOT NULL, SalesOrderNumber NVARCHAR(25) COLLATE SQL_Latin1_General_CP1_CI_AI NOT NULL, CustomerID INTEGER NOT NULL, ); GO CREATE TABLE #OrdDetail ( SalesOrderID INTEGER NOT NULL, OrderQty SMALLINT NOT NULL, LineTotal NUMERIC(38,6) NOT NULL, ProductMainID INTEGER NOT NULL, ProductSubID INTEGER NOT NULL, ProductSubSubID INTEGER NOT NULL, ); GO INSERT #Custs ( CustomerID, TerritoryID, CustomerType ) SELECT C.CustomerID, C.TerritoryID, C.CustomerType FROM AdventureWorks.Sales.Customer C WITH (TABLOCK); GO INSERT #Prods ( ProductMainID, ProductSubID, ProductSubSubID, Name ) SELECT P.ProductID, P.ProductID, P.ProductID, P.Name FROM AdventureWorks.Production.Product P WITH (TABLOCK); GO INSERT #OrdHeader ( SalesOrderID, OrderDate, SalesOrderNumber, CustomerID ) SELECT H.SalesOrderID, H.OrderDate, H.SalesOrderNumber, H.CustomerID FROM AdventureWorks.Sales.SalesOrderHeader H WITH (TABLOCK); GO INSERT #OrdDetail ( SalesOrderID, OrderQty, LineTotal, ProductMainID, ProductSubID, ProductSubSubID ) SELECT D.SalesOrderID, D.OrderQty, D.LineTotal, D.ProductID, D.ProductID, D.ProductID FROM AdventureWorks.Sales.SalesOrderDetail D WITH (TABLOCK); The query itself is a simple join of the four tables: SELECT P.ProductMainID AS PID, P.Name, D.OrderQty, H.SalesOrderNumber, H.OrderDate, C.TerritoryID FROM #Prods P JOIN #OrdDetail D ON P.ProductMainID = D.ProductMainID AND P.ProductSubID = D.ProductSubID AND P.ProductSubSubID = D.ProductSubSubID JOIN #OrdHeader H ON D.SalesOrderID = H.SalesOrderID JOIN #Custs C ON H.CustomerID = C.CustomerID ORDER BY P.ProductMainID ASC OPTION (RECOMPILE, MAXDOP 1); Remember that these tables have no indexes at all, and only the single-column sampled statistics SQL Server automatically creates (assuming default settings).  The estimated query plan produced for the test query looks like this (click to enlarge): The Problem The problem here is one of cardinality estimation – the number of rows SQL Server expects to find at each step of the plan.  The lack of indexes and useful statistical information means that SQL Server does not have the information it needs to make a good estimate.  Every join in the plan shown above estimates that it will produce just a single row as output.  Brad covers the factors that lead to the low estimates in his post. In reality, the join between the #Prods and #OrdDetail tables will produce 121,317 rows.  It should not surprise you that this has rather dire consequences for the remainder of the query plan.  In particular, it makes a nonsense of the optimizer’s decision to use Nested Loops to join to the two remaining tables.  Instead of scanning the #OrdHeader and #Custs tables once (as it expected), it has to perform 121,317 full scans of each.  The query takes somewhere in the region of twenty minutes to run to completion on my development machine. A Solution At this point, you may be thinking the same thing I was: if we really are stuck with no indexes, the best we can do is to use hash joins everywhere. We can force the exclusive use of hash joins in several ways, the two most common being join and query hints.  A join hint means writing the query using the INNER HASH JOIN syntax; using a query hint involves adding OPTION (HASH JOIN) at the bottom of the query.  The difference is that using join hints also forces the order of the join, whereas the query hint gives the optimizer freedom to reorder the joins at its discretion. Adding the OPTION (HASH JOIN) hint results in this estimated plan: That produces the correct output in around seven seconds, which is quite an improvement!  As a purely practical matter, and given the rigid rules of the environment we find ourselves in, we might leave things there.  (We can improve the hashing solution a bit – I’ll come back to that later on). Faster Nested Loops It might surprise you to hear that we can beat the performance of the hash join solution shown above using nested loops joins exclusively, and without breaking the rules we have been set. The key to this part is to realize that a condition like (A = B) can be expressed as (A <= B) AND (A >= B).  Armed with this tremendous new insight, we can rewrite the join predicates like so: SELECT P.ProductMainID AS PID, P.Name, D.OrderQty, H.SalesOrderNumber, H.OrderDate, C.TerritoryID FROM #OrdDetail D JOIN #OrdHeader H ON D.SalesOrderID >= H.SalesOrderID AND D.SalesOrderID <= H.SalesOrderID JOIN #Custs C ON H.CustomerID >= C.CustomerID AND H.CustomerID <= C.CustomerID JOIN #Prods P ON P.ProductMainID >= D.ProductMainID AND P.ProductMainID <= D.ProductMainID AND P.ProductSubID = D.ProductSubID AND P.ProductSubSubID = D.ProductSubSubID ORDER BY D.ProductMainID OPTION (RECOMPILE, LOOP JOIN, MAXDOP 1, FORCE ORDER); I’ve also added LOOP JOIN and FORCE ORDER query hints to ensure that only nested loops joins are used, and that the tables are joined in the order they appear.  The new estimated execution plan is: This new query runs in under 2 seconds. Why Is It Faster? The main reason for the improvement is the appearance of the eager Index Spools, which are also known as index-on-the-fly spools.  If you read my Inside The Optimiser series you might be interested to know that the rule responsible is called JoinToIndexOnTheFly. An eager index spool consumes all rows from the table it sits above, and builds a index suitable for the join to seek on.  Taking the index spool above the #Custs table as an example, it reads all the CustomerID and TerritoryID values with a single scan of the table, and builds an index keyed on CustomerID.  The term ‘eager’ means that the spool consumes all of its input rows when it starts up.  The index is built in a work table in tempdb, has no associated statistics, and only exists until the query finishes executing. The result is that each unindexed table is only scanned once, and just for the columns necessary to build the temporary index.  From that point on, every execution of the inner side of the join is answered by a seek on the temporary index – not the base table. A second optimization is that the sort on ProductMainID (required by the ORDER BY clause) is performed early, on just the rows coming from the #OrdDetail table.  The optimizer has a good estimate for the number of rows it needs to sort at that stage – it is just the cardinality of the table itself.  The accuracy of the estimate there is important because it helps determine the memory grant given to the sort operation.  Nested loops join preserves the order of rows on its outer input, so sorting early is safe.  (Hash joins do not preserve order in this way, of course). The extra lazy spool on the #Prods branch is a further optimization that avoids executing the seek on the temporary index if the value being joined (the ‘outer reference’) hasn’t changed from the last row received on the outer input.  It takes advantage of the fact that rows are still sorted on ProductMainID, so if duplicates exist, they will arrive at the join operator one after the other. The optimizer is quite conservative about introducing index spools into a plan, because creating and dropping a temporary index is a relatively expensive operation.  It’s presence in a plan is often an indication that a useful index is missing. I want to stress that I rewrote the query in this way primarily as an educational exercise – I can’t imagine having to do something so horrible to a production system. Improving the Hash Join I promised I would return to the solution that uses hash joins.  You might be puzzled that SQL Server can create three new indexes (and perform all those nested loops iterations) faster than it can perform three hash joins.  The answer, again, is down to the poor information available to the optimizer.  Let’s look at the hash join plan again: Two of the hash joins have single-row estimates on their build inputs.  SQL Server fixes the amount of memory available for the hash table based on this cardinality estimate, so at run time the hash join very quickly runs out of memory. This results in the join spilling hash buckets to disk, and any rows from the probe input that hash to the spilled buckets also get written to disk.  The join process then continues, and may again run out of memory.  This is a recursive process, which may eventually result in SQL Server resorting to a bailout join algorithm, which is guaranteed to complete eventually, but may be very slow.  The data sizes in the example tables are not large enough to force a hash bailout, but it does result in multiple levels of hash recursion.  You can see this for yourself by tracing the Hash Warning event using the Profiler tool. The final sort in the plan also suffers from a similar problem: it receives very little memory and has to perform multiple sort passes, saving intermediate runs to disk (the Sort Warnings Profiler event can be used to confirm this).  Notice also that because hash joins don’t preserve sort order, the sort cannot be pushed down the plan toward the #OrdDetail table, as in the nested loops plan. Ok, so now we understand the problems, what can we do to fix it?  We can address the hash spilling by forcing a different order for the joins: SELECT P.ProductMainID AS PID, P.Name, D.OrderQty, H.SalesOrderNumber, H.OrderDate, C.TerritoryID FROM #Prods P JOIN #Custs C JOIN #OrdHeader H ON H.CustomerID = C.CustomerID JOIN #OrdDetail D ON D.SalesOrderID = H.SalesOrderID ON P.ProductMainID = D.ProductMainID AND P.ProductSubID = D.ProductSubID AND P.ProductSubSubID = D.ProductSubSubID ORDER BY D.ProductMainID OPTION (MAXDOP 1, HASH JOIN, FORCE ORDER); With this plan, each of the inputs to the hash joins has a good estimate, and no hash recursion occurs.  The final sort still suffers from the one-row estimate problem, and we get a single-pass sort warning as it writes rows to disk.  Even so, the query runs to completion in three or four seconds.  That’s around half the time of the previous hashing solution, but still not as fast as the nested loops trickery. Final Thoughts SQL Server’s optimizer makes cost-based decisions, so it is vital to provide it with accurate information.  We can’t really blame the performance problems highlighted here on anything other than the decision to use completely unindexed tables, and not to allow the creation of additional statistics. I should probably stress that the nested loops solution shown above is not one I would normally contemplate in the real world.  It’s there primarily for its educational and entertainment value.  I might perhaps use it to demonstrate to the sceptical that SQL Server itself is crying out for an index. Be sure to read Brad’s original post for more details.  My grateful thanks to him for granting permission to reuse some of his material. Paul White Email: [email protected] Twitter: @PaulWhiteNZ

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  • Beware Sneaky Reads with Unique Indexes

    - by Paul White NZ
    A few days ago, Sandra Mueller (twitter | blog) asked a question using twitter’s #sqlhelp hash tag: “Might SQL Server retrieve (out-of-row) LOB data from a table, even if the column isn’t referenced in the query?” Leaving aside trivial cases (like selecting a computed column that does reference the LOB data), one might be tempted to say that no, SQL Server does not read data you haven’t asked for.  In general, that’s quite correct; however there are cases where SQL Server might sneakily retrieve a LOB column… Example Table Here’s a T-SQL script to create that table and populate it with 1,000 rows: CREATE TABLE dbo.LOBtest ( pk INTEGER IDENTITY NOT NULL, some_value INTEGER NULL, lob_data VARCHAR(MAX) NULL, another_column CHAR(5) NULL, CONSTRAINT [PK dbo.LOBtest pk] PRIMARY KEY CLUSTERED (pk ASC) ); GO DECLARE @Data VARCHAR(MAX); SET @Data = REPLICATE(CONVERT(VARCHAR(MAX), 'x'), 65540);   WITH Numbers (n) AS ( SELECT ROW_NUMBER() OVER (ORDER BY (SELECT 0)) FROM master.sys.columns C1, master.sys.columns C2 ) INSERT LOBtest WITH (TABLOCKX) ( some_value, lob_data ) SELECT TOP (1000) N.n, @Data FROM Numbers N WHERE N.n <= 1000; Test 1: A Simple Update Let’s run a query to subtract one from every value in the some_value column: UPDATE dbo.LOBtest WITH (TABLOCKX) SET some_value = some_value - 1; As you might expect, modifying this integer column in 1,000 rows doesn’t take very long, or use many resources.  The STATITICS IO and TIME output shows a total of 9 logical reads, and 25ms elapsed time.  The query plan is also very simple: Looking at the Clustered Index Scan, we can see that SQL Server only retrieves the pk and some_value columns during the scan: The pk column is needed by the Clustered Index Update operator to uniquely identify the row that is being changed.  The some_value column is used by the Compute Scalar to calculate the new value.  (In case you are wondering what the Top operator is for, it is used to enforce SET ROWCOUNT). Test 2: Simple Update with an Index Now let’s create a nonclustered index keyed on the some_value column, with lob_data as an included column: CREATE NONCLUSTERED INDEX [IX dbo.LOBtest some_value (lob_data)] ON dbo.LOBtest (some_value) INCLUDE ( lob_data ) WITH ( FILLFACTOR = 100, MAXDOP = 1, SORT_IN_TEMPDB = ON ); This is not a useful index for our simple update query; imagine that someone else created it for a different purpose.  Let’s run our update query again: UPDATE dbo.LOBtest WITH (TABLOCKX) SET some_value = some_value - 1; We find that it now requires 4,014 logical reads and the elapsed query time has increased to around 100ms.  The extra logical reads (4 per row) are an expected consequence of maintaining the nonclustered index. The query plan is very similar to before (click to enlarge): The Clustered Index Update operator picks up the extra work of maintaining the nonclustered index. The new Compute Scalar operators detect whether the value in the some_value column has actually been changed by the update.  SQL Server may be able to skip maintaining the nonclustered index if the value hasn’t changed (see my previous post on non-updating updates for details).  Our simple query does change the value of some_data in every row, so this optimization doesn’t add any value in this specific case. The output list of columns from the Clustered Index Scan hasn’t changed from the one shown previously: SQL Server still just reads the pk and some_data columns.  Cool. Overall then, adding the nonclustered index hasn’t had any startling effects, and the LOB column data still isn’t being read from the table.  Let’s see what happens if we make the nonclustered index unique. Test 3: Simple Update with a Unique Index Here’s the script to create a new unique index, and drop the old one: CREATE UNIQUE NONCLUSTERED INDEX [UQ dbo.LOBtest some_value (lob_data)] ON dbo.LOBtest (some_value) INCLUDE ( lob_data ) WITH ( FILLFACTOR = 100, MAXDOP = 1, SORT_IN_TEMPDB = ON ); GO DROP INDEX [IX dbo.LOBtest some_value (lob_data)] ON dbo.LOBtest; Remember that SQL Server only enforces uniqueness on index keys (the some_data column).  The lob_data column is simply stored at the leaf-level of the non-clustered index.  With that in mind, we might expect this change to make very little difference.  Let’s see: UPDATE dbo.LOBtest WITH (TABLOCKX) SET some_value = some_value - 1; Whoa!  Now look at the elapsed time and logical reads: Scan count 1, logical reads 2016, physical reads 0, read-ahead reads 0, lob logical reads 36015, lob physical reads 0, lob read-ahead reads 15992.   CPU time = 172 ms, elapsed time = 16172 ms. Even with all the data and index pages in memory, the query took over 16 seconds to update just 1,000 rows, performing over 52,000 LOB logical reads (nearly 16,000 of those using read-ahead). Why on earth is SQL Server reading LOB data in a query that only updates a single integer column? The Query Plan The query plan for test 3 looks a bit more complex than before: In fact, the bottom level is exactly the same as we saw with the non-unique index.  The top level has heaps of new stuff though, which I’ll come to in a moment. You might be expecting to find that the Clustered Index Scan is now reading the lob_data column (for some reason).  After all, we need to explain where all the LOB logical reads are coming from.  Sadly, when we look at the properties of the Clustered Index Scan, we see exactly the same as before: SQL Server is still only reading the pk and some_value columns – so what’s doing the LOB reads? Updates that Sneakily Read Data We have to go as far as the Clustered Index Update operator before we see LOB data in the output list: [Expr1020] is a bit flag added by an earlier Compute Scalar.  It is set true if the some_value column has not been changed (part of the non-updating updates optimization I mentioned earlier). The Clustered Index Update operator adds two new columns: the lob_data column, and some_value_OLD.  The some_value_OLD column, as the name suggests, is the pre-update value of the some_value column.  At this point, the clustered index has already been updated with the new value, but we haven’t touched the nonclustered index yet. An interesting observation here is that the Clustered Index Update operator can read a column into the data flow as part of its update operation.  SQL Server could have read the LOB data as part of the initial Clustered Index Scan, but that would mean carrying the data through all the operations that occur prior to the Clustered Index Update.  The server knows it will have to go back to the clustered index row to update it, so it delays reading the LOB data until then.  Sneaky! Why the LOB Data Is Needed This is all very interesting (I hope), but why is SQL Server reading the LOB data?  For that matter, why does it need to pass the pre-update value of the some_value column out of the Clustered Index Update? The answer relates to the top row of the query plan for test 3.  I’ll reproduce it here for convenience: Notice that this is a wide (per-index) update plan.  SQL Server used a narrow (per-row) update plan in test 2, where the Clustered Index Update took care of maintaining the nonclustered index too.  I’ll talk more about this difference shortly. The Split/Sort/Collapse combination is an optimization, which aims to make per-index update plans more efficient.  It does this by breaking each update into a delete/insert pair, reordering the operations, removing any redundant operations, and finally applying the net effect of all the changes to the nonclustered index. Imagine we had a unique index which currently holds three rows with the values 1, 2, and 3.  If we run a query that adds 1 to each row value, we would end up with values 2, 3, and 4.  The net effect of all the changes is the same as if we simply deleted the value 1, and added a new value 4. By applying net changes, SQL Server can also avoid false unique-key violations.  If we tried to immediately update the value 1 to a 2, it would conflict with the existing value 2 (which would soon be updated to 3 of course) and the query would fail.  You might argue that SQL Server could avoid the uniqueness violation by starting with the highest value (3) and working down.  That’s fine, but it’s not possible to generalize this logic to work with every possible update query. SQL Server has to use a wide update plan if it sees any risk of false uniqueness violations.  It’s worth noting that the logic SQL Server uses to detect whether these violations are possible has definite limits.  As a result, you will often receive a wide update plan, even when you can see that no violations are possible. Another benefit of this optimization is that it includes a sort on the index key as part of its work.  Processing the index changes in index key order promotes sequential I/O against the nonclustered index. A side-effect of all this is that the net changes might include one or more inserts.  In order to insert a new row in the index, SQL Server obviously needs all the columns – the key column and the included LOB column.  This is the reason SQL Server reads the LOB data as part of the Clustered Index Update. In addition, the some_value_OLD column is required by the Split operator (it turns updates into delete/insert pairs).  In order to generate the correct index key delete operation, it needs the old key value. The irony is that in this case the Split/Sort/Collapse optimization is anything but.  Reading all that LOB data is extremely expensive, so it is sad that the current version of SQL Server has no way to avoid it. Finally, for completeness, I should mention that the Filter operator is there to filter out the non-updating updates. Beating the Set-Based Update with a Cursor One situation where SQL Server can see that false unique-key violations aren’t possible is where it can guarantee that only one row is being updated.  Armed with this knowledge, we can write a cursor (or the WHILE-loop equivalent) that updates one row at a time, and so avoids reading the LOB data: SET NOCOUNT ON; SET STATISTICS XML, IO, TIME OFF;   DECLARE @PK INTEGER, @StartTime DATETIME; SET @StartTime = GETUTCDATE();   DECLARE curUpdate CURSOR LOCAL FORWARD_ONLY KEYSET SCROLL_LOCKS FOR SELECT L.pk FROM LOBtest L ORDER BY L.pk ASC;   OPEN curUpdate;   WHILE (1 = 1) BEGIN FETCH NEXT FROM curUpdate INTO @PK;   IF @@FETCH_STATUS = -1 BREAK; IF @@FETCH_STATUS = -2 CONTINUE;   UPDATE dbo.LOBtest SET some_value = some_value - 1 WHERE CURRENT OF curUpdate; END;   CLOSE curUpdate; DEALLOCATE curUpdate;   SELECT DATEDIFF(MILLISECOND, @StartTime, GETUTCDATE()); That completes the update in 1280 milliseconds (remember test 3 took over 16 seconds!) I used the WHERE CURRENT OF syntax there and a KEYSET cursor, just for the fun of it.  One could just as well use a WHERE clause that specified the primary key value instead. Clustered Indexes A clustered index is the ultimate index with included columns: all non-key columns are included columns in a clustered index.  Let’s re-create the test table and data with an updatable primary key, and without any non-clustered indexes: IF OBJECT_ID(N'dbo.LOBtest', N'U') IS NOT NULL DROP TABLE dbo.LOBtest; GO CREATE TABLE dbo.LOBtest ( pk INTEGER NOT NULL, some_value INTEGER NULL, lob_data VARCHAR(MAX) NULL, another_column CHAR(5) NULL, CONSTRAINT [PK dbo.LOBtest pk] PRIMARY KEY CLUSTERED (pk ASC) ); GO DECLARE @Data VARCHAR(MAX); SET @Data = REPLICATE(CONVERT(VARCHAR(MAX), 'x'), 65540);   WITH Numbers (n) AS ( SELECT ROW_NUMBER() OVER (ORDER BY (SELECT 0)) FROM master.sys.columns C1, master.sys.columns C2 ) INSERT LOBtest WITH (TABLOCKX) ( pk, some_value, lob_data ) SELECT TOP (1000) N.n, N.n, @Data FROM Numbers N WHERE N.n <= 1000; Now here’s a query to modify the cluster keys: UPDATE dbo.LOBtest SET pk = pk + 1; The query plan is: As you can see, the Split/Sort/Collapse optimization is present, and we also gain an Eager Table Spool, for Halloween protection.  In addition, SQL Server now has no choice but to read the LOB data in the Clustered Index Scan: The performance is not great, as you might expect (even though there is no non-clustered index to maintain): Table 'LOBtest'. Scan count 1, logical reads 2011, physical reads 0, read-ahead reads 0, lob logical reads 36015, lob physical reads 0, lob read-ahead reads 15992.   Table 'Worktable'. Scan count 1, logical reads 2040, physical reads 0, read-ahead reads 0, lob logical reads 34000, lob physical reads 0, lob read-ahead reads 8000.   SQL Server Execution Times: CPU time = 483 ms, elapsed time = 17884 ms. Notice how the LOB data is read twice: once from the Clustered Index Scan, and again from the work table in tempdb used by the Eager Spool. If you try the same test with a non-unique clustered index (rather than a primary key), you’ll get a much more efficient plan that just passes the cluster key (including uniqueifier) around (no LOB data or other non-key columns): A unique non-clustered index (on a heap) works well too: Both those queries complete in a few tens of milliseconds, with no LOB reads, and just a few thousand logical reads.  (In fact the heap is rather more efficient). There are lots more fun combinations to try that I don’t have space for here. Final Thoughts The behaviour shown in this post is not limited to LOB data by any means.  If the conditions are met, any unique index that has included columns can produce similar behaviour – something to bear in mind when adding large INCLUDE columns to achieve covering queries, perhaps. Paul White Email: [email protected] Twitter: @PaulWhiteNZ

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  • Problem installing eclipse-platform in fresh Ubuntu 10.10

    - by pablo
    I am trying to install the eclipse-platform package in a new Ubuntu 10.10 and I am getting the following error (via the Ubuntu software center): Failed to fetch http://nz.archive.ubuntu.com/ubuntu/pool/universe/libs/libservlet2.4-java/libservlet2.4-java_5.0.30-12_all.deb 404 Not Found Browsing to the mentioned URL, I can obviously verify that the .deb file in question is missing. Is the package broken, or is it just the NZ mirror?

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  • How do I stop VMware Workstation 6.5 from giving up input focus for no reason on Ubuntu 10.4?

    - by Matt
    After patching some kernel modules, I got VMware Workstation 6.5.4 running on my Ubuntu 10.4 x86_64 machine. However, now my Windows XP SP3 guest instance cannot keep mouse input captured for any length of time. I can sometimes activate a control in the guest if a double click very quickly, but it's not reliable (and extremely annoying). Everything appears to be fine in Unity; the problem just appears when I'm running the instance in the VMware window.

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  • How to set the default input focus/caret position in Outlook 2007 stationery?

    - by Ronald
    When using stationery/templates in Outlook 2007, I want to set the caret position between the header and footer by default. Now you have to click in the right place to start typing, which is annoying... Is the some special markup that would allow me to set a default caret position? Something like this (for Outlook Express 5/6): http://email.about.com/od/outlookexpresstips/qt/et041205.htm.

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  • How can I prevent a textbox from taking focus on the postback when I have a calendar extender on it?

    - by Biff MaGriff
    Hello, I have repeater, inside this repeater is a user control. In my c# codebehind on my user control I dynamically add a textbox and assign a calendar extender to it. Similar to this. //custom control protected void Page_Load(object o, EventArgs e) { TextBox tb = new TextBox(); tb.ID = "myTextBox"; MaskedEditExtender meeDate = new MaskedEditExtender(); meeDate.ID = "meeDate"; meeDate.TargetControlID = this.UniqueID + "$" + tb.ID; meeDate.Mask = "99/99/9999"; meeDate.MaskType = MaskedEditType.Date; CalendarExtender ce = new CalendarExtender(); ce.ID = "ceCalendar"; ce.TargetControlID = this.UniqueID + "$" + tb.ID; this.Controls.Add(tbDate); this.Controls.Add(meeDate); this.Controls.Add(ce); } This works well, however after I postback the textbox takes focus and the calendar extender fires and it looks really.... dumb. How can I stop this?

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  • Unobstrusive pseudo-classes and attribute selectors emulation in IE

    - by Álvaro G. Vicario
    I'm trying to emulate some pseudo-classes and attribute selectors in Internet Explorer 6 and 7, such as :focus, :hover or [type=text]. So far, I've managed to add a class name to the affected elements: $("input, textarea, select") .hover(function(){ $(this).addClass("hover"); }, function(){ $(this).removeClass("hover"); }) .focus(function(){ $(this).addClass("focus"); }) .blur(function(){ $(this).removeClass("focus"); }); $("input[type=text]").each(function(){ $(this).addClass("text"); }); However, I'm still forced to duplicate selector in my style sheets: textarea:focus, textarea.focus{ } And, to make things worse, IE6 seems to ignore all the selectors when it finds an attribute: input[type=text], input.text{ /* IE6 ignores this */ } And, of course, IE6 ignores selectors with multiple classes: input.text.focus{ /* IE6 ignores this */ } So I'm likely to end up with this mess: input[type=text]{ /* Rules here */ } input.text{ /* Same rules again */ } input[type=text]:focus{ } input.text_and_focus{ } input.text_and_hover{ } input.text_and_focus_and_hover{ } My question: is there any way to read the rules or computed style defined for a CSS selector and apply it to certain elements, so I only need to maintain one set of standard CSS?

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  • Cannot Access IIS Website Locally Using www

    - by Reafidy
    I have small website hosted on our WS 2008 R2 server using IIS 7. I can access our website from anywhere in the world using: www.ourwebsite.co.nz But from any local computer on our internal network I can only access the website using: http://ourwebsite.co.nz Our employees are constantly asking why they cant just use www.ourwebsite.co.nz I'm not sure what info to provide. I presume that because the wesbite correctly functions from outside the local network that I have correctly setup our Web DNS A records at our domain host. And the problem may lie with our local DNS configuration.

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  • iChat can't authenticate to Lion Server 10.7.2 [migrated]

    - by glenstorey
    I've enabled iChat and iCal Server through our local 10.7.2 Server which has DNS set up correctly. I can add the server account via a client's System Preferences (under other - Mac OS X server) and it authenticates with my shortname correctly. However, when I load iChat, I get this error message: Where the account is [email protected].nz. The password and username is correct. Console throws this error: 22/11/11 3:03:31.135 PM imagent: [Warning] XMPPConnection: Error: Error Domain=XMPPErrorDomain Code=105 "The operation couldn?t be completed. (XMPPErrorDomain error 105.)" UserInfo=0x7f81bbe2a3e0 {XMPPErrorText=service requested for unknown domain} DNS is set up correctly (it's working for Profile Management, Software Update Server and Web Services) but I can't get iChat to work correctly. How can I get clients to authenticate? FYI: It's probably worth noting that I get the exact same error messages when I use [email protected].nz instead of [email protected].nz. Also posted this question on Apple Discussion here.

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  • Guest Post: Christian Finn: Is Facebook About to Become a Victim of its Own Success?

    - by Michael Snow
    12.00 Print 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Cambria","serif"; mso-ascii-font-family:Cambria; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:Cambria; mso-fareast-theme-font:minor-latin; mso-hansi-font-family:Cambria; mso-hansi-theme-font:minor-latin;}  Since we have a number of new members of the WebCenter Evangelist team - I thought it would be appropriate to close the week with the newest hire and leader of the global WebCenter Evangelists, Christian Finn, who has just joined the Red team after many years with the small technology company up in Redmond, WA. He gave an intro to himself in an earlier post this morning but his post below is a great example of how customer engagement takes on a life of its own in our global online connected and social digital ecosystem. Is Facebook About to Become a Victim of its Own Success? What if I told you that your brand could advertise so successfully, you wouldn’t have to pay for the ads? A recent campaign by Ford Motor Company for the Ford Focus featuring Doug the spokespuppet (I am not making this up) did just that—and it raises some interesting issues for marketers and social media alike in the brave new world of customer engagement that is the Social Web. Allow me to elaborate. An article in the Wall Street Journal last week—“Big Brands Like Facebook, But They Don’t Like to Pay” tells the story of Ford’s recently concluded online campaign for the 2012 Ford Focus. (Ford, by the way, under the leadership of people such as Scott Monty, has been a pioneer of effective social campaigns.) The centerpiece of the campaign was the aforementioned Doug, who appeared as a character on Facebook in videos and via chat. (If you are not familiar with Doug, you can see him in action here, and read the WSJ story here.) You may be thinking puppet ads are a sign of Internet Bubble 2.0 and want to stop now, but bear with me. The Journal reported that Ford spent about $95M on its overall Ford Focus campaign, with TV accounting for over $60M of that spend. The Internet buy for the campaign was just over $10M, which included ad buys to drive traffic to Facebook for people to meet and ‘Like’ Doug and some amount on Facebook ads, too, to promote Doug and by extension, the Ford Focus. So far, a fairly straightforward consumer marketing story in the Internet Era. Yet here’s the curious thing: once Doug reached 10,000 fans on Facebook, Ford stopped paying for Facebook ads. Doug had gone viral with people sharing his videos with one another; once critical mass was reached there was no need to buy more ads on Facebook. Doug went on to be Liked by over 43,000 people, and 61% of his fans said they would be more likely to consider buying a Focus. According to the article, Ford says Focus sales are up this year—and increasing sales is every marketer’s goal. And so in effect, Ford found its Facebook campaign so successful that it could stop paying for it, instead letting its target consumers communicate its messages for fun—and for free. Not only did they get a 3X increase in fans beyond their paid campaign, they had thousands of customers sharing their messages in video form for months. Since free advertising is the Holy Grail of marketing both old and new-- and it appears social networks have an advantage in generating that buzz—it seems reasonable to ask: what would happen to brands’ advertising strategies—and the media they use to engage customers, if this success were repeated at scale? It seems logical to conclude that, at least initially, more ad dollars would be spent with social networks like Facebook as brands attempt to replicate Ford’s success. Certainly Facebook ad revenues are on the rise—eMarketer expects Facebook’s ad revenues to quintuple by 2012 compared with 2009 levels, to nearly 2.9B. That’s bad news for TV and the already battered print media and good news for Facebook. But perhaps not so over the longer run. With TV buys, you have to keep paying to generate impressions. If Doug the spokespuppet is any guide, however, that may not be true for social media campaigns. After an initial outlay, if a social campaign takes off, the audience will generate more impressions on its own. Thus a social medium like Facebook could be the victim of its own success when it comes to ad revenue. It may be there is an inherent limiting factor in the ad spend they can capture, as exemplified by Ford’s experience with Dough and the Focus. And brands may spend much less overall on advertising, with as good or better results, than they ever have in the past. How will these trends evolve? Can brands create social campaigns that repeat Ford’s formula for the Focus with effective results? Can social networks find ways to capture more spend and overcome their potential tendency to make further spend unnecessary? And will consumers become tired and insulated from social campaigns, much as they have to traditional advertising channels? These are the questions CMOs and Facebook execs alike will be asking themselves in the brave new world of customer engagement. As always, your thoughts and comments are most welcome.

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  • In SELENIUM, how to I change focus to a new popup tab?

    I'm using Selenium and Firefox. I have a link on a page (say linkA) that opens a new page in a new tab. The new tab is displayed when linkA is clicked. I then want to interact with the new page. Here is my selenium script: click linkA pause 5000 selectWindow Title click linkB (note: linkB is on the new page) Selenium cannot identify the new tab. It reports: [warn] Link has target '_blank', which is not supported in Selenium! Randomizing target to be: selenium_blank24003 Is there any way to tell Selenium to interact with the displayed tab?

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  • If I do "jquery sortable" on a contenteditable item(s), I then can't focus mouse anywhere inside con

    - by Matej
    Strangely this is broken only in Firefox and Opera (IE, Chrome and Safari works as it should). Any suggestion for a quick fix? <html> <head> <script src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js" type="text/javascript"></script> <script src="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.2/jquery-ui.min.js" type="text/javascript"></script> <script> $(document).ready(function(){ $('#sortable').sortable(); }); </script> </head> <body> <span id="sortable"> <p contenteditable="true">One apple</p> <p>Two pears</p> <p>Three oranges</p> </span> </body> </html>

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  • Does Unity support disabling the global application menu?

    - by Michael E
    I'm fairly excited for Unity, as it looks like a promising new direction for Ubuntu. However, I do have a concern - will it be possible to use Unity without the global menu? I have my window manager set to focus-follows-mouse/sloppy focus, and find the productivity gains to be immense. Sloppy focus is incompatible, however, with global menus, as it is possible for the focus to change while you move from window to menu. Will Unity support an option to use window menus while still using Unity?

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  • How do I disable the global application menu?

    - by Michael Ekstrand
    I'm fairly excited for Unity, as it looks like a promising new direction for Ubuntu. However, I do have a concern - will it be possible to use Unity without the global menu? I have my window manager set to focus-follows-mouse/sloppy focus, and find the productivity gains to be immense. Sloppy focus is incompatible, however, with global menus, as it is possible for the focus to change while you move from window to menu. Will Unity support an option to use window menus while still using Unity?

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  • How do I enable or disable the global application menu?

    - by Michael Ekstrand
    I'm fairly excited for Unity, as it looks like a promising new direction for Ubuntu. However, I do have a concern - will it be possible to use Unity without the global menu? I have my window manager set to focus-follows-mouse/sloppy focus, and find the productivity gains to be immense. Sloppy focus is incompatible, however, with global menus, as it is possible for the focus to change while you move from window to menu. Will Unity support an option to use window menus while still using Unity?

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  • How can I tell which TextBox had focus last?

    - by Carlos
    I have an MVVM application with various TextBox controls and a virtual keypad. (This application is to run on a touch screen system, with no keyboard). To change the value of a TextBox, the user has to touch the TextBox and then use the virtual keypad to enter a number. How can my VM know which TextBox to change when it gets the command from the keypad?

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