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  • Efficiency: what block size of kernel-mode memory allocations?

    - by Robert
    I need a big, driver-internal memory buffer with several tens of megabytes (non-paged, since accessed at dispatcher level). Since I think that allocating chunks of non-continuous memory will more likely succeed than allocating one single continuous memory block (especially when memory becomes fragmented) I want to implement that memory buffer as a linked list of memory blocks. What size should the blocks have to efficiently load the memory pages? (read: not to waste any page space) A multiple of 4096? (equally to the page size of the OS) A multiple of 4000? (not to waste another page for OS-internal memory allocation information) Another size? Target platform is Windows NT = 5.1 (XP and above) Target architectures are x86 and amd64 (not Itanium)

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  • c# 4.0 - best way to refactor a block of "If (something is Type) {}" statements?

    - by Andrew Johns
    I've got some code that looks like this, public void ResetControls(Control controlOnPage) { if (controlOnPage is TextBox) { ResetTextBoxControl(controlOnPage); } if (controlOnPage is MediaPicker) { ((MediaPicker)controlOnPage).Media = null; } if (controlOnPage is RelatedContentPicker) { ((RelatedContentPicker)controlOnPage).RelatedContentCollection = null; } ... ... foreach (Control child in controlOnPage.Controls) { ResetControls(child); } } The idea behind it is that I can pass a page to the method and it'll recursively reset all the controls on it to their default states - in the case of MediaPicker and RelatedContentPicker, these are user controls that I've created. FXCop warns me "Do Not Cast Unnecessarily" for this code - but I'm unsure how to rewrite it to make it better. Any ideas?

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  • How can I reference only a portion of a TextArea's htmlText block?

    - by Charles Shoults
    I have a number of very poor-quality pdf documents that look like 80's photocopies, which I'm rebuilding in Flash (Flex Builder 3 MXML application), representing paragraphs of text in TextAreas so that selected portions can be bold or italic, or whatever I need. I need a way to apply toolTips or event listeners to individual words within the block of text to link those words to a glossary. I'm perfectly happy to create a definition panel that is populated and made visible with a mouseOver, but don't know how to do it to just a portion of the text. Is there a good / clean / easy way to do this?

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  • Where can I find an array of the (un)assigned Unicode code points for a particular block?

    - by gitparade
    At the moment, I'm writing these arrays by hand. For example, the Miscellaneous Mathematical Symbols-A block has an entry in hash like this: my %symbols = ( ... miscellaneous_mathematical_symbols_a => [(0x27C0..0x27CA), 0x27CC, (0x27D0..0x27EF)], ... ) The simpler, 'continuous' array miscellaneous_mathematical_symbols_a => [0x27C0..0x27EF] doesn't work because Unicode blocks have holes in them. For example, there's nothing at 0x27CB. Take a look at the code chart [PDF]. Writing these arrays by hand is tedious, error-prone and a bit fun. And I get the feeling that someone has already tackled this in Perl!

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  • What will happen if the code can't finished on time...

    - by Tattat
    If I set a timer to execute a code every 3 seconds. If the code isn't finished in 3 seconds, what will happen? The computer will terminal the code or wait for the code finish or continue the timer, and execute the code with the unfinished code concurrently. int delay = 0; // delay for 0 sec. int period = 3000; // repeat 3 sec. Timer timer = new Timer(); timer.scheduleAtFixedRate(new TimerTask() { public void run() { // Task here ... // It may take more than 3 sec to finish, what will happen? } }, delay, period);

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  • Unhandled exception, even after adding try-catch block ? C++

    - by user2525503
    try { bool numericname=false; std::cout <<"\n\nEnter the Name of Customer: "; std::getline(cin,Name); std::cout<<"\nEnter the Number of Customer: "; std::cin>>Number; std::string::iterator i=Name.begin(); while(i!=Name.end()) { if(isdigit(*i)) { numericname=true; } i++; } if(numericname) { throw "Name cannot be numeric."; } } catch(string message) { cout<<"\nError Found: "<< message <<"\n\n"; } Why am I getting unhandled exception error ? Even after I have added the catch block to catch thrown string messages?

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  • How to implement message passing in GNUradio?

    - by xuandl
    I need to implement message passing, my idea is to make some sort of message source (I inherit from public gr_sync_block) that works as a controller for another block (it has to send a message each 6 minutes). I read that is necessary to inherit from gnuradio::block -and by the way, installing grextras is mandatory-. In the .h file I added the #include and inherited from block"class JDFM_API jdfm_control : public gr_sync_block, public gnuradio::block". I know that I have redefine some things like the gnuradio::block constructor but I dont know what msg_signature is, I also don't get the relation between block's parameters and work parameter, the last thing that I am not sure is if I still can use gnuradio-companion if I create a block like this. I haven't been able to find a simple example of messages implementation. If anyone can guide me or show me an example, it would be awesome. Thanks in advance.

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  • is there a good reason to fear closed-source code *inside* of open-source libraries?

    - by jcollum
    Here's the situation. At work here, I hear there is resistance to using open source code (Nant in particular) because there might be copyrighted code in there. Meaning somewhere in that open source tool or library there might be a chunk of code that was directly lifted from copyrighted code. In theory, this means our company (which is quite large) get sued for big money because they used an open source library. We don't ship any software, so how this theoretical plaintiff would find this out is a mystery. I have also heard that some group of people came through a year or two ago and actually found instances of this in our codebase. That's hearsay of course, so who knows. Is this simple paranoia? Didn't something similar to this happen with Linux a while ago? Wouldn't the burden of checking for copyrighted code lie with the people who made the code, not the people who use it?

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  • How i can block calling onCreate while rotating device when My AsyncTask start?

    - by Labeeb P
    Hi, Me testing in Samsung Galaxy tab. In that i have made two layout folder for both ORIENTATION_LANDSCAPE and ORIENTATION_PORTRAIT with specific layout xml in it. In that layout i have a button and on clicking it start a progress dialog (doing some stuff using AsyncTask, after that going to new intent) But when the device is rotated when the progress dialog is working, that dialog and AsyncTask stop and new layout is loaded. If i understood correctly, I think the onCreate is called when device is rotated How i can block calling onCreate while rotating device when My AsyncTask start? Thank you

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  • How can I execute a block of code exactly once in PHP?

    - by Jack
    I have one main.php file with a class definition. Other php files use this main.php file //main.php <?php class A{ } //I want to execute the following statements exactly once $a = new A(); /* Some code */ ?> I use main.php in other php files like //php1.php <?php require_once("main.php"); $b = new A(); /* Some code */ ?> Is there any statement in PHP like execute_once()? How do I solve this?

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  • How to remove space under images?

    - by user2831652
    So here's my problem, there's a small white space showing up under the pictures on my tumblr, but the space only shows up under photosets, not under photos. I have on my CSS: #post{padding:10px;} #post img{display:block;} And then on my html: {block:Posts} <div id="post"> {block:Photo}<img src="{PhotoURL-500}"/>{/block:Photo} {block:Photoset}{Photoset-500}{/block:Photoset} </div> {/block:Posts} But the photoset adds a 3px space under the images, turning the padding to 13px for no reason. Can someone help me figure out this?

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  • Getting information about where c++ exceptions are thrown inside of catch block?

    - by tfinniga
    I've got a c++ app that wraps large parts of code in try blocks. When I catch exceptions I can return the user to a stable state, which is nice. But I'm not longer receiving crash dumps. I'd really like to figure out where in the code the exception is taking place, so I can log it and fix it. Being able to get a dump without halting the application would be ideal, but I'm not sure that's possible. Is there some way I can figure out where the exception was thrown from within the catch block? If it's useful, I'm using native msvc++ on windows xp and higher. My plan is to simply log the crashes to a file on the various users' machines, and then upload the crashlogs once they get to a certain size.

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  • Which to use - "operator new" or "operator new[]" - to allocate a block of raw memory in C++?

    - by sharptooth
    My C++ program needs a block of uninitialized memory. In C I would use malloc() and later free(). In C++ I can either call ::operator new or ::operator new[] and ::operator delete or operator delete[] respectively later. Looks like both ::operator new and ::operator new[] have exactly the same signature and exactly the same behavior. The same for ::operator delete and ::operator delete[]. The only thing I shouldn't do is pairing operator new with operator delete[] and vice versa - undefined behavior. Other than that which pair do I choose and why?

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  • C++ Beginner - Simple block of code crashing, reason unknown.

    - by Francisco P.
    Hello everyone, Here's a block of code I'm having trouble with. string Game::tradeRandomPieces(Player & player) { string hand = player.getHand(); string piecesRemoved; size_t index; for (size_t numberOfPiecesToTrade = rand() % hand.size() + 1; numberOfPiecesToTrade != 0; --numberOfPiecesToTrade) { index = rand() % hand.size(); piecesRemoved += hand[index]; hand.erase(index,1); } player.removePiecesFromHand(piecesRemoved); player.fillHand(_deck); return piecesRemoved; } I believe the code is pretty self explanatory. fillhand and removepiecesfromhand are working fine, so that's not it. I really can't get what's wrong with this :( Thanks for your time

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  • Where can I find an array of the Unicode code points for a particular block?

    - by gitparade
    At the moment, I'm writing these arrays by hand. For example, the Miscellaneous Mathematical Symbols-A block has an entry in hash like this: my %symbols = ( ... miscellaneous_mathematical_symbols_a => [(0x27C0..0x27CA), 0x27CC, (0x27D0..0x27EF)], ... ) The simpler, 'continuous' array miscellaneous_mathematical_symbols_a => [0x27C0..0x27EF] doesn't work because Unicode blocks have holes in them. For example, there's nothing at 0x27CB. Take a look at the code chart [PDF]. Writing these arrays by hand is tedious, error-prone and a bit fun. And I get the feeling that someone has already tackled this in Perl!

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  • [perl] where can i find an array of the Unicode code points for a particular block?

    - by gitparade
    At the moment, I'm writing these arrays by hand. For example, the Miscellaneous Mathematical Symbols-A block has an entry in hash like this: my %symbols = ( ... miscellaneous_mathematical_symbols_a => [(0x27C0..0x27CA), 0x27CC, (0x27D0..0x27EF)], ... ) The simpler, 'continuous' array miscellaneous_mathematical_symbols_a => [0x27C0..0x27EF] doesn't work because Unicode blocks have holes in them. For example, there's nothing at 0x27CB. Take a look at the code chart [PDF]. Writing these arrays by hand is tedious, error-prone and a bit fun. And I get the feeling that someone has already tackled this in Perl!

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  • What is the quikest method to see actual color of any hex code #a7a7a7?

    - by metal-gear-solid
    What is the quikest method to see actual color of any hex code #a7a7a7? When i work on other's CSS then if i deal with color codes then i quickly wan to see the color of that particular hex code. suppose if i'm editing css in notepad and i found code #a7a7a7 then how can i know what is the color of this code. If i have a color on my screen then i quickly know what would be hex code for this with the help of some tools ,but i need just opposite of this. i'm not talking about to see whole color chart of site. I want to see color of particular hex code.

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  • Can I float a block of text like an image?

    - by george.entenman.name
    If you change "float:right" to "float:left" in this W3schools example, you'll get an image floating to the left of the paragraph. I want to do the same thing with a block of text. The purpose is to be able to have little annotations to the left of paragraphs. If you know of any way to do this, I'd be very grateful. I'd be really grateful (and amazed) if there were a way to place this annotation midway in a paragraph and have text flow around it. I've searched all over for an answer but possibly don't know how to ask the question so that search engines can help me. So now I'm appealing to humans!!

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  • Understanding EDI 997.

    - by VishnuTiwariBlog
    Hi Guys, This is for the EDI starter. Below is the complete detail of EDI 997 segment and element details. 997 Functional Acknowledgment Transaction Layout: No. Seg ID Name Description Example M/O 010 ST Transaction Set Header To indicate the start of a transaction set and to assign a control number ST*997*382823~   M ST01   Code uniquely identifying a Transaction Set   M ST02   Identifying control number that must be unique within the transaction set functional group assigned by the originator for a transaction set   M 020 AK1 Functional Group Response Header To start acknowledgment of a functional group AK1*QM*2459823 M        AK101   Code identifying a group of application related transaction sets IN Invoice Information (810) SH Ship Notice/Manifest (856)     AK102   Assigned number originated and maintained by the sender     030 AK2 Transaction Set Response Header To start acknowledgment of a single transaction set AK2*856*001 M AK201   Code uniquely identifying a Transaction Set 810 Invoice 856 Ship Notice/Manifest   M AK202   Identifying control number that must be unique within the transaction set functional group assigned by the originator for a transaction set   M 040 AK3 Data Segment Note To report errors in a data segment and identify the location of the data segment AK3*TD3*9 O AK301 Segment ID Code Code defining the segment ID of the data segment in error (See Appendix A - Number 77)     AK302 Segment Position in Transaction Set The numerical count position of this data segment from the start of the transaction set: the transaction set header is count position 1     050 AK4 Data Element Note To report errors in a data element or composite data structure and identify the location of the data element AK4*2**2 O AK401 Position in Segment Code indicating the relative position of a simple data element, or the relative position of a composite data structure combined with the relative position of the component data element within the composite data structure, in error; the count starts with 1 for the simple data element or composite data structure immediately following the segment ID     AK402 Element Position in Segment This is used to indicate the relative position of a simple data element, or the relative position of a composite data structure with the relative position of the component within the composite data structure, in error; in the data segment the count starts with 1 for the simple data element or composite data structure immediately following the segment ID     AK403 Data Element Syntax Error Code Code indicating the error found after syntax edits of a data element 1 Mandatory Data Element Missing 2 Conditional Required Data Element Missing 3 Too Many Data Elements 4 Data Element Too Short 5 Data Element Too Long 6 Invalid Character in Data Element 7 Invalid Code Value 8 Invalid Date 9 Invalid Time 10 Exclusion Condition Violated     AK404 Copy of Bad Data Element This is a copy of the data element in error     060 AK5 AK5 Transaction Set Response Trailer To acknowledge acceptance or rejection and report errors in a transaction set AK5*A~ AK5*R*5~ M AK501 Transaction Set Acknowledgment Code Code indicating accept or reject condition based on the syntax editing of the transaction set A Accepted E Accepted But Errors Were Noted R Rejected     AK502 Transaction Set Syntax Error Code Code indicating error found based on the syntax editing of a transaction set 1 Transaction Set Not Supported 2 Transaction Set Trailer Missing 3 Transaction Set Control Number in Header and Trailer Do Not Match 4 Number of Included Segments Does Not Match Actual Count 5 One or More Segments in Error 6 Missing or Invalid Transaction Set Identifier 7 Missing or Invalid Transaction Set Control Number     070 AK9 Functional Group Response Trailer To acknowledge acceptance or rejection of a functional group and report the number of included transaction sets from the original trailer, the accepted sets, and the received sets in this functional group AK9*A*1*1*1~ AK9*R*1*1*0~ M AK901 Functional Group Acknowledge Code Code indicating accept or reject condition based on the syntax editing of the functional group A Accepted E Accepted, But Errors Were Noted. R Rejected     AK902 Number of Transaction Sets Included Total number of transaction sets included in the functional group or interchange (transmission) group terminated by the trailer containing this data element     AK903 Number of Received Transaction Sets Number of Transaction Sets received     AK904 Number of Accepted Transaction Sets Number of accepted Transaction Sets in a Functional Group     AK905 Functional Group Syntax Error Code Code indicating error found based on the syntax editing of the functional group header and/or trailer 1 Functional Group Not Supported 2 Functional Group Version Not Supported 3 Functional Group Trailer Missing 4 Group Control Number in the Functional Group Header and Trailer Do Not Agree 5 Number of Included Transaction Sets Does Not Match Actual Count 6 Group Control Number Violates Syntax     080 SE Transaction Set Trailer To indicate the end of the transaction set and provide the count of the transmitted segments (including the beginning (ST) and ending (SE) segments) SE*9*223~ M SE01 Number of Included Segments Total number of segments included in a transaction set including ST and SE segments     SE02 Transaction Set Control Number Identifying control number that must be unique within the transaction set functional group assigned by the originator for a transaction set

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  • Understanding EDI 997

    - by VishnuTiwariBlog
    Hi Guys, This is for the EDI starter. Below is the complete detail of EDI 997 segment and element details. 997 Functional Acknowledgment Transaction Layout:   No. Seg ID Name Description Example M/O 010 ST Transaction Set Header To indicate the start of a transaction set and to assign a control number ST*997*382823~   M ST01   Code uniquely identifying a Transaction Set   M ST02   Identifying control number that must be unique within the transaction set functional group assigned by the originator for a transaction set   M 020 AK1 Functional Group Response Header To start acknowledgment of a functional group AK1*QM*2459823 M        AK101   Code identifying a group of application related transaction sets IN Invoice Information (810) SH Ship Notice/Manifest (856)     AK102   Assigned number originated and maintained by the sender     030 AK2 Transaction Set Response Header To start acknowledgment of a single transaction set AK2*856*001 M AK201   Code uniquely identifying a Transaction Set 810 Invoice 856 Ship Notice/Manifest   M AK202   Identifying control number that must be unique within the transaction set functional group assigned by the originator for a transaction set   M 040 AK3 Data Segment Note To report errors in a data segment and identify the location of the data segment AK3*TD3*9 O AK301 Segment ID Code Code defining the segment ID of the data segment in error (See Appendix A - Number 77)     AK302 Segment Position in Transaction Set The numerical count position of this data segment from the start of the transaction set: the transaction set header is count position 1     050 AK4 Data Element Note To report errors in a data element or composite data structure and identify the location of the data element AK4*2**2 O AK401 Position in Segment Code indicating the relative position of a simple data element, or the relative position of a composite data structure combined with the relative position of the component data element within the composite data structure, in error; the count starts with 1 for the simple data element or composite data structure immediately following the segment ID     AK402 Element Position in Segment This is used to indicate the relative position of a simple data element, or the relative position of a composite data structure with the relative position of the component within the composite data structure, in error; in the data segment the count starts with 1 for the simple data element or composite data structure immediately following the segment ID     AK403 Data Element Syntax Error Code Code indicating the error found after syntax edits of a data element 1 Mandatory Data Element Missing 2 Conditional Required Data Element Missing 3 Too Many Data Elements 4 Data Element Too Short 5 Data Element Too Long 6 Invalid Character in Data Element 7 Invalid Code Value 8 Invalid Date 9 Invalid Time 10 Exclusion Condition Violated     AK404 Copy of Bad Data Element This is a copy of the data element in error     060 AK5 AK5 Transaction Set Response Trailer To acknowledge acceptance or rejection and report errors in a transaction set AK5*A~ AK5*R*5~ M AK501 Transaction Set Acknowledgment Code Code indicating accept or reject condition based on the syntax editing of the transaction set A Accepted E Accepted But Errors Were Noted R Rejected     AK502 Transaction Set Syntax Error Code Code indicating error found based on the syntax editing of a transaction set 1 Transaction Set Not Supported 2 Transaction Set Trailer Missing 3 Transaction Set Control Number in Header and Trailer Do Not Match 4 Number of Included Segments Does Not Match Actual Count 5 One or More Segments in Error 6 Missing or Invalid Transaction Set Identifier 7 Missing or Invalid Transaction Set Control Number     070 AK9 Functional Group Response Trailer To acknowledge acceptance or rejection of a functional group and report the number of included transaction sets from the original trailer, the accepted sets, and the received sets in this functional group AK9*A*1*1*1~ AK9*R*1*1*0~ M AK901 Functional Group Acknowledge Code Code indicating accept or reject condition based on the syntax editing of the functional group A Accepted E Accepted, But Errors Were Noted. R Rejected     AK902 Number of Transaction Sets Included Total number of transaction sets included in the functional group or interchange (transmission) group terminated by the trailer containing this data element     AK903 Number of Received Transaction Sets Number of Transaction Sets received     AK904 Number of Accepted Transaction Sets Number of accepted Transaction Sets in a Functional Group     AK905 Functional Group Syntax Error Code Code indicating error found based on the syntax editing of the functional group header and/or trailer 1 Functional Group Not Supported 2 Functional Group Version Not Supported 3 Functional Group Trailer Missing 4 Group Control Number in the Functional Group Header and Trailer Do Not Agree 5 Number of Included Transaction Sets Does Not Match Actual Count 6 Group Control Number Violates Syntax     080 SE Transaction Set Trailer To indicate the end of the transaction set and provide the count of the transmitted segments (including the beginning (ST) and ending (SE) segments) SE*9*223~ M SE01 Number of Included Segments Total number of segments included in a transaction set including ST and SE segments     SE02 Transaction Set Control Number Identifying control number that must be unique within the transaction set functional group assigned by the originator for a transaction set

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  • When is a SQL function not a function?

    - by Rob Farley
    Should SQL Server even have functions? (Oh yeah – this is a T-SQL Tuesday post, hosted this month by Brad Schulz) Functions serve an important part of programming, in almost any language. A function is a piece of code that is designed to return something, as opposed to a piece of code which isn’t designed to return anything (which is known as a procedure). SQL Server is no different. You can call stored procedures, even from within other stored procedures, and you can call functions and use these in other queries. Stored procedures might query something, and therefore ‘return data’, but a function in SQL is considered to have the type of the thing returned, and can be used accordingly in queries. Consider the internal GETDATE() function. SELECT GETDATE(), SomeDatetimeColumn FROM dbo.SomeTable; There’s no logical difference between the field that is being returned by the function and the field that’s being returned by the table column. Both are the datetime field – if you didn’t have inside knowledge, you wouldn’t necessarily be able to tell which was which. And so as developers, we find ourselves wanting to create functions that return all kinds of things – functions which look up values based on codes, functions which do string manipulation, and so on. But it’s rubbish. Ok, it’s not all rubbish, but it mostly is. And this isn’t even considering the SARGability impact. It’s far more significant than that. (When I say the SARGability aspect, I mean “because you’re unlikely to have an index on the result of some function that’s applied to a column, so try to invert the function and query the column in an unchanged manner”) I’m going to consider the three main types of user-defined functions in SQL Server: Scalar Inline Table-Valued Multi-statement Table-Valued I could also look at user-defined CLR functions, including aggregate functions, but not today. I figure that most people don’t tend to get around to doing CLR functions, and I’m going to focus on the T-SQL-based user-defined functions. Most people split these types of function up into two types. So do I. Except that most people pick them based on ‘scalar or table-valued’. I’d rather go with ‘inline or not’. If it’s not inline, it’s rubbish. It really is. Let’s start by considering the two kinds of table-valued function, and compare them. These functions are going to return the sales for a particular salesperson in a particular year, from the AdventureWorks database. CREATE FUNCTION dbo.FetchSales_inline(@salespersonid int, @orderyear int) RETURNS TABLE AS  RETURN (     SELECT e.LoginID as EmployeeLogin, o.OrderDate, o.SalesOrderID     FROM Sales.SalesOrderHeader AS o     LEFT JOIN HumanResources.Employee AS e     ON e.EmployeeID = o.SalesPersonID     WHERE o.SalesPersonID = @salespersonid     AND o.OrderDate >= DATEADD(year,@orderyear-2000,'20000101')     AND o.OrderDate < DATEADD(year,@orderyear-2000+1,'20000101') ) ; GO CREATE FUNCTION dbo.FetchSales_multi(@salespersonid int, @orderyear int) RETURNS @results TABLE (     EmployeeLogin nvarchar(512),     OrderDate datetime,     SalesOrderID int     ) AS BEGIN     INSERT @results (EmployeeLogin, OrderDate, SalesOrderID)     SELECT e.LoginID, o.OrderDate, o.SalesOrderID     FROM Sales.SalesOrderHeader AS o     LEFT JOIN HumanResources.Employee AS e     ON e.EmployeeID = o.SalesPersonID     WHERE o.SalesPersonID = @salespersonid     AND o.OrderDate >= DATEADD(year,@orderyear-2000,'20000101')     AND o.OrderDate < DATEADD(year,@orderyear-2000+1,'20000101')     ;     RETURN END ; GO You’ll notice that I’m being nice and responsible with the use of the DATEADD function, so that I have SARGability on the OrderDate filter. Regular readers will be hoping I’ll show what’s going on in the execution plans here. Here I’ve run two SELECT * queries with the “Show Actual Execution Plan” option turned on. Notice that the ‘Query cost’ of the multi-statement version is just 2% of the ‘Batch cost’. But also notice there’s trickery going on. And it’s nothing to do with that extra index that I have on the OrderDate column. Trickery. Look at it – clearly, the first plan is showing us what’s going on inside the function, but the second one isn’t. The second one is blindly running the function, and then scanning the results. There’s a Sequence operator which is calling the TVF operator, and then calling a Table Scan to get the results of that function for the SELECT operator. But surely it still has to do all the work that the first one is doing... To see what’s actually going on, let’s look at the Estimated plan. Now, we see the same plans (almost) that we saw in the Actuals, but we have an extra one – the one that was used for the TVF. Here’s where we see the inner workings of it. You’ll probably recognise the right-hand side of the TVF’s plan as looking very similar to the first plan – but it’s now being called by a stack of other operators, including an INSERT statement to be able to populate the table variable that the multi-statement TVF requires. And the cost of the TVF is 57% of the batch! But it gets worse. Let’s consider what happens if we don’t need all the columns. We’ll leave out the EmployeeLogin column. Here, we see that the inline function call has been simplified down. It doesn’t need the Employee table. The join is redundant and has been eliminated from the plan, making it even cheaper. But the multi-statement plan runs the whole thing as before, only removing the extra column when the Table Scan is performed. A multi-statement function is a lot more powerful than an inline one. An inline function can only be the result of a single sub-query. It’s essentially the same as a parameterised view, because views demonstrate this same behaviour of extracting the definition of the view and using it in the outer query. A multi-statement function is clearly more powerful because it can contain far more complex logic. But a multi-statement function isn’t really a function at all. It’s a stored procedure. It’s wrapped up like a function, but behaves like a stored procedure. It would be completely unreasonable to expect that a stored procedure could be simplified down to recognise that not all the columns might be needed, but yet this is part of the pain associated with this procedural function situation. The biggest clue that a multi-statement function is more like a stored procedure than a function is the “BEGIN” and “END” statements that surround the code. If you try to create a multi-statement function without these statements, you’ll get an error – they are very much required. When I used to present on this kind of thing, I even used to call it “The Dangers of BEGIN and END”, and yes, I’ve written about this type of thing before in a similarly-named post over at my old blog. Now how about scalar functions... Suppose we wanted a scalar function to return the count of these. CREATE FUNCTION dbo.FetchSales_scalar(@salespersonid int, @orderyear int) RETURNS int AS BEGIN     RETURN (         SELECT COUNT(*)         FROM Sales.SalesOrderHeader AS o         LEFT JOIN HumanResources.Employee AS e         ON e.EmployeeID = o.SalesPersonID         WHERE o.SalesPersonID = @salespersonid         AND o.OrderDate >= DATEADD(year,@orderyear-2000,'20000101')         AND o.OrderDate < DATEADD(year,@orderyear-2000+1,'20000101')     ); END ; GO Notice the evil words? They’re required. Try to remove them, you just get an error. That’s right – any scalar function is procedural, despite the fact that you wrap up a sub-query inside that RETURN statement. It’s as ugly as anything. Hopefully this will change in future versions. Let’s have a look at how this is reflected in an execution plan. Here’s a query, its Actual plan, and its Estimated plan: SELECT e.LoginID, y.year, dbo.FetchSales_scalar(p.SalesPersonID, y.year) AS NumSales FROM (VALUES (2001),(2002),(2003),(2004)) AS y (year) CROSS JOIN Sales.SalesPerson AS p LEFT JOIN HumanResources.Employee AS e ON e.EmployeeID = p.SalesPersonID; We see here that the cost of the scalar function is about twice that of the outer query. Nicely, the query optimizer has worked out that it doesn’t need the Employee table, but that’s a bit of a red herring here. There’s actually something way more significant going on. If I look at the properties of that UDF operator, it tells me that the Estimated Subtree Cost is 0.337999. If I just run the query SELECT dbo.FetchSales_scalar(281,2003); we see that the UDF cost is still unchanged. You see, this 0.0337999 is the cost of running the scalar function ONCE. But when we ran that query with the CROSS JOIN in it, we returned quite a few rows. 68 in fact. Could’ve been a lot more, if we’d had more salespeople or more years. And so we come to the biggest problem. This procedure (I don’t want to call it a function) is getting called 68 times – each one between twice as expensive as the outer query. And because it’s calling it in a separate context, there is even more overhead that I haven’t considered here. The cheek of it, to say that the Compute Scalar operator here costs 0%! I know a number of IT projects that could’ve used that kind of costing method, but that’s another story that I’m not going to go into here. Let’s look at a better way. Suppose our scalar function had been implemented as an inline one. Then it could have been expanded out like a sub-query. It could’ve run something like this: SELECT e.LoginID, y.year, (SELECT COUNT(*)     FROM Sales.SalesOrderHeader AS o     LEFT JOIN HumanResources.Employee AS e     ON e.EmployeeID = o.SalesPersonID     WHERE o.SalesPersonID = p.SalesPersonID     AND o.OrderDate >= DATEADD(year,y.year-2000,'20000101')     AND o.OrderDate < DATEADD(year,y.year-2000+1,'20000101')     ) AS NumSales FROM (VALUES (2001),(2002),(2003),(2004)) AS y (year) CROSS JOIN Sales.SalesPerson AS p LEFT JOIN HumanResources.Employee AS e ON e.EmployeeID = p.SalesPersonID; Don’t worry too much about the Scan of the SalesOrderHeader underneath a Nested Loop. If you remember from plenty of other posts on the matter, execution plans don’t push the data through. That Scan only runs once. The Index Spool sucks the data out of it and populates a structure that is used to feed the Stream Aggregate. The Index Spool operator gets called 68 times, but the Scan only once (the Number of Executions property demonstrates this). Here, the Query Optimizer has a full picture of what’s being asked, and can make the appropriate decision about how it accesses the data. It can simplify it down properly. To get this kind of behaviour from a function, we need it to be inline. But without inline scalar functions, we need to make our function be table-valued. Luckily, that’s ok. CREATE FUNCTION dbo.FetchSales_inline2(@salespersonid int, @orderyear int) RETURNS table AS RETURN (SELECT COUNT(*) as NumSales     FROM Sales.SalesOrderHeader AS o     LEFT JOIN HumanResources.Employee AS e     ON e.EmployeeID = o.SalesPersonID     WHERE o.SalesPersonID = @salespersonid     AND o.OrderDate >= DATEADD(year,@orderyear-2000,'20000101')     AND o.OrderDate < DATEADD(year,@orderyear-2000+1,'20000101') ); GO But we can’t use this as a scalar. Instead, we need to use it with the APPLY operator. SELECT e.LoginID, y.year, n.NumSales FROM (VALUES (2001),(2002),(2003),(2004)) AS y (year) CROSS JOIN Sales.SalesPerson AS p LEFT JOIN HumanResources.Employee AS e ON e.EmployeeID = p.SalesPersonID OUTER APPLY dbo.FetchSales_inline2(p.SalesPersonID, y.year) AS n; And now, we get the plan that we want for this query. All we’ve done is tell the function that it’s returning a table instead of a single value, and removed the BEGIN and END statements. We’ve had to name the column being returned, but what we’ve gained is an actual inline simplifiable function. And if we wanted it to return multiple columns, it could do that too. I really consider this function to be superior to the scalar function in every way. It does need to be handled differently in the outer query, but in many ways it’s a more elegant method there too. The function calls can be put amongst the FROM clause, where they can then be used in the WHERE or GROUP BY clauses without fear of calling the function multiple times (another horrible side effect of functions). So please. If you see BEGIN and END in a function, remember it’s not really a function, it’s a procedure. And then fix it. @rob_farley

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  • Microsoft Introduces WebMatrix

    - by Rick Strahl
    originally published in CoDe Magazine Editorial Microsoft recently released the first CTP of a new development environment called WebMatrix, which along with some of its supporting technologies are squarely aimed at making the Microsoft Web Platform more approachable for first-time developers and hobbyists. But in the process, it also provides some updated technologies that can make life easier for existing .NET developers. Let’s face it: ASP.NET development isn’t exactly trivial unless you already have a fair bit of familiarity with sophisticated development practices. Stick a non-developer in front of Visual Studio .NET or even the Visual Web Developer Express edition and it’s not likely that the person in front of the screen will be very productive or feel inspired. Yet other technologies like PHP and even classic ASP did provide the ability for non-developers and hobbyists to become reasonably proficient in creating basic web content quickly and efficiently. WebMatrix appears to be Microsoft’s attempt to bring back some of that simplicity with a number of technologies and tools. The key is to provide a friendly and fully self-contained development environment that provides all the tools needed to build an application in one place, as well as tools that allow publishing of content and databases easily to the web server. WebMatrix is made up of several components and technologies: IIS Developer Express IIS Developer Express is a new, self-contained development web server that is fully compatible with IIS 7.5 and based on the same codebase that IIS 7.5 uses. This new development server replaces the much less compatible Cassini web server that’s been used in Visual Studio and the Express editions. IIS Express addresses a few shortcomings of the Cassini server such as the inability to serve custom ISAPI extensions (i.e., things like PHP or ASP classic for example), as well as not supporting advanced authentication. IIS Developer Express provides most of the IIS 7.5 feature set providing much better compatibility between development and live deployment scenarios. SQL Server Compact 4.0 Database access is a key component for most web-driven applications, but on the Microsoft stack this has mostly meant you have to use SQL Server or SQL Server Express. SQL Server Compact is not new-it’s been around for a few years, but it’s been severely hobbled in the past by terrible tool support and the inability to support more than a single connection in Microsoft’s attempt to avoid losing SQL Server licensing. The new release of SQL Server Compact 4.0 supports multiple connections and you can run it in ASP.NET web applications simply by installing an assembly into the bin folder of the web application. In effect, you don’t have to install a special system configuration to run SQL Compact as it is a drop-in database engine: Copy the small assembly into your BIN folder (or from the GAC if installed fully), create a connection string against a local file-based database file, and then start firing SQL requests. Additionally WebMatrix includes nice tools to edit the database tables and files, along with tools to easily upsize (and hopefully downsize in the future) to full SQL Server. This is a big win, pending compatibility and performance limits. In my simple testing the data engine performed well enough for small data sets. This is not only useful for web applications, but also for desktop applications for which a fully installed SQL engine like SQL Server would be overkill. Having a local data store in those applications that can potentially be accessed by multiple users is a welcome feature. ASP.NET Razor View Engine What? Yet another native ASP.NET view engine? We already have Web Forms and various different flavors of using that view engine with Web Forms and MVC. Do we really need another? Microsoft thinks so, and Razor is an implementation of a lightweight, script-only view engine. Unlike the Web Forms view engine, Razor works only with inline code, snippets, and markup; therefore, it is more in line with current thinking of what a view engine should represent. There’s no support for a “page model” or any of the other Web Forms features of the full-page framework, but just a lightweight scripting engine that works with plain markup plus embedded expressions and code. The markup syntax for Razor is geared for minimal typing, plus some progressive detection of where a script block/expression starts and ends. This results in a much leaner syntax than the typical ASP.NET Web Forms alligator (<% %>) tags. Razor uses the @ sign plus standard C# (or Visual Basic) block syntax to delineate code snippets and expressions. Here’s a very simple example of what Razor markup looks like along with some comment annotations: <!DOCTYPE html> <html>     <head>         <title></title>     </head>     <body>     <h1>Razor Test</h1>          <!-- simple expressions -->     @DateTime.Now     <hr />     <!-- method expressions -->     @DateTime.Now.ToString("T")          <!-- code blocks -->     @{         List<string> names = new List<string>();         names.Add("Rick");         names.Add("Markus");         names.Add("Claudio");         names.Add("Kevin");     }          <!-- structured block statements -->     <ul>     @foreach(string name in names){             <li>@name</li>     }     </ul>           <!-- Conditional code -->        @if(true) {                        <!-- Literal Text embedding in code -->        <text>         true        </text>;    }    else    {        <!-- Literal Text embedding in code -->       <text>       false       </text>;    }    </body> </html> Like the Web Forms view engine, Razor parses pages into code, and then executes that run-time compiled code. Effectively a “page” becomes a code file with markup becoming literal text written into the Response stream, code snippets becoming raw code, and expressions being written out with Response.Write(). The code generated from Razor doesn’t look much different from similar Web Forms code that only uses script tags; so although the syntax may look different, the operational model is fairly similar to the Web Forms engine minus the overhead of the large Page object model. However, there are differences: -Razor pages are based on a new base class, Microsoft.WebPages.WebPage, which is hosted in the Microsoft.WebPages assembly that houses all the Razor engine parsing and processing logic. Browsing through the assembly (in the generated ASP.NET Temporary Files folder or GAC) will give you a good idea of the functionality that Razor provides. If you look closely, a lot of the feature set matches ASP.NET MVC’s view implementation as well as many of the helper classes found in MVC. It’s not hard to guess the motivation for this sort of view engine: For beginning developers the simple markup syntax is easier to work with, although you obviously still need to have some understanding of the .NET Framework in order to create dynamic content. The syntax is easier to read and grok and much shorter to type than ASP.NET alligator tags (<% %>) and also easier to understand aesthetically what’s happening in the markup code. Razor also is a better fit for Microsoft’s vision of ASP.NET MVC: It’s a new view engine without the baggage of Web Forms attached to it. The engine is more lightweight since it doesn’t carry all the features and object model of Web Forms with it and it can be instantiated directly outside of the HTTP environment, which has been rather tricky to do for the Web Forms view engine. Having a standalone script parser is a huge win for other applications as well – it makes it much easier to create script or meta driven output generators for many types of applications from code/screen generators, to simple form letters to data merging applications with user customizability. For me personally this is very useful side effect and who knows maybe Microsoft will actually standardize they’re scripting engines (die T4 die!) on this engine. Razor also better fits the “view-based” approach where the view is supposed to be mostly a visual representation that doesn’t hold much, if any, code. While you can still use code, the code you do write has to be self-contained. Overall I wouldn’t be surprised if Razor will become the new standard view engine for MVC in the future – and in fact there have been announcements recently that Razor will become the default script engine in ASP.NET MVC 3.0. Razor can also be used in existing Web Forms and MVC applications, although that’s not working currently unless you manually configure the script mappings and add the appropriate assemblies. It’s possible to do it, but it’s probably better to wait until Microsoft releases official support for Razor scripts in Visual Studio. Once that happens, you can simply drop .cshtml and .vbhtml pages into an existing ASP.NET project and they will work side by side with classic ASP.NET pages. WebMatrix Development Environment To tie all of these three technologies together, Microsoft is shipping WebMatrix with an integrated development environment. An integrated gallery manager makes it easy to download and load existing projects, and then extend them with custom functionality. It seems to be a prominent goal to provide community-oriented content that can act as a starting point, be it via a custom templates or a complete standard application. The IDE includes a project manager that works with a single project and provides an integrated IDE/editor for editing the .cshtml and .vbhtml pages. A run button allows you to quickly run pages in the project manager in a variety of browsers. There’s no debugging support for code at this time. Note that Razor pages don’t require explicit compilation, so making a change, saving, and then refreshing your page in the browser is all that’s needed to see changes while testing an application locally. It’s essentially using the auto-compiling Web Project that was introduced with .NET 2.0. All code is compiled during run time into dynamically created assemblies in the ASP.NET temp folder. WebMatrix also has PHP Editing support with syntax highlighting. You can load various PHP-based applications from the WebMatrix Web Gallery directly into the IDE. Most of the Web Gallery applications are ready to install and run without further configuration, with Wizards taking you through installation of tools, dependencies, and configuration of the database as needed. WebMatrix leverages the Web Platform installer to pull the pieces down from websites in a tight integration of tools that worked nicely for the four or five applications I tried this out on. Click a couple of check boxes and fill in a few simple configuration options and you end up with a running application that’s ready to be customized. Nice! You can easily deploy completed applications via WebDeploy (to an IIS server) or FTP directly from within the development environment. The deploy tool also can handle automatically uploading and installing the database and all related assemblies required, making deployment a simple one-click install step. Simplified Database Access The IDE contains a database editor that can edit SQL Compact and SQL Server databases. There is also a Database helper class that facilitates database access by providing easy-to-use, high-level query execution and iteration methods: @{       var db = Database.OpenFile("FirstApp.sdf");     string sql = "select * from customers where Id > @0"; } <ul> @foreach(var row in db.Query(sql,1)){         <li>@row.FirstName @row.LastName</li> } </ul> The query function takes a SQL statement plus any number of positional (@0,@1 etc.) SQL parameters by simple values. The result is returned as a collection of rows which in turn have a row object with dynamic properties for each of the columns giving easy (though untyped) access to each of the fields. Likewise Execute and ExecuteNonQuery allow execution of more complex queries using similar parameter passing schemes. Note these queries use string-based queries rather than LINQ or Entity Framework’s strongly typed LINQ queries. While this may seem like a step back, it’s also in line with the expectations of non .NET script developers who are quite used to writing and using SQL strings in code rather than using OR/M frameworks. The only question is why was something not included from the beginning in .NET and Microsoft made developers build custom implementations of these basic building blocks. The implementation looks a lot like a DataTable-style data access mechanism, but to be fair, this is a common approach in scripting languages. This type of syntax that uses simple, static, data object methods to perform simple data tasks with one line of code are common in scripting languages and are a good match for folks working in PHP/Python, etc. Seems like Microsoft has taken great advantage of .NET 4.0’s dynamic typing to provide this sort of interface for row iteration where each row has properties for each field. FWIW, all the examples demonstrate using local SQL Compact files - I was unable to get a SQL Server connection string to work with the Database class (the connection string wasn’t accepted). However, since the code in the page is still plain old .NET, you can easily use standard ADO.NET code or even LINQ or Entity Framework models that are created outside of WebMatrix in separate assemblies as required. The good the bad the obnoxious - It’s still .NET The beauty (or curse depending on how you look at it :)) of Razor and the compilation model is that, behind it all, it’s still .NET. Although the syntax may look foreign, it’s still all .NET behind the scenes. You can easily access existing tools, helpers, and utilities simply by adding them to the project as references or to the bin folder. Razor automatically recognizes any assembly reference from assemblies in the bin folder. In the default configuration, Microsoft provides a host of helper functions in a Microsoft.WebPages assembly (check it out in the ASP.NET temp folder for your application), which includes a host of HTML Helpers. If you’ve used ASP.NET MVC before, a lot of the helpers should look familiar. Documentation at the moment is sketchy-there’s a very rough API reference you can check out here: http://www.asp.net/webmatrix/tutorials/asp-net-web-pages-api-reference Who needs WebMatrix? Uhm… good Question Clearly Microsoft is trying hard to create an environment with WebMatrix that is easy to use for newbie developers. The goal seems to be simplicity in providing a minimal development environment and an easy-to-use script engine/language that makes it easy to get started with. There’s also some focus on community features that can be used as starting points, such as Web Gallery applications and templates. The community features in particular are very nice and something that would be nice to eventually see in Visual Studio as well. The question is whether this is too little too late. Developers who have been clamoring for a simpler development environment on the .NET stack have mostly left for other simpler platforms like PHP or Python which are catering to the down and dirty developer. Microsoft will be hard pressed to win those folks-and other hardcore PHP developers-back. Regardless of how much you dress up a script engine fronted by the .NET Framework, it’s still the .NET Framework and all the complexity that drives it. While .NET is a fine solution in its breadth and features once you get a basic handle on the core features, the bar of entry to being productive with the .NET Framework is still pretty high. The MVC style helpers Microsoft provides are a good step in the right direction, but I suspect it’s not enough to shield new developers from having to delve much deeper into the Framework to get even basic applications built. Razor and its helpers is trying to make .NET more accessible but the reality is that in order to do useful stuff that goes beyond the handful of simple helpers you still are going to have to write some C# or VB or other .NET code. If the target is a hobby/amateur/non-programmer the learning curve isn’t made any easier by WebMatrix it’s just been shifted a tad bit further along in your development endeavor when you run out of canned components that are supplied either by Microsoft or the community. The database helpers are interesting and actually I’ve heard a lot of discussion from various developers who’ve been resisting .NET for a really long time perking up at the prospect of easier data access in .NET than the ridiculous amount of code it takes to do even simple data access with raw ADO.NET. It seems sad that such a simple concept and implementation should trigger this sort of response (especially since it’s practically trivial to create helpers like these or pick them up from countless libraries available), but there it is. It also shows that there are plenty of developers out there who are more interested in ‘getting stuff done’ easily than necessarily following the latest and greatest practices which are overkill for many development scenarios. Sometimes it seems that all of .NET is focused on the big life changing issues of development, rather than the bread and butter scenarios that many developers are interested in to get their work accomplished. And that in the end may be WebMatrix’s main raison d'être: To bring some focus back at Microsoft that simpler and more high level solutions are actually needed to appeal to the non-high end developers as well as providing the necessary tools for the high end developers who want to follow the latest and greatest trends. The current version of WebMatrix hits many sweet spots, but it also feels like it has a long way to go before it really can be a tool that a beginning developer or an accomplished developer can feel comfortable with. Although there are some really good ideas in the environment (like the gallery for downloading apps and components) which would be a great addition for Visual Studio as well, the rest of the development environment just feels like crippleware with required functionality missing especially debugging and Intellisense, but also general editor support. It’s not clear whether these are because the product is still in an early alpha release or whether it’s simply designed that way to be a really limited development environment. While simple can be good, nobody wants to feel left out when it comes to necessary tool support and WebMatrix just has that left out feeling to it. If anything WebMatrix’s technology pieces (which are really independent of the WebMatrix product) are what are interesting to developers in general. The compact IIS implementation is a nice improvement for development scenarios and SQL Compact 4.0 seems to address a lot of concerns that people have had and have complained about for some time with previous SQL Compact implementations. By far the most interesting and useful technology though seems to be the Razor view engine for its light weight implementation and it’s decoupling from the ASP.NET/HTTP pipeline to provide a standalone scripting/view engine that is pluggable. The first winner of this is going to be ASP.NET MVC which can now have a cleaner view model that isn’t inconsistent due to the baggage of non-implemented WebForms features that don’t work in MVC. But I expect that Razor will end up in many other applications as a scripting and code generation engine eventually. Visual Studio integration for Razor is currently missing, but is promised for a later release. The ASP.NET MVC team has already mentioned that Razor will eventually become the default MVC view engine, which will guarantee continued growth and development of this tool along those lines. And the Razor engine and support tools actually inherit many of the features that MVC pioneered, so there’s some synergy flowing both ways between Razor and MVC. As an existing ASP.NET developer who’s already familiar with Visual Studio and ASP.NET development, the WebMatrix IDE doesn’t give you anything that you want. The tools provided are minimal and provide nothing that you can’t get in Visual Studio today, except the minimal Razor syntax highlighting, so there’s little need to take a step back. With Visual Studio integration coming later there’s little reason to look at WebMatrix for tooling. It’s good to see that Microsoft is giving some thought about the ease of use of .NET as a platform For so many years, we’ve been piling on more and more new features without trying to take a step back and see how complicated the development/configuration/deployment process has become. Sometimes it’s good to take a step - or several steps - back and take another look and realize just how far we’ve come. WebMatrix is one of those reminders and one that likely will result in some positive changes on the platform as a whole. © Rick Strahl, West Wind Technologies, 2005-2010Posted in ASP.NET   IIS7  

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