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  • .NET/C#: How to remove/minimize code clutter while 'triggering' Events

    - by eibhrum
    Hi, I just wanna find out if there's a way I could minimize code clutter in my application. I have written code/s similar to this: private void btnNext_MouseEnter(object sender, System.Windows.Input.MouseEventArgs e) { btnNext.Opacity = 1; } private void btnNext_MouseLeave(object sender, System.Windows.Input.MouseEventArgs e) { btnNext.Opacity = 0.5; } private void btnShowAll_MouseEnter(object sender, System.Windows.Input.MouseEventArgs e) { btnShowAll.Opacity = 1; } private void btnShowAll_MouseLeave(object sender, System.Windows.Input.MouseEventArgs e) { btnShowAll.Opacity = 0.5; } private void btnPrev_MouseEnter(object sender, System.Windows.Input.MouseEventArgs e) { btnPrev.Opacity = 1; } private void btnPrev_MouseLeave(object sender, System.Windows.Input.MouseEventArgs e) { btnPrev.Opacity = 0.5; } private void btnSearch_MouseEnter(object sender, System.Windows.Input.MouseEventArgs e) { btnSearch.Opacity = 1; } private void btnSearch_MouseLeave(object sender, System.Windows.Input.MouseEventArgs e) { btnSearch.Opacity = 0.5; } private void btnSearchStore_MouseEnter(object sender, System.Windows.Input.MouseEventArgs e) { btnSearchStore.Opacity = 1; } private void btnSearchStore_MouseLeave(object sender, System.Windows.Input.MouseEventArgs e) { btnSearchStore.Opacity = 0.5; } private void btnCloseSearch_MouseEnter(object sender, System.Windows.Input.MouseEventArgs e) { btnCloseSearch.Opacity = 1; } private void btnCloseSearch_MouseLeave(object sender, System.Windows.Input.MouseEventArgs e) { btnCloseSearch.Opacity = 0.5; } private void btnHome_MouseEnter(object sender, System.Windows.Input.MouseEventArgs e) { btnHome.Opacity = 1; } private void btnHome_MouseLeave(object sender, System.Windows.Input.MouseEventArgs e) { btnHome.Opacity = 0.5; } and so on and so forth... Do I need to create a 'function' that will run initially? Or do I have to create another class just so I can 'organize' them? Any suggestions?

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  • Should I store generated code in source control

    - by Ron Harlev
    This is a debate I'm taking a part in. I would like to get more opinions and points of view. We have some classes that are generated in build time to handle DB operations (in This specific case, with SubSonic, but I don't think it is very important for the question). The generation is set as a pre-build step in Visual Studio. So every time a developer (or the official build process) runs a build, these classes are generated, and then compiled into the project. Now some people are claiming, that having these classes saved in source control could cause confusion, in case the code you get, doesn't match what would have been generated in your own environment. I would like to have a way to trace back the history of the code, even if it is usually treated as a black box. Any arguments or counter arguments? UPDATE: I asked this question since I really believed there is one definitive answer. Looking at all the responses, I could say with high level of certainty, that there is no such answer. The decision should be made based on more than one parameter. Reading the answers below could provide a very good guideline to the types of questions you should be asking yourself when having to decide on this issue. I won't select an accepted answer at this point for the reasons mentioned above.

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  • Organizing code, logical layout of segmented files

    - by David H
    I have known enough about programming to get me in trouble for about 10 years now. I have no formal education, though I've read many books on the subject for various languages. The language I am primarily focused on now would be php, atleast for the scale of things I am doing now. I have used some OOP classes for a while, but never took the dive into understanding principals behind the scenes. I am still not at the level I would like to be expression-wise...however my recent reading into a book titled The OOP Thought Process has me wanting to advance my programming skills. With motivation from the new concepts, I have started with a new project that I've coded some re-usable classes that deal with user auth, user profiles, database interfacing, and some other stuff I use regularly on most projects. Now having split my typical garbled spaghetti bowl mess of code into somewhat organized files, I've come into some problems when it comes to making sure files are all included when they need to be, and how to logically divide the scripts up into classes, aswell as how segmented I should be making each class. I guess I have rambled on enough about much of nothing, but what I am really asking for is advise from people, or suggested reading that focuses not on specific functions and formats of code, but the logical layout of projects that are larger than just a hobby project. I want to learn how to do things proper, and while I am still learning in some areas, this is something that I have no clue about other than just being creative, and trial/error. Mostly error. Thanks for any replies. This place is great.

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  • Linq2sql code generator misbehaving

    - by Martin
    Sometime the linq2sql just makes its mind up about things. I've been pulling my hair for the past hours trying to work out what I'm doing differently from all the other times when I don't get ForeignKeyReferenceAlreadyHasValueException. Turns out that if (this._Activity.HasLoadedOrAssignedValue) { throw new System.Data.Linq.ForeignKeyReferenceAlreadyHasValueException(); } is present on my primary key in this particular table, and in no other. No matter what I do with the association, I've even tried deleting and dragging the thing back to the designer, it's still there and I'm sure it's not supposed to be. I know why, of course, but I don't know why, so to speak. A while back the association went the other way. Whereas I've left that era behind me, the code generator seems to exhibit phantom pains. The same phenomenon, is responsible for me having to change the namespace in the designer.cs everytime I make changes in the designer. I made the mistake of renaming my namespace and the code generator just doesn't get it. Somebody please help this poor boy out.

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  • How to debug/break in codedom compiled code

    - by Jason Coyne
    I have an application which loads up c# source files dynamically and runs them as plugins. When I am running the main application in debug mode, is it possible to debug into the dynamic assembly? Obviously setting breakpoints is problematic, since the source is not part of the original project, but should I be able to step into, or break on exceptions for the code? Is there a way to get codedom to generate PDBs for this or something? Here is the code I am using for dynamic compliation. CSharpCodeProvider codeProvider = new CSharpCodeProvider(new Dictionary<string, string>() { { "CompilerVersion", "v3.5" } }); //codeProvider. ICodeCompiler icc = codeProvider.CreateCompiler(); CompilerParameters parameters = new CompilerParameters(); parameters.GenerateExecutable = false; parameters.GenerateInMemory = true; parameters.CompilerOptions = string.Format("/lib:\"{0}\"", Application.StartupPath); parameters.ReferencedAssemblies.Add("System.dll"); parameters.ReferencedAssemblies.Add("System.Core.dll"); CompilerResults results = icc.CompileAssemblyFromSource(parameters, Source); DLL.CreateInstance(t.FullName, false, BindingFlags.Default, null, new object[] { engine }, null, null);

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  • Code Golf: Rotating Maze

    - by trinithis
    Code Golf: Rotating Maze Make a program that takes in a file consisting of a maze. The maze has walls given by '#'. The maze must include a single ball, given by a 'o' and any number of holes given by a '@'. The maze file can either be entered via command line or read in as a line through standard input. Please specify which in your solution. Your program then does the following: 1: If the ball is not directly above a wall, drop it down to the nearest wall. 2: If the ball passes through a hole during step 1, remove the ball. 3: Display the maze. 4: If there is no ball in the maze, exit. 5: Read a line from the standard input. Given a 1, rotate the maze counterclockwise. Given a 2, rotate the maze clockwise. Rotations are done by 90 degrees. It is up to you to decide if extraneous whitespace is allowed. If the user enters other inputs, repeat this step. 6: Goto step 1. You may assume all input mazes are closed. Note, a hole effectively acts as a wall in this regard. You may assume all input mazes have no extraneous whitespace. The shortest source code by character count wins. Example mazes: ###### #o @# ###### ########### #o # # ####### # ###@ # ######### ########################### # # # # @ # # # # ## # # ####o#### # # # # # # ######### # @ ######################

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  • Memory leak in Apples 'Scrolling' sample code

    - by John
    Hi All, I'm using code based on Apple's "Scrolling" sample code - here's where I have a problem: // load all the images from our bundle and add them to the scroll view NSUInteger i; for (i = 1; i <= jNumImages; i++) { NSString *imageName = [NSString stringWithFormat:@"page%d.png", i]; UIImage *image = [UIImage imageNamed:imageName]; UIImageView *imageView2 = [[UIImageView alloc] initWithImage:image]; The UIImageView causes a leak - it doesn't seem to be releasing (though I do state [imageView2 release]; after adding the imageView as a subView to scrollView2 I have say 15 chapters of a book each held in a nav bar, each containing a scroll view with one chapters worth of these image views (each image is a page). When I get to around the second last chapter the app crashes due to the memory leaks... really annoying! I think it might be because imageView's been alloc'd twice (in alloc and in addSubView) but i'm not sure.... tried releasing twice but it didn't seem to help. any pointers? Thanks in advance ^.^

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  • Remove redundant SQL code

    - by Dave Jarvis
    Code The following code calculates the slope and intercept for a linear regression against a slathering of data. It then applies the equation y = mx + b against the same result set to calculate the value of the regression line for each row. Can the two separate sub-selects be joined so that the data and its slope/intercept are calculated without executing the data gathering part of the query twice? SELECT AVG(D.AMOUNT) as AMOUNT, Y.YEAR * ymxb.SLOPE + ymxb.INTERCEPT as REGRESSION_LINE, Y.YEAR as YEAR, MAKEDATE(Y.YEAR,1) as AMOUNT_DATE FROM CITY C, STATION S, YEAR_REF Y, MONTH_REF M, DAILY D, (SELECT ((avg(t.AMOUNT * t.YEAR)) - avg(t.AMOUNT) * avg(t.YEAR)) / (stddev( t.AMOUNT ) * stddev( t.YEAR )) as CORRELATION, ((sum(t.YEAR) * sum(t.AMOUNT)) - (count(1) * sum(t.YEAR * t.AMOUNT))) / (power(sum(t.YEAR), 2) - count(1) * sum(power(t.YEAR, 2))) as SLOPE, ((sum( t.YEAR ) * sum( t.YEAR * t.AMOUNT )) - (sum( t.AMOUNT ) * sum(power(t.YEAR, 2)))) / (power(sum(t.YEAR), 2) - count(1) * sum(power(t.YEAR, 2))) as INTERCEPT FROM ( SELECT AVG(D.AMOUNT) as AMOUNT, Y.YEAR as YEAR, MAKEDATE(Y.YEAR,1) as AMOUNT_DATE FROM CITY C, STATION S, YEAR_REF Y, MONTH_REF M, DAILY D WHERE $X{ IN, C.ID, CityCode } AND SQRT( POW( C.LATITUDE - S.LATITUDE, 2 ) + POW( C.LONGITUDE - S.LONGITUDE, 2 ) ) < $P{Radius} AND S.STATION_DISTRICT_ID = Y.STATION_DISTRICT_ID AND Y.YEAR BETWEEN 1900 AND 2009 AND M.YEAR_REF_ID = Y.ID AND M.CATEGORY_ID = $P{CategoryCode} AND M.ID = D.MONTH_REF_ID AND D.DAILY_FLAG_ID <> 'M' GROUP BY Y.YEAR ) t ) ymxb WHERE $X{ IN, C.ID, CityCode } AND SQRT( POW( C.LATITUDE - S.LATITUDE, 2 ) + POW( C.LONGITUDE - S.LONGITUDE, 2 ) ) < $P{Radius} AND S.STATION_DISTRICT_ID = Y.STATION_DISTRICT_ID AND Y.YEAR BETWEEN 1900 AND 2009 AND M.YEAR_REF_ID = Y.ID AND M.CATEGORY_ID = $P{CategoryCode} AND M.ID = D.MONTH_REF_ID AND D.DAILY_FLAG_ID <> 'M' GROUP BY Y.YEAR Question How do I execute the duplicate bits only once per query, instead of twice? The duplicate bit is the WHERE clause: $X{ IN, C.ID, CityCode } AND SQRT( POW( C.LATITUDE - S.LATITUDE, 2 ) + POW( C.LONGITUDE - S.LONGITUDE, 2 ) ) < $P{Radius} AND S.STATION_DISTRICT_ID = Y.STATION_DISTRICT_ID AND Y.YEAR BETWEEN 1900 AND 2009 AND M.YEAR_REF_ID = Y.ID AND M.CATEGORY_ID = $P{CategoryCode} AND M.ID = D.MONTH_REF_ID AND D.DAILY_FLAG_ID <> 'M' Related http://stackoverflow.com/questions/1595659/how-to-eliminate-duplicate-calculation-in-sql Thank you!

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  • Code-Golf: one line PHP syntax

    - by Kendall Hopkins
    Explanation PHP has some holes in its' syntax and occasionally in development a programmer will step in them. This can lead to much frustration as these syntax holes seem to exist for no reason. For example, one can't easily create an array and access an arbitrary element of that array on the same line (func1()[100] is not valid PHP syntax). The workaround for this issue is to use a temporary variable and break the statement into two lines, but sometimes that can lead to very verbose, clunky code. Challenge I know of a few of these holes (I'm sure there are more). It is quite hard to even come up with a solution, let alone in a code-golf style. Winner is the person with in the least characters total for all four Syntax Holes. Rules Statement must be one line in this form: $output = ...;, where ... doesn't contain any ;'s. Only use standard library functions (no custom functions allowed) Statement works identically to the assumed functional of the non-working syntax (even in cases that it fails). Statement must run without syntax error of any kind with E_STRICT | E_ALL. Syntax Holes $output = func_return_array()[$key]; - accessing an arbitrary offset (string or integer) of the returned array of a function $output = new {$class_base.$class_suffix}(); - arbitrary string concatenation being used to create a new class $output = {$func_base.$func_suffix}(); - arbitrary string concatenation being called as function $output = func_return_closure()(); - call a closure being returned from another function

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  • Code Golf: Find the possible ways on a numpad

    - by ikar
    I was bored today at school and so I tried to amuse myself using my calculator and a "game" I've invented which isn't really a game but keeps the boringness away. Also some time has passed since the last real code-golf here, so I decided to create this one. Imagine a simplified numpad like you know it from your phone (I'll leave the 0 out for this code-golf as it kinda destroys all the fun) 1 2 3 4 5 6 7 8 9 Now the rules of the game were always: At the end every digit must have been visited exactly once You can start at any digit you want You can always move one digit up, down, left or right. You can't move diagonally! There a quite a lot of possible ways (or not; I haven't found out yet), here some trivial examples: > > v v < < > > | The output of the golf-program should look something like the above, I'll try to explain: Symbols: Go right < Go left ^ Go up v Go down | End of the way Example solutions: (Program output can either be the numbers pressed in the right order from beginning point to end, or an (ASCII) picture like above) 147852369 569874123 523698741 So if we speak out the example above it would be: Start at 1, move right to 2, move right to 3, go down to 6, go left to 5, go left to 4, go down to 7, go right to 8 then go right to 9 and we are finished! Now there are many different ways possible: You could as well start at 5 and go around it in a circle. So the task would be: Write a program that can compute (using brute-force or whatever) the possible solutions for the numpad problem described above. (Friendly rethorical question with smiley removed because it made some people think that this is homework)

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  • How to run OpenGL code with out compiling?

    - by Ole Jak
    So I have some openGL code (such code for example) /* FUNCTION: YCamera :: CalculateWorldCoordinates ARGUMENTS: x mouse x coordinate y mouse y coordinate vec where to store coordinates RETURN: n/a DESCRIPTION: Convert mouse coordinates into world coordinates */ void YCamera :: CalculateWorldCoordinates(float x, float y, YVector3 *vec) { // START GLint viewport[4]; GLdouble mvmatrix[16], projmatrix[16]; GLint real_y; GLdouble mx, my, mz; glGetIntegerv(GL_VIEWPORT, viewport); glGetDoublev(GL_MODELVIEW_MATRIX, mvmatrix); glGetDoublev(GL_PROJECTION_MATRIX, projmatrix); real_y = viewport[3] - (GLint) y - 1; // viewport[3] is height of window in pixels gluUnProject((GLdouble) x, (GLdouble) real_y, 1.0, mvmatrix, projmatrix, viewport, &mx, &my, &mz); /* 'mouse' is the point where mouse projection reaches FAR_PLANE. World coordinates is intersection of line(camera->mouse) with plane(z=0) (see LaMothe 306) Equation of line in 3D: (x-x0)/a = (y-y0)/b = (z-z0)/c Intersection of line with plane: z = 0 x-x0 = a(z-z0)/c <=> x = x0+a(0-z0)/c <=> x = x0 -a*z0/c y = y0 - b*z0/c */ double lx = fPosition.x - mx; double ly = fPosition.y - my; double lz = fPosition.z - mz; double sum = lx*lx + ly*ly + lz*lz; double normal = sqrt(sum); double z0_c = fPosition.z / (lz/normal); vec->x = (float) (fPosition.x - (lx/normal)*z0_c); vec->y = (float) (fPosition.y - (ly/normal)*z0_c); vec->z = 0.0f; } I want to run It but with out precompiling. Is there any way to do such thing

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  • An online php debugger/code editor

    - by Zirak
    It's a simple deal: I'm sometimes in places where I don't have my laptop, and find myself with spare time and an idea for a project. But unfortunately, I can't do anything about it. I tried a variety of solutions, which include running IDEs (like phpstorm or Aptana) on a disc-on-key or cd (very slow and unappealing), trying several online solutions (like http://phpanywhere.net) and found that all of them are either buggy, overloaded or underloaded with features, just difficult to use, require FTP etc etc. All that is required here is a syntax highlighting and debugging alerts; no actual running of code. So the question is split into two: 1)Do you know of a good online php editor that you've used and enjoyed? 2)If no, then how would you go about making one? The second one seems a bit general, so I'll try and expand...It might be a good idea; if you can't find one, make one. The question is about the concept of making a syntax highlighter (shouldn't be too difficult), and the difficult part of catching php errors WITHOUT executing any php code. Thank you in advance.

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  • XSD, restrictions and code generation

    - by bob
    Hello, I'm working on some code generation for an existing project and I want to start from a xsd. So I can use tools as Xsd2Code / xsd.exe to generate the code and also the use the xsd to validate the xml. That part works without any problems. I also want to translate some of the restrictions to DataAnnotations (enrich Xsd2Code). For example xs:minInclusive / xs:maxInclusive I can translate to a RangeAttribute. But what to do with custom validation attributes that we created? Can I add custom facets / restrictions? And how? Or is there another solution / best practice. I would like to collect everything in a single (xsd) file so that one file contains the structure of the class (model) including the validation (attributes) that has to be added. <xs:element name="CertainValue"> <xs:simpleType> <xs:restriction base="xs:double"> <xs:minInclusive value="1" /> <xs:maxInclusive value="100" /> <xs_custom:customRule attribute="value" /> </xs:restriction> </xs:simpleType> </xs:element>

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  • C++: Code assistance in Netbeans on Linux

    - by Martijn Courteaux
    Hi, My IDE (NetBeans) thinks this is wrong code, but it compiles correct: std::cout << "i = " << i << std::endl; std::cout << add(5, 7) << std::endl; std::string test = "Boe"; std::cout << test << std::endl; He always says: unable to resolve identifier .... (.... = cout, endl, string); So I think it has something to do with the code assistance. I think I have to change/add/remove some folders. Currently, I have this include folders: C compiler: /usr/local/include /usr/lib/gcc/i486-linux-gnu/4.4.3/include /usr/lib/gcc/i486-linux-gnu/4.4.3/include-fixed /usr/include C++ compiler: /usr/include/c++/4.4.3 /usr/include/c++/4.4.3/i486-linux-gnu /usr/include/c++/4.4.3/backward /usr/local/include /usr/lib/gcc/i486-linux-gnu/4.4.3/include /usr/include Thanks

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  • Oddities in Linq-to-SQL generated code related to property change/changing events

    - by Lasse V. Karlsen
    I'm working on creating my own Linq-to-Sql generated classes in order to learn the concepts behind it all. I have some questions, if anyone knows the answer to one or more of these I'd be much obliged. The code below, and thus the questions, are from looking at code generated by creating a .DBML file in the Visual Studio 2010 designer, and inspecting the .Designer.cs file afterwards. 1. Why is INotifyPropertyChanging not passing the property name The event raising method is defined like this: protected virtual void SendPropertyChanging() Why isn't the name of the property that is changing passed to the event here? It is defined to be part of the EventArgs descendant that is passed to the event handler, but the method only passes an empty such value to it. 2. Why are the EntitySet<X> attach/detach methods not raising property changed? For an EntitySet<X> reference, the following two methods are generated: private void attach_EmailAddress1s(EmailAddress1 entity) { this.SendPropertyChanging(); entity.Person1 = this; } private void detach_EmailAddress1s(EmailAddress1 entity) { this.SendPropertyChanging(); entity.Person1 = null; } Why isn't SendPropertyChanged also called here? I'm sure I have more questions later, but for now these will suffice :)

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  • C++: IDE Code assistance (Linux)

    - by Martijn Courteaux
    Hi, My IDE (NetBeans) thinks this is wrong code, but it compiles correct: std::cout << "i = " << i << std::endl; std::cout << add(5, 7) << std::endl; std::string test = "Boe"; std::cout << test << std::endl; He always says: unable to resolve identifier .... (.... = cout, endl, string); So I think it has something to do with the code assistance. I think I have to change/add/remove some folders. Currently, I have this include folders: C compiler: /usr/local/include /usr/lib/gcc/i486-linux-gnu/4.4.3/include /usr/lib/gcc/i486-linux-gnu/4.4.3/include-fixed /usr/include C++ compiler: /usr/include/c++/4.4.3 /usr/include/c++/4.4.3/i486-linux-gnu /usr/include/c++/4.4.3/backward /usr/local/include /usr/lib/gcc/i486-linux-gnu/4.4.3/include /usr/include Thanks

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  • SQL SERVER – Update Statistics are Sampled By Default

    - by pinaldave
    After reading my earlier post SQL SERVER – Create Primary Key with Specific Name when Creating Table on Statistics, I have received another question by a blog reader. The question is as follows: Question: Are the statistics sampled by default? Answer: Yes. The sampling rate can be specified by the user and it can be anywhere between a very low value to 100%. Let us do a small experiment to verify if the auto update on statistics is left on. Also, let’s examine a very large table that is created and statistics by default- whether the statistics are sampled or not. USE [AdventureWorks] GO -- Create Table CREATE TABLE [dbo].[StatsTest]( [ID] [int] IDENTITY(1,1) NOT NULL, [FirstName] [varchar](100) NULL, [LastName] [varchar](100) NULL, [City] [varchar](100) NULL, CONSTRAINT [PK_StatsTest] PRIMARY KEY CLUSTERED ([ID] ASC) ) ON [PRIMARY] GO -- Insert 1 Million Rows INSERT INTO [dbo].[StatsTest] (FirstName,LastName,City) SELECT TOP 1000000 'Bob', CASE WHEN ROW_NUMBER() OVER (ORDER BY a.name)%2 = 1 THEN 'Smith' ELSE 'Brown' END, CASE WHEN ROW_NUMBER() OVER (ORDER BY a.name)%10 = 1 THEN 'New York' WHEN ROW_NUMBER() OVER (ORDER BY a.name)%10 = 5 THEN 'San Marino' WHEN ROW_NUMBER() OVER (ORDER BY a.name)%10 = 3 THEN 'Los Angeles' ELSE 'Houston' END FROM sys.all_objects a CROSS JOIN sys.all_objects b GO -- Update the statistics UPDATE STATISTICS [dbo].[StatsTest] GO -- Shows the statistics DBCC SHOW_STATISTICS ("StatsTest"PK_StatsTest) GO -- Clean up DROP TABLE [dbo].[StatsTest] GO Now let us observe the result of the DBCC SHOW_STATISTICS. The result shows that Resultset is for sure sampling for a large dataset. The percentage of sampling is based on data distribution as well as the kind of data in the table. Before dropping the table, let us check first the size of the table. The size of the table is 35 MB. Now, let us run the above code with lesser number of the rows. USE [AdventureWorks] GO -- Create Table CREATE TABLE [dbo].[StatsTest]( [ID] [int] IDENTITY(1,1) NOT NULL, [FirstName] [varchar](100) NULL, [LastName] [varchar](100) NULL, [City] [varchar](100) NULL, CONSTRAINT [PK_StatsTest] PRIMARY KEY CLUSTERED ([ID] ASC) ) ON [PRIMARY] GO -- Insert 1 Hundred Thousand Rows INSERT INTO [dbo].[StatsTest] (FirstName,LastName,City) SELECT TOP 100000 'Bob', CASE WHEN ROW_NUMBER() OVER (ORDER BY a.name)%2 = 1 THEN 'Smith' ELSE 'Brown' END, CASE WHEN ROW_NUMBER() OVER (ORDER BY a.name)%10 = 1 THEN 'New York' WHEN ROW_NUMBER() OVER (ORDER BY a.name)%10 = 5 THEN 'San Marino' WHEN ROW_NUMBER() OVER (ORDER BY a.name)%10 = 3 THEN 'Los Angeles' ELSE 'Houston' END FROM sys.all_objects a CROSS JOIN sys.all_objects b GO -- Update the statistics UPDATE STATISTICS [dbo].[StatsTest] GO -- Shows the statistics DBCC SHOW_STATISTICS ("StatsTest"PK_StatsTest) GO -- Clean up DROP TABLE [dbo].[StatsTest] GO You can see that Rows Sampled is just the same as Rows of the table. In this case, the sample rate is 100%. Before dropping the table, let us also check the size of the table. The size of the table is less than 4 MB. Let us compare the Result set just for a valid reference. Test 1: Total Rows: 1000000, Rows Sampled: 255420, Size of the Table: 35.516 MB Test 2: Total Rows: 100000, Rows Sampled: 100000, Size of the Table: 3.555 MB The reason behind the sample in the Test1 is that the data space is larger than 8 MB, and therefore it uses more than 1024 data pages. If the data space is smaller than 8 MB and uses less than 1024 data pages, then the sampling does not happen. Sampling aids in reducing excessive data scan; however, sometimes it reduces the accuracy of the data as well. Please note that this is just a sample test and there is no way it can be claimed as a benchmark test. The result can be dissimilar on different machines. There are lots of other information can be included when talking about this subject. I will write detail post covering all the subject very soon. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Index, SQL Optimization, SQL Performance, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: SQL Statistics

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  • SQL SERVER – Server Side Paging in SQL Server 2011 Performance Comparison

    - by pinaldave
    Earlier, I have written about SQL SERVER – Server Side Paging in SQL Server 2011 – A Better Alternative. I got many emails asking for performance analysis of paging. Here is the quick analysis of it. The real challenge of paging is all the unnecessary IO reads from the database. Network traffic was one of the reasons why paging has become a very expensive operation. I have seen many legacy applications where a complete resultset is brought back to the application and paging has been done. As what you have read earlier, SQL Server 2011 offers a better alternative to an age-old solution. This article has been divided into two parts: Test 1: Performance Comparison of the Two Different Pages on SQL Server 2011 Method In this test, we will analyze the performance of the two different pages where one is at the beginning of the table and the other one is at its end. Test 2: Performance Comparison of the Two Different Pages Using CTE (Earlier Solution from SQL Server 2005/2008) and the New Method of SQL Server 2011 We will explore this in the next article. This article will tackle test 1 first. Test 1: Retrieving Page from two different locations of the table. Run the following T-SQL Script and compare the performance. SET STATISTICS IO ON; USE AdventureWorks2008R2 GO DECLARE @RowsPerPage INT = 10, @PageNumber INT = 5 SELECT * FROM Sales.SalesOrderDetail ORDER BY SalesOrderDetailID OFFSET @PageNumber*@RowsPerPage ROWS FETCH NEXT 10 ROWS ONLY GO USE AdventureWorks2008R2 GO DECLARE @RowsPerPage INT = 10, @PageNumber INT = 12100 SELECT * FROM Sales.SalesOrderDetail ORDER BY SalesOrderDetailID OFFSET @PageNumber*@RowsPerPage ROWS FETCH NEXT 10 ROWS ONLY GO You will notice that when we are reading the page from the beginning of the table, the database pages read are much lower than when the page is read from the end of the table. This is very interesting as when the the OFFSET changes, PAGE IO is increased or decreased. In the normal case of the search engine, people usually read it from the first few pages, which means that IO will be increased as we go further in the higher parts of navigation. I am really impressed because using the new method of SQL Server 2011,  PAGE IO will be much lower when the first few pages are searched in the navigation. Test 2: Retrieving Page from two different locations of the table and comparing to earlier versions. In this test, we will compare the queries of the Test 1 with the earlier solution via Common Table Expression (CTE) which we utilized in SQL Server 2005 and SQL Server 2008. Test 2 A : Page early in the table -- Test with pages early in table USE AdventureWorks2008R2 GO DECLARE @RowsPerPage INT = 10, @PageNumber INT = 5 ;WITH CTE_SalesOrderDetail AS ( SELECT *, ROW_NUMBER() OVER( ORDER BY SalesOrderDetailID) AS RowNumber FROM Sales.SalesOrderDetail PC) SELECT * FROM CTE_SalesOrderDetail WHERE RowNumber >= @PageNumber*@RowsPerPage+1 AND RowNumber <= (@PageNumber+1)*@RowsPerPage ORDER BY SalesOrderDetailID GO SET STATISTICS IO ON; USE AdventureWorks2008R2 GO DECLARE @RowsPerPage INT = 10, @PageNumber INT = 5 SELECT * FROM Sales.SalesOrderDetail ORDER BY SalesOrderDetailID OFFSET @PageNumber*@RowsPerPage ROWS FETCH NEXT 10 ROWS ONLY GO Test 2 B : Page later in the table -- Test with pages later in table USE AdventureWorks2008R2 GO DECLARE @RowsPerPage INT = 10, @PageNumber INT = 12100 ;WITH CTE_SalesOrderDetail AS ( SELECT *, ROW_NUMBER() OVER( ORDER BY SalesOrderDetailID) AS RowNumber FROM Sales.SalesOrderDetail PC) SELECT * FROM CTE_SalesOrderDetail WHERE RowNumber >= @PageNumber*@RowsPerPage+1 AND RowNumber <= (@PageNumber+1)*@RowsPerPage ORDER BY SalesOrderDetailID GO SET STATISTICS IO ON; USE AdventureWorks2008R2 GO DECLARE @RowsPerPage INT = 10, @PageNumber INT = 12100 SELECT * FROM Sales.SalesOrderDetail ORDER BY SalesOrderDetailID OFFSET @PageNumber*@RowsPerPage ROWS FETCH NEXT 10 ROWS ONLY GO From the resultset, it is very clear that in the earlier case, the pages read in the solution are always much higher than the new technique introduced in SQL Server 2011 even if we don’t retrieve all the data to the screen. If you carefully look at both the comparisons, the PAGE IO is much lesser in the case of the new technique introduced in SQL Server 2011 when we read the page from the beginning of the table and when we read it from the end. I consider this as a big improvement as paging is one of the most used features for the most part of the application. The solution introduced in SQL Server 2011 is very elegant because it also improves the performance of the query and, at large, the database. Reference : Pinal Dave (http://blog.SQLAuthority.com) Filed under: SQL, SQL Authority, SQL Optimization, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – Introduction to Wait Stats and Wait Types – Wait Type – Day 1 of 28

    - by pinaldave
    I have been working a lot on Wait Stats and Wait Types recently. Last Year, I requested blog readers to send me their respective server’s wait stats. I appreciate their kind response as I have received  Wait stats from my readers. I took each of the results and carefully analyzed them. I provided necessary feedback to the person who sent me his wait stats and wait types. Based on the feedbacks I got, many of the readers have tuned their server. After a while I got further feedbacks on my recommendations and again, I collected wait stats. I recorded the wait stats and my recommendations and did further research. At some point at time, there were more than 10 different round trips of the recommendations and suggestions. Finally, after six month of working my hands on performance tuning, I have collected some real world wisdom because of this. Now I plan to share my findings with all of you over here. Before anything else, please note that all of these are based on my personal observations and opinions. They may or may not match the theory available at other places. Some of the suggestions may not match your situation. Remember, every server is different and consequently, there is more than one solution to a particular problem. However, this series is written with kept wait stats in mind. While I was working on various performance tuning consultations, I did many more things than just tuning wait stats. Today we will discuss how to capture the wait stats. I use the script diagnostic script created by my friend and SQL Server Expert Glenn Berry to collect wait stats. Here is the script to collect the wait stats: -- Isolate top waits for server instance since last restart or statistics clear WITH Waits AS (SELECT wait_type, wait_time_ms / 1000. AS wait_time_s, 100. * wait_time_ms / SUM(wait_time_ms) OVER() AS pct, ROW_NUMBER() OVER(ORDER BY wait_time_ms DESC) AS rn FROM sys.dm_os_wait_stats WHERE wait_type NOT IN ('CLR_SEMAPHORE','LAZYWRITER_SLEEP','RESOURCE_QUEUE','SLEEP_TASK' ,'SLEEP_SYSTEMTASK','SQLTRACE_BUFFER_FLUSH','WAITFOR', 'LOGMGR_QUEUE','CHECKPOINT_QUEUE' ,'REQUEST_FOR_DEADLOCK_SEARCH','XE_TIMER_EVENT','BROKER_TO_FLUSH','BROKER_TASK_STOP','CLR_MANUAL_EVENT' ,'CLR_AUTO_EVENT','DISPATCHER_QUEUE_SEMAPHORE', 'FT_IFTS_SCHEDULER_IDLE_WAIT' ,'XE_DISPATCHER_WAIT', 'XE_DISPATCHER_JOIN', 'SQLTRACE_INCREMENTAL_FLUSH_SLEEP')) SELECT W1.wait_type, CAST(W1.wait_time_s AS DECIMAL(12, 2)) AS wait_time_s, CAST(W1.pct AS DECIMAL(12, 2)) AS pct, CAST(SUM(W2.pct) AS DECIMAL(12, 2)) AS running_pct FROM Waits AS W1 INNER JOIN Waits AS W2 ON W2.rn <= W1.rn GROUP BY W1.rn, W1.wait_type, W1.wait_time_s, W1.pct HAVING SUM(W2.pct) - W1.pct < 99 OPTION (RECOMPILE); -- percentage threshold GO This script uses Dynamic Management View sys.dm_os_wait_stats to collect the wait stats. It omits the system-related wait stats which are not useful to diagnose performance-related bottleneck. Additionally, not OPTION (RECOMPILE) at the end of the DMV will ensure that every time the query runs, it retrieves new data and not the cached data. This dynamic management view collects all the information since the time when the SQL Server services have been restarted. You can also manually clear the wait stats using the following command: DBCC SQLPERF('sys.dm_os_wait_stats', CLEAR); Once the wait stats are collected, we can start analysis them and try to see what is causing any particular wait stats to achieve higher percentages than the others. Many waits stats are related to one another. When the CPU pressure is high, all the CPU-related wait stats show up on top. But when that is fixed, all the wait stats related to the CPU start showing reasonable percentages. It is difficult to have a sure solution, but there are good indications and good suggestions on how to solve this. I will keep this blog post updated as I will post more details about wait stats and how I reduce them. The reference to Book On Line is over here. Of course, I have selected February to run this Wait Stats series. I am already cheating by having the smallest month to run this series. :) Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: DMV, Pinal Dave, PostADay, SQL, SQL Authority, SQL Optimization, SQL Performance, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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  • SQL SERVER – Video – Beginning Performance Tuning with SQL Server Execution Plan

    - by pinaldave
    Traveling can be most interesting or most exhausting experience. However, traveling is always the most enlightening experience one can have. While going to long journey one has to prepare a lot of things. Pack necessary travel gears, clothes and medicines. However, the most essential part of travel is the journey to the destination. There are many variations one prefer but the ultimate goal is to have a delightful experience during the journey. Here is the video available which explains how to begin with SQL Server Execution plans. Performance Tuning is a Journey Performance tuning is just like a long journey. The goal of performance tuning is efficient and least resources consuming query execution with accurate results. Just as maps are the most essential aspect of performance tuning the same way, execution plans are essentially maps for SQL Server to reach to the resultset. The goal of the execution plan is to find the most efficient path which translates the least usage of the resources (CPU, memory, IO etc). Execution Plans are like Maps When online maps were invented (e.g. Bing, Google, Mapquests etc) initially it was not possible to customize them. They were given a single route to reach to the destination. As time evolved now it is possible to give various hints to the maps, for example ‘via public transport’, ‘walking’, ‘fastest route’, ‘shortest route’, ‘avoid highway’. There are places where we manually drag the route and make it appropriate to our needs. The same situation is with SQL Server Execution Plans, if we want to tune the queries, we need to understand the execution plans and execution plans internals. We need to understand the smallest details which relate to execution plan when we our destination is optimal queries. Understanding Execution Plans The biggest challenge with maps are figuring out the optimal path. The same way the  most common challenge with execution plans is where to start from and which precise route to take. Here is a quick list of the frequently asked questions related to execution plans: Should I read the execution plans from bottoms up or top down? Is execution plans are left to right or right to left? What is the relational between actual execution plan and estimated execution plan? When I mouse over operator I see CPU and IO but not memory, why? Sometime I ran the query multiple times and I get different execution plan, why? How to cache the query execution plan and data? I created an optimal index but the query is not using it. What should I change – query, index or provide hints? What are the tools available which helps quickly to debug performance problems? Etc… Honestly the list is quite a big and humanly impossible to write everything in the words. SQL Server Performance:  Introduction to Query Tuning My friend Vinod Kumar and I have created for the same a video learning course for beginning performance tuning. We have covered plethora of the subject in the course. Here is the quick list of the same: Execution Plan Basics Essential Indexing Techniques Query Design for Performance Performance Tuning Tools Tips and Tricks Checklist: Performance Tuning We believe we have covered a lot in this four hour course and we encourage you to go over the video course if you are interested in Beginning SQL Server Performance Tuning and Query Tuning. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Optimization, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology, Video Tagged: Execution Plan

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  • SQL SERVER – Reducing CXPACKET Wait Stats for High Transactional Database

    - by pinaldave
    While engaging in a performance tuning consultation for a client, a situation occurred where they were facing a lot of CXPACKET Waits Stats. The client asked me if I could help them reduce this huge number of wait stats. I usually receive this kind of request from other client as well, but the important thing to understand is whether this question has any merits or benefits, or not. Before we continue the resolution, let us understand what CXPACKET Wait Stats are. The official definition suggests that CXPACKET Wait Stats occurs when trying to synchronize the query processor exchange iterator. You may consider lowering the degree of parallelism if a conflict concerning this wait type develops into a problem. (from BOL) In simpler words, when a parallel operation is created for SQL Query, there are multiple threads for a single query. Each query deals with a different set of the data (or rows). Due to some reasons, one or more of the threads lag behind, creating the CXPACKET Wait Stat. Threads which came first have to wait for the slower thread to finish. The Wait by a specific completed thread is called CXPACKET Wait Stat. Note that CXPACKET Wait is done by completed thread and not the one which are unfinished. “Note that not all the CXPACKET wait types are bad. You might experience a case when it totally makes sense. There might also be cases when this is also unavoidable. If you remove this particular wait type for any query, then that query may run slower because the parallel operations are disabled for the query.” Now let us see what the best practices to reduce the CXPACKET Wait Stats are. The suggestions, with which you will find that if you search online through the browser, would play a major role as and might be asked about their jobs In addition, might tell you that you should set ‘maximum degree of parallelism’ to 1. I do agree with these suggestions, too; however, I think this is not the final resolutions. As soon as you set your entire query to run on single CPU, you will get a very bad performance from the queries which are actually performing okay when using parallelism. The best suggestion to this is that you set ‘the maximum degree of parallelism’ to a lower number or 1 (be very careful with this – it can create more problems) but tune the queries which can be benefited from multiple CPU’s. You can use query hint OPTION (MAXDOP 0) to run the server to use parallelism. Here is the two-quick script which helps to resolve these issues: Change MAXDOP at Server Level EXEC sys.sp_configure N'max degree of parallelism', N'1' GO RECONFIGURE WITH OVERRIDE GO Run Query with all the CPU (using parallelism) USE AdventureWorks GO SELECT * FROM Sales.SalesOrderDetail ORDER BY ProductID OPTION (MAXDOP 0) GO Below is the blog post which will help you to find all the parallel query in your server. SQL SERVER – Find Queries using Parallelism from Cached Plan Please note running Queries in single CPU may worsen your performance and it is not recommended at all. Infect this can be very bad advise. I strongly suggest that you identify the queries which are offending and tune them instead of following any other suggestions. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: SQL, SQL Authority, SQL Optimization, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, SQL White Papers, SQLAuthority News, T SQL, Technology

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  • SQL SERVER – Data Pages in Buffer Pool – Data Stored in Memory Cache

    - by pinaldave
    This will drop all the clean buffers so we will be able to start again from there. Now, run the following script and check the execution plan of the query. Have you ever wondered what types of data are there in your cache? During SQL Server Trainings, I am usually asked if there is any way one can know how much data in a table is stored in the memory cache? The more detailed question I usually get is if there are multiple indexes on table (and used in a query), were the data of the single table stored multiple times in the memory cache or only for a single time? Here is a query you can run to figure out what kind of data is stored in the cache. USE AdventureWorks GO SELECT COUNT(*) AS cached_pages_count, name AS BaseTableName, IndexName, IndexTypeDesc FROM sys.dm_os_buffer_descriptors AS bd INNER JOIN ( SELECT s_obj.name, s_obj.index_id, s_obj.allocation_unit_id, s_obj.OBJECT_ID, i.name IndexName, i.type_desc IndexTypeDesc FROM ( SELECT OBJECT_NAME(OBJECT_ID) AS name, index_id ,allocation_unit_id, OBJECT_ID FROM sys.allocation_units AS au INNER JOIN sys.partitions AS p ON au.container_id = p.hobt_id AND (au.type = 1 OR au.type = 3) UNION ALL SELECT OBJECT_NAME(OBJECT_ID) AS name, index_id, allocation_unit_id, OBJECT_ID FROM sys.allocation_units AS au INNER JOIN sys.partitions AS p ON au.container_id = p.partition_id AND au.type = 2 ) AS s_obj LEFT JOIN sys.indexes i ON i.index_id = s_obj.index_id AND i.OBJECT_ID = s_obj.OBJECT_ID ) AS obj ON bd.allocation_unit_id = obj.allocation_unit_id WHERE database_id = DB_ID() GROUP BY name, index_id, IndexName, IndexTypeDesc ORDER BY cached_pages_count DESC; GO Now let us run the query above and observe the output of the same. We can see in the above query that there are four columns. Cached_Pages_Count lists the pages cached in the memory. BaseTableName lists the original base table from which data pages are cached. IndexName lists the name of the index from which pages are cached. IndexTypeDesc lists the type of index. Now, let us do one more experience here. Please note that you should not run this test on a production server as it can extremely reduce the performance of the database. DBCC DROPCLEANBUFFERS This will drop all the clean buffers and we will be able to start again from there. Now run following script and check the execution plan for the same. USE AdventureWorks GO SELECT UnitPrice, ModifiedDate FROM Sales.SalesOrderDetail WHERE SalesOrderDetailID BETWEEN 1 AND 100 GO The execution plans contain the usage of two different indexes. Now, let us run the script that checks the pages cached in SQL Server. It will give us the following output. It is clear from the Resultset that when more than one index is used, datapages related to both or all of the indexes are stored in Memory Cache separately. Let me know what you think of this article. I had a great pleasure while writing this article because I was able to write on this subject, which I like the most. In the next article, we will exactly see what data are cached and those that are not cached, using a few undocumented commands. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: DMV, Pinal Dave, SQL, SQL Authority, SQL Optimization, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: SQL DMV

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  • Code excavations, wishful invocations, perimeters and domain specific unit test frameworks

    - by RoyOsherove
    One of the talks I did at QCON London was about a subject that I’ve come across fairly recently , when I was building SilverUnit – a “pure” unit test framework for silverlight objects that depend on the silverlight runtime to run. It is the concept of “cogs in the machine” – when your piece of code needs to run inside a host framework or runtime that you have little or no control over for testability related matters. Examples of such cogs and machines can be: your custom control running inside silverlight runtime in the browser your plug-in running inside an IDE your activity running inside a windows workflow your code running inside a java EE bean your code inheriting from a COM+ (enterprise services) component etc.. Not all of these are necessarily testability problems. The main testability problem usually comes when your code actually inherits form something inside the system. For example. one of the biggest problems with testing objects like silverlight controls is the way they depend on the silverlight runtime – they don’t implement some silverlight interface, they don’t just call external static methods against the framework runtime that surrounds them – they actually inherit parts of the framework: they all inherit (in this case) from the silverlight DependencyObject Wrapping it up? An inheritance dependency is uniquely challenging to bring under test, because “classic” methods such as wrapping the object under test with a framework wrapper will not work, and the only way to do manually is to create parallel testable objects that get delegated with all the possible actions from the dependencies.    In silverlight’s case, that would mean creating your own custom logic class that would be called directly from controls that inherit from silverlight, and would be tested independently of these controls. The pro side is that you get the benefit of understanding the “contract” and the “roles” your system plays against your logic, but unfortunately, more often than not, it can be very tedious to create, and may sometimes feel unnecessary or like code duplication. About perimeters A perimeter is that invisible line that your draw around your pieces of logic during a test, that separate the code under test from any dependencies that it uses. Most of the time, a test perimeter around an object will be the list of seams (dependencies that can be replaced such as interfaces, virtual methods etc.) that are actually replaced for that test or for all the tests. Role based perimeters In the case of creating a wrapper around an object – one really creates a “role based” perimeter around the logic that is being tested – that wrapper takes on roles that are required by the code under test, and also communicates with the host system to implement those roles and provide any inputs to the logic under test. in the image below – we have the code we want to test represented as a star. No perimeter is drawn yet (we haven’t wrapped it up in anything yet). in the image below is what happens when you wrap your logic with a role based wrapper – you get a role based perimeter anywhere your code interacts with the system: There’s another way to bring that code under test – using isolation frameworks like typemock, rhino mocks and MOQ (but if your code inherits from the system, Typemock might be the only way to isolate the code from the system interaction.   Ad-Hoc Isolation perimeters the image below shows what I call ad-hoc perimeter that might be vastly different between different tests: This perimeter’s surface is much smaller, because for that specific test, that is all the “change” that is required to the host system behavior.   The third way of isolating the code from the host system is the main “meat” of this post: Subterranean perimeters Subterranean perimeters are Deep rooted perimeters  - “always on” seams that that can lie very deep in the heart of the host system where they are fully invisible even to the test itself, not just to the code under test. Because they lie deep inside a system you can’t control, the only way I’ve found to control them is with runtime (not compile time) interception of method calls on the system. One way to get such abilities is by using Aspect oriented frameworks – for example, in SilverUnit, I’ve used the CThru AOP framework based on Typemock hooks and CLR profilers to intercept such system level method calls and effectively turn them into seams that lie deep down at the heart of the silverlight runtime. the image below depicts an example of what such a perimeter could look like: As you can see, the actual seams can be very far away form the actual code under test, and as you’ll discover, that’s actually a very good thing. Here is only a partial list of examples of such deep rooted seams : disabling the constructor of a base class five levels below the code under test (this.base.base.base.base) faking static methods of a type that’s being called several levels down the stack: method x() calls y() calls z() calls SomeType.StaticMethod()  Replacing an async mechanism with a synchronous one (replacing all timers with your own timer behavior that always Ticks immediately upon calls to “start()” on the same caller thread for example) Replacing event mechanisms with your own event mechanism (to allow “firing” system events) Changing the way the system saves information with your own saving behavior (in silverunit, I replaced all Dependency Property set and get with calls to an in memory value store instead of using the one built into silverlight which threw exceptions without a browser) several questions could jump in: How do you know what to fake? (how do you discover the perimeter?) How do you fake it? Wouldn’t this be problematic  - to fake something you don’t own? it might change in the future How do you discover the perimeter to fake? To discover a perimeter all you have to do is start with a wishful invocation. a wishful invocation is the act of trying to invoke a method (or even just create an instance ) of an object using “regular” test code. You invoke the thing that you’d like to do in a real unit test, to see what happens: Can I even create an instance of this object without getting an exception? Can I invoke this method on that instance without getting an exception? Can I verify that some call into the system happened? You make the invocation, get an exception (because there is a dependency) and look at the stack trace. choose a location in the stack trace and disable it. Then try the invocation again. if you don’t get an exception the perimeter is good for that invocation, so you can move to trying out other methods on that object. in a future post I will show the process using CThru, and how you end up with something close to a domain specific test framework after you’re done creating the perimeter you need.

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  • SQL SERVER – How to Ignore Columnstore Index Usage in Query

    - by pinaldave
    Earlier I wrote about SQL SERVER – Fundamentals of Columnstore Index and very first question I received in email was as following. “We are using SQL Server 2012 CTP3 and so far so good. In our data warehouse solution we have created 1 non-clustered columnstore index on our large fact table. We have very unique situation but your article did not cover it. We are running few queries on our fact table which is working very efficiently but there is one query which earlier was running very fine but after creating this non-clustered columnstore index this query is running very slow. We dropped the columnstore index and suddenly this one query is running fast but other queries which were benefited by this columnstore index it is running slow. Any workaround in this situation?” In summary the question in simple words “How can we ignore using columnstore index in selective queries?” Very interesting question – you can use I can understand there may be the cases when columnstore index is not ideal and needs to be ignored the same. You can use the query hint IGNORE_NONCLUSTERED_COLUMNSTORE_INDEX to ignore the columnstore index. SQL Server Engine will use any other index which is best after ignoring the columnstore index. Here is the quick script to prove the same. We will first create sample database and then create columnstore index on the same. Once columnstore index is created we will write simple query. This query will use columnstore index. We will then show the usage of the query hint. USE AdventureWorks GO -- Create New Table CREATE TABLE [dbo].[MySalesOrderDetail]( [SalesOrderID] [int] NOT NULL, [SalesOrderDetailID] [int] NOT NULL, [CarrierTrackingNumber] [nvarchar](25) NULL, [OrderQty] [smallint] NOT NULL, [ProductID] [int] NOT NULL, [SpecialOfferID] [int] NOT NULL, [UnitPrice] [money] NOT NULL, [UnitPriceDiscount] [money] NOT NULL, [LineTotal] [numeric](38, 6) NOT NULL, [rowguid] [uniqueidentifier] NOT NULL, [ModifiedDate] [datetime] NOT NULL ) ON [PRIMARY] GO -- Create clustered index CREATE CLUSTERED INDEX [CL_MySalesOrderDetail] ON [dbo].[MySalesOrderDetail] ( [SalesOrderDetailID]) GO -- Create Sample Data Table -- WARNING: This Query may run upto 2-10 minutes based on your systems resources INSERT INTO [dbo].[MySalesOrderDetail] SELECT S1.* FROM Sales.SalesOrderDetail S1 GO 100 -- Create ColumnStore Index CREATE NONCLUSTERED COLUMNSTORE INDEX [IX_MySalesOrderDetail_ColumnStore] ON [MySalesOrderDetail] (UnitPrice, OrderQty, ProductID) GO Now we have created columnstore index so if we run following query it will use for sure the same index. -- Select Table with regular Index SELECT ProductID, SUM(UnitPrice) SumUnitPrice, AVG(UnitPrice) AvgUnitPrice, SUM(OrderQty) SumOrderQty, AVG(OrderQty) AvgOrderQty FROM [dbo].[MySalesOrderDetail] GROUP BY ProductID ORDER BY ProductID GO We can specify Query Hint IGNORE_NONCLUSTERED_COLUMNSTORE_INDEX as described in following query and it will not use columnstore index. -- Select Table with regular Index SELECT ProductID, SUM(UnitPrice) SumUnitPrice, AVG(UnitPrice) AvgUnitPrice, SUM(OrderQty) SumOrderQty, AVG(OrderQty) AvgOrderQty FROM [dbo].[MySalesOrderDetail] GROUP BY ProductID ORDER BY ProductID OPTION (IGNORE_NONCLUSTERED_COLUMNSTORE_INDEX) GO Let us clean up the database. -- Cleanup DROP INDEX [IX_MySalesOrderDetail_ColumnStore] ON [dbo].[MySalesOrderDetail] GO TRUNCATE TABLE dbo.MySalesOrderDetail GO DROP TABLE dbo.MySalesOrderDetail GO Again, make sure that you use hint sparingly and understanding the proper implication of the same. Make sure that you test it with and without hint and select the best option after review of your administrator. Here is the question for you – have you started to use SQL Server 2012 for your validation and development (not on production)? It will be interesting to know the answer. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Index, SQL Optimization, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • Code Contracts: How they look after compiling?

    - by DigiMortal
    When you are using new tools that make also something at code level then it is good idea to check out what additions are made to code during compilation. Code contracts have simple syntax when we are writing code at Visual Studio but what happens after compilation? Are our methods same as they look in code or are they different after compilation? In this posting I will show you how code contracts look after compiling. In my previous examples about code contracts I used randomizer class with method called GetRandomFromRangeContracted. public int GetRandomFromRangeContracted(int min, int max) {     Contract.Requires<ArgumentOutOfRangeException>(         min < max,         "Min must be less than max"     );       Contract.Ensures(         Contract.Result<int>() >= min &&         Contract.Result<int>() <= max,         "Return value is out of range"     );       return _generator.Next(min, max); } Okay, it is nice to dream about similar code when we open our assembly with Reflector and disassemble it. But… this time we have something interesting. While reading this code don’t feel uncomfortable about the names of variables. This is disassembled code. .NET Framework internally allows these names. It is our compilators that doesn’t accept them when we are building our code. public int GetRandomFromRangeContracted(int min, int max) {     int Contract.Old(min);     int Contract.Old(max);     if (__ContractsRuntime.insideContractEvaluation <= 4)     {         try         {             __ContractsRuntime.insideContractEvaluation++;             __ContractsRuntime.Requires<ArgumentOutOfRangeException>(                min < max,                "Min must be less than max", "min < max");         }         finally         {             __ContractsRuntime.insideContractEvaluation--;         }     }     try     {         Contract.Old(min) = min;     }     catch (Exception exception1)     {         if (exception1 == null)         {             throw;         }     }     try     {         Contract.Old(max) = max;         catch (Exception exception2)     {         if (exception2 == null)         {             throw;         }     }     int CS$1$0000 = this._generator.Next(min, max);     int Contract.Result<int>() = CS$1$0000;     if (__ContractsRuntime.insideContractEvaluation <= 4)     {         try         {             __ContractsRuntime.insideContractEvaluation++;             __ContractsRuntime.Ensures(                (Contract.Result<int>() >= Contract.Old(min)) &&                (Contract.Result<int>() <= Contract.Old(max)),                "Return value is out of range",                "Contract.Result<int>() >= min && Contract.Result<int>() <= max");         }         finally         {             __ContractsRuntime.insideContractEvaluation--;         }     }     return Contract.Result<int>(); } As we can see then contracts are not simply if-then-else checks and exceptions throwing. We can see that there is counter that is incremented before checks and decremented after these whatever the result of check was. One thing that is annoying for me are null checks for exception1 and exception2. Is there really some situation possible when null is thrown instead of some instance that is Exception or that inherits from exception? Conclusion Code contracts are more complex mechanism that it seems when we look at it on our code level. Internally there are done more things than we know. I don’t say it is wrong, it is just good to know how our code looks after compiling. Looking at this example it is sure we need also performance tests for contracted code to see how heavy is their impact to system performance when we run code that makes heavy use of code contracts.

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