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  • Add periods in a string [closed]

    - by Garling Beard
    I'm unable to determine why I don't get my expected output, given this code: int periods = (location.Length / 2) - 1; for (int index = 2, i = 0; i < periods; index += 3, ++i ) { location = location.Insert(index, "."); } And a location of "C5032AC", I expect that location will equal "C.50.32.A.C" after my loop terminates; it is instead "C5.03.2AC". Can anyone explain what I'm missing here?

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  • Creating a Document Library with Content Type in code

    - by David Jacobus
    Originally posted on: http://geekswithblogs.net/djacobus/archive/2013/10/15/154360.aspxIn the past, I have shown how to create a list content type and add the content type to a list in code.  As a Developer, many of the artifacts which we create are widgets which have a List or Document Library as the back end.   We need to be able to create our applications (Web Part, etc.) without having the user involved except to enter the list item data.  Today, I will show you how to do the same with a document library.    A summary of what we will do is as follows:   1.   Create an Empty SharePoint Project in Visual Studio 2.   Add a Code Folder in the solution and Drag and Drop Utilities and Extensions Libraries to the solution 3.   Create a new Feature and add and event receiver  all the code will be in the event receiver 4.   Add the fields which will extend the built-in Document content type 5.   If the Content Type does not exist, Create it 6.   If the Document Library does not exist, Create it with the new Content Type inherited from the Document Content Type 7.   Delete the Document Content Type from the Library (as we have a new one which inherited from it) 8.   Add the fields which we want to be visible from the fields added to the new Content Type   Here we go:   Create an Empty SharePoint Project in Visual Studio      Add a Code Folder in the solution and Drag and Drop Utilities and Extensions Libraries to the solution       The Utilities and Extensions Library will be part of this project which I will provide a download link at the end of this post.  Drag and drop them into your project.  If Dragged and Dropped from windows explorer you will need to show all files and then include them in your project.  Change the Namespace to agree with your project.   Create a new Feature and add and event receiver  all the code will be in the event receiver.  Here We added a new Feature called “CreateDocLib”  and then right click to add an Event Receiver All of our code will be in this Event Receiver.  For this Demo I will only be using the Feature Activated Event.      From this point on we will be looking at code!    We are adding two constants for use columGroup (How we want SharePoint to Group them, usually Company Name) and ctName(ContentType Name)  using System; using System.Runtime.InteropServices; using System.Security.Permissions; using Microsoft.SharePoint; namespace CreateDocLib.Features.CreateDocLib { /// <summary> /// This class handles events raised during feature activation, deactivation, installation, uninstallation, and upgrade. /// </summary> /// <remarks> /// The GUID attached to this class may be used during packaging and should not be modified. /// </remarks> [Guid("56e6897c-97c4-41ac-bc5b-5cd2c04f2dd1")] public class CreateDocLibEventReceiver : SPFeatureReceiver { const string columnGroup = "DJ"; const string ctName = "DJDocLib"; } }     Here we are creating the Feature Activated event.   Adding the new fields (Site Columns) ,  Testing if the Content Type Exists, if not adding it.  Testing if the document Library exists, if not adding it.   #region DocLib public override void FeatureActivated(SPFeatureReceiverProperties properties) { using (SPWeb spWeb = properties.GetWeb() as SPWeb) { //add the fields addFields(spWeb); //add content type SPContentType testCT = spWeb.ContentTypes[ctName]; // we will not create the content type if it exists if (testCT == null) { //the content type does not exist add it addContentType(spWeb, ctName); } if ((spWeb.Lists.TryGetList("MyDocuments") == null)) { //create the list if it dosen't to exist CreateDocLib(spWeb); } } } #endregion The addFields method uses the utilities library to add site columns to the site. We can add as many fields within this method as we like. Here we are adding one for demonstration purposes. Icon as a Url type.  public void addFields(SPWeb spWeb) { Utilities.addField(spWeb, "Icon", SPFieldType.URL, false, columnGroup); }The addContentType method add the new Content Type to the site Content Types. We have already checked to see that it does not exist. In addition, here is where we add the linkages from our site columns previously created to our new Content Type   private static void addContentType(SPWeb spWeb, string name) { SPContentType myContentType = new SPContentType(spWeb.ContentTypes["Document"], spWeb.ContentTypes, name) { Group = columnGroup }; spWeb.ContentTypes.Add(myContentType); addContentTypeLinkages(spWeb, myContentType); myContentType.Update(); } Here we are adding just one linkage as we only have one additional field in our Content Type public static void addContentTypeLinkages(SPWeb spWeb, SPContentType ct) { Utilities.addContentTypeLink(spWeb, "Icon", ct); } Next we add the logic to create our new Document Library, which we have already checked to see if it exists.  We create the document library and turn on content types.  Add the new content type and then delete the old “Document” content types.   private void CreateDocLib(SPWeb web) { using (var site = new SPSite(web.Url)) { var web1 = site.RootWeb; var listId = web1.Lists.Add("MyDocuments", string.Empty, SPListTemplateType.DocumentLibrary); var lib = web1.Lists[listId] as SPDocumentLibrary; lib.ContentTypesEnabled = true; var docType = web.ContentTypes[ctName]; lib.ContentTypes.Add(docType); lib.ContentTypes.Delete(lib.ContentTypes["Document"].Id); lib.Update(); AddLibrarySettings(web1, lib); } }  Finally, we set some document library settings on our new document library with the AddLibrarySettings method. We then ensure that the new site column is visible when viewed in the browser.  private void AddLibrarySettings(SPWeb web, SPDocumentLibrary lib) { lib.OnQuickLaunch = true; lib.ForceCheckout = true; lib.EnableVersioning = true; lib.MajorVersionLimit = 5; lib.EnableMinorVersions = true; lib.MajorWithMinorVersionsLimit = 5; lib.Update(); var view = lib.DefaultView; view.ViewFields.Add("Icon"); view.Update(); } Okay, what's cool here: In a few lines of code, we have created site columns, A content Type, a document library. As a developer, I use this functionality all the time. For instance, I could now just add a web part to this same solutionwhich uses this document Library. I love SharePoint! Here is the complete solution: Create Document Library Code

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  • Installation problem: What does"Add this path and evaluate require" mean?

    - by PENG TENG
    I'm installing a software from github:OPEN-VRP It is said that : ~$ git clone git://github.com/mck-/Open-VRP.git Add this path and evaluate require: (push "/path/to/Open-VRP/" asdf:*central-registry*) (require 'open-vrp) (in-package 'open-vrp) What does "Add this path and evaluate require:" mean? I have followed the instruction and the termianl said peng@peng-ThinkPad-SL410:~/??/VRP$ push "/home/peng/??/VRP/Open-VRP" asdf:*central-registry* push: getaddrinfo(/home/peng/??/VRP/Open-VRP): Name or service not known

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  • How can I get add-apt-repository to work?

    - by Kristopher Arens
    Whenever I try to add a repository via the command line, I get the following error message: Traceback (most recent call last): File "/usr/bin/add-apt-repository", line 125, in ppa_info = get_ppa_info_from_lp(user, ppa_name) File "/usr/lib/python2.7/dist-packages/softwareproperties/ppa.py", line 80, in get_ppa_info_from_lp curl.perform() pycurl.error: (60, 'server certificate verification failed. CAfile: /etc/ssl/certs/ca-certificates.crt CRLfile: none') Is there a way to remedy this situation?

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  • Use command line to add application to gnome classic panel?

    - by dmd
    How can I add an application shortcut to a panel in gnome-classic, using the command line? I used dconf watch / to see what was happening when I did it by hand, but when I try reproducing that myself: dmd@rossum:~ $ dconf write '/org/gnome/gnome-panel/layout/objects/test1234/object-iid' 'PanelInternalFactory::Launcher' error: 0-1:unknown keyword I run into trouble right away. How can I add (e.g.) a terminal launcher icon to a panel using the command line?

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  • Should I add a "nofollow" attribute to download links, or disallow the URLs in robots.txt?

    - by Laurent
    I have a download link very similar to Opera's one - it's just a script that sends the file. It doesn't have an extension and there's no obvious way to tell that it's actually a download link. So since I don't want robots to crawl this link, do I need to add it to robots.txt or maybe add a "nofollow" attribute to it? I see that on Opera's website they didn't do either of this, so perhaps it's not necessary?

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  • Should I install Firefox add-ons via the Software Center or the webbrowser?

    - by Agmenor
    I would like to install some Firefox add-ons, also called 'extensions' or 'plugins', like for example Adblock Plus, Ubufox or Greasemonkey. Should I install them from the Mozilla website, using the Firefox browser, or should I search Firefox in the Software Center and then select the interesting applications ? I suppose the issue is about how the extensions are kept up-to-date. If your answer is 'via the Software Center', how can I migrate well from my former add-ons without losing all my preferences?

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  • I add a PPA but the software does not show up in Ubuntu 11.10 updates nor Software Centre

    - by dunderhead
    Every time I add a PPA I cannot see the package I'm trying to install. I suppose I must be doing something wrong! So here's my latest effort: In a Terminal I typed: sudo add-apt-repository ppa:jeromerobert/misc and that seemed to work correctly Then I typed: sudo apt-get update But when I go to Synaptic or Software Center the application I want to install is not there. Could someone please tell me what I'm doing wrong?

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  • Need help merging 2 AHK scripts

    - by Mikey
    i have two functioning scripts that i want to merge into a single AHK File. My problem is that when i combine both scripts, the second script doesnt function or causes an error on script 1. Either way, script 2 ist not functioning at all. Here are some facts: Script 1 = a simple menu script where i want to assign hotkeys to. Script 2 = A small launcher script from a user named Tertius in autohotkey forum. Can someone please look at both codes and help me merge this? The INI File for script 2 looks like this: Keywords.ini npff|Firefox|Firefox gm|Gmail|http://gmail.google.com ;;;;;;;;;;;; BEGIN SCRIPT 2 DetectHiddenWindows, On SetWinDelay, -1 SetKeyDelay, -1 SetBatchLines, -1 GoSub Remin SetTimer, Remin, % 1000 * 60 Loop, read, %A_ScriptDir%\keywords.ini { LineNumber = %A_Index% Loop, parse, A_LoopReadLine, | { if (A_Index == 1) abbrevs%LineNumber% := A_LoopField else if (A_Index == 2) tips%LineNumber% := A_LoopField else if (A_Index == 3) programs%LineNumber% := A_LoopField else if (A_Index == 4) params%LineNumber% := A_LoopField } tosay := abbrevs%LineNumber% } cnt = %LineNumber% Loop { Input, Key, L1 V, % "{LControl}{RControl}{LAlt}{RAlt}{LShift}{RShift}{LWin}{RWin}" . "{AppsKey}{F1}{F2}{F3}{F4}{F5}{F6}{F7}{F8}{F9}{F10}{F11}{F12}{Left}{Right}{Up}{Down}" . "{Home}{End}{PgUp}{PgDn}{Del}{Ins}{BS}{Capslock}{Numlock}{PrintScreen}{Pause}{Escape}" If( ( Asc(Key) = 65 && Asc(Key) <= 90 ) || ( Asc(Key) = 97 && Asc(Key) <= 122 ) ) Word .= Key Else { Word := "" Continue } tipup := false Loop %cnt% { if (Word == abbrevs%A_index%) { tip := tips%A_index% ToolTip %tip% tipup := true } else { if (tipup == false) ToolTip } } } $Tab:: Loop %cnt% { if (Word != "" && Word == abbrevs%A_index%) { Word := "" StringLen, len, abbrevs%A_index% Loop %len% Send {Shift Down}{Left} Send {Shift Up}{BS} ToolTip program := programs%A_index% param := params%A_index% run, %program% %param% return } } Word := "" Send {Tab} Return ~LButton:: ~MButton:: ~RButton:: ~XButton1:: ~XButton2:: Word := "" Tooltip Return Remin: WinMinimize, %A_ScriptFullPath% - AutoHotkey v WinHide, %A_ScriptFullPath% - AutoHotkey v Return ;;;;;;;;;; END SCRIPT 2 ;;;;;;;;;;;;;; BEGIN SCRIPT 1 ;This is a working script that creates a popup menu. ; Create the popup menu by adding some items to it. Menu, MyMenu, Add, FIS 201, MenuHandler Menu, MyMenu, Add ; Add a separator line. Menu, MyMenu, Color, Lime, Single ;Define the Menu Color ; Create another menu destined to become a submenu of the above menu. Menu, Submenu1, Add, Item2, MenuHandler Menu, Submenu1, Add, Item3, MenuHandler Menu, Submenu1, Color, Yellow ;Define the Menu Color ; Create another menu destined to become a submenu of the above menu. Menu, Submenu2, Add, Item1a, MenuHandler Menu, Submenu2, Add, Item2a, MenuHandler Menu, Submenu2, Add, Item3a, MenuHandler Menu, Submenu2, Add, Item4a, MenuHandler Menu, Submenu2, Add, Item5a, MenuHandler Menu, Submenu2, Add, Item6a, MenuHandler Menu, Submenu2, Color, Aqua ;Define the Menu Color ; Create a submenu in the first menu (a right-arrow indicator). When the user selects it, the second menu is displayed. Menu, MyMenu, Add, BKRS 119, :Submenu1 Menu, MyMenu, Add ; Add a separator line below the submenu. Menu, MyMenu, Add, BKRS 201, :Submenu2 Menu, MyMenu, Add ; Add a separator line below the submenu. Menu, MyMenu, Add ; Add a separator line below the submenu. Menu, MyMenu, Add, Google Search, Google ; Add another menu item beneath the submenu. return ; End of script's auto-execute section. Capslock & LButton::Menu, MyMenu, Show ; i.e. press the Win-Z hotkey to show the menu. MenuHandler: MsgBox You selected %A_ThisMenuItem% from the menu %A_ThisMenu%. return ;;;;;;;;;;;;;;;;;;;;;;;; ;;;;;;;; Google Search ;;; FORMAT InputBox, OutputVar [, Title, Prompt, HIDE, Width, Height, X, Y, Font, Timeout, Default] Google: InputBox, SearchTerm, Google Search,,,350, 120 if SearchTerm < "" Run http://www.google.de/search?sclient=psy-ab&hl=de&site=&source=hp&q=%SearchTerm%&btnG=Suche return ; Make Window Transparent Space::WinSet, Transparent, 125, A ^!Space UP::WinSet, Transparent, OFF, A return ;;;;;;;;;;; END SCRIPT 1 Help is appreciated. Kind Regards, Mikey

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  • Excel 2013: Is it possible to collapse rows only in a specific column?

    - by h7u9i
    In my spreadsheet, I'm trying to figure out a way to collapse rows in a specific column. Right now, if I do Data - Group - Group... - Rows, it'll collapse the entire row. I want to collapse rows only in a specific column. Example: |---------|----------| | hi | + data | |---------|----------| | hello | + data2 | |---------|----------| | | | |---------|----------| | | | And opening data 1 would turn into: |---------|----------| | hi | - data1 | |---------|----------| | hello | point1 | |---------|----------| | | point2 | |---------|----------| | | + data2 | |---------|----------| | | | |---------|----------| | | | Is this possible to do in Excel?

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  • Thunderbird 3: create a single column to display the 'From' field on a received message and the 'Rec

    - by dfree
    If the title doesn't say it all let me know. This would be helpful for IMAP folders within T-bird, when I'm looking through threads on a particular issue, but don't know if I sent the last message to the recipient, or they sent the last message to me. I would be able to quickly scroll in one column and see exactly when the last communication on that issue was. Is there a way to make a 'smart' column that would do this?

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  • How do I get SQL Profiler to show statements with column names like 'password'?

    - by Kev
    I'm profiling a database just now and need to see the UPDATE and INSERT statements being executed on a particular table. However, because the table has a 'Password' column the SQL Profiler is being understandingly cautious and replacing the TextData column with: -- 'password' was found in the text of this event. -- The text has been replaced with this comment for security reasons. How do I prevent it doing this because I need to see the SQL statement being executed?

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  • What's the syntax to add a calendar reminder from Google Command Line?

    - by Traveling Tech Guy
    I've been using googlecl successfully to add events to my calendar. Things like: google calendar add "call Paul tomorrow at 8:30am" work great, and add the appropriate event t the right time. But no reminder is added for the event. I tried: google calendar add "call Paul tomorrow at 8:30am reminder 10 minutes" and other combinations. It just ends up adding the "reminder" instruction to the event description. What's the syntax I should use to add a, let's say, 10 minutes pop-up reminder? Thanks

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  • Collapsing rows of duplicate dates in a column leaving one row with a subtotal?

    - by Will
    I have several thousand rows of date, time, and values in columns. Each row is contains a date, time for that date, and a value for that time period (hour) So each 24 rows has the same date with each having the next hour of the day. I'd like to collapse or group the 24 rows leaving the last row with a subtotal of the value (column D) to the right in column F. While this can obviously be done manually, several years of data would take a while and there ought to be a way to do this other wise?

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  • NHibernate won't persist DateTime SqlDateTime overflow

    - by chris raethke
    I am working on an ASP.NET MVC project with NHibernate as the backend and am having some trouble getting some dates to write back to my SQL Server database tables. These date fields are NOT nullable, so the many answers here about how to setup nullable datetimes have not helped. Basically when I try to save the entity which has a DateAdded and a LastUpdated fields, I am getting a SqlDateTime overflow exception. I have had a similar problem in the past where I was trying to write a datetime field into a smalldatetime column, updating the type on the column appeared to fix the problem. My gut feeling is that its going to be some problem with the table definition or some type of incompatible data types, and the overflow exception is a bit of a bum steer. I have attached an example of the table definition and the query that NHibernate is trying to run, any help or suggestions would be greatly appreciated. CREATE TABLE [dbo].[CustomPages]( [ID] [uniqueidentifier] NOT NULL, [StoreID] [uniqueidentifier] NOT NULL, [DateAdded] [datetime] NOT NULL, [AddedByID] [uniqueidentifier] NOT NULL, [LastUpdated] [datetime] NOT NULL, [LastUpdatedByID] [uniqueidentifier] NOT NULL, [Title] [nvarchar](150) NOT NULL, [Term] [nvarchar](150) NOT NULL, [Content] [ntext] NULL ) exec sp_executesql N'INSERT INTO CustomPages (Title, Term, Content, LastUpdated, DateAdded, StoreID, LastUpdatedById, AddedById, ID) VALUES (@p0, @p1, @p2, @p3, @p4, @p5, @p6, @p7, @p8)',N'@p0 nvarchar(21),@p1 nvarchar(21),@p2 nvarchar(33),@p3 datetime,@p4 datetime,@p5 uniqueidentifier,@p6 uniqueidentifier,@p7 uniqueidentifier,@p8 uniqueidentifier',@p0=N'Size and Colour Chart',@p1=N'size-and-colour-chart',@p2=N'This is the size and colour chart',@p3=''2009-03-14 14:29:37:000'',@p4=''2009-03-14 14:29:37:000'',@p5='48315F9F-0E00-4654-A2C0-62FB466E529D',@p6='1480221A-605A-4D72-B0E5-E1FE72C5D43C',@p7='1480221A-605A-4D72-B0E5-E1FE72C5D43C',@p8='1E421F9E-9A00-49CF-9180-DCD22FCE7F55' In response the the answers/comments, I am using Fluent NHibernate and the generated mapping is below public CustomPageMap() { WithTable("CustomPages"); Id( x => x.ID, "ID" ) .WithUnsavedValue(Guid.Empty) . GeneratedBy.Guid(); References(x => x.Store, "StoreID"); Map(x => x.DateAdded, "DateAdded"); References(x => x.AddedBy, "AddedById"); Map(x => x.LastUpdated, "LastUpdated"); References(x => x.LastUpdatedBy, "LastUpdatedById"); Map(x => x.Title, "Title"); Map(x => x.Term, "Term"); Map(x => x.Content, "Content"); } <?xml version="1.0" encoding="utf-8"?> <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" default-lazy="false" assembly="MyNamespace.Core" namespace="MyNamespace.Core"> <class name="CustomPage" table="CustomPages" xmlns="urn:nhibernate-mapping-2.2"> <id name="ID" column="ID" type="Guid" unsaved-value="00000000-0000-0000-0000-000000000000"><generator class="guid" /></id> <property name="Title" column="Title" length="100" type="String"><column name="Title" /></property> <property name="Term" column="Term" length="100" type="String"><column name="Term" /></property> <property name="Content" column="Content" length="100" type="String"><column name="Content" /></property> <property name="LastUpdated" column="LastUpdated" type="DateTime"><column name="LastUpdated" /></property> <property name="DateAdded" column="DateAdded" type="DateTime"><column name="DateAdded" /></property> <many-to-one name="Store" column="StoreID" /><many-to-one name="LastUpdatedBy" column="LastUpdatedById" /> <many-to-one name="AddedBy" column="AddedById" /></class></hibernate-mapping>

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  • Hibernate won't save into database

    - by Blitzkr1eg
    I mapped some classes to some tables with hibernate in java, i set hibernate to show SQL, it opens the session, it show that id does the SQL, it closes the session but there are no modifications to the database. Entity public class Profesor implements Comparable<Profesor> { private int id; private String nume; private String prenume; private int departament_id; private Set<Disciplina> listaDiscipline; //the teacher gives some courses} public class Disciplina implements Comparable<Disciplina>{ //the course class private int id; private String denumire; private String syllabus; private String schNotare; private Set<Lectie> lectii; private Set<Tema> listaTeme; private Set<Grup> listaGrupuri; // the course gets teached/assigmened to some groups of students private Set<Assignment> listAssignments;} Mapping <hibernate-mapping default-cascade="all"> <class name="model.Profesor" table="devgar_scoala.profesori"> <id name="id" column="id"> <generator class="increment"/> </id> <set name="listaDiscipline" table="devgar_scoala.`profesori-discipline`"> <key column="Profesori_id" /> <many-to-many class="model.Disciplina" column="Discipline_id" /> </set> <property name="nume" column="Nume" type="string" /> <property name="prenume" column="Prenume" type="string" /> <property name="departament_id" column="Departamente_id" type="integer" /> </class> <class name="model.Grup" table="devgar_scoala.grupe"> <id name="id" unsaved-value="0"> <generator class="increment"/> </id> <set name="listaStudenti" table="devgar_scoala.`studenti-grupe`"> <key column="Grupe_id" /> <many-to-many column="Studenti_nrMatricol" class="model.Student" /> </set> <property name="nume" column="Grupa" type="string"/> <property name="programStudiu" column="progStudii_id" type="integer" /> </class> <class name="model.Disciplina" table="devgar_scoala.discipline" > <id name="id" > <generator class="increment"/> </id> <property name="denumire" column="Denumire" type="string"/> <property name="syllabus" type="string" column="Syllabus"/> <property name="schNotare" type="string" column="SchemaNotare"/> <set name="listaGrupuri" table="devgar_scoala.`Discipline-Grupe`"> <key column="Discipline_id" /> <many-to-many column="Grupe_id" class="model.Grup" /> </set> <set name="lectii" table="devgar_scoala.lectii"> <key column="Discipline_id" not-null="true"/> <one-to-many class="model.Lectie" /> </set> </class> The only 'funny' thing is that the Profesor object gets loaded not with/by Hibernate but with manual classic SQL Java. Thats why i save the Profesor object like this p - the manually loaded Profesor object Profesor p2 = (Profesor) session.merge(p); session.saveOrUpdate(p2); //flush session of course After this i get in the Java console: Hibernate: insert into devgar_scoala.grupe (Grupa, progStudii_id, id) values (?, ?, ?) but when i look into the database there are no new rows in the table Grupe (the Groups table)

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  • proper way to creation multiple similiar buttons/panels

    - by JayAvon
    I have the below Code which i tried to do, but it only shows(the minus/plus button) on the last GirdLayout (Intelligence stat): JButton plusButton = new JButton("+"); JButton minusButton = new JButton("-"); statStrengthGridPanel = new JPanel(new GridLayout(1,3)); statStrengthGridPanel.add(minusButton); statStrengthGridPanel.add(new JLabel("10")); statStrengthGridPanel.add(plusButton); statConstitutionGridPanel = new JPanel(new GridLayout(1,3)); statConstitutionGridPanel.add(minusButton); statConstitutionGridPanel.add(new JLabel("10")); statConstitutionGridPanel.add(plusButton); statDexterityGridPanel = new JPanel(new GridLayout(1,3)); statDexterityGridPanel.add(minusButton); statDexterityGridPanel.add(new JLabel("10")); statDexterityGridPanel.add(plusButton); statIntelligenceGridPanel = new JPanel(new GridLayout(1,3)); statIntelligenceGridPanel.add(minusButton); statIntelligenceGridPanel.add(new JLabel("10")); statIntelligenceGridPanel.add(plusButton); I know I can do something like I did for the Panel names(have multiple ones), but I did not want to do that for the Panels in the first place. I am trying to use best practice and not have my code be repetitive. Any suggestions?? The goal is to have 4 stats, to assign points to, with decrement and increment buttons(I decided against sliders). Eventually I will have them have upper and lower limits, decrement the "unused" label, and all of that good stuff, but I just want to not be repetitive. Thanks for any help.

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  • Static vs. dynamic memory allocation - lots of constant objects, only small part of them used at runtime

    - by k29
    Here are two options: Option 1: enum QuizCategory { CATEGORY_1(new MyCollection<Question>() .add(Question.QUESTION_A) .add(Question.QUESTION_B) .add...), CATEGORY_2(new MyCollection<Question>() .add(Question.QUESTION_B) .add(Question.QUESTION_C) .add...), ... ; public MyCollection<Question> collection; private QuizCategory(MyCollection<Question> collection) { this.collection = collection; } public Question getRandom() { return collection.getRandomQuestion(); } } Option 2: enum QuizCategory2 { CATEGORY_1 { @Override protected MyCollection<Question> populateWithQuestions() { return new MyCollection<Question>() .add(Question.QUESTION_A) .add(Question.QUESTION_B) .add...; } }, CATEGORY_2 { @Override protected MyCollection<Question> populateWithQuestions() { return new MyCollection<Question>() .add(Question.QUESTION_B) .add(Question.QUESTION_C) .add...; } }; public Question getRandom() { MyCollection<Question> collection = populateWithQuestions(); return collection.getRandomQuestion(); } protected abstract MyCollection<Question> populateWithQuestions(); } There will be around 1000 categories, each containing 10 - 300 questions (100 on average). At runtime typically only 10 categories and 30 questions will be used. Each question is itself an enum constant (with its fields and methods). I'm trying to decide between those two options in the mobile application context. I haven't done any measurements since I have yet to write the questions and would like to gather more information before committing to one or another option. As far as I understand: (a) Option 1 will perform better since there will be no need to populate the collection and then garbage-collect the questions; (b) Option 1 will require extra memory: 1000 categories x 100 questions x 4 bytes for each reference = 400 Kb, which is not significant. So I'm leaning to Option 1, but just wondered if I'm correct in my assumptions and not missing something important? Perhaps someone has faced a similar dilemma? Or perhaps it doesn't actually matter that much?

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  • Advanced TSQL Tuning: Why Internals Knowledge Matters

    - by Paul White
    There is much more to query tuning than reducing logical reads and adding covering nonclustered indexes.  Query tuning is not complete as soon as the query returns results quickly in the development or test environments.  In production, your query will compete for memory, CPU, locks, I/O and other resources on the server.  Today’s entry looks at some tuning considerations that are often overlooked, and shows how deep internals knowledge can help you write better TSQL. As always, we’ll need some example data.  In fact, we are going to use three tables today, each of which is structured like this: Each table has 50,000 rows made up of an INTEGER id column and a padding column containing 3,999 characters in every row.  The only difference between the three tables is in the type of the padding column: the first table uses CHAR(3999), the second uses VARCHAR(MAX), and the third uses the deprecated TEXT type.  A script to create a database with the three tables and load the sample data follows: USE master; GO IF DB_ID('SortTest') IS NOT NULL DROP DATABASE SortTest; GO CREATE DATABASE SortTest COLLATE LATIN1_GENERAL_BIN; GO ALTER DATABASE SortTest MODIFY FILE ( NAME = 'SortTest', SIZE = 3GB, MAXSIZE = 3GB ); GO ALTER DATABASE SortTest MODIFY FILE ( NAME = 'SortTest_log', SIZE = 256MB, MAXSIZE = 1GB, FILEGROWTH = 128MB ); GO ALTER DATABASE SortTest SET ALLOW_SNAPSHOT_ISOLATION OFF ; ALTER DATABASE SortTest SET AUTO_CLOSE OFF ; ALTER DATABASE SortTest SET AUTO_CREATE_STATISTICS ON ; ALTER DATABASE SortTest SET AUTO_SHRINK OFF ; ALTER DATABASE SortTest SET AUTO_UPDATE_STATISTICS ON ; ALTER DATABASE SortTest SET AUTO_UPDATE_STATISTICS_ASYNC ON ; ALTER DATABASE SortTest SET PARAMETERIZATION SIMPLE ; ALTER DATABASE SortTest SET READ_COMMITTED_SNAPSHOT OFF ; ALTER DATABASE SortTest SET MULTI_USER ; ALTER DATABASE SortTest SET RECOVERY SIMPLE ; USE SortTest; GO CREATE TABLE dbo.TestCHAR ( id INTEGER IDENTITY (1,1) NOT NULL, padding CHAR(3999) NOT NULL,   CONSTRAINT [PK dbo.TestCHAR (id)] PRIMARY KEY CLUSTERED (id), ) ; CREATE TABLE dbo.TestMAX ( id INTEGER IDENTITY (1,1) NOT NULL, padding VARCHAR(MAX) NOT NULL,   CONSTRAINT [PK dbo.TestMAX (id)] PRIMARY KEY CLUSTERED (id), ) ; CREATE TABLE dbo.TestTEXT ( id INTEGER IDENTITY (1,1) NOT NULL, padding TEXT NOT NULL,   CONSTRAINT [PK dbo.TestTEXT (id)] PRIMARY KEY CLUSTERED (id), ) ; -- ============= -- Load TestCHAR (about 3s) -- ============= INSERT INTO dbo.TestCHAR WITH (TABLOCKX) ( padding ) SELECT padding = REPLICATE(CHAR(65 + (Data.n % 26)), 3999) FROM ( SELECT TOP (50000) n = ROW_NUMBER() OVER (ORDER BY (SELECT 0)) - 1 FROM master.sys.columns C1, master.sys.columns C2, master.sys.columns C3 ORDER BY n ASC ) AS Data ORDER BY Data.n ASC ; -- ============ -- Load TestMAX (about 3s) -- ============ INSERT INTO dbo.TestMAX WITH (TABLOCKX) ( padding ) SELECT CONVERT(VARCHAR(MAX), padding) FROM dbo.TestCHAR ORDER BY id ; -- ============= -- Load TestTEXT (about 5s) -- ============= INSERT INTO dbo.TestTEXT WITH (TABLOCKX) ( padding ) SELECT CONVERT(TEXT, padding) FROM dbo.TestCHAR ORDER BY id ; -- ========== -- Space used -- ========== -- EXECUTE sys.sp_spaceused @objname = 'dbo.TestCHAR'; EXECUTE sys.sp_spaceused @objname = 'dbo.TestMAX'; EXECUTE sys.sp_spaceused @objname = 'dbo.TestTEXT'; ; CHECKPOINT ; That takes around 15 seconds to run, and shows the space allocated to each table in its output: To illustrate the points I want to make today, the example task we are going to set ourselves is to return a random set of 150 rows from each table.  The basic shape of the test query is the same for each of the three test tables: SELECT TOP (150) T.id, T.padding FROM dbo.Test AS T ORDER BY NEWID() OPTION (MAXDOP 1) ; Test 1 – CHAR(3999) Running the template query shown above using the TestCHAR table as the target, we find that the query takes around 5 seconds to return its results.  This seems slow, considering that the table only has 50,000 rows.  Working on the assumption that generating a GUID for each row is a CPU-intensive operation, we might try enabling parallelism to see if that speeds up the response time.  Running the query again (but without the MAXDOP 1 hint) on a machine with eight logical processors, the query now takes 10 seconds to execute – twice as long as when run serially. Rather than attempting further guesses at the cause of the slowness, let’s go back to serial execution and add some monitoring.  The script below monitors STATISTICS IO output and the amount of tempdb used by the test query.  We will also run a Profiler trace to capture any warnings generated during query execution. DECLARE @read BIGINT, @write BIGINT ; SELECT @read = SUM(num_of_bytes_read), @write = SUM(num_of_bytes_written) FROM tempdb.sys.database_files AS DBF JOIN sys.dm_io_virtual_file_stats(2, NULL) AS FS ON FS.file_id = DBF.file_id WHERE DBF.type_desc = 'ROWS' ; SET STATISTICS IO ON ; SELECT TOP (150) TC.id, TC.padding FROM dbo.TestCHAR AS TC ORDER BY NEWID() OPTION (MAXDOP 1) ; SET STATISTICS IO OFF ; SELECT tempdb_read_MB = (SUM(num_of_bytes_read) - @read) / 1024. / 1024., tempdb_write_MB = (SUM(num_of_bytes_written) - @write) / 1024. / 1024., internal_use_MB = ( SELECT internal_objects_alloc_page_count / 128.0 FROM sys.dm_db_task_space_usage WHERE session_id = @@SPID ) FROM tempdb.sys.database_files AS DBF JOIN sys.dm_io_virtual_file_stats(2, NULL) AS FS ON FS.file_id = DBF.file_id WHERE DBF.type_desc = 'ROWS' ; Let’s take a closer look at the statistics and query plan generated from this: Following the flow of the data from right to left, we see the expected 50,000 rows emerging from the Clustered Index Scan, with a total estimated size of around 191MB.  The Compute Scalar adds a column containing a random GUID (generated from the NEWID() function call) for each row.  With this extra column in place, the size of the data arriving at the Sort operator is estimated to be 192MB. Sort is a blocking operator – it has to examine all of the rows on its input before it can produce its first row of output (the last row received might sort first).  This characteristic means that Sort requires a memory grant – memory allocated for the query’s use by SQL Server just before execution starts.  In this case, the Sort is the only memory-consuming operator in the plan, so it has access to the full 243MB (248,696KB) of memory reserved by SQL Server for this query execution. Notice that the memory grant is significantly larger than the expected size of the data to be sorted.  SQL Server uses a number of techniques to speed up sorting, some of which sacrifice size for comparison speed.  Sorts typically require a very large number of comparisons, so this is usually a very effective optimization.  One of the drawbacks is that it is not possible to exactly predict the sort space needed, as it depends on the data itself.  SQL Server takes an educated guess based on data types, sizes, and the number of rows expected, but the algorithm is not perfect. In spite of the large memory grant, the Profiler trace shows a Sort Warning event (indicating that the sort ran out of memory), and the tempdb usage monitor shows that 195MB of tempdb space was used – all of that for system use.  The 195MB represents physical write activity on tempdb, because SQL Server strictly enforces memory grants – a query cannot ‘cheat’ and effectively gain extra memory by spilling to tempdb pages that reside in memory.  Anyway, the key point here is that it takes a while to write 195MB to disk, and this is the main reason that the query takes 5 seconds overall. If you are wondering why using parallelism made the problem worse, consider that eight threads of execution result in eight concurrent partial sorts, each receiving one eighth of the memory grant.  The eight sorts all spilled to tempdb, resulting in inefficiencies as the spilled sorts competed for disk resources.  More importantly, there are specific problems at the point where the eight partial results are combined, but I’ll cover that in a future post. CHAR(3999) Performance Summary: 5 seconds elapsed time 243MB memory grant 195MB tempdb usage 192MB estimated sort set 25,043 logical reads Sort Warning Test 2 – VARCHAR(MAX) We’ll now run exactly the same test (with the additional monitoring) on the table using a VARCHAR(MAX) padding column: DECLARE @read BIGINT, @write BIGINT ; SELECT @read = SUM(num_of_bytes_read), @write = SUM(num_of_bytes_written) FROM tempdb.sys.database_files AS DBF JOIN sys.dm_io_virtual_file_stats(2, NULL) AS FS ON FS.file_id = DBF.file_id WHERE DBF.type_desc = 'ROWS' ; SET STATISTICS IO ON ; SELECT TOP (150) TM.id, TM.padding FROM dbo.TestMAX AS TM ORDER BY NEWID() OPTION (MAXDOP 1) ; SET STATISTICS IO OFF ; SELECT tempdb_read_MB = (SUM(num_of_bytes_read) - @read) / 1024. / 1024., tempdb_write_MB = (SUM(num_of_bytes_written) - @write) / 1024. / 1024., internal_use_MB = ( SELECT internal_objects_alloc_page_count / 128.0 FROM sys.dm_db_task_space_usage WHERE session_id = @@SPID ) FROM tempdb.sys.database_files AS DBF JOIN sys.dm_io_virtual_file_stats(2, NULL) AS FS ON FS.file_id = DBF.file_id WHERE DBF.type_desc = 'ROWS' ; This time the query takes around 8 seconds to complete (3 seconds longer than Test 1).  Notice that the estimated row and data sizes are very slightly larger, and the overall memory grant has also increased very slightly to 245MB.  The most marked difference is in the amount of tempdb space used – this query wrote almost 391MB of sort run data to the physical tempdb file.  Don’t draw any general conclusions about VARCHAR(MAX) versus CHAR from this – I chose the length of the data specifically to expose this edge case.  In most cases, VARCHAR(MAX) performs very similarly to CHAR – I just wanted to make test 2 a bit more exciting. MAX Performance Summary: 8 seconds elapsed time 245MB memory grant 391MB tempdb usage 193MB estimated sort set 25,043 logical reads Sort warning Test 3 – TEXT The same test again, but using the deprecated TEXT data type for the padding column: DECLARE @read BIGINT, @write BIGINT ; SELECT @read = SUM(num_of_bytes_read), @write = SUM(num_of_bytes_written) FROM tempdb.sys.database_files AS DBF JOIN sys.dm_io_virtual_file_stats(2, NULL) AS FS ON FS.file_id = DBF.file_id WHERE DBF.type_desc = 'ROWS' ; SET STATISTICS IO ON ; SELECT TOP (150) TT.id, TT.padding FROM dbo.TestTEXT AS TT ORDER BY NEWID() OPTION (MAXDOP 1, RECOMPILE) ; SET STATISTICS IO OFF ; SELECT tempdb_read_MB = (SUM(num_of_bytes_read) - @read) / 1024. / 1024., tempdb_write_MB = (SUM(num_of_bytes_written) - @write) / 1024. / 1024., internal_use_MB = ( SELECT internal_objects_alloc_page_count / 128.0 FROM sys.dm_db_task_space_usage WHERE session_id = @@SPID ) FROM tempdb.sys.database_files AS DBF JOIN sys.dm_io_virtual_file_stats(2, NULL) AS FS ON FS.file_id = DBF.file_id WHERE DBF.type_desc = 'ROWS' ; This time the query runs in 500ms.  If you look at the metrics we have been checking so far, it’s not hard to understand why: TEXT Performance Summary: 0.5 seconds elapsed time 9MB memory grant 5MB tempdb usage 5MB estimated sort set 207 logical reads 596 LOB logical reads Sort warning SQL Server’s memory grant algorithm still underestimates the memory needed to perform the sorting operation, but the size of the data to sort is so much smaller (5MB versus 193MB previously) that the spilled sort doesn’t matter very much.  Why is the data size so much smaller?  The query still produces the correct results – including the large amount of data held in the padding column – so what magic is being performed here? TEXT versus MAX Storage The answer lies in how columns of the TEXT data type are stored.  By default, TEXT data is stored off-row in separate LOB pages – which explains why this is the first query we have seen that records LOB logical reads in its STATISTICS IO output.  You may recall from my last post that LOB data leaves an in-row pointer to the separate storage structure holding the LOB data. SQL Server can see that the full LOB value is not required by the query plan until results are returned, so instead of passing the full LOB value down the plan from the Clustered Index Scan, it passes the small in-row structure instead.  SQL Server estimates that each row coming from the scan will be 79 bytes long – 11 bytes for row overhead, 4 bytes for the integer id column, and 64 bytes for the LOB pointer (in fact the pointer is rather smaller – usually 16 bytes – but the details of that don’t really matter right now). OK, so this query is much more efficient because it is sorting a very much smaller data set – SQL Server delays retrieving the LOB data itself until after the Sort starts producing its 150 rows.  The question that normally arises at this point is: Why doesn’t SQL Server use the same trick when the padding column is defined as VARCHAR(MAX)? The answer is connected with the fact that if the actual size of the VARCHAR(MAX) data is 8000 bytes or less, it is usually stored in-row in exactly the same way as for a VARCHAR(8000) column – MAX data only moves off-row into LOB storage when it exceeds 8000 bytes.  The default behaviour of the TEXT type is to be stored off-row by default, unless the ‘text in row’ table option is set suitably and there is room on the page.  There is an analogous (but opposite) setting to control the storage of MAX data – the ‘large value types out of row’ table option.  By enabling this option for a table, MAX data will be stored off-row (in a LOB structure) instead of in-row.  SQL Server Books Online has good coverage of both options in the topic In Row Data. The MAXOOR Table The essential difference, then, is that MAX defaults to in-row storage, and TEXT defaults to off-row (LOB) storage.  You might be thinking that we could get the same benefits seen for the TEXT data type by storing the VARCHAR(MAX) values off row – so let’s look at that option now.  This script creates a fourth table, with the VARCHAR(MAX) data stored off-row in LOB pages: CREATE TABLE dbo.TestMAXOOR ( id INTEGER IDENTITY (1,1) NOT NULL, padding VARCHAR(MAX) NOT NULL,   CONSTRAINT [PK dbo.TestMAXOOR (id)] PRIMARY KEY CLUSTERED (id), ) ; EXECUTE sys.sp_tableoption @TableNamePattern = N'dbo.TestMAXOOR', @OptionName = 'large value types out of row', @OptionValue = 'true' ; SELECT large_value_types_out_of_row FROM sys.tables WHERE [schema_id] = SCHEMA_ID(N'dbo') AND name = N'TestMAXOOR' ; INSERT INTO dbo.TestMAXOOR WITH (TABLOCKX) ( padding ) SELECT SPACE(0) FROM dbo.TestCHAR ORDER BY id ; UPDATE TM WITH (TABLOCK) SET padding.WRITE (TC.padding, NULL, NULL) FROM dbo.TestMAXOOR AS TM JOIN dbo.TestCHAR AS TC ON TC.id = TM.id ; EXECUTE sys.sp_spaceused @objname = 'dbo.TestMAXOOR' ; CHECKPOINT ; Test 4 – MAXOOR We can now re-run our test on the MAXOOR (MAX out of row) table: DECLARE @read BIGINT, @write BIGINT ; SELECT @read = SUM(num_of_bytes_read), @write = SUM(num_of_bytes_written) FROM tempdb.sys.database_files AS DBF JOIN sys.dm_io_virtual_file_stats(2, NULL) AS FS ON FS.file_id = DBF.file_id WHERE DBF.type_desc = 'ROWS' ; SET STATISTICS IO ON ; SELECT TOP (150) MO.id, MO.padding FROM dbo.TestMAXOOR AS MO ORDER BY NEWID() OPTION (MAXDOP 1, RECOMPILE) ; SET STATISTICS IO OFF ; SELECT tempdb_read_MB = (SUM(num_of_bytes_read) - @read) / 1024. / 1024., tempdb_write_MB = (SUM(num_of_bytes_written) - @write) / 1024. / 1024., internal_use_MB = ( SELECT internal_objects_alloc_page_count / 128.0 FROM sys.dm_db_task_space_usage WHERE session_id = @@SPID ) FROM tempdb.sys.database_files AS DBF JOIN sys.dm_io_virtual_file_stats(2, NULL) AS FS ON FS.file_id = DBF.file_id WHERE DBF.type_desc = 'ROWS' ; TEXT Performance Summary: 0.3 seconds elapsed time 245MB memory grant 0MB tempdb usage 193MB estimated sort set 207 logical reads 446 LOB logical reads No sort warning The query runs very quickly – slightly faster than Test 3, and without spilling the sort to tempdb (there is no sort warning in the trace, and the monitoring query shows zero tempdb usage by this query).  SQL Server is passing the in-row pointer structure down the plan and only looking up the LOB value on the output side of the sort. The Hidden Problem There is still a huge problem with this query though – it requires a 245MB memory grant.  No wonder the sort doesn’t spill to tempdb now – 245MB is about 20 times more memory than this query actually requires to sort 50,000 records containing LOB data pointers.  Notice that the estimated row and data sizes in the plan are the same as in test 2 (where the MAX data was stored in-row). The optimizer assumes that MAX data is stored in-row, regardless of the sp_tableoption setting ‘large value types out of row’.  Why?  Because this option is dynamic – changing it does not immediately force all MAX data in the table in-row or off-row, only when data is added or actually changed.  SQL Server does not keep statistics to show how much MAX or TEXT data is currently in-row, and how much is stored in LOB pages.  This is an annoying limitation, and one which I hope will be addressed in a future version of the product. So why should we worry about this?  Excessive memory grants reduce concurrency and may result in queries waiting on the RESOURCE_SEMAPHORE wait type while they wait for memory they do not need.  245MB is an awful lot of memory, especially on 32-bit versions where memory grants cannot use AWE-mapped memory.  Even on a 64-bit server with plenty of memory, do you really want a single query to consume 0.25GB of memory unnecessarily?  That’s 32,000 8KB pages that might be put to much better use. The Solution The answer is not to use the TEXT data type for the padding column.  That solution happens to have better performance characteristics for this specific query, but it still results in a spilled sort, and it is hard to recommend the use of a data type which is scheduled for removal.  I hope it is clear to you that the fundamental problem here is that SQL Server sorts the whole set arriving at a Sort operator.  Clearly, it is not efficient to sort the whole table in memory just to return 150 rows in a random order. The TEXT example was more efficient because it dramatically reduced the size of the set that needed to be sorted.  We can do the same thing by selecting 150 unique keys from the table at random (sorting by NEWID() for example) and only then retrieving the large padding column values for just the 150 rows we need.  The following script implements that idea for all four tables: SET STATISTICS IO ON ; WITH TestTable AS ( SELECT * FROM dbo.TestCHAR ), TopKeys AS ( SELECT TOP (150) id FROM TestTable ORDER BY NEWID() ) SELECT T1.id, T1.padding FROM TestTable AS T1 WHERE T1.id = ANY (SELECT id FROM TopKeys) OPTION (MAXDOP 1) ; WITH TestTable AS ( SELECT * FROM dbo.TestMAX ), TopKeys AS ( SELECT TOP (150) id FROM TestTable ORDER BY NEWID() ) SELECT T1.id, T1.padding FROM TestTable AS T1 WHERE T1.id IN (SELECT id FROM TopKeys) OPTION (MAXDOP 1) ; WITH TestTable AS ( SELECT * FROM dbo.TestTEXT ), TopKeys AS ( SELECT TOP (150) id FROM TestTable ORDER BY NEWID() ) SELECT T1.id, T1.padding FROM TestTable AS T1 WHERE T1.id IN (SELECT id FROM TopKeys) OPTION (MAXDOP 1) ; WITH TestTable AS ( SELECT * FROM dbo.TestMAXOOR ), TopKeys AS ( SELECT TOP (150) id FROM TestTable ORDER BY NEWID() ) SELECT T1.id, T1.padding FROM TestTable AS T1 WHERE T1.id IN (SELECT id FROM TopKeys) OPTION (MAXDOP 1) ; SET STATISTICS IO OFF ; All four queries now return results in much less than a second, with memory grants between 6 and 12MB, and without spilling to tempdb.  The small remaining inefficiency is in reading the id column values from the clustered primary key index.  As a clustered index, it contains all the in-row data at its leaf.  The CHAR and VARCHAR(MAX) tables store the padding column in-row, so id values are separated by a 3999-character column, plus row overhead.  The TEXT and MAXOOR tables store the padding values off-row, so id values in the clustered index leaf are separated by the much-smaller off-row pointer structure.  This difference is reflected in the number of logical page reads performed by the four queries: Table 'TestCHAR' logical reads 25511 lob logical reads 000 Table 'TestMAX'. logical reads 25511 lob logical reads 000 Table 'TestTEXT' logical reads 00412 lob logical reads 597 Table 'TestMAXOOR' logical reads 00413 lob logical reads 446 We can increase the density of the id values by creating a separate nonclustered index on the id column only.  This is the same key as the clustered index, of course, but the nonclustered index will not include the rest of the in-row column data. CREATE UNIQUE NONCLUSTERED INDEX uq1 ON dbo.TestCHAR (id); CREATE UNIQUE NONCLUSTERED INDEX uq1 ON dbo.TestMAX (id); CREATE UNIQUE NONCLUSTERED INDEX uq1 ON dbo.TestTEXT (id); CREATE UNIQUE NONCLUSTERED INDEX uq1 ON dbo.TestMAXOOR (id); The four queries can now use the very dense nonclustered index to quickly scan the id values, sort them by NEWID(), select the 150 ids we want, and then look up the padding data.  The logical reads with the new indexes in place are: Table 'TestCHAR' logical reads 835 lob logical reads 0 Table 'TestMAX' logical reads 835 lob logical reads 0 Table 'TestTEXT' logical reads 686 lob logical reads 597 Table 'TestMAXOOR' logical reads 686 lob logical reads 448 With the new index, all four queries use the same query plan (click to enlarge): Performance Summary: 0.3 seconds elapsed time 6MB memory grant 0MB tempdb usage 1MB sort set 835 logical reads (CHAR, MAX) 686 logical reads (TEXT, MAXOOR) 597 LOB logical reads (TEXT) 448 LOB logical reads (MAXOOR) No sort warning I’ll leave it as an exercise for the reader to work out why trying to eliminate the Key Lookup by adding the padding column to the new nonclustered indexes would be a daft idea Conclusion This post is not about tuning queries that access columns containing big strings.  It isn’t about the internal differences between TEXT and MAX data types either.  It isn’t even about the cool use of UPDATE .WRITE used in the MAXOOR table load.  No, this post is about something else: Many developers might not have tuned our starting example query at all – 5 seconds isn’t that bad, and the original query plan looks reasonable at first glance.  Perhaps the NEWID() function would have been blamed for ‘just being slow’ – who knows.  5 seconds isn’t awful – unless your users expect sub-second responses – but using 250MB of memory and writing 200MB to tempdb certainly is!  If ten sessions ran that query at the same time in production that’s 2.5GB of memory usage and 2GB hitting tempdb.  Of course, not all queries can be rewritten to avoid large memory grants and sort spills using the key-lookup technique in this post, but that’s not the point either. The point of this post is that a basic understanding of execution plans is not enough.  Tuning for logical reads and adding covering indexes is not enough.  If you want to produce high-quality, scalable TSQL that won’t get you paged as soon as it hits production, you need a deep understanding of execution plans, and as much accurate, deep knowledge about SQL Server as you can lay your hands on.  The advanced database developer has a wide range of tools to use in writing queries that perform well in a range of circumstances. By the way, the examples in this post were written for SQL Server 2008.  They will run on 2005 and demonstrate the same principles, but you won’t get the same figures I did because 2005 had a rather nasty bug in the Top N Sort operator.  Fair warning: if you do decide to run the scripts on a 2005 instance (particularly the parallel query) do it before you head out for lunch… This post is dedicated to the people of Christchurch, New Zealand. © 2011 Paul White email: @[email protected] twitter: @SQL_Kiwi

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  • Do you have an address column somewhere in your database?

    - by shay.shmeltzer
    Do you have an address column somewhere in your database? If the answer is yes - then the Web seminar I'm going to run together with the guys from Navteq on May 26th, might be of interest to you. You see, we all have geographical related information in our database, but many of us don't actually use this to do any geographical type of operations/representation with it. Well once you attend the "Add Maps to Your Java Applications - the Easy Way" seminar this might change. In the seminar we'll give you a quick overview of the Spatial related capabilities of the Oracle DB, Middleware and tools. And a demo showing you how easy it is to actually get data to show up on a map in your application and to interact with it. So register today, and mark your calendar.

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  • Having a generic data type for a database table column, is it "good" practice?

    - by Yanick Rochon
    I'm working on a PHP project where some object (class member) may contain different data type. For example : class Property { private $_id; // (PK) private $_ref_id; // the object reference id (FK) private $_name; // the name of the property private $_type; // 'string', 'int', 'float(n,m)', 'datetime', etc. private $_data; // ... // ..snip.. public getters/setters } Now, I need to perform some persistence on these objects. Some properties may be a text data type, but nothing bigger than what a varchar may hold. Also, later on, I need to be able to perform searches and sorting. Is it a good practice to use a single database table for this (ie. is there a non negligible performance impact)? If it's "acceptable", then what could be the data type for the data column?

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  • The Column Prediction_Status, MDP_Matrix and Engine. How are they Related? Understand Prediction_status Values

    - by user702295
    Do you know what these values are telling you? COUNT(*) PREDICTION_STATUS DO_FORE DO_AGGRI AGGRI_98 AGGRI_99 LEVEL_ID 19854 99 1 1 1 1 3 1077 99 0 1 1 1 0 262691 99 1 1 -1 56 99 0 1 1 1 2 1 98 1 1 1 1 1 99 0 1 1 1 748796 1 1 1 4 351633 1 1 1 1 1 2 1877829 97 1 1 4 840 99 1 1 1 1 27 99 0 1 1 1 3 1 97 1 1 -1 66712 99 1 1 1 1 2 53213 1 1 1 1 1 3 2560 98 1 1 4   Check out The Column Prediction_Status, MDP_Matrix and Engine. How are they Related? Understand Prediction_status Values (Doc ID 1509754.1) This customer is adding an additional processing burden, adding no value.  The incoming data should be scrubbed to eliminate the overhead. 

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