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• Is it possible to write a SQL query to return specific rows, but then join some columns of those row

  - by Rob

  I'm having trouble wrapping my head around how to write this query. A hypothetical problem that is that same as the one I'm trying to solve: Say I have a table of apples. Each apple has numerous attributes, such as color_id, variety_id and the orchard_id they were picked from. The color_id, variety_id, and orchard_id all refer to their respective tables: colors, varieties, and orchards. Now, say I need to query for all apples that have color_id = '3', which refers to yellow in the colors table. I want to somehow obtain this yellow value from the query. Make sense? Here's what I was trying: SELECT * FROM apples, colors.id WHERE color_id = '3' LEFT JOIN colors ON apples.color_id = colors.id

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• After grouping by, can I refer to the elements of the original IEnumerable in a LINQ query?

  - by michielvoo

  Example: from OriginalObject in ListOfOriginalObjects group new CustomObject { X = OriginalObject.A, Y = OriginalObject.B } by OriginalObject.Z into grouping select new GroupOfCustomObjects { Z = grouping.Key, C = OriginalObject.C, group = grouping } In the select part of the query, I'd like to add a property (OriginalObject.C) to the type GroupOfCustomObjects. But it seems that OriginalObject is out of scope in that part of the query. I can sort of understand why, since I am not grouping on that property and I am also not making that property part of CustomObject that I'm grouping. One workaround is to add a property C to CustomObject and the in the GroupOfCustomObjects read the value of the first CustomObject in the grouping. My issue with that is that I'm adding a property to an object that doesn't need it (CustomObject), just to be able to add it to the GroupOfCustomObjects. I hope I have explained this properly! Is there a way to refer to the OriginalObject that the query starts with? Thanks!

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• MySQL: selecting totals as three fields from same table as one query?

  - by coderama

  I have a table with various orders in it: ID | Date | etc... 1 | 2013-01-01 | etc 2 | 2013-02-01 | etc 3 | 2013-03-01 | etc 4 | 2013-04-01 | etc 5 | 2013-05-01 | etc 6 | 2013-06-01 | etc 7 | 2013-06-01 | etc 8 | 2013-03-01 | etc 9 | 2013-04-01 | etc 10 | 2013-05-01 | etc I want a query that ends wit the result: overallTotal | totalThisMonth | totalLastMonth 10 | 2 | 1 But I want to do this in one query! I am trying to find a way to use subqueries to do this. SO far I have: SELECT * from ( SELECT count(*) as overallTotal from ORDERS ) How can I combine this with other subqueries so I can get the totals in one query?

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• c# How to make linq master detail query for 0..n relationship?

  - by JK

  Given a classic DB structure of Orders has zero or more OrderLines and OrderLine has exactly one Product, how do I write a linq query to express this? The output would be OrderNumber - OrderLine - Product Name Order-1 null null // (this order has no lines) Order-2 1 Red widget I tried this query but is not getting the orders with no lines var model = (from po in Orders from line in po.OrderLines select new { OrderNumber = po.Id, OrderLine = line.LineNumber, ProductName = line.Product.ProductDescription, } ) I think that the 2nd from is limiting the query to only those that have OrderLines, but I dont know another way to express it. LINQ is very non-obvious if you ask me!

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• How does the dataset determine the return type of a scalar query?

  - by Tobias Funke

  I am attempting to add a scalar query to a dataset. The query is pretty straight forward, it's just adding up some decimal values in a few columns and returning them. I am 100% confident that only one row and one column is returned, and that it is of decimal type (SQL money type). The problem is that for some reason, the generated method (in the .designer.cs code file) is returning a value of type object, when it should be decimal. What's strange is that there's another scalar query that has the exact same SQL but is returning decimal like it should. How does the dataset designer determine the data type, and how can I tell it to return decimal?

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• How does the dataset designer determine the return type of a scalar query?

  - by Tobias Funke

  I am attempting to add a scalar query to a dataset. The query is pretty straight forward, it's just adding up some decimal values in a few columns and returning them. I am 100% confident that only one row and one column is returned, and that it is of decimal type (SQL money type). The problem is that for some reason, the generated method (in the .designer.cs code file) is returning a value of type object, when it should be decimal. What's strange is that there's another scalar query that has the exact same SQL but is returning decimal like it should. How does the dataset designer determine the data type, and how can I tell it to return decimal?

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• Want to avoid the particular rows from select join query... See description

  - by OM The Eternity

  I have a Select Left Join Query whis displays me the rows for the latest changedone(its a time) column name ("field" should not be equal) column name ("trackid" should not be equal), and column name "Operation should be "UPDATE" ", below is the query I am talking about... SELECT j1. * FROM jos_audittrail j1 LEFT OUTER JOIN jos_audittrail j2 ON ( j1.trackid != j2.trackid AND j1.field != j2.field AND j1.changedone < j2.changedone ) WHERE j1.operation = 'UPDATE' AND j2.id IS NULL Now here I don't want a row to be displayed with a two particular column's value i.e. "field's value" the value is "LastvisitDate" and "hits" Now if if append the condition in the above query that " AND j1.field != 'lastvistDate' AND j1.field != 'hits' " theni do not get any result... The table structure is jos_audittrail: id trackid operation oldvalue newvalue table_name live changedone(its a time) I hope i have given the details properly If u still find something missing I will try to provide it more better way... Pls help me to avoid those two rows with those to mentioned value of "field"

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• How do I specify a default value in a MS Access query?

  - by jheddings

  I have three tables similar to the following: tblInvoices: Number | Date | Customer tblInvDetails: Invoice | Quantity | Rate | Description tblPayments: Invoice | Date | Amount I have created a query called exInvDetails that adds an Amount column to tblInvDetails: SELECT tblInvDetails.*, [tblInvDetails.Quantity]*[tblInvDetails.Rate]* AS Amount FROM tblInvDetails; I then created a query exInvoices to add Total and Balance columns to tblInvoices: SELECT tblInvoices.*, (SELECT Sum(exInvDetails.Amount) FROM exInvDetails WHERE exInvDetails.Invoice = tblInvoices.Number) AS Total, (SELECT Sum(tblPayments.Amount) FROM tblPayments WHERE tblPayments.Invoice = tblInvoices.Number) AS Payments, (Total-Payments) AS Balance FROM tblInvoices; If there are no corresponding payments in tblPayments, the fields are null instead of 0. Is there a way to force the resulting query to put a 0 in this column?

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• MVC more specified models should be populated by more precise query too?

  - by KevinUK

  If you have a Car model with 20 or so properties (and several table joins) for a carDetail page then your LINQ to SQL query will be quite large. If you have a carListing page which uses under 5 properties (all from 1 table) then you use a CarSummary model. Should the CarSummary model be populated using the same query as the Car model? Or should you use a separate LINQ to SQL query which would be more precise? I am just thinking of performance but LINQ uses lazy loading anyway so I am wondering if this is an issue or not.

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• how to query sqlite for certain rows, i.e. dividing it into pages (perl DBI)

  - by user1380641

  sorry for my noob question, I'm currently writing a perl web application with sqlite database behind it. I would like to be able to show in my app query results which might get thousands of rows - these should be split in pages - routing should be like /webapp/N - where N is the page number. what is the correct way to query the sqlite db using DBI, in order to fetch only the relavent rows. for instance, if I show 25 rows per page so I want to query the db for 1-25 rows in the first page, 26-50 in the second page etc.... Thanks in advanced!

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• how to get the second batch and 3rd batch in the same query result in oracle sql + yii framework?

  - by sasori

  let' say i have 20 results in the sql query. if am gonna use the limit in the yii active record, I'll obviously get the first four from the result, but what if i wanna get the 2nd four and then 3rd four in the same query result ? how to query that via sql ? e.g $criteria2 = new CDbCriteria(); $criteria2->select = 'USERID, ADID ,ADTYPE, ADTITLE, ADDESC, PAGEVIEW, DISPPUBLISHDATE'; $criteria2->addCondition("STATUS = 1"); $criteria2->order = '"t".PAGEVIEW DESC,"t".PUBLISHDATE DESC'; $criteria2->limit = 4; $criteria2->with = array('subcat','adimages'); $result = $this->findAll($criteria2); return $result;

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• How do I use 2 include statements in a single MVC EF query?

  - by alockrem

  I am trying to write a query that includes 2 joins. 1 StoryTemplate can have multiple Stories 1 Story can have multiple StoryDrafts I am starting the query on the StoryDrafts object because that is where it's linked to the UserId. I don't have a reference from the StoryDrafts object directly to the StoryTemplates object. How would I build this query properly? public JsonResult Index(int userId) { return Json( db.StoryDrafts .Include("Story") .Include("StoryTemplate") .Where(d => d.UserId == userId) ,JsonRequestBehavior.AllowGet); } Thank you for any help.

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• Installing SharePoint 2013 on Windows 2012- standalone installation

  - by sreejukg

  In this article, I am going to share my experience while installing SharePoint 2013 on Windows 2012. This was the first time I tried SharePoint 2013. So I thought sharing the same will benefit somebody who would like to install SharePoint 2013 as a standalone installation. Standalone installation is meant for evaluation/development purposes. For production environments, you need to follow the best practices and create required service accounts. Microsoft has published the deployment guide for SharePoint 2013, you can download this from the below link. http://www.microsoft.com/en-us/download/details.aspx?id=30384 Since this is for development environment, I am not going to create any service account, I logged in to Windows 2012 as an administrator and just placed my installation DVD on the drive. When I run the setup from the DVD, the below splash screen appears. This reflects the new UI changes happening with all Microsoft based applications; the interface matches the metro style applications (Windows 8 style). As you can see the options are same as that of the SharePoint 2010 installation screen. Click on the “install software prerequisites” link to get all the prerequisites get installed. You need a valid internet connection to do this. Clicking on the install software prerequisites will bring the following dialog. Click Next, you will see the terms and conditions. Select I accept check box and click Next. The installation will start immediately. For any reason, if you stop the installation and start it later, the product preparation tool will check whether a particular component is installed and if yes, then the installation of that particular component will be skipped. If you do not have internet connection, you will face the download error as follows. At any point of failure, the error log will be available for you to review. If all OK, you will reach the below dialog, this means some components will be installed once the PC is rebooted. Be noted that the clicking on finish will not ask you for further confirmation. So make sure to save all your work before clicking on finish button. Once the server is restarted, the product preparation tool will start automatically and you will see the following dialog. Now go to the SharePoint 2013 splash page and click on “Install SharePoint Server” link. You need to enter the product key here. Enter the product key as you received and click continue. Select the Checkbox for the license agreement and click on continue button. Now you need to select the installation type. Select Stand-alone and click on “Install Now” button. A dialog will pop up that updates you with the process and progress. The installation took around 15-20 minutes with 2 GB or Ram installed in the server, seems fair. Once the installation is over, you will see the following Dialog. Make sure you select the Run the products and configuration wizard. If you miss to select the check box, you can find the products and configuration wizard from the start tiles. The products and configuration wizard will start. If you get any dialog saying some of the services will be stopped, you just accept it. Since we selected standalone installation, it will not ask for any user input, as it already knows the database to be configured. Once the configuration is over without any problems you will see the configuration successful message. Also you can find the link to central administration on the Start Screen.     Troubleshooting During my first setup process, I got the below error. System.ArgumentException: The SDDL string contains an invalid sid or a sid that cannot be translated. Parameter name: sddlForm at System.Security.AccessControl.RawSecurityDescriptor.BinaryFormFromSddlForm(String sddlForm) at System.Security.AccessControl.RawSecurityDescriptor..ctor(String sddlForm) at Microsoft.SharePoint.Win32.SPNetApi32.CreateShareSecurityDescriptor(String[] readNames, String[] changeNames, String[] fullControlNames, String& sddl) at Microsoft.SharePoint.Win32.SPNetApi32.CreateFileShare(String name, String description, String path) at Microsoft.SharePoint.Administration.SPServer.CreateFileShare(String name, String description, String path) at Microsoft.Office.Server.Search.Administration.AnalyticsAdministration.CreateAnalyticsUNCShare(String dirParentLocation, String shareName) at Microsoft.Office.Server.Search.Administration.AnalyticsAdministration.ProvisionAnalyticsShare(SearchServiceApplication serviceApplication) ………………………………………… ………………………………………… The configuration wizard displayed the error as below. The error occurred in step 8 of the configuration wizard and by the time the central administration is already provisioned. So from the start, I was able to open the central administration website, but the search service application was showing as error. I found a good blog that specifies the reason for error. http://kbdump.com/sharepoint2013-standalone-config-error-create-sample-data/ The workaround specified in the blog works fine. I think SharePoint must be provisioning Search using the Network Service account, so instead of giving permission to everyone, you could try giving permission to Network Service account(I didn’t try this yet, buy you could try and post your feedback here). In production environment you will have specific accounts that have access rights as recommended by Microsoft guidelines. Installation of SharePoint 2013 is pretty straight forward. Hope you enjoyed the article!

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• Understanding LINQ to SQL (11) Performance

  - by Dixin

  [LINQ via C# series] LINQ to SQL has a lot of great features like strong typing query compilation deferred execution declarative paradigm etc., which are very productive. Of course, these cannot be free, and one price is the performance. O/R mapping overhead Because LINQ to SQL is based on O/R mapping, one obvious overhead is, data changing usually requires data retrieving:private static void UpdateProductUnitPrice(int id, decimal unitPrice) { using (NorthwindDataContext database = new NorthwindDataContext()) { Product product = database.Products.Single(item => item.ProductID == id); // SELECT... product.UnitPrice = unitPrice; // UPDATE... database.SubmitChanges(); } } Before updating an entity, that entity has to be retrieved by an extra SELECT query. This is slower than direct data update via ADO.NET:private static void UpdateProductUnitPrice(int id, decimal unitPrice) { using (SqlConnection connection = new SqlConnection( "Data Source=localhost;Initial Catalog=Northwind;Integrated Security=True")) using (SqlCommand command = new SqlCommand( @"UPDATE [dbo].[Products] SET [UnitPrice] = @UnitPrice WHERE [ProductID] = @ProductID", connection)) { command.Parameters.Add("@ProductID", SqlDbType.Int).Value = id; command.Parameters.Add("@UnitPrice", SqlDbType.Money).Value = unitPrice; connection.Open(); command.Transaction = connection.BeginTransaction(); command.ExecuteNonQuery(); // UPDATE... command.Transaction.Commit(); } } The above imperative code specifies the “how to do” details with better performance. For the same reason, some articles from Internet insist that, when updating data via LINQ to SQL, the above declarative code should be replaced by:private static void UpdateProductUnitPrice(int id, decimal unitPrice) { using (NorthwindDataContext database = new NorthwindDataContext()) { database.ExecuteCommand( "UPDATE [dbo].[Products] SET [UnitPrice] = {0} WHERE [ProductID] = {1}", id, unitPrice); } } Or just create a stored procedure:CREATE PROCEDURE [dbo].[UpdateProductUnitPrice] ( @ProductID INT, @UnitPrice MONEY ) AS BEGIN BEGIN TRANSACTION UPDATE [dbo].[Products] SET [UnitPrice] = @UnitPrice WHERE [ProductID] = @ProductID COMMIT TRANSACTION END and map it as a method of NorthwindDataContext (explained in this post):private static void UpdateProductUnitPrice(int id, decimal unitPrice) { using (NorthwindDataContext database = new NorthwindDataContext()) { database.UpdateProductUnitPrice(id, unitPrice); } } As a normal trade off for O/R mapping, a decision has to be made between performance overhead and programming productivity according to the case. In a developer’s perspective, if O/R mapping is chosen, I consistently choose the declarative LINQ code, unless this kind of overhead is unacceptable. Data retrieving overhead After talking about the O/R mapping specific issue. Now look into the LINQ to SQL specific issues, for example, performance in the data retrieving process. The previous post has explained that the SQL translating and executing is complex. Actually, the LINQ to SQL pipeline is similar to the compiler pipeline. It consists of about 15 steps to translate an C# expression tree to SQL statement, which can be categorized as: Convert: Invoke SqlProvider.BuildQuery() to convert the tree of Expression nodes into a tree of SqlNode nodes; Bind: Used visitor pattern to figure out the meanings of names according to the mapping info, like a property for a column, etc.; Flatten: Figure out the hierarchy of the query; Rewrite: for SQL Server 2000, if needed Reduce: Remove the unnecessary information from the tree. Parameterize Format: Generate the SQL statement string; Parameterize: Figure out the parameters, for example, a reference to a local variable should be a parameter in SQL; Materialize: Executes the reader and convert the result back into typed objects. So for each data retrieving, even for data retrieving which looks simple: private static Product[] RetrieveProducts(int productId) { using (NorthwindDataContext database = new NorthwindDataContext()) { return database.Products.Where(product => product.ProductID == productId) .ToArray(); } } LINQ to SQL goes through above steps to translate and execute the query. Fortunately, there is a built-in way to cache the translated query. Compiled query When such a LINQ to SQL query is executed repeatedly, The CompiledQuery can be used to translate query for one time, and execute for multiple times:internal static class CompiledQueries { private static readonly Func<NorthwindDataContext, int, Product[]> _retrieveProducts = CompiledQuery.Compile((NorthwindDataContext database, int productId) => database.Products.Where(product => product.ProductID == productId).ToArray()); internal static Product[] RetrieveProducts( this NorthwindDataContext database, int productId) { return _retrieveProducts(database, productId); } } The new version of RetrieveProducts() gets better performance, because only when _retrieveProducts is first time invoked, it internally invokes SqlProvider.Compile() to translate the query expression. And it also uses lock to make sure translating once in multi-threading scenarios. Static SQL / stored procedures without translating Another way to avoid the translating overhead is to use static SQL or stored procedures, just as the above examples. Because this is a functional programming series, this article not dive into. For the details, Scott Guthrie already has some excellent articles: LINQ to SQL (Part 6: Retrieving Data Using Stored Procedures) LINQ to SQL (Part 7: Updating our Database using Stored Procedures) LINQ to SQL (Part 8: Executing Custom SQL Expressions) Data changing overhead By looking into the data updating process, it also needs a lot of work: Begins transaction Processes the changes (ChangeProcessor) Walks through the objects to identify the changes Determines the order of the changes Executes the changings LINQ queries may be needed to execute the changings, like the first example in this article, an object needs to be retrieved before changed, then the above whole process of data retrieving will be went through If there is user customization, it will be executed, for example, a table’s INSERT / UPDATE / DELETE can be customized in the O/R designer It is important to keep these overhead in mind. Bulk deleting / updating Another thing to be aware is the bulk deleting:private static void DeleteProducts(int categoryId) { using (NorthwindDataContext database = new NorthwindDataContext()) { database.Products.DeleteAllOnSubmit( database.Products.Where(product => product.CategoryID == categoryId)); database.SubmitChanges(); } } The expected SQL should be like:BEGIN TRANSACTION exec sp_executesql N'DELETE FROM [dbo].[Products] AS [t0] WHERE [t0].[CategoryID] = @p0',N'@p0 int',@p0=9 COMMIT TRANSACTION Hoverer, as fore mentioned, the actual SQL is to retrieving the entities, and then delete them one by one:-- Retrieves the entities to be deleted: exec sp_executesql N'SELECT [t0].[ProductID], [t0].[ProductName], [t0].[SupplierID], [t0].[CategoryID], [t0].[QuantityPerUnit], [t0].[UnitPrice], [t0].[UnitsInStock], [t0].[UnitsOnOrder], [t0].[ReorderLevel], [t0].[Discontinued] FROM [dbo].[Products] AS [t0] WHERE [t0].[CategoryID] = @p0',N'@p0 int',@p0=9 -- Deletes the retrieved entities one by one: BEGIN TRANSACTION exec sp_executesql N'DELETE FROM [dbo].[Products] WHERE ([ProductID] = @p0) AND ([ProductName] = @p1) AND ([SupplierID] IS NULL) AND ([CategoryID] = @p2) AND ([QuantityPerUnit] IS NULL) AND ([UnitPrice] = @p3) AND ([UnitsInStock] = @p4) AND ([UnitsOnOrder] = @p5) AND ([ReorderLevel] = @p6) AND (NOT ([Discontinued] = 1))',N'@p0 int,@p1 nvarchar(4000),@p2 int,@p3 money,@p4 smallint,@p5 smallint,@p6 smallint',@p0=78,@p1=N'Optimus Prime',@p2=9,@p3=$0.0000,@p4=0,@p5=0,@p6=0 exec sp_executesql N'DELETE FROM [dbo].[Products] WHERE ([ProductID] = @p0) AND ([ProductName] = @p1) AND ([SupplierID] IS NULL) AND ([CategoryID] = @p2) AND ([QuantityPerUnit] IS NULL) AND ([UnitPrice] = @p3) AND ([UnitsInStock] = @p4) AND ([UnitsOnOrder] = @p5) AND ([ReorderLevel] = @p6) AND (NOT ([Discontinued] = 1))',N'@p0 int,@p1 nvarchar(4000),@p2 int,@p3 money,@p4 smallint,@p5 smallint,@p6 smallint',@p0=79,@p1=N'Bumble Bee',@p2=9,@p3=$0.0000,@p4=0,@p5=0,@p6=0 -- ... COMMIT TRANSACTION And the same to the bulk updating. This is really not effective and need to be aware. Here is already some solutions from the Internet, like this one. The idea is wrap the above SELECT statement into a INNER JOIN:exec sp_executesql N'DELETE [dbo].[Products] FROM [dbo].[Products] AS [j0] INNER JOIN ( SELECT [t0].[ProductID], [t0].[ProductName], [t0].[SupplierID], [t0].[CategoryID], [t0].[QuantityPerUnit], [t0].[UnitPrice], [t0].[UnitsInStock], [t0].[UnitsOnOrder], [t0].[ReorderLevel], [t0].[Discontinued] FROM [dbo].[Products] AS [t0] WHERE [t0].[CategoryID] = @p0) AS [j1] ON ([j0].[ProductID] = [j1].[[Products])', -- The Primary Key N'@p0 int',@p0=9 Query plan overhead The last thing is about the SQL Server query plan. Before .NET 4.0, LINQ to SQL has an issue (not sure if it is a bug). LINQ to SQL internally uses ADO.NET, but it does not set the SqlParameter.Size for a variable-length argument, like argument of NVARCHAR type, etc. So for two queries with the same SQL but different argument length:using (NorthwindDataContext database = new NorthwindDataContext()) { database.Products.Where(product => product.ProductName == "A") .Select(product => product.ProductID).ToArray(); // The same SQL and argument type, different argument length. database.Products.Where(product => product.ProductName == "AA") .Select(product => product.ProductID).ToArray(); } Pay attention to the argument length in the translated SQL:exec sp_executesql N'SELECT [t0].[ProductID] FROM [dbo].[Products] AS [t0] WHERE [t0].[ProductName] = @p0',N'@p0 nvarchar(1)',@p0=N'A' exec sp_executesql N'SELECT [t0].[ProductID] FROM [dbo].[Products] AS [t0] WHERE [t0].[ProductName] = @p0',N'@p0 nvarchar(2)',@p0=N'AA' Here is the overhead: The first query’s query plan cache is not reused by the second one:SELECT sys.syscacheobjects.cacheobjtype, sys.dm_exec_cached_plans.usecounts, sys.syscacheobjects.[sql] FROM sys.syscacheobjects INNER JOIN sys.dm_exec_cached_plans ON sys.syscacheobjects.bucketid = sys.dm_exec_cached_plans.bucketid; They actually use different query plans. Again, pay attention to the argument length in the [sql] column (@p0 nvarchar(2) / @p0 nvarchar(1)). Fortunately, in .NET 4.0 this is fixed:internal static class SqlTypeSystem { private abstract class ProviderBase : TypeSystemProvider { protected int? GetLargestDeclarableSize(SqlType declaredType) { SqlDbType sqlDbType = declaredType.SqlDbType; if (sqlDbType <= SqlDbType.Image) { switch (sqlDbType) { case SqlDbType.Binary: case SqlDbType.Image: return 8000; } return null; } if (sqlDbType == SqlDbType.NVarChar) { return 4000; // Max length for NVARCHAR. } if (sqlDbType != SqlDbType.VarChar) { return null; } return 8000; } } } In this above example, the translated SQL becomes:exec sp_executesql N'SELECT [t0].[ProductID] FROM [dbo].[Products] AS [t0] WHERE [t0].[ProductName] = @p0',N'@p0 nvarchar(4000)',@p0=N'A' exec sp_executesql N'SELECT [t0].[ProductID] FROM [dbo].[Products] AS [t0] WHERE [t0].[ProductName] = @p0',N'@p0 nvarchar(4000)',@p0=N'AA' So that they reuses the same query plan cache: Now the [usecounts] column is 2.

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• Hello Operator, My Switch Is Bored

  - by Paul White

  This is a post for T-SQL Tuesday #43 hosted by my good friend Rob Farley. The topic this month is Plan Operators. I haven’t taken part in T-SQL Tuesday before, but I do like to write about execution plans, so this seemed like a good time to start. This post is in two parts. The first part is primarily an excuse to use a pretty bad play on words in the title of this blog post (if you’re too young to know what a telephone operator or a switchboard is, I hate you). The second part of the post looks at an invisible query plan operator (so to speak). 1. My Switch Is Bored Allow me to present the rare and interesting execution plan operator, Switch: Books Online has this to say about Switch: Following that description, I had a go at producing a Fast Forward Cursor plan that used the TOP operator, but had no luck. That may be due to my lack of skill with cursors, I’m not too sure. The only application of Switch in SQL Server 2012 that I am familiar with requires a local partitioned view: CREATE TABLE dbo.T1 (c1 int NOT NULL CHECK (c1 BETWEEN 00 AND 24)); CREATE TABLE dbo.T2 (c1 int NOT NULL CHECK (c1 BETWEEN 25 AND 49)); CREATE TABLE dbo.T3 (c1 int NOT NULL CHECK (c1 BETWEEN 50 AND 74)); CREATE TABLE dbo.T4 (c1 int NOT NULL CHECK (c1 BETWEEN 75 AND 99)); GO CREATE VIEW V1 AS SELECT c1 FROM dbo.T1 UNION ALL SELECT c1 FROM dbo.T2 UNION ALL SELECT c1 FROM dbo.T3 UNION ALL SELECT c1 FROM dbo.T4; Not only that, but it needs an updatable local partitioned view. We’ll need some primary keys to meet that requirement: ALTER TABLE dbo.T1 ADD CONSTRAINT PK_T1 PRIMARY KEY (c1);   ALTER TABLE dbo.T2 ADD CONSTRAINT PK_T2 PRIMARY KEY (c1);   ALTER TABLE dbo.T3 ADD CONSTRAINT PK_T3 PRIMARY KEY (c1);   ALTER TABLE dbo.T4 ADD CONSTRAINT PK_T4 PRIMARY KEY (c1); We also need an INSERT statement that references the view. Even more specifically, to see a Switch operator, we need to perform a single-row insert (multi-row inserts use a different plan shape): INSERT dbo.V1 (c1) VALUES (1); And now…the execution plan: The Constant Scan manufactures a single row with no columns. The Compute Scalar works out which partition of the view the new value should go in. The Assert checks that the computed partition number is not null (if it is, an error is returned). The Nested Loops Join executes exactly once, with the partition id as an outer reference (correlated parameter). The Switch operator checks the value of the parameter and executes the corresponding input only. If the partition id is 0, the uppermost Clustered Index Insert is executed, adding a row to table T1. If the partition id is 1, the next lower Clustered Index Insert is executed, adding a row to table T2…and so on. In case you were wondering, here’s a query and execution plan for a multi-row insert to the view: INSERT dbo.V1 (c1) VALUES (1), (2); Yuck! An Eager Table Spool and four Filters! I prefer the Switch plan. My guess is that almost all the old strategies that used a Switch operator have been replaced over time, using things like a regular Concatenation Union All combined with Start-Up Filters on its inputs. Other new (relative to the Switch operator) features like table partitioning have specific execution plan support that doesn’t need the Switch operator either. This feels like a bit of a shame, but perhaps it is just nostalgia on my part, it’s hard to know. Please do let me know if you encounter a query that can still use the Switch operator in 2012 – it must be very bored if this is the only possible modern usage! 2. Invisible Plan Operators The second part of this post uses an example based on a question Dave Ballantyne asked using the SQL Sentry Plan Explorer plan upload facility. If you haven’t tried that yet, make sure you’re on the latest version of the (free) Plan Explorer software, and then click the Post to SQLPerformance.com button. That will create a site question with the query plan attached (which can be anonymized if the plan contains sensitive information). Aaron Bertrand and I keep a close eye on questions there, so if you have ever wanted to ask a query plan question of either of us, that’s a good way to do it. The problem The issue I want to talk about revolves around a query issued against a calendar table. The script below creates a simplified version and adds 100 years of per-day information to it: USE tempdb; GO CREATE TABLE dbo.Calendar ( dt date NOT NULL, isWeekday bit NOT NULL, theYear smallint NOT NULL,   CONSTRAINT PK__dbo_Calendar_dt PRIMARY KEY CLUSTERED (dt) ); GO -- Monday is the first day of the week for me SET DATEFIRST 1;   -- Add 100 years of data INSERT dbo.Calendar WITH (TABLOCKX) (dt, isWeekday, theYear) SELECT CA.dt, isWeekday = CASE WHEN DATEPART(WEEKDAY, CA.dt) IN (6, 7) THEN 0 ELSE 1 END, theYear = YEAR(CA.dt) FROM Sandpit.dbo.Numbers AS N CROSS APPLY ( VALUES (DATEADD(DAY, N.n - 1, CONVERT(date, '01 Jan 2000', 113))) ) AS CA (dt) WHERE N.n BETWEEN 1 AND 36525; The following query counts the number of weekend days in 2013: SELECT Days = COUNT_BIG(*) FROM dbo.Calendar AS C WHERE theYear = 2013 AND isWeekday = 0; It returns the correct result (104) using the following execution plan: The query optimizer has managed to estimate the number of rows returned from the table exactly, based purely on the default statistics created separately on the two columns referenced in the query’s WHERE clause. (Well, almost exactly, the unrounded estimate is 104.289 rows.) There is already an invisible operator in this query plan – a Filter operator used to apply the WHERE clause predicates. We can see it by re-running the query with the enormously useful (but undocumented) trace flag 9130 enabled: Now we can see the full picture. The whole table is scanned, returning all 36,525 rows, before the Filter narrows that down to just the 104 we want. Without the trace flag, the Filter is incorporated in the Clustered Index Scan as a residual predicate. It is a little bit more efficient than using a separate operator, but residual predicates are still something you will want to avoid where possible. The estimates are still spot on though: Anyway, looking to improve the performance of this query, Dave added the following filtered index to the Calendar table: CREATE NONCLUSTERED INDEX Weekends ON dbo.Calendar(theYear) WHERE isWeekday = 0; The original query now produces a much more efficient plan: Unfortunately, the estimated number of rows produced by the seek is now wrong (365 instead of 104): What’s going on? The estimate was spot on before we added the index! Explanation You might want to grab a coffee for this bit. Using another trace flag or two (8606 and 8612) we can see that the cardinality estimates were exactly right initially: The highlighted information shows the initial cardinality estimates for the base table (36,525 rows), the result of applying the two relational selects in our WHERE clause (104 rows), and after performing the COUNT_BIG(*) group by aggregate (1 row). All of these are correct, but that was before cost-based optimization got involved :) Cost-based optimization When cost-based optimization starts up, the logical tree above is copied into a structure (the ‘memo’) that has one group per logical operation (roughly speaking). The logical read of the base table (LogOp_Get) ends up in group 7; the two predicates (LogOp_Select) end up in group 8 (with the details of the selections in subgroups 0-6). These two groups still have the correct cardinalities as trace flag 8608 output (initial memo contents) shows: During cost-based optimization, a rule called SelToIdxStrategy runs on group 8. It’s job is to match logical selections to indexable expressions (SARGs). It successfully matches the selections (theYear = 2013, is Weekday = 0) to the filtered index, and writes a new alternative into the memo structure. The new alternative is entered into group 8 as option 1 (option 0 was the original LogOp_Select): The new alternative is to do nothing (PhyOp_NOP = no operation), but to instead follow the new logical instructions listed below the NOP. The LogOp_GetIdx (full read of an index) goes into group 21, and the LogOp_SelectIdx (selection on an index) is placed in group 22, operating on the result of group 21. The definition of the comparison ‘the Year = 2013’ (ScaOp_Comp downwards) was already present in the memo starting at group 2, so no new memo groups are created for that. New Cardinality Estimates The new memo groups require two new cardinality estimates to be derived. First, LogOp_Idx (full read of the index) gets a predicted cardinality of 10,436. This number comes from the filtered index statistics: DBCC SHOW_STATISTICS (Calendar, Weekends) WITH STAT_HEADER; The second new cardinality derivation is for the LogOp_SelectIdx applying the predicate (theYear = 2013). To get a number for this, the cardinality estimator uses statistics for the column ‘theYear’, producing an estimate of 365 rows (there are 365 days in 2013!): DBCC SHOW_STATISTICS (Calendar, theYear) WITH HISTOGRAM; This is where the mistake happens. Cardinality estimation should have used the filtered index statistics here, to get an estimate of 104 rows: DBCC SHOW_STATISTICS (Calendar, Weekends) WITH HISTOGRAM; Unfortunately, the logic has lost sight of the link between the read of the filtered index (LogOp_GetIdx) in group 22, and the selection on that index (LogOp_SelectIdx) that it is deriving a cardinality estimate for, in group 21. The correct cardinality estimate (104 rows) is still present in the memo, attached to group 8, but that group now has a PhyOp_NOP implementation. Skipping over the rest of cost-based optimization (in a belated attempt at brevity) we can see the optimizer’s final output using trace flag 8607: This output shows the (incorrect, but understandable) 365 row estimate for the index range operation, and the correct 104 estimate still attached to its PhyOp_NOP. This tree still has to go through a few post-optimizer rewrites and ‘copy out’ from the memo structure into a tree suitable for the execution engine. One step in this process removes PhyOp_NOP, discarding its 104-row cardinality estimate as it does so. To finish this section on a more positive note, consider what happens if we add an OVER clause to the query aggregate. This isn’t intended to be a ‘fix’ of any sort, I just want to show you that the 104 estimate can survive and be used if later cardinality estimation needs it: SELECT Days = COUNT_BIG(*) OVER () FROM dbo.Calendar AS C WHERE theYear = 2013 AND isWeekday = 0; The estimated execution plan is: Note the 365 estimate at the Index Seek, but the 104 lives again at the Segment! We can imagine the lost predicate ‘isWeekday = 0’ as sitting between the seek and the segment in an invisible Filter operator that drops the estimate from 365 to 104. Even though the NOP group is removed after optimization (so we don’t see it in the execution plan) bear in mind that all cost-based choices were made with the 104-row memo group present, so although things look a bit odd, it shouldn’t affect the optimizer’s plan selection. I should also mention that we can work around the estimation issue by including the index’s filtering columns in the index key: CREATE NONCLUSTERED INDEX Weekends ON dbo.Calendar(theYear, isWeekday) WHERE isWeekday = 0 WITH (DROP_EXISTING = ON); There are some downsides to doing this, including that changes to the isWeekday column may now require Halloween Protection, but that is unlikely to be a big problem for a static calendar table ;)  With the updated index in place, the original query produces an execution plan with the correct cardinality estimation showing at the Index Seek: That’s all for today, remember to let me know about any Switch plans you come across on a modern instance of SQL Server! Finally, here are some other posts of mine that cover other plan operators: Segment and Sequence Project Common Subexpression Spools Why Plan Operators Run Backwards Row Goals and the Top Operator Hash Match Flow Distinct Top N Sort Index Spools and Page Splits Singleton and Range Seeks Bitmaps Hash Join Performance Compute Scalar © 2013 Paul White – All Rights Reserved Twitter: @SQL_Kiwi

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• Wrapping ASP.NET Client Callbacks

  - by Ricardo Peres

  Client Callbacks are probably the less known (and I dare say, less loved) of all the AJAX options in ASP.NET, which also include the UpdatePanel, Page Methods and Web Services. The reason for that, I believe, is it’s relative complexity: Get a reference to a JavaScript function; Dynamically register function that calls the above reference; Have a JavaScript handler call the registered function. However, it has some the nice advantage of being self-contained, that is, doesn’t need additional files, such as web services, JavaScript libraries, etc, or static methods declared on a page, or any kind of attributes. So, here’s what I want to do: Have a DOM element which exposes a method that is executed server side, passing it a string and returning a string; Have a server-side event that handles the client-side call; Have two client-side user-supplied callback functions for handling the success and error results. I’m going to develop a custom control without user interface that does the registration of the client JavaScript method as well as a server-side event that can be hooked by some handler on a page. My markup will look like this: 1: <script type="text/javascript"> 1:  2:  3: function onCallbackSuccess(result, context) 4: { 5: } 6:  7: function onCallbackError(error, context) 8: { 9: } 10:  </script> 2: <my:CallbackControl runat="server" ID="callback" SendAllData="true" OnCallback="OnCallback"/> The control itself looks like this: 1: public class CallbackControl : Control, ICallbackEventHandler 2: { 3: #region Public constructor 4: public CallbackControl() 5: { 6: this.SendAllData = false; 7: this.Async = true; 8: } 9: #endregion 10:  11: #region Public properties and events 12: public event EventHandler<CallbackEventArgs> Callback; 13:  14: [DefaultValue(true)] 15: public Boolean Async 16: { 17: get; 18: set; 19: } 20:  21: [DefaultValue(false)] 22: public Boolean SendAllData 23: { 24: get; 25: set; 26: } 27:  28: #endregion 29:  30: #region Protected override methods 31:  32: protected override void Render(HtmlTextWriter writer) 33: { 34: writer.AddAttribute(HtmlTextWriterAttribute.Id, this.ClientID); 35: writer.RenderBeginTag(HtmlTextWriterTag.Span); 36:  37: base.Render(writer); 38:  39: writer.RenderEndTag(); 40: } 41:  42: protected override void OnInit(EventArgs e) 43: { 44: String reference = this.Page.ClientScript.GetCallbackEventReference(this, "arg", "onCallbackSuccess", "context", "onCallbackError", this.Async); 45: String script = String.Concat("\ndocument.getElementById('", this.ClientID, "').callback = function(arg, context, onCallbackSuccess, onCallbackError){", ((this.SendAllData == true) ? "__theFormPostCollection.length = 0; __theFormPostData = ''; WebForm_InitCallback(); " : String.Empty), reference, ";};\n"); 46:  47: this.Page.ClientScript.RegisterStartupScript(this.GetType(), String.Concat("callback", this.ClientID), script, true); 48:  49: base.OnInit(e); 50: } 51:  52: #endregion 53:  54: #region Protected virtual methods 55: protected virtual void OnCallback(CallbackEventArgs args) 56: { 57: EventHandler<CallbackEventArgs> handler = this.Callback; 58:  59: if (handler != null) 60: { 61: handler(this, args); 62: } 63: } 64:  65: #endregion 66:  67: #region ICallbackEventHandler Members 68:  69: String ICallbackEventHandler.GetCallbackResult() 70: { 71: CallbackEventArgs args = new CallbackEventArgs(this.Context.Items["Data"] as String); 72:  73: this.OnCallback(args); 74:  75: return (args.Result); 76: } 77:  78: void ICallbackEventHandler.RaiseCallbackEvent(String eventArgument) 79: { 80: this.Context.Items["Data"] = eventArgument; 81: } 82:  83: #endregion 84: } And the event argument class: 1: [Serializable] 2: public class CallbackEventArgs : EventArgs 3: { 4: public CallbackEventArgs(String argument) 5: { 6: this.Argument = argument; 7: this.Result = String.Empty; 8: } 9:  10: public String Argument 11: { 12: get; 13: private set; 14: } 15:  16: public String Result 17: { 18: get; 19: set; 20: } 21: } You will notice two properties on the CallbackControl: Async: indicates if the call should be made asynchronously or synchronously (the default); SendAllData: indicates if the callback call will include the view and control state of all of the controls on the page, so that, on the server side, they will have their properties set when the Callback event is fired. The CallbackEventArgs class exposes two properties: Argument: the read-only argument passed to the client-side function; Result: the result to return to the client-side callback function, set from the Callback event handler. An example of an handler for the Callback event would be: 1: protected void OnCallback(Object sender, CallbackEventArgs e) 2: { 3: e.Result = String.Join(String.Empty, e.Argument.Reverse()); 4: } Finally, in order to fire the Callback event from the client, you only need this: 1: <input type="text" id="input"/> 2: <input type="button" value="Get Result" onclick="document.getElementById('callback').callback(callback(document.getElementById('input').value, 'context', onCallbackSuccess, onCallbackError))"/> The syntax of the callback function is: arg: some string argument; context: some context that will be passed to the callback functions (success or failure); callbackSuccessFunction: some function that will be called when the callback succeeds; callbackFailureFunction: some function that will be called if the callback fails for some reason. Give it a try and see if it helps!

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• C#: Optional Parameters - Pros and Pitfalls

  - by James Michael Hare

  When Microsoft rolled out Visual Studio 2010 with C# 4, I was very excited to learn how I could apply all the new features and enhancements to help make me and my team more productive developers. Default parameters have been around forever in C++, and were intentionally omitted in Java in favor of using overloading to satisfy that need as it was though that having too many default parameters could introduce code safety issues.  To some extent I can understand that move, as I’ve been bitten by default parameter pitfalls before, but at the same time I feel like Java threw out the baby with the bathwater in that move and I’m glad to see C# now has them. This post briefly discusses the pros and pitfalls of using default parameters.  I’m avoiding saying cons, because I really don’t believe using default parameters is a negative thing, I just think there are things you must watch for and guard against to avoid abuses that can cause code safety issues. Pro: Default Parameters Can Simplify Code Let’s start out with positives.  Consider how much cleaner it is to reduce all the overloads in methods or constructors that simply exist to give the semblance of optional parameters.  For example, we could have a Message class defined which allows for all possible initializations of a Message: 1: public class Message 2: { 3: // can either cascade these like this or duplicate the defaults (which can introduce risk) 4: public Message() 5: : this(string.Empty) 6: { 7: } 8:  9: public Message(string text) 10: : this(text, null) 11: { 12: } 13:  14: public Message(string text, IDictionary<string, string> properties) 15: : this(text, properties, -1) 16: { 17: } 18:  19: public Message(string text, IDictionary<string, string> properties, long timeToLive) 20: { 21: // ... 22: } 23: }   Now consider the same code with default parameters: 1: public class Message 2: { 3: // can either cascade these like this or duplicate the defaults (which can introduce risk) 4: public Message(string text = "", IDictionary<string, string> properties = null, long timeToLive = -1) 5: { 6: // ... 7: } 8: }   Much more clean and concise and no repetitive coding!  In addition, in the past if you wanted to be able to cleanly supply timeToLive and accept the default on text and properties above, you would need to either create another overload, or pass in the defaults explicitly.  With named parameters, though, we can do this easily: 1: var msg = new Message(timeToLive: 100);   Pro: Named Parameters can Improve Readability I must say one of my favorite things with the default parameters addition in C# is the named parameters.  It lets code be a lot easier to understand visually with no comments.  Think how many times you’ve run across a TimeSpan declaration with 4 arguments and wondered if they were passing in days/hours/minutes/seconds or hours/minutes/seconds/milliseconds.  A novice running through your code may wonder what it is.  Named arguments can help resolve the visual ambiguity: 1: // is this days/hours/minutes/seconds (no) or hours/minutes/seconds/milliseconds (yes) 2: var ts = new TimeSpan(1, 2, 3, 4); 3:  4: // this however is visually very explicit 5: var ts = new TimeSpan(days: 1, hours: 2, minutes: 3, seconds: 4);   Or think of the times you’ve run across something passing a Boolean literal and wondered what it was: 1: // what is false here? 2: var sub = CreateSubscriber(hostname, port, false); 3:  4: // aha! Much more visibly clear 5: var sub = CreateSubscriber(hostname, port, isBuffered: false);   Pitfall: Don't Insert new Default Parameters In Between Existing Defaults Now let’s consider a two potential pitfalls.  The first is really an abuse.  It’s not really a fault of the default parameters themselves, but a fault in the use of them.  Let’s consider that Message constructor again with defaults.  Let’s say you want to add a messagePriority to the message and you think this is more important than a timeToLive value, so you decide to put messagePriority before it in the default, this gives you: 1: public class Message 2: { 3: public Message(string text = "", IDictionary<string, string> properties = null, int priority = 5, long timeToLive = -1) 4: { 5: // ... 6: } 7: }   Oh boy have we set ourselves up for failure!  Why?  Think of all the code out there that could already be using the library that already specified the timeToLive, such as this possible call: 1: var msg = new Message(“An error occurred”, myProperties, 1000);   Before this specified a message with a TTL of 1000, now it specifies a message with a priority of 1000 and a time to live of -1 (infinite).  All of this with NO compiler errors or warnings. So the rule to take away is if you are adding new default parameters to a method that’s currently in use, make sure you add them to the end of the list or create a brand new method or overload. Pitfall: Beware of Default Parameters in Inheritance and Interface Implementation Now, the second potential pitfalls has to do with inheritance and interface implementation.  I’ll illustrate with a puzzle: 1: public interface ITag 2: { 3: void WriteTag(string tagName = "ITag"); 4: } 5:  6: public class BaseTag : ITag 7: { 8: public virtual void WriteTag(string tagName = "BaseTag") { Console.WriteLine(tagName); } 9: } 10:  11: public class SubTag : BaseTag 12: { 13: public override void WriteTag(string tagName = "SubTag") { Console.WriteLine(tagName); } 14: } 15:  16: public static class Program 17: { 18: public static void Main() 19: { 20: SubTag subTag = new SubTag(); 21: BaseTag subByBaseTag = subTag; 22: ITag subByInterfaceTag = subTag; 23:  24: // what happens here? 25: subTag.WriteTag(); 26: subByBaseTag.WriteTag(); 27: subByInterfaceTag.WriteTag(); 28: } 29: }   What happens?  Well, even though the object in each case is SubTag whose tag is “SubTag”, you will get: 1: SubTag 2: BaseTag 3: ITag   Why?  Because default parameter are resolved at compile time, not runtime!  This means that the default does not belong to the object being called, but by the reference type it’s being called through.  Since the SubTag instance is being called through an ITag reference, it will use the default specified in ITag. So the moral of the story here is to be very careful how you specify defaults in interfaces or inheritance hierarchies.  I would suggest avoiding repeating them, and instead concentrating on the layer of classes or interfaces you must likely expect your caller to be calling from. For example, if you have a messaging factory that returns an IMessage which can be either an MsmqMessage or JmsMessage, it only makes since to put the defaults at the IMessage level since chances are your user will be using the interface only. So let’s sum up.  In general, I really love default and named parameters in C# 4.0.  I think they’re a great tool to help make your code easier to read and maintain when used correctly. On the plus side, default parameters: Reduce redundant overloading for the sake of providing optional calling structures. Improve readability by being able to name an ambiguous argument. But remember to make sure you: Do not insert new default parameters in the middle of an existing set of default parameters, this may cause unpredictable behavior that may not necessarily throw a syntax error – add to end of list or create new method. Be extremely careful how you use default parameters in inheritance hierarchies and interfaces – choose the most appropriate level to add the defaults based on expected usage. Technorati Tags: C#,.NET,Software,Default Parameters

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• Gnome Do not Launching

  - by PyRulez

  When I try running gnome do, I get this. chris@Chris-Ubuntu-Laptop:~$ gnome-do pgrep: invalid user name: -u and it is not writable Trying sudo: chris@Chris-Ubuntu-Laptop:~$ sudo gnome-do [NetworkService] Could not initialize Network Manager dbus: Unable to open the session message bus. [Error 17:54:30.122] [SystemService] Could not initialize dbus: Unable to open the session message bus. (Do:2401): Wnck-CRITICAL **: wnck_set_client_type got called multiple times. (Do:2401): libdo-WARNING **: Binding '<Super>space' failed! [Error 17:54:30.649] [AbstractKeyBindingService] Key "" is already mapped. Tomboy.NotesItemSource "Tomboy Notes" encountered an error in UpdateItems: System.TypeInitializationException: An exception was thrown by the type initializer for Tomboy.TomboyDBus ---> System.Exception: Unable to open the session message bus. ---> System.ArgumentNullException: Argument cannot be null. Parameter name: address at NDesk.DBus.Bus.Open (System.String address) [0x00000] in <filename unknown>:0 at NDesk.DBus.Bus.get_Session () [0x00000] in <filename unknown>:0 --- End of inner exception stack trace --- at NDesk.DBus.Bus.get_Session () [0x00000] in <filename unknown>:0 at Tomboy.TomboyDBus..cctor () [0x00000] in <filename unknown>:0 --- End of inner exception stack trace --- at Tomboy.NotesItemSource.UpdateItems () [0x00000] in <filename unknown>:0 at Do.Universe.Safe.SafeItemSource.UpdateItems () [0x00000] in <filename unknown>:0 . Firefox.PlacesItemSource "Firefox Places" encountered an error in UpdateItems: System.InvalidCastException: Cannot cast from source type to destination type. at Mono.Data.Sqlite.SqliteDataReader.VerifyType (Int32 i, DbType typ) [0x00000] in <filename unknown>:0 at Mono.Data.Sqlite.SqliteDataReader.GetString (Int32 i) [0x00000] in <filename unknown>:0 at Firefox.PlacesItemSource+<LoadPlaceItems>c__Iterator3.MoveNext () [0x00000] in <filename unknown>:0 at System.Collections.Generic.List`1[Firefox.PlaceItem].AddEnumerable (IEnumerable`1 enumerable) [0x00000] in <filename unknown>:0 at System.Collections.Generic.List`1[Firefox.PlaceItem]..ctor (IEnumerable`1 collection) [0x00000] in <filename unknown>:0 at System.Linq.Enumerable.ToArray[PlaceItem] (IEnumerable`1 source) [0x00000] in <filename unknown>:0 at Firefox.PlacesItemSource.UpdateItems () [0x00000] in <filename unknown>:0 at Do.Universe.Safe.SafeItemSource.UpdateItems () [0x00000] in <filename unknown>:0 . Do.Universe.Linux.GNOMESpecialLocationsItemSource "GNOME Special Locations" encountered an error in UpdateItems: System.IO.FileNotFoundException: Could not find file "/root/.gtk-bookmarks". File name: '/root/.gtk-bookmarks' at System.IO.FileStream..ctor (System.String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize, Boolean anonymous, FileOptions options) [0x00000] in <filename unknown>:0 at System.IO.FileStream..ctor (System.String path, FileMode mode, FileAccess access, FileShare share) [0x00000] in <filename unknown>:0 at (wrapper remoting-invoke-with-check) System.IO.FileStream:.ctor (string,System.IO.FileMode,System.IO.FileAccess,System.IO.FileShare) at System.IO.File.OpenRead (System.String path) [0x00000] in <filename unknown>:0 at System.IO.StreamReader..ctor (System.String path, System.Text.Encoding encoding, Boolean detectEncodingFromByteOrderMarks, Int32 bufferSize) [0x00000] in <filename unknown>:0 at System.IO.StreamReader..ctor (System.String path) [0x00000] in <filename unknown>:0 at (wrapper remoting-invoke-with-check) System.IO.StreamReader:.ctor (string) at Do.Universe.Linux.GNOMESpecialLocationsItemSource+<ReadBookmarkItems>c__Iterator3.MoveNext () [0x00000] in <filename unknown>:0 at Do.Universe.Linux.GNOMESpecialLocationsItemSource.UpdateItems () [0x00000] in <filename unknown>:0 at Do.Universe.Safe.SafeItemSource.UpdateItems () [0x00000] in <filename unknown>:0 . ^[^\Full thread dump: "<unnamed thread>" tid=0x0xb7570700 this=0x0x56f18 thread handle 0x403 state : not waiting owns () at (wrapper managed-to-native) Mono.Unix.Native.Syscall.read (int,intptr,ulong) <0xffffffff> at Mono.Unix.Native.Syscall.read (int,void*,ulong) <0x00023> at Mono.Unix.UnixStream.Read (byte[],int,int) <0x0008b> at NDesk.DBus.Connection.ReadMessage () <0x0003c> at NDesk.DBus.Connection.Iterate () <0x0001b> at NDesk.DBus.BusG/<Init>c__AnonStorey0.<>m__0 (intptr,NDesk.GLib.IOCondition,intptr) <0x00033> at (wrapper native-to-managed) NDesk.DBus.BusG/<Init>c__AnonStorey0.<>m__0 (intptr,NDesk.GLib.IOCondition,intptr) <0xffffffff> at (wrapper managed-to-native) Gtk.Clipboard.gtk_clipboard_wait_is_text_available (intptr) <0xffffffff> at Gtk.Clipboard.WaitIsTextAvailable () <0x00017> at Do.Universe.SelectedTextItem.UpdateSelection (object,System.EventArgs) <0x00027> at Do.Platform.AbstractApplicationService.OnSummoned () <0x00025> at Do.Platform.ApplicationService.<ApplicationService>m__31 (object,System.EventArgs) <0x00013> at Do.Core.Controller.OnSummoned () <0x00025> at Do.Core.Controller.Summon () <0x00027> at Do.Do.Main (string[]) <0x001eb> at (wrapper runtime-invoke) <Module>.runtime_invoke_void_object (object,intptr,intptr,intptr) <0xffffffff> "<unnamed thread>" tid=0x0xb2c81b40 this=0x0x194150 thread handle 0x412 state : interrupted state owns () at (wrapper managed-to-native) System.IO.InotifyWatcher.ReadFromFD (intptr,byte[],intptr) <0xffffffff> at System.IO.InotifyWatcher.Monitor () <0x0005f> at System.Threading.Thread.StartInternal () <0x00057> at (wrapper runtime-invoke) object.runtime_invoke_void__this__ (object,intptr,intptr,intptr) <0xffffffff> "Universe Update Dispatcher" tid=0x0xb29ffb40 this=0x0x569d8 thread handle 0x41b state : interrupted state owns () at (wrapper managed-to-native) System.Threading.WaitHandle.WaitOne_internal (System.Threading.WaitHandle,intptr,int,bool) <0xffffffff> at System.Threading.WaitHandle.WaitOne (System.TimeSpan,bool) <0x00133> at System.Threading.WaitHandle.WaitOne (System.TimeSpan) <0x00022> at Do.Core.UniverseManager.UniverseUpdateLoop () <0x0007a> at System.Threading.Thread.StartInternal () <0x00057> at (wrapper runtime-invoke) object.runtime_invoke_void__this__ (object,intptr,intptr,intptr) <0xffffffff> Tomboy.NotesItemSource "Tomboy Notes" encountered an error in UpdateItems: System.TypeInitializationException: An exception was thrown by the type initializer for Tomboy.TomboyDBus ---> System.Exception: Unable to open the session message bus. ---> System.ArgumentNullException: Argument cannot be null. Parameter name: address at NDesk.DBus.Bus.Open (System.String address) [0x00000] in <filename unknown>:0 at NDesk.DBus.Bus.get_Session () [0x00000] in <filename unknown>:0 --- End of inner exception stack trace --- at NDesk.DBus.Bus.get_Session () [0x00000] in <filename unknown>:0 at Tomboy.TomboyDBus..cctor () [0x00000] in <filename unknown>:0 --- End of inner exception stack trace --- at Tomboy.NotesItemSource.UpdateItems () [0x00000] in <filename unknown>:0 at Do.Universe.Safe.SafeItemSource.UpdateItems () [0x00000] in <filename unknown>:0 . Firefox.PlacesItemSource "Firefox Places" encountered an error in UpdateItems: System.InvalidCastException: Cannot cast from source type to destination type. at Mono.Data.Sqlite.SqliteDataReader.VerifyType (Int32 i, DbType typ) [0x00000] in <filename unknown>:0 at Mono.Data.Sqlite.SqliteDataReader.GetString (Int32 i) [0x00000] in <filename unknown>:0 at Firefox.PlacesItemSource+<LoadPlaceItems>c__Iterator3.MoveNext () [0x00000] in <filename unknown>:0 at System.Collections.Generic.List`1[Firefox.PlaceItem].AddEnumerable (IEnumerable`1 enumerable) [0x00000] in <filename unknown>:0 at System.Collections.Generic.List`1[Firefox.PlaceItem]..ctor (IEnumerable`1 collection) [0x00000] in <filename unknown>:0 at System.Linq.Enumerable.ToArray[PlaceItem] (IEnumerable`1 source) [0x00000] in <filename unknown>:0 at Firefox.PlacesItemSource.UpdateItems () [0x00000] in <filename unknown>:0 at Do.Universe.Safe.SafeItemSource.UpdateItems () [0x00000] in <filename unknown>:0 . Do.Universe.Linux.GNOMESpecialLocationsItemSource "GNOME Special Locations" encountered an error in UpdateItems: System.IO.FileNotFoundException: Could not find file "/root/.gtk-bookmarks". File name: '/root/.gtk-bookmarks' at System.IO.FileStream..ctor (System.String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize, Boolean anonymous, FileOptions options) [0x00000] in <filename unknown>:0 at System.IO.FileStream..ctor (System.String path, FileMode mode, FileAccess access, FileShare share) [0x00000] in <filename unknown>:0 at (wrapper remoting-invoke-with-check) System.IO.FileStream:.ctor (string,System.IO.FileMode,System.IO.FileAccess,System.IO.FileShare) at System.IO.File.OpenRead (System.String path) [0x00000] in <filename unknown>:0 at System.IO.StreamReader..ctor (System.String path, System.Text.Encoding encoding, Boolean detectEncodingFromByteOrderMarks, Int32 bufferSize) [0x00000] in <filename unknown>:0 at System.IO.StreamReader..ctor (System.String path) [0x00000] in <filename unknown>:0 at (wrapper remoting-invoke-with-check) System.IO.StreamReader:.ctor (string) at Do.Universe.Linux.GNOMESpecialLocationsItemSource+<ReadBookmarkItems>c__Iterator3.MoveNext () [0x00000] in <filename unknown>:0 at Do.Universe.Linux.GNOMESpecialLocationsItemSource.UpdateItems () [0x00000] in <filename unknown>:0 at Do.Universe.Safe.SafeItemSource.UpdateItems () [0x00000] in <filename unknown>:0 . It stops when I try my key combination, ctrl-alt-. It does not pop up though.

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• Anatomy of a .NET Assembly - Custom attribute encoding

  - by Simon Cooper

  In my previous post, I covered how field, method, and other types of signatures are encoded in a .NET assembly. Custom attribute signatures differ quite a bit from these, which consequently affects attribute specifications in C#. Custom attribute specifications In C#, you can apply a custom attribute to a type or type member, specifying a constructor as well as the values of fields or properties on the attribute type: public class ExampleAttribute : Attribute { public ExampleAttribute(int ctorArg1, string ctorArg2) { ... } public Type ExampleType { get; set; } } [Example(5, "6", ExampleType = typeof(string))] public class C { ... } How does this specification actually get encoded and stored in an assembly? Specification blob values Custom attribute specification signatures use the same building blocks as other types of signatures; the ELEMENT_TYPE structure. However, they significantly differ from other types of signatures, in that the actual parameter values need to be stored along with type information. There are two types of specification arguments in a signature blob; fixed args and named args. Fixed args are the arguments to the attribute type constructor, named arguments are specified after the constructor arguments to provide a value to a field or property on the constructed attribute type (PropertyName = propValue) Values in an attribute blob are limited to one of the basic types (one of the number types, character, or boolean), a reference to a type, an enum (which, in .NET, has to use one of the integer types as a base representation), or arrays of any of those. Enums and the basic types are easy to store in a blob - you simply store the binary representation. Strings are stored starting with a compressed integer indicating the length of the string, followed by the UTF8 characters. Array values start with an integer indicating the number of elements in the array, then the item values concatentated together. Rather than using a coded token, Type values are stored using a string representing the type name and fully qualified assembly name (for example, MyNs.MyType, MyAssembly, Version=1.0.0.0, Culture=neutral, PublicKeyToken=0123456789abcdef). If the type is in the current assembly or mscorlib then just the type name can be used. This is probably done to prevent direct references between assemblies solely because of attribute specification arguments; assemblies can be loaded in the reflection-only context and attribute arguments still processed, without loading the entire assembly. Fixed and named arguments Each entry in the CustomAttribute metadata table contains a reference to the object the attribute is applied to, the attribute constructor, and the specification blob. The number and type of arguments to the constructor (the fixed args) can be worked out by the method signature referenced by the attribute constructor, and so the fixed args can simply be concatenated together in the blob without any extra type information. Named args are different. These specify the value to assign to a field or property once the attribute type has been constructed. In the CLR, fields and properties can be overloaded just on their type; different fields and properties can have the same name. Therefore, to uniquely identify a field or property you need: Whether it's a field or property (indicated using byte values 0x53 and 0x54, respectively) The field or property type The field or property name After the fixed arg values is a 2-byte number specifying the number of named args in the blob. Each named argument has the above information concatenated together, mostly using the basic ELEMENT_TYPE values, in the same way as a method or field signature. A Type argument is represented using the byte 0x50, and an enum argument is represented using the byte 0x55 followed by a string specifying the name and assembly of the enum type. The named argument property information is followed by the argument value, using the same encoding as fixed args. Boxed objects This would be all very well, were it not for object and object[]. Arguments and properties of type object allow a value of any allowed argument type to be specified. As a result, more information needs to be specified in the blob to interpret the argument bytes as the correct type. So, the argument value is simple prepended with the type of the value by specifying the ELEMENT_TYPE or name of the enum the value represents. For named arguments, a field or property of type object is represented using the byte 0x51, with the actual type specified in the argument value. Some examples... All property signatures start with the 2-byte value 0x0001. Similar to my previous post in the series, names in capitals correspond to a particular byte value in the ELEMENT_TYPE structure. For strings, I'll simply give the string value, rather than the length and UTF8 encoding in the actual blob. I'll be using the following enum and attribute types to demonstrate specification encodings: class AttrAttribute : Attribute { public AttrAttribute() {} public AttrAttribute(Type[] tArray) {} public AttrAttribute(object o) {} public AttrAttribute(MyEnum e) {} public AttrAttribute(ushort x, int y) {} public AttrAttribute(string str, Type type1, Type type2) {} public int Prop1 { get; set; } public object Prop2 { get; set; } public object[] ObjectArray; } enum MyEnum : int { Val1 = 1, Val2 = 2 } Now, some examples: Here, the the specification binds to the (ushort, int) attribute constructor, with fixed args only. The specification blob starts off with a prolog, followed by the two constructor arguments, then the number of named arguments (zero): [Attr(42, 84)] 0x0001 0x002a 0x00000054 0x0000 An example of string and type encoding: [Attr("MyString", typeof(Array), typeof(System.Windows.Forms.Form))] 0x0001 "MyString" "System.Array" "System.Windows.Forms.Form, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" 0x0000 As you can see, the full assembly specification of a type is only needed if the type isn't in the current assembly or mscorlib. Note, however, that the C# compiler currently chooses to fully-qualify mscorlib types anyway. An object argument (this binds to the object attribute constructor), and two named arguments (a null string is represented by 0xff and the empty string by 0x00) [Attr((ushort)40, Prop1 = 12, Prop2 = "")] 0x0001 U2 0x0028 0x0002 0x54 I4 "Prop1" 0x0000000c 0x54 0x51 "Prop2" STRING 0x00 Right, more complicated now. A type array as a fixed argument: [Attr(new[] { typeof(string), typeof(object) })] 0x0001 0x00000002 // the number of elements "System.String" "System.Object" 0x0000 An enum value, which is simply represented using the underlying value. The CLR works out that it's an enum using information in the attribute constructor signature: [Attr(MyEnum.Val1)] 0x0001 0x00000001 0x0000 And finally, a null array, and an object array as a named argument: [Attr((Type[])null, ObjectArray = new object[] { (byte)2, typeof(decimal), null, MyEnum.Val2 })] 0x0001 0xffffffff 0x0001 0x53 SZARRAY 0x51 "ObjectArray" 0x00000004 U1 0x02 0x50 "System.Decimal" STRING 0xff 0x55 "MyEnum" 0x00000002 As you'll notice, a null object is encoded as a null string value, and a null array is represented using a length of -1 (0xffffffff). How does this affect C#? So, we can now explain why the limits on attribute arguments are so strict in C#. Attribute specification blobs are limited to basic numbers, enums, types, and arrays. As you can see, this is because the raw CLR encoding can only accommodate those types. Special byte patterns have to be used to indicate object, string, Type, or enum values in named arguments; you can't specify an arbitary object type, as there isn't a generalised way of encoding the resulting value in the specification blob. In particular, decimal values can't be encoded, as it isn't a 'built-in' CLR type that has a native representation (you'll notice that decimal constants in C# programs are compiled as several integer arguments to DecimalConstantAttribute). Jagged arrays also aren't natively supported, although you can get around it by using an array as a value to an object argument: [Attr(new object[] { new object[] { new Type[] { typeof(string) } }, 42 })] Finally... Phew! That was a bit longer than I thought it would be. Custom attribute encodings are complicated! Hopefully this series has been an informative look at what exactly goes on inside a .NET assembly. In the next blog posts, I'll be carrying on with the 'Inside Red Gate' series.

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• Running Multiple Queries in Oracle SQL Developer

  - by thatjeffsmith

  There are two methods for running queries in SQL Developer: Run Statement Run Statement, Shift+Enter, F9, or this button Run Script No grids, just script (SQL*Plus like) ouput is fine, thank you very much! What’s the Difference? There are some obvious differences between the two features, the most obvious being the format of the output delivered. But there are some other, more subtle differences here, primarily around fetching. What is Fetch? After you run send your query to Oracle, it has to do 3 things: Parse Execute Fetch Technically it has to do at least 2 things, and sometimes only 1. But, to get the data back to the user, the fetch must occur. If you have a 10 row query or a 1,000,000 row query, this can mean 1 or many fetches in groups of records. Ok, before I went on the Fetch tangent, I said there were two ways to run statements in SQL Developer: Run Statement Run statement brings your query results to a grid with a single fetch. The user sees 50, 100, 500, etc rows come back, but SQL Developer and the database know that there are more rows waiting to be retrieved. The process on the server that was used to execute the query is still hanging around too. To alleviate this, increase your fetch size to 500. Every query ran will come back with the first 500 rows, and rows will be continued to be fetched in 500 row increments. You’ll then see most of your ad hoc queries complete with a single fetch. Scroll down, or hit Ctrl+End to force a full fetch and get all your rows back. Run Script Run Script runs the contents of the worksheet (or what’s highlighted) as a ‘script.’ What does that mean exactly? Think of this as being equivalent to running this in SQL*Plus: @my_script.sql; Each statement is executed. Also, ALL rows are fetched. So once it’s finished executing, there are no open cursors left around. The more obvious difference here is that the output comes back formatted as plain old text. Run one or more commands plus SQL*Plus commands like SET and SPOOL The Trick: Run Statement Works With Multiple Statements! It says ‘run statement,’ but if you select more than one with your mouse and hit the button – it will run each and throw the results to 1 grid for each statement. If you mouse hover over the Query Result panel tab, SQL Developer will tell you the query used to populate that grid. This will work regardless of what you have this preference set to: DATABASE – WORKSHEET – SHOW QUERY RESULTS IN NEW TABS Mind the fetch though! Close those cursors by bring back all the records or closing the grids when you’re done with them.

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• Retreiving upcoming calendar events from a Google Calendar

  - by brian_ritchie

  Google has a great cloud-based calendar service that is part of their Gmail product.  Besides using it as a personal calendar, you can use it to store events for display on your web site.  The calendar is accessible through Google's GData API for which they provide a C# SDK. Here's some code to retrieve the upcoming entries from the calendar:  .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: Consolas, "Courier New", Courier, Monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } 1: public class CalendarEvent 2: { 3: public string Title { get; set; } 4: public DateTime StartTime { get; set; } 5: } 6:   7: public class CalendarHelper 8: { 9: public static CalendarEvent[] GetUpcomingCalendarEvents 10: (int numberofEvents) 11: { 12: CalendarService service = new CalendarService("youraccount"); 13: EventQuery query = new EventQuery(); 14: query.Uri = new Uri( 15: "http://www.google.com/calendar/feeds/userid/public/full"); 16: query.FutureEvents = true; 17: query.SingleEvents = true; 18: query.SortOrder = CalendarSortOrder.ascending; 19: query.NumberToRetrieve = numberofEvents; 20: query.ExtraParameters = "orderby=starttime"; 21: var events = service.Query(query); 22: return (from e in events.Entries select new CalendarEvent() 23: { StartTime=(e as EventEntry).Times[0].StartTime, 24: Title = e.Title.Text }).ToArray(); 25: } 26: } There are a few special "tricks" to make this work: "SingleEvents" flag will flatten out reoccurring events "FutureEvents", "SortOrder", and the "orderby" parameters will get the upcoming events. "NumberToRetrieve" will limit the amount coming back  I then using Linq to Objects to put the results into my own DTO for use by my model.  It is always a good idea to place data into your own DTO for use within your MVC model.  This protects the rest of your code from changes to the underlying calendar source or API.

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• Use Expressions with LINQ to Entities

  - by EltonStoneman

  [Source: http://geekswithblogs.net/EltonStoneman] Recently I've been putting together a generic approach for paging the response from a WCF service. Paging changes the service signature, so it's not as simple as adding a behavior to an existing service in config, but the complexity of the paging is isolated in a generic base class. We're using the Entity Framework talking to SQL Server, so when we ask for a page using LINQ's .Take() method we get a nice efficient SQL query for just the rows we want, with minimal impact on SQL Server and network traffic. We use the maximum ID of the record returned as a high-water mark (rather than using .Skip() to go to the next record), so the approach caters for records being deleted between page requests. In the paged response we include a HasMorePages indicator, computed by comparing the max ID in the page of results to the max ID for the whole resultset - if the latter is bigger, then there are more pages. In some quick performance testing, the paged version of the service performed much more slowly than the unpaged version, which was unexpected. We narrowed it down to the code which gets the max ID for the full resultset - instead of building an efficient MAX() SQL query, EF was returning the whole resultset and then computing the max ID in the service layer. It's easy to reproduce - take this AdventureWorks query:             var context = new AdventureWorksEntities();             var query = from od in context.SalesOrderDetail                         where od.ModifiedDate >= modified                          && od.SalesOrderDetailID.CompareTo(id) > 0                         orderby od.SalesOrderDetailID                         select od;   We can find the maximum SalesOrderDetailID like this:             var maxIdEfficiently = query.Max(od => od.SalesOrderDetailID);   which produces our efficient MAX() SQL query. If we're doing this generically and we already have the ID function in a Func:             Func<SalesOrderDetail, int> idFunc = od => od.SalesOrderDetailID;             var maxIdInefficiently = query.Max(idFunc);   This fetches all the results from the query and then runs the Max() function in code. If you look at the difference in Reflector, the first call passes an Expression to the Max(), while the second call passes a Func. So it's an easy fix - wrap the Func in an Expression:             Expression<Func<SalesOrderDetail, int>> idExpression = od => od.SalesOrderDetailID;             var maxIdEfficientlyAgain = query.Max(idExpression);   - and we're back to running an efficient MAX() statement. Evidently the EF provider can dissect an Expression and build its equivalent in SQL, but it can't do that with Funcs.

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• Synchronized Property Changes (Part 4)

  - by Geertjan

  The next step is to activate the undo/redo functionality... for a Node. Something I've not seen done before. I.e., when the Node is renamed via F2 on the Node, the "Undo/Redo" buttons should start working. Here is the start of the solution, via this item in the mailing list and Timon Veenstra's BeanNode class, note especially the items in bold: public class ShipNode extends BeanNode implements PropertyChangeListener, UndoRedo.Provider { private final InstanceContent ic; private final ShipSaveCapability saveCookie; private UndoRedo.Manager manager; private String oldDisplayName; private String newDisplayName; private Ship ship; public ShipNode(Ship bean) throws IntrospectionException { this(bean, new InstanceContent()); } private ShipNode(Ship bean, InstanceContent ic) throws IntrospectionException { super(bean, Children.LEAF, new ProxyLookup(new AbstractLookup(ic), Lookups.singleton(bean))); this.ic = ic; setDisplayName(bean.getType()); setShortDescription(String.valueOf(bean.getYear())); saveCookie = new ShipSaveCapability(bean); bean.addPropertyChangeListener(WeakListeners.propertyChange(this, bean)); } @Override public Action[] getActions(boolean context) { List<? extends Action> shipActions = Utilities.actionsForPath("Actions/Ship"); return shipActions.toArray(new Action[shipActions.size()]); } protected void fire(boolean modified) { if (modified) { ic.add(saveCookie); } else { ic.remove(saveCookie); } } @Override public UndoRedo getUndoRedo() { manager = Lookup.getDefault().lookup( UndoRedo.Manager.class); return manager; } private class ShipSaveCapability implements SaveCookie { private final Ship bean; public ShipSaveCapability(Ship bean) { this.bean = bean; } @Override public void save() throws IOException { StatusDisplayer.getDefault().setStatusText("Saving..."); fire(false); } } @Override public boolean canRename() { return true; } @Override public void setName(String newDisplayName) { Ship c = getLookup().lookup(Ship.class); oldDisplayName = c.getType(); c.setType(newDisplayName); fireNameChange(oldDisplayName, newDisplayName); fire(true); fireUndoableEvent("type", ship, oldDisplayName, newDisplayName); } public void fireUndoableEvent(String property, Ship source, Object oldValue, Object newValue) { ReUndoableEdit reUndoableEdit = new ReUndoableEdit( property, source, oldValue, newValue); UndoableEditEvent undoableEditEvent = new UndoableEditEvent( this, reUndoableEdit); manager.undoableEditHappened(undoableEditEvent); } private class ReUndoableEdit extends AbstractUndoableEdit { private Object oldValue; private Object newValue; private Ship source; private String property; public ReUndoableEdit(String property, Ship source, Object oldValue, Object newValue) { super(); this.oldValue = oldValue; this.newValue = newValue; this.source = source; this.property = property; } @Override public void undo() throws CannotUndoException { setName(oldValue.toString()); } @Override public void redo() throws CannotRedoException { setName(newValue.toString()); } } @Override public String getDisplayName() { Ship c = getLookup().lookup(Ship.class); if (null != c.getType()) { return c.getType(); } return super.getDisplayName(); } @Override public String getShortDescription() { Ship c = getLookup().lookup(Ship.class); if (null != String.valueOf(c.getYear())) { return String.valueOf(c.getYear()); } return super.getShortDescription(); } @Override public void propertyChange(PropertyChangeEvent evt) { if (evt.getPropertyName().equals("type")) { String oldDisplayName = evt.getOldValue().toString(); String newDisplayName = evt.getNewValue().toString(); fireDisplayNameChange(oldDisplayName, newDisplayName); } else if (evt.getPropertyName().equals("year")) { String oldToolTip = evt.getOldValue().toString(); String newToolTip = evt.getNewValue().toString(); fireShortDescriptionChange(oldToolTip, newToolTip); } fire(true); } } Undo works when rename is done, but Redo never does, because Undo is constantly activated, since it is reactivated whenever there is a name change. And why must the UndoRedoManager be retrieved from the Lookup (it doesn't work otherwise)? Don't get that part of the code either. Help welcome!

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• Allow connections to only a specific URL via HTTPS with iptables, -m recent (potentially) and -m string (definitely)

  - by The Consumer

  Hello, Let's say that, for example, I want to allow connections only to subdomain.mydomain.com; I have it partially working, but it sometimes gets in a freaky loop with the client key exchange once the Client Hello is allowed. Ah, to make it even more annoying, it's a self-signed certificate, and the page requires authentication, and HTTPS is listening on a non-standard port... So the TCP/SSL Handshake experience will differ greatly for many users. Is -m recent the right route? Is there a more graceful method to allow the complete TCP stream once the string is seen? Here's what I have so far: #iptables -N SSL #iptables -A INPUT -i eth0 -p tcp -j SSL #iptables -A SSL -m recent --set -p tcp --syn --dport 400 #iptables -A SSL -m recent --update -p tcp --tcp-flags PSH,SYN,ACK SYN,ACK --sport 400 #iptables -A SSL -m recent --update -p tcp --tcp-flags PSH,SYN,ACK ACK --dport 400 #iptables -A SSL -m recent --remove -p tcp --tcp-flags PSH,ACK PSH,ACK --dport 400 -m string --algo kmp --string "subdomain.mydomain.com" -j ACCEPT Yes, I have tried to get around this with nginx tweaks, but I can't get nginx to return a 444 or abrupt disconnect before the client hello, if you can think of a way to achieve this instead, I'm all ears, err, eyes. (As suggested by a user, bringing this inquiry over from http://stackoverflow.com/questions/4628157/allow-connections-to-only-a-specific-url-via-https-with-iptables-m-recent-pote)

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• Starting php-cgi at boot on mac os x 10.6.8

  - by nikhil

  I'm new to mac os, I have installed and configured nginx with php-fastcgi. I need to run this command in a terminal and keep that terminal open to access php files from my browser. php-cgi -b 127.0.0.1:9000 -q Here's the plist that I wrote by looking up sources on the internet <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd"> <plist version="1.0"> <dict> <key>Debug</key> <false/> <key>EnvironmentVariables</key> <dict> <key>PHP_FCGI_CHILDREN</key> <string>2</string> <key>PHP_FCGI_MAX_REQUESTS</key> <string>1000</string> </dict> <key>RunAtLoad</key> <true/> <key>KeepAlive</key> <true/> <key>UserName</key> <string>nikhil</string> <key>Label</key> <string>php-fastcgi</string> <key>ProgramArguments</key> <array> <string>/usr/bin/php-cgi</string> <string>-b 127.0.0.1:9000</string> <string>-q</string> </array> </dict> </plist> I'm loading it using launchctl load -w ~/Library/LaunchAgents/php-fastcgi.plist without any success, can anyone tell me how this can be done.

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