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  • Complex SQL Query similar to a z order problem

    - by AaronLS
    I have a complex SQL problem in MS SQL Server, and in drawing on a piece of paper I realized that I could think of it as a single bar filled with rectangles, each rectangle having segments with different Z orders. In reality it has nothing to do with z order or graphics at all, but more to do with some complex business rules that would be difficult to explain. Howoever, if anyone has ideas on how to solve the below that will give me my solution. I have the following data: ObjectID, PercentOfBar, ZOrder (where smaller is closer) A, 100, 6 B, 50, 5 B, 50, 4 C, 30, 3 C, 70, 6 The result of my query that I want is this, in any order: PercentOfBar, ZOrder 50, 5 20, 4 30, 3 Think of it like this, if I drew rectangle A, it would fill 100% of the bar and have a z order of 6. 66666666666 AAAAAAAAAAA If I then layed out rectangle B, consisting of two segments, both segments would cover up rectangle A resulting in the following rendering: 4444455555 BBBBBBBBBB As a rule of thumb, for a given rectangle, it's segments should be layed out such that the highest z order is to the right of the lower Z orders. Finally rectangle C would cover up only portions of Rectangle B with it's 30% segment that is z order 3, which would be on the left. You can hopefully see how the is represented in the output dataset I listed above: 3334455555 CCCBBBBBBB Now to make things more complicated I actually have a 4th column such that this grouping occurs for each key: Input: SomeKey, ObjectID, PercentOfBar, ZOrder (where smaller is closer) X, A, 100, 6 X, B, 50, 5 X, B, 50, 4 X, C, 30, 3 X, C, 70, 6 Y, A, 100, 6 Z, B, 50, 2 Z, B, 50, 6 Z, C, 100, 5 Output: SomeKey, PercentOfBar, ZOrder X, 50, 5 X, 20, 4 X, 30, 3 Y, 100, 6 Z, 50, 2 Z, 50, 5 Notice in the output, the PercentOfBar for each SomeKey would add up to 100%. This is one I know I'm going to be thinking about when I go to bed tonight. Just to be explicit and have a question: What would be a query that would produce the results described above?

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  • Atomic UPSERT in SQL Server 2005

    - by rabidpebble
    What is the correct pattern for doing an atomic "UPSERT" (UPDATE where exists, INSERT otherwise) in SQL Server 2005? I see a lot of code on SO (e.g. see http://stackoverflow.com/questions/639854/tsql-check-if-a-row-exists-otherwise-insert) with the following two-part pattern: UPDATE ... FROM ... WHERE <condition> -- race condition risk here IF @@ROWCOUNT = 0 INSERT ... or IF (SELECT COUNT(*) FROM ... WHERE <condition>) = 0 -- race condition risk here INSERT ... ELSE UPDATE ... where will be an evaluation of natural keys. None of the above approaches seem to deal well with concurrency. If I cannot have two rows with the same natural key, it seems like all of the above risk inserting rows with the same natural keys in race condition scenarios. I have been using the following approach but I'm surprised not to see it anywhere in people's responses so I'm wondering what is wrong with it: INSERT INTO <table> SELECT <natural keys>, <other stuff...> FROM <table> WHERE NOT EXISTS -- race condition risk here? ( SELECT 1 FROM <table> WHERE <natural keys> ) UPDATE ... WHERE <natural keys> (Note: I'm assuming that rows will not be deleted from this table. Although it would be nice to discuss how to handle the case where they can be deleted -- are transactions the only option? Which level of isolation?) Is this atomic? I can't locate where this would be documented in SQL Server documentation.

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  • Fastest way to remove non-numeric characters from a VARCHAR in SQL Server

    - by Dan Herbert
    I'm writing an import utility that is using phone numbers as a unique key within the import. I need to check that the phone number does not already exist in my DB. The problem is that phone numbers in the DB could have things like dashes and parenthesis and possibly other things. I wrote a function to remove these things, the problem is that it is slow and with thousands of records in my DB and thousands of records to import at once, this process can be unacceptably slow. I've already made the phone number column an index. I tried using the script from this post: http://stackoverflow.com/questions/52315/t-sql-trim-nbsp-and-other-non-alphanumeric-characters But that didn't speed it up any. Is there a faster way to remove non-numeric characters? Something that can perform well when 10,000 to 100,000 records have to be compared. Whatever is done needs to perform fast. Update Given what people responded with, I think I'm going to have to clean the fields before I run the import utility. To answer the question of what I'm writing the import utility in, it is a C# app. I'm comparing BIGINT to BIGINT now, with no need to alter DB data and I'm still taking a performance hit with a very small set of data (about 2000 records). Could comparing BIGINT to BIGINT be slowing things down? I've optimized the code side of my app as much as I can (removed regexes, removed unneccessary DB calls). Although I can't isolate SQL as the source of the problem anymore, I still feel like it is.

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  • Can I select 0 columns in SQL Server?

    - by Woody Zenfell III
    I am hoping this question fares a little better than the similar Create a table without columns. Yes, I am asking about something that will strike most as pointlessly academic. It is easy to produce a SELECT result with 0 rows (but with columns), e.g. SELECT a = 1 WHERE 1 = 0. Is it possible to produce a SELECT result with 0 columns (but with rows)? e.g. something like SELECT NO COLUMNS FROM Foo. (This is not valid T-SQL.) I came across this because I wanted to insert several rows without specifying any column data for any of them. e.g. (SQL Server 2005) CREATE TABLE Bar (id INT NOT NULL IDENTITY PRIMARY KEY) INSERT INTO Bar SELECT NO COLUMNS FROM Foo -- Invalid column name 'NO'. -- An explicit value for the identity column in table 'Bar' can only be specified when a column list is used and IDENTITY_INSERT is ON. One can insert a single row without specifying any column data, e.g. INSERT INTO Foo DEFAULT VALUES. One can query for a count of rows (without retrieving actual column data from the table), e.g. SELECT COUNT(*) FROM Foo. (But that result set, of course, has a column.) I tried things like INSERT INTO Bar () SELECT * FROM Foo -- Parameters supplied for object 'Bar' which is not a function. -- If the parameters are intended as a table hint, a WITH keyword is required. and INSERT INTO Bar DEFAULT VALUES SELECT * FROM Foo -- which is a standalone INSERT statement followed by a standalone SELECT statement. I can do what I need to do a different way, but the apparent lack of consistency in support for degenerate cases surprises me. I read through the relevant sections of BOL and didn't see anything. I was surprised to come up with nothing via Google either.

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  • List stored functions using a table in PostgreSQL

    - by Paolo B.
    Just a quick and simple question: in PostgreSQL, how do you list the names of all stored functions/stored procedures using a table using just a SELECT statement, if possible? If a simple SELECT is insufficient, I can make do with a stored function. My question, I think, is somewhat similar to this other question, but this other question is for SQL Server 2005: http://stackoverflow.com/questions/119679/list-of-stored-procedure-from-table (optional) For that matter, how do you also list the triggers and constraints that use the same table in the same manner?

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  • How to Convert using of SqlLit to Simple SQL command in C#

    - by Nasser Hajloo
    I want to get start with DayPilot control I do not use SQLLite and this control documented based on SQLLite. I want to use SQL instead of SQL Lite so if you can, please do this for me. main site with samples http://www.daypilot.org/calendar-tutorial.html The database contains a single table with the following structure CREATE TABLE event ( id VARCHAR(50), name VARCHAR(50), eventstart DATETIME, eventend DATETIME); Loading Events private DataTable dbGetEvents(DateTime start, int days) { SQLiteDataAdapter da = new SQLiteDataAdapter("SELECT [id], [name], [eventstart], [eventend] FROM [event] WHERE NOT (([eventend] <= @start) OR ([eventstart] >= @end))", ConfigurationManager.ConnectionStrings["db"].ConnectionString); da.SelectCommand.Parameters.AddWithValue("start", start); da.SelectCommand.Parameters.AddWithValue("end", start.AddDays(days)); DataTable dt = new DataTable(); da.Fill(dt); return dt; } Update private void dbUpdateEvent(string id, DateTime start, DateTime end) { using (SQLiteConnection con = new SQLiteConnection(ConfigurationManager.ConnectionStrings["db"].ConnectionString)) { con.Open(); SQLiteCommand cmd = new SQLiteCommand("UPDATE [event] SET [eventstart] = @start, [eventend] = @end WHERE [id] = @id", con); cmd.Parameters.AddWithValue("id", id); cmd.Parameters.AddWithValue("start", start); cmd.Parameters.AddWithValue("end", end); cmd.ExecuteNonQuery(); } }

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  • Linq to SQL not inserting data onto the DB

    - by Jesus Rodriguez
    Hello! I have a little / weird behaviour here and Im looking over internet and SO and I didn't find a response. I have to admit that this is my first time using databases, I know how to use them with SQL but never used it actually. Anyway, I have a problem with my app inserting data, I just created a very simple project for testing that and no solution yet. I have an example database with Sql Server Id - int (identity primary key) Name - nchar(10) (not null) The table is called "Person", simple as pie. I have this: static void Main(string[] args) { var db = new ExampleDBDataContext {Log = Console.Out}; var jesus = new Person {Name = "Jesus"}; db.Persons.InsertOnSubmit(jesus); db.SubmitChanges(); var query = from person in db.Persons select person; foreach (var p in query) { Console.WriteLine(p.Name); } } As you can see, nothing extrange. It show Jesus in the console. But if you see the table data, there is no data, just empty. I comment the object creation and insertion and the foreach doesn't print a thing (normal, there is no data in the database) The weird thing is that I created a row in the database manually and the Id was 2 and no 1 (Was the linq really playing with the database but it didn't create the row?) There is the log: INSERT INTO [dbo].Person VALUES (@p0) SELECT CONVERT(Int,SCOPE_IDENTITY()) AS [value] -- @p0: Input NChar (Size = 10; Prec = 0; Scale = 0) [Jesus] -- Context: SqlProvider(Sql2005) Model: AttributedMetaModel Build: 3.5.30729.4926 SELECT [t0].[Id], [t0].[Name] FROM [dbo].[Person] AS [t0] -- Context: SqlProvider(Sql2005) Model: AttributedMetaModel Build: 3.5.30729.4926 I am really confused, All the blogs / books use this kind of snippet to insert an element to a database. Thank you for helping.

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  • What does SQL Server's BACKUPIO wait type mean?

    - by solublefish
    I'm using Sql Server 2008 ("R1"), with some maintenance plans that back up my databases to a network share. Some of my backup jobs show long waits of type "BACKUPIO". Of course it seems like this is an I/O subsystem limitation, but I'm skeptical. Perfmon stats for I/O on the production (source) server are well within normal trends for that server. The destination server shows a sustained 7MB/s write rate, which seems incredibly low, even for a slow disk. The network link is gigabit ethernet and nowhere near saturated. The few docs I've turned up about BACKUPIO indicate that it's not specifically a wait on I/O, surprisingly enough. This MSFT doc says it's abnormal unless you're using a tape drive, which I'm not. But it doesn't say (or I don't understand) exactly what resource is missing. http://www.docstoc.com/docs/24580659/Performance-Tuning-in-SQL-Server-2005 And this piece says it's not related to I/O performance at all. http://www.informit.com/articles/article.aspx?p=686168&seqNum=5 "Note that BACKUPIO and IO_AUDIT_MUTEX are not related to IO performance." Anyway, does anyone know what BACKUPIO actually means and/or what I can do to diagnose or eliminate it?

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  • SQL Server 2005 Reporting Services and the Report Viewer

    - by Kendra
    I am having an issue embedding my report into an aspx page. Here's my setup: 1 Server running SQL Server 2005 and SQL Server 2005 Reporting Services 1 Workstation running XP and VS 2005 The server is not on a domain. Reporting Services is a default installation. I have one report called TestMe in a folder called TestReports using a shared datasource. If I view the report in Report Manager, it renders fine. If I view the report using the http ://myserver/reportserver url it renders fine. If I view the report using the http ://myserver/reportserver?/TestReports/TestMe it renders fine. If I try to view the report using http ://myserver/reportserver/TestReports/TestMe, it just goes to the folder navigation page of the home directory. My web application is impersonating somebody specific to get around the server not being on a domain. When I call the report from the report viewer using http ://myserver/reportserver as the server and /TestReports/TestMe as the path I get this error: For security reasons DTD is prohibited in this XML document. To enable DTD processing set the ProhibitDtd property on XmlReaderSettings to false and pass the settings into XmlReader.Create method. When I change the server to http ://myserver/reportserver? I get this error when I run the report: Client found response content type of '', but expected 'text/xml'. The request failed with an empty response. I have been searching for a while and haven't found anything that fixes my issue. Please let me know if there is more information needed. Thanks in advance, Kendra

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  • SQL Query slow in .NET application but instantaneous in SQL Server Management Studio

    - by user203882
    Here is the SQL SELECT tal.TrustAccountValue FROM TrustAccountLog AS tal INNER JOIN TrustAccount ta ON ta.TrustAccountID = tal.TrustAccountID INNER JOIN Users usr ON usr.UserID = ta.UserID WHERE usr.UserID = 70402 AND ta.TrustAccountID = 117249 AND tal.trustaccountlogid = ( SELECT MAX (tal.trustaccountlogid) FROM TrustAccountLog AS tal INNER JOIN TrustAccount ta ON ta.TrustAccountID = tal.TrustAccountID INNER JOIN Users usr ON usr.UserID = ta.UserID WHERE usr.UserID = 70402 AND ta.TrustAccountID = 117249 AND tal.TrustAccountLogDate < '3/1/2010 12:00:00 AM' ) Basicaly there is a Users table a TrustAccount table and a TrustAccountLog table. Users: Contains users and their details TrustAccount: A User can have multiple TrustAccounts. TrustAccountLog: Contains an audit of all TrustAccount "movements". A TrustAccount is associated with multiple TrustAccountLog entries. Now this query executes in milliseconds inside SQL Server Management Studio, but for some strange reason it takes forever in my C# app and even timesout (120s) sometimes. Here is the code in a nutshell. It gets called multiple times in a loop and the statement gets prepared. cmd.CommandTimeout = Configuration.DBTimeout; cmd.CommandText = "SELECT tal.TrustAccountValue FROM TrustAccountLog AS tal INNER JOIN TrustAccount ta ON ta.TrustAccountID = tal.TrustAccountID INNER JOIN Users usr ON usr.UserID = ta.UserID WHERE usr.UserID = @UserID1 AND ta.TrustAccountID = @TrustAccountID1 AND tal.trustaccountlogid = (SELECT MAX (tal.trustaccountlogid) FROM TrustAccountLog AS tal INNER JOIN TrustAccount ta ON ta.TrustAccountID = tal.TrustAccountID INNER JOIN Users usr ON usr.UserID = ta.UserID WHERE usr.UserID = @UserID2 AND ta.TrustAccountID = @TrustAccountID2 AND tal.TrustAccountLogDate < @TrustAccountLogDate2 ))"; cmd.Parameters.Add("@TrustAccountID1", SqlDbType.Int).Value = trustAccountId; cmd.Parameters.Add("@UserID1", SqlDbType.Int).Value = userId; cmd.Parameters.Add("@TrustAccountID2", SqlDbType.Int).Value = trustAccountId; cmd.Parameters.Add("@UserID2", SqlDbType.Int).Value = userId; cmd.Parameters.Add("@TrustAccountLogDate2", SqlDbType.DateTime).Value =TrustAccountLogDate; // And then... reader = cmd.ExecuteReader(); if (reader.Read()) { double value = (double)reader.GetValue(0); if (System.Double.IsNaN(value)) return 0; else return value; } else return 0;

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  • SQL Server 2005 standard filegroups / files for performance on SAN

    - by Blootac
    Ok so I've just been on a SQL Server course and we discussed the usage scenarios of multiple filegroups and files when in use over local RAID and local disks but we didn't touch SAN scenarios so my question is as follows; I currently have a 250 gig database running on SQL Server 2005 where some tables have a huge number of writes and others are fairly static. The database and all objects reside in a single file group with a single data file. The log file is also on the same volume. My interpretation is that separate data files should be used across different disks to lessen disk contention and that file groups should be used for partitioning of data. However, with a SAN you obviously don't really have the same issue of disk contention that you do with a small RAID setup (or at least we don't at the moment), and standard edition doesn't support partitioning. So in order to improve parallelism what should I do? My understanding of various Microsoft publications is that if I increase the number of data files, separate threads can act across each file separately. Which leads me to the question how many files should I have. One per core? Should I be putting tables and indexes with high levels of activity in separate file groups, each with the same number of data files as we have cores? Thank you

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  • Retrieving the an SQL Agent job's specific error

    - by Tom Andrews
    I am using msdb..sp_help_job to access whether a job succeeded or failed and can retrieve a general error. But, I want to access the specific error for the step that failed. I cannot seem to find it. It is not in this list of helpful stored procedures provided by MS http://msdn.microsoft.com/en-us/library/ms187763%28v=SQL.100%29.aspx The account running the query is limited but does have the SQLUserAgent role and owns the Jobs that it is accessing.

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  • Prolog newbie question: Making a procedure to print Hello World

    - by dmindreader
    I want to load this simple something into my Editor: Write:-repeat,write("hi"),nl,fail. So that it prints "hi". What should I do? I'm currently trying to do File->New and Saving a file named Write into E:\Program Files\pl\xpce\prolog\lib When doing the query: ?-Write. It's printing: 1 ?- Write. % ... 1,000,000 ............ 10,000,000 years later % % >> 42 << (last release gives the question) Why?

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  • SQL Where Clause Against View

    - by Adam Carr
    I have a view (actually, it's a table valued function, but the observed behavior is the same in both) that inner joins and left outer joins several other tables. When I query this view with a where clause similar to SELECT * FROM [v_MyView] WHERE [Name] like '%Doe, John%' ... the query is very slow, but if I do the following... SELECT * FROM [v_MyView] WHERE [ID] in ( SELECT [ID] FROM [v_MyView] WHERE [Name] like '%Doe, John%' ) it is MUCH faster. The first query is taking at least 2 minutes to return, if not longer where the second query will return in less than 5 seconds. Any suggestions on how I can improve this? If I run the whole command as one SQL statement (without the use of a view) it is very fast as well. I believe this result is because of how a view should behave as a table in that if a view has OUTER JOINS, GROUP BYS or TOP ##, if the where clause was interpreted prior to vs after the execution of the view, the results could differ. My question is why wouldn't SQL optimize my first query to something as efficient as my second query?

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  • SQL Server Clustered Index: (Physical) Data Page Order

    - by scherand
    I am struggling understanding what a clustered index in SQL Server 2005 is. I read the MSDN article Clustered Index Structures (among other things) but I am still unsure if I understand it correctly. The (main) question is: what happens if I insert a row (with a "low" key) into a table with a clustered index? The above mentioned MSDN article states: The pages in the data chain and the rows in them are ordered on the value of the clustered index key. And Using Clustered Indexes for example states: For example, if a record is added to the table that is close to the beginning of the sequentially ordered list, any records in the table after that record will need to shift to allow the record to be inserted. Does this mean that if I insert a row with a very "low" key into a table that already contains a gazillion rows literally all rows are physically shifted on disk? I cannot believe that. This would take ages, no? Or is it rather (as I suspect) that there are two scenarios depending on how "full" the first data page is. A) If the page has enough free space to accommodate the record it is placed into the existing data page and data might be (physically) reordered within that page. B) If the page does not have enough free space for the record a new data page would be created (anywhere on the disk!) and "linked" to the front of the leaf level of the B-Tree? This would then mean the "physical order" of the data is restricted to the "page level" (i.e. within a data page) but not to the pages residing on consecutive blocks on the physical hard drive. The data pages are then just linked together in the correct order. Or formulated in an alternative way: if SQL Server needs to read the first N rows of a table that has a clustered index it can read data pages sequentially (following the links) but these pages are not (necessarily) block wise in sequence on disk (so the disk head has to move "randomly"). How close am I? :)

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  • Microsoft OLE DB Provider for SQL Server error '80040e14' Could not find stored procedure

    - by BBlake
    I am migrating a classic ASP web app to new servers. The database back end is migrating from SQL Server 2000 to SQL Server 2008, and the app is moving from Win2000 x86 to Win2003R2 x64. I am getting the above error on every single stored procedure call within the application. I have verified: Yes, the SQL user is set up, using correct username and password Yes, the SQL user has execute permissions on the stored procedures in the database Yes, I have updated the TypeLib references to the new UUID Yes, I have logged into the database via SSMS with the SQL user id and it can see and execute the stored procedures just fine in SSMS, but not from the web app. Yes, the SQL user has the database set as its default database. The most frustrating thing is it works fine on the DEV server, but not on the production server. I have gone through every IIS setting 5 or 6 times and the web app is set up precisely the same in both environments. The only difference is the database server name in the connection string (DEV vs prod) EDIT: I have also tried pointing the prod web box at the dev database server and get the same error so I'm fairly sure the issue isn't on the database side.

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  • sp_addlinkedserver on sql server 2005 giving problem

    - by Jit
    I am trying to create a link server of a remote database(both the servers are SQL serve2005). I am able to connect that remote server from my SQL Server management studio. I used the following syntax to create it. EXEC sp_addlinkedserver @server = N'LINKSQL2005', @srvproduct = N'', @provider = N'SQLNCLI', @provstr = N'SERVER=IP Address of remote server ;User ID=XXXXXX;Password=***' I have provided the IP addressntax. and user name and password in the above syntax. The link server is getting created. But when I try to execute a query on it I get the error below. Query Used. select * from LINKSQL2005.<DBName>.dbo.<TableName> OLE DB provider "SQLNCLI" for linked server "LINKSQL2005" returned message "Communication link failure". Msg 10054, Level 16, State 1, Line 0 TCP Provider: An existing connection was forcibly closed by the remote host. Msg 18456, Level 14, State 1, Line 0 Login failed for user 'sa'. OLE DB provider "SQLNCLI" for linked server "LINKSQL2005" returned message "Invalid connection string attribute". Pls help me, where am I making mistake.

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  • Execute sybase stored proc from hibernate

    - by Padmanabh
    I am having issues with executing a simple sybase stored proc from hibernate. The procedure takes some input and returns one record. I tried with the following tag in hibernate mappings file and java code. <hibernate-mapping> <sql-query name="sybaseproc" callable="true"> <return class="Myentity"> <return-property name="next" column="next"/> </return> { ? = call nextnum(?,?) } </sql-query> </hibernate-mapping> java code is as follows Query q = session.getNamedQuery("sybaseproc"); q.setString(0,"test"); q.setInteger(1,new Integer(10)); Myentity entity = (Myentity) q.uniqueResult(); When I run my test. I get a error saying "Errors in Named Query sybaseproc" and the test does not run. Any help is appreciated. Thanks Padmanabh

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  • General SQL Server query performance

    - by Kiril
    Hey guys, This might be stupid, but databases are not my thing :) Imagine the following scenario. A user can create a post and other users can reply to his post, thus forming a thread. Everything goes in a single table called Posts. All the posts that form a thread are connected with each other through a generated key called ThreadID. This means that when user #1 creates a new post, a ThreadID is generated, and every reply that follows has a ThreadID pointing to the initial post (created by user #1). What I am trying to do is limit the number of replies to let's say 20 per thread. I'm wondering which of the approaches bellow is faster: 1 I add a new integer column (e.x. Counter) to Posts. After a user replies to the initial post, I update the initial post's Counter field. If it reaches 20 I lock the thread. 2 After a user replies to the initial post, I select all the posts that have the same ThreadID. If this collection has more than 20 items, I lock the thread. For further information: I am using SQL Server database and Linq-to-SQL entity model. I'd be glad if you tell me your opinions on the two approaches or share another, faster approach. Best Regards, Kiril

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  • "Order By" in LINQ-to-SQL Causes performance issues

    - by panamack
    I've set out to write a method in my C# application which can return an ordered subset of names from a table containing about 2000 names starting at the 100th name and returning the next 20 names. I'm doing this so I can populate a WPF DataGrid in my UI and do some custom paging. I've been using LINQ to SQL but hit a snag with this long executing query so I'm examining the SQL the LINQ query is using (Query B below). Query A runs well: SELECT TOP (20) [t0].[subject_id] AS [Subject_id], [t0].[session_id] AS [Session_id], [t0].[name] AS [Name] FROM [Subjects] AS [t0] WHERE (NOT (EXISTS( SELECT NULL AS [EMPTY] FROM ( SELECT TOP (100) [t1].[subject_id] FROM [Subjects] AS [t1] WHERE [t1].[session_id] = 1 ORDER BY [t1].[name] ) AS [t2] WHERE [t0].[subject_id] = [t2].[subject_id] ))) AND ([t0].[session_id] = 1) Query B takes 40 seconds: SELECT TOP (20) [t0].[subject_id] AS [Subject_id], [t0].[session_id] AS [Session_id], [t0].[name] AS [Name] FROM [Subjects] AS [t0] WHERE (NOT (EXISTS( SELECT NULL AS [EMPTY] FROM ( SELECT TOP (100) [t1].[subject_id] FROM [Subjects] AS [t1] WHERE [t1].[session_id] = 1 ORDER BY [t1].[name] ) AS [t2] WHERE [t0].[subject_id] = [t2].[subject_id] ))) AND ([t0].[session_id] = 1) ORDER BY [t0].[name] When I add the ORDER BY [t0].[name] to the outer query it slows down the query. How can I improve the second query? This was my LINQ stuff Nick int sessionId = 1; int start = 100; int count = 20; // Query subjects with the shoot's session id var subjects = cldb.Subjects.Where<Subject>(s => s.Session_id == sessionId); // Filter as per params var orderedSubjects = subjects .OrderBy<Subject, string>( s => s.Col_zero ); var filteredSubjects = orderedSubjects .Skip<Subject>(start) .Take<Subject>(count);

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  • Using SQL dB column as a lock for concurrent operations in Entity Framework

    - by Sid
    We have a long running user operation that is handled by a pool of worker processes. Data input and output is from Azure SQL. The master Azure SQL table structure columns are approximated to [UserId, col1, col2, ... , col N, beingProcessed, lastTimeProcessed ] beingProcessed is boolean and lastTimeProcessed is DateTime. The logic in every worker role is: public void WorkerRoleMain() { while(true) { try { dbContext db = new dbContext(); // Read foreach (UserProfile user in db.UserProfile .Where(u => DateTime.UtcNow.Subtract(u.lastTimeProcessed) > TimeSpan.FromHours(24) & u.beingProcessed == false)) { user.beingProcessed = true; // Modify db.SaveChanges(); // Write // Do some long drawn processing here ... ... ... user.lastTimeProcessed = DateTime.UtcNow; user.beingProcessed = false; db.SaveChanges(); } } catch(Exception ex) { LogException(ex); Sleep(TimeSpan.FromMinutes(5)); } } // while () } With multiple workers processing as above (each with their own Entity Framework layer), in essence beingProcessed is being used a lock for MutEx purposes Question: How can I deal with concurrency issues on the beingProcessed "lock" itself based on the above load? I think read-modify-write operation on the beingProcessed needs to be atomic but I'm open to other strategies. Open to other code refinements too.

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  • Group / User based security. Table / SQL question

    - by Brett
    Hi, I'm setting up a group / user based security system. I have 4 tables as follows: user groups group_user_mappings acl where acl is the mapping between an item_id and either a group or a user. The way I've done the acl table, I have 3 columns of note (actually 4th one as an auto-id, but that is irrelevant) col 1 item_id (item to access) col 3 user_id (user that is allowed to access) col 3 group_id (group that is allowed to access) So for example item1, peter, , item2, , group1 item3, jane, , so either the acl will give access to a user or a group. Any one line in the ACL table with either have an item - user mapping, or an item group. If I want to have a query that returns all objects a user has access to, I think I need to have a SQL query with a UNION, because I need 2 separate queries that join like.. item - acl - group - user AND item - acl - user This I guess will work OK. Is this how its normally done? Am I doing this the right way? Seems a little messy. I was thinking I could get around it by creating a single user group for each person, so I only ever deal with groups in my SQL, but this seems a little messy as well..

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  • SQL Images in different tables

    - by Adonis L
    I am storing images in a SQL database , right now I have images being stored in separate tables depending on the object the images belong to, is there any reason ( performance etc..) why I should keep it this way and not store all images in the same table?

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