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  • Caching and cache invalidation in user controls?

    - by Rishabh Ohri
    HI, In our .aspx pages we have many user controls. each user control executes a sql query. The caching mechanism to be followed is to fragment cache each user control on the page and add the query dependency to the respective queries of the user controls. How to achieve query dependency on fragment cached data for invalidation?

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  • What is the big deal with IQueryable?

    - by jjr2527
    I've seen a lot of people talking about IQueryable and I haven't quite picked up on what all the buzz is about. I always work with generic List's and find they are very rich in the way you can "query" them and work with them, even run LINQ queries against them. So I'm wondering if there is a good reason to start considering a different default collection in my projects.

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  • Get sum of two columns in one LINQ query

    - by Axarydax
    Hi, let's say that I have a table called Items (ID int, Done int, Total int) I can do it by two queries: int total = m.Items.Sum(p=>p.Total) int done = m.Items.Sum(p=>p.Done) But I'd like to do it in one query, something like this: var x = from p in m.Items select new { Sum(p.Total), Sum(p.Done)}; Surely there is a way to call aggregate functions from LINQ syntax...?

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  • How does the setup bootstrapper detect if prerequisites are installed?

    - by Marek
    Trying to solve this problem. I would like to learn how the bootstrapper detects if prerequisites (specifically .NET 3.5) are installed. According to this reference, a way to detect if .NET is installed is to check the following registry key: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\NET Framework Setup\NDP\v3.5 Using process monitor, I have inspected registry queries done by the bootstrapper (setup.exe) and it did not show any access to this registry key. Does anybody know how the bootstrapper determines whether the prerequisites are installed on the target system?

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  • Do I only have to worry about XSS and Sql injection?

    - by Pranali Desai
    Hi All, I am writing an application and for this to make it safe I have decided to HtmlEncode and HtmlDecode the data to avoid Javascript Injection and Paramaterised queries to avoid Sql injection. But I want to know whether these are the best ways to avoid these attacks and what are the other ways to damage the application that I should take into consideration.

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  • Deferring frequent updates in MySQL

    - by cdecker
    I have frequent updates to a user table that simply sets the last seen time of a user, and I was wondering whether there is a simple way to defer them and group them into a single query after a short timeout (5 minutes or so). This would reduce queries on my user database quite a lot.

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  • How web browser works ?

    - by Anil Namde
    I have tired to find good documentation of browsers using google but failed to get what i am looking for. Can some one guide me to location where i can actually see how browser functions. The whole purpose of the exercise is to get answers for following queries and more like these.... How images, css and js files are downloaded How js is executed How Ajax request is executed and many more like these..... Thanks all,

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  • SQLiteException and SQLite error near "(": syntax error with Subsonic ActiveRecord

    - by nvuono
    I ran into an interesting error with the following LiNQ query using LiNQPad and when using Subsonic 3.0.x w/ActiveRecord within my project and wanted to share the error and resolution for anyone else who runs into it. The linq statement below is meant to group entries in the tblSystemsValues collection into their appropriate system and then extract the system with the highest ID. from ksf in KeySafetyFunction where ksf.Unit == 2 && ksf.Condition_ID == 1 join sys in tblSystems on ksf.ID equals sys.KeySafetyFunction join xval in (from t in tblSystemsValues group t by t.tblSystems_ID into groupedT select new { sysId = groupedT.Key, MaxID = groupedT.Max(g=>g.ID), MaxText = groupedT.First(gt2 => gt2.ID == groupedT.Max(g=>g.ID)).TextValue, MaxChecked = groupedT.First(gt2 => gt2.ID == groupedT.Max(g=>g.ID)).Checked }) on sys.ID equals xval.sysId select new {KSFDesc=ksf.Description, sys.Description, xval.MaxText, xval.MaxChecked} On its own, the subquery for grouping into groupedT works perfectly and the query to match up KeySafetyFunctions with their System in tblSystems also works perfectly on its own. However, when trying to run the completed query in linqpad or within my project I kept running into a SQLiteException SQLite Error Near "(" First I tried splitting the queries up within my project because I knew that I could just run a foreach loop over the results if necessary. However, I continued to receive the same exception! I eventually separated the query into three separate parts before I realized that it was the lazy execution of the queries that was killing me. It then became clear that adding the .ToList() specifier after the myProtectedSystem query below was the key to avoiding the lazy execution after combining and optimizing the query and being able to get my results despite the problems I encountered with the SQLite driver. // determine the max Text/Checked values for each system in tblSystemsValue var myProtectedValue = from t in tblSystemsValue.All() group t by t.tblSystems_ID into groupedT select new { sysId = groupedT.Key, MaxID = groupedT.Max(g => g.ID), MaxText = groupedT.First(gt2 => gt2.ID ==groupedT.Max(g => g.ID)).TextValue, MaxChecked = groupedT.First(gt2 => gt2.ID ==groupedT.Max(g => g.ID)).Checked}; // get the system description information and filter by Unit/Condition ID var myProtectedSystem = (from ksf in KeySafetyFunction.All() where ksf.Unit == 2 && ksf.Condition_ID == 1 join sys in tblSystem.All() on ksf.ID equals sys.KeySafetyFunction select new {KSFDesc = ksf.Description, sys.Description, sys.ID}).ToList(); // finally join everything together AFTER forcing execution with .ToList() var joined = from protectedSys in myProtectedSystem join protectedVal in myProtectedValue on protectedSys.ID equals protectedVal.sysId select new {protectedSys.KSFDesc, protectedSys.Description, protectedVal.MaxChecked, protectedVal.MaxText}; // print the gratifying debug results foreach(var protectedItem in joined) { System.Diagnostics.Debug.WriteLine(protectedItem.Description + ", " + protectedItem.KSFDesc + ", " + protectedItem.MaxText + ", " + protectedItem.MaxChecked); }

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  • Select random row from MySQL (with probability)

    - by James Simpson
    I have a MySQL table that has a row called cur_odds which is a percent number with the percent probability that that row will get selected. How do I make a query that will actually select the rows in approximately that frequency when you run through 100 queries for example? I tried the following, but a row that has a probability of 0.35 ends up getting selected around 60-70% of the time. SELECT * FROM table ORDER BY RAND()*cur_odds DESC

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  • How to salvage SQL server 2008 query from KILLED/ROLLBACK state?

    - by littlegreen
    I have a stored procedure that inserts batches of millions of rows, emerging from a certain query, into an SQL database. It has one parameter selecting the batch; when this parameter is omitted, it will gather a list of batches and recursively call itself, in order to iterate over batches. In (pseudo-)code, it looks something like this: CREATE PROCEDURE spProcedure AS BEGIN IF @code = 0 BEGIN ... WHILE @@Fetch_Status=0 BEGIN EXEC spProcedure @code FETCH NEXT ... INTO @code END END ELSE BEGIN -- Disable indexes ... INSERT INTO table SELECT (...) -- Enable indexes ... Now it can happen that this procedure is slow, for whatever reason: it can't get a lock, one of the indexes it uses is misdefined or disabled. In that case, I want to be able kill the procedure, truncate and recreate the resulting table, and try again. However, when I try and kill the procedure, the process frequently oozes into a KILLED/ROLLBACK state from which there seems to be no return. From Google I have learned to do an sp_lock, find the spid, and then kill it with KILL <spid>. But when I try to kill it, it tells me SPID 75: transaction rollback in progress. Estimated rollback completion: 0%. Estimated time remaining: 554 seconds. I did find a forum message hinting that another spid should be killed before the other one can start a rollback. But that didn't work for me either, plus I do not understand, why that would be the case... could it be because I am recursively calling my own stored procedure? (But it should be having the same spid, right?) In any case, my process is just sitting there, being dead, not responding to kills, and locking the table. This is very frustrating, as I want to go on developing my queries, not waiting hours on my server sitting dead while pretending to be finishing a supposed rollback. Is there some way in which I can tell the server not to store any rollback information for my query? Or not to allow any other queries to interfere with the rollback, so that it will not take so long? Or how to rewrite my query in a better way, or how kill the process successfully without restarting the server?

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  • Programicaly measure size and way-order of L1 and L2 caches

    - by osgx
    Hello How can I measure programicaly (not query the OS, but measure) the size and order of associativity of L1 and L2 caches (data caches)? Assumtions about system: It has L1 and L2 cache (may be L3 too, may be cache sharing), It may have a hardware prefetch unit (just like P4+), it has a stable clocksource (tickcounter or good HPET for gettimeofday). There are no assumtions about OS (it can be Linux, Windows, smth non-standart), and we can't use posix queries. Language is C. And Compiler optimizations may be disabled.

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  • How does MySQL's ORDER BY RAND() work?

    - by Eugene
    Hi, I've been doing some research and testing on how to do fast random selection in MySQL. In the process I've faced some unexpected results and now I am not fully sure I know how ORDER BY RAND() really works. I always thought that when you do ORDER BY RAND() on the table, MySQL adds a new column to the table which is filled with random values, then it sorts data by that column and then e.g. you take the above value which got there randomly. I've done lots of googling and testing and finally found that the query Jay offers in his blog is indeed the fastest solution: SELECT * FROM Table T JOIN (SELECT CEIL(MAX(ID)*RAND()) AS ID FROM Table) AS x ON T.ID >= x.ID LIMIT 1; While common ORDER BY RAND() takes 30-40 seconds on my test table, his query does the work in 0.1 seconds. He explains how this functions in the blog so I'll just skip this and finally move to the odd thing. My table is a common table with a PRIMARY KEY id and other non-indexed stuff like username, age, etc. Here's the thing I am struggling to explain SELECT * FROM table ORDER BY RAND() LIMIT 1; /*30-40 seconds*/ SELECT id FROM table ORDER BY RAND() LIMIT 1; /*0.25 seconds*/ SELECT id, username FROM table ORDER BY RAND() LIMIT 1; /*90 seconds*/ I was sort of expecting to see approximately the same time for all three queries since I am always sorting on a single column. But for some reason this didn't happen. Please let me know if you any ideas about this. I have a project where I need to do fast ORDER BY RAND() and personally I would prefer to use SELECT id FROM table ORDER BY RAND() LIMIT 1; SELECT * FROM table WHERE id=ID_FROM_PREVIOUS_QUERY LIMIT 1; which, yes, is slower than Jay's method, however it is smaller and easier to understand. My queries are rather big ones with several JOINs and with WHERE clause and while Jay's method still works, the query grows really big and complex because I need to use all the JOINs and WHERE in the JOINed (called x in his query) sub request. Thanks for your time!

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  • Facebook .net return internal server error when using Multiquery

    - by Simon
    Hello I am having trouble using multiquery in facebook .net. I am trying to create 3 queries: Friends, Like and Photo using multiquery in the toolkit. It returns me with this The remote server returned an error: (500) Internal Server Error. Although, it is not happened all the time but it does occur frequently... I thought about what cause the problem but don't have a luck Please help

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  • JDBC profiling tools

    - by antispam
    We need to profile the JDBC operations of several web applications, number of queries, time spent, rows returned, ... Have you used any free/commercial JDBC profiling tool? What are your experiences? Thank you.

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  • Easy to use web-based reporting tool

    - by SuperFurryToad
    I'm looking for recommendations for an easy to use reporting/business intelligence tool that can interface with an sql server or access database. It can be web-based or a desktop tool. Ideally it would be freeware or low cost, and easy to use for users who are not that technically savvy (below the level of someone who can generate reports and complicated queries in Access). Any tools I've seen so far (such as Crystal Reports) are either too expensive or too complicated to use for non-power users.

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  • How to find similar/related text with Zend Lucene?

    - by Arty
    Say I need to make searching for related titles just like stackoverflow does before you add your question or digg.com before submitting news. I didn't find a way how to do this with Zend Lucene. There are setSlop method for queries, but as I understand, it doesn't help. Is there any way to do this kind of searches?

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  • Should I include user_id in multiple tables?

    - by Drarok
    I'm at the planning stages of a multi-user application where each user will only have access their own data. There'll be a few tables that relate to each other, so I could use JOINs to ensure they're accessing only their data, but should I include user_id in each table? Would this be faster? It would certainly make some of the queries easier in the long run. Thanks!

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  • Making(programming) virtual drives on windows XP

    - by Manux
    Ahoy, I'd like to mount a "virtual drive" myself on Windows XP, I guess using the windows API. What I thought about would be like a server interface, meaning explorer.exe would send "queries", like, list directory, or get file through a pipe or whatever... I know some programs do it, maybe not the way I think it is done, but what the heck, if you know anything, enlighten me please!

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  • transactions in MS Access

    - by arcticpenguin
    Let's say I have the following code in a form that is triggered on some click event. DoCmd.SetWarnings False DoCmd.OpenQuery "AddSomeStuff" DoCmd.OpenQuery "UpdateSomeOtherStuff" DoCmd.OpenQuery "DeleteABunchOfCrap" DoCmd.SetWarnings True Can I assume that the three update queries I executed (in SQL Server) are not transactional in that they are run is separate transactions?

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  • How to get parameter values for dm_exec_sql_text

    - by Ted Elliott
    I'm running the following statement to see what queries are executing in sql server: select * from sys.dm_exec_requests r cross apply sys.dm_exec_sql_text(r.sql_handle) where r.database_id = DB_ID('<dbname>') The sql text that comes back is parameterized: (@Parm0 int) select * from foo where foo_id = @Parm0 Is there any way to get the values for the parameters that the statement is using? Say by joining to another table perhaps?

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  • Calculate the Hilbert value of a point for use in a Hilbert R-Tree?

    - by wrt
    I have an application where a Hilbert R-Tree (wikipedia) (citeseer) would seem to be an appropriate data structure. Specifically, it requires reasonably fast spatial queries over a data set that will experience a lot of updates. However, as far as I can see, none of the descriptions of the algorithms for this data structure even mention how to actually calculate the requisite Hilbert Value; which is the distance along a Hilbert Curve to the point. So any suggestions for how to go about calculating this?

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  • How to approach performance issues?

    - by jess
    Hi, We are developing a client-server desktop application(winforms with sql server 2008, using LINQ-SQL).We are now finding many issues related to performance.These relate to querying too much data with LINQ , bad database design,not much caching etc.What do you suggest,we should do - how to go about solving these performance issues? One thing,I am doing is doing sql profiling,and trying to fix some queries.As far caching is concerned,we have static lists.But,how to keep them updated,we don't have any server side implementation.So,these lists can be stale,if someone changes data. regards

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