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• Linq to SQL Problem System.Data.Linq.IdentityManager.StandardIdentityManager.MultiKeyManager

  - by luckyluke

  I have a really tricky thing going up here. My project has around 100 tables and they are all mapped by LINQ. Everything works fine in a dev and test environment. These enviroments are MS Win 2008 r2 servers with SQL 2008 sp1 databases. IIS and SQL are on a different machines. Now on production enviroment which is MS Win 2003 x64 web farm + geoclustered SQL 2008 IT DOES not work. All I get is the exception System.IndexOutOfRangeException: Index was outside the bounds of the array. at System.Data.Linq.IdentityManager.StandardIdentityManager.MultiKeyManager3.TryCreateKeyFr>om Values(Object[] values, MultiKey& k) at System.Data.Linq.IdentityManager.StandardIdentityManager.IdentityCache2.Find(Object[] keyValues) at System.Data.Linq.ChangeProcessor.GetOtherItem(MetaAssociation assoc, Object instance) at System.Data.Linq.ChangeProcessor.BuildEdgeMaps() at System.Data.Linq.ChangeProcessor.SubmitChanges(ConflictMode failureMode) at System.Data.Linq.DataContext.SubmitChanges(ConflictMode failureMode) at ERS.IIMP.Services.ExposuresSrv.Update(Int32 ExpID, Int32 AssID) Services\ExposuresSrv.cs` My question is What the hell. They have precisely the same DBML, the DB has exactly THE SAME structure (when I get the DB from prod to TEST and mount it eveything works just great), the binaries on the WEB Server are the same. I seriously do not know what to do.... Did anyone found that Linq works on one env and does not on the second?? I mam really lost here. I really hope You can help me:)

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• h2 (embedded mode ) database files problem

  - by aeter

  There is a h2-database file in my src directory (Java, Eclipse): h2test.db The problem: starting the h2.jar from the command line (and thus the h2 browser interface on port 8082), I have created 2 tables, 'test1' and 'test2' in h2test.db and I have put some data in them; when trying to access them from java code (JDBC), it throws me "table not found exception". A "show tables" from the java code shows a resultset with 0 rows. Also, when creating a new table ('newtest') from the java code (CREATE TABLE ... etc), I cannot see it when starting the h2.jar browser interface afterwards; just the other two tables ('test1' and 'test2') are shown (but then the newly created table 'newtest' is accessible from the java code). I'm inexperienced with embedded databases; I believe I'm doing something fundamentally wrong here. My assumption is, that I'm accessing the same file - once from the java app, and once from the h2 console-browser interface. I cannot seem to understand it, what am I doing wrong here?

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• Which Django 1.2.x multilingual application to use?

  - by mawimawi

  There are a couple of different applications for internationalized content in Django. As of now I only have used http://code.google.com/p/django-multilingual/ in my production environments, but I wonder if there are "better" solutions for my wishes. What my staff users need is the following: An object is being created by a staff user in any language (e.g. "de") This object should be displayed in the german version of the website. When a staff user translates the object into a different language (e.g. "fr"), then the page must be visible in the french version as well. If an object is not translated in the visitor's currently selected language (e.g. "en"), then calling the objects url shall raise a 404 Error (or even better a notice that the object is only available in the languages "de" and "fr", and the visitor might be able to select one of the languages) My staff users are working in the admin interface, so the multilingual application must support this as well. I don't really care whether the multilingual app uses a single table with many fields (like title_en, title_de, title_fr) or a foreign key to a related table (as it is implemented in django-multlingual). I only want it to have a good admin interface and no "default" language, because some content might be available just in "de", and some other just in "fr" and "en". And the most important issue of course is compatibility with Django 1.2.x. What are your experiences and preferred apps, and why?

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• Oracle T4CPreparedStatement memory leaks?

  - by Jay

  A little background on the application that I am gonna talk about in the next few lines: XYZ is a data masking workbench eclipse RCP application: You give it a source table column, and a target table column, it would apply a trasformation (encryption/shuffling/etc) and copy the row data from source table to target table. Now, when I mask n tables at a time, n threads are launched by this app. Here is the issue: I have run into a production issue on first roll out of the above said app. Unfortunately, I don't have any logs to get to the root. However, I tried to run this app in test region and do a stress test. When I collected .hprof files and ran 'em through an analyzer (yourKit), I noticed that objects of oracle.jdbc.driver.T4CPreparedStatement was retaining heap. The analysis also tells me that one of my classes is holding a reference to this preparedstatement object and thereby, n threads have n such objects. T4CPreparedStatement seemed to have character arrays: lastBoundChars and bindChars each of size char[300000]. So, I researched a bit (google!), obtained ojdbc6.jar and tried decompiling T4CPreparedStatement. I see that T4CPreparedStatement extends OraclePreparedStatement, which dynamically manages array size of lastBoundChars and bindChars. So, my questions here are: Have you ever run into an issue like this? Do you know the significance of lastBoundChars / bindChars? I am new to profiling, so do you think I am not doing it correct? (I also ran the hprofs through MAT - and this was the main identified issue - so, I don't really think I could be wrong?) I have found something similar on the web here: http://forums.oracle.com/forums/thread.jspa?messageID=2860681 Appreciate your suggestions / advice.

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• MissingMethodException thrown when calling new form in Compact Framework

  - by Boerema

  I'm updating an old mobile device application for better flexibility. I had basically added the ability to configure the address of our SQL server in the case that we want to use our test server as opposed to our production server. I don't think this is causing the problem, but I wanted to state it. I also upgraded the project from a VS 2000 project to a VS 2005 project. The issue I am having is that when I try to run the program in the VS emulator for Pocket PC, I get an error. It occurs after our "main menu" form loads and the user selects the next form to load. The form is initialized without issue, but when we try to run the .ShowDialog() method, it throws a System.MissingMethodException. I don't have a lot of experience with the Compact Framework and really have no idea where to start looking for problems. I stepped the debugger through the entire initializing process for the new form and it ran without issue. But, again, when we come to the ShowDialog call, it throws the error. Any ideas in where to start looking or known issues would be greatly appreciated.

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• Java errors on Lotus Domino Designer Client 8.5.1

  - by ajcooper

  I have a clean install of Lotus Notes 8.5.1 (now with FP3) and I'm getting the following errors in Designer. This is with a new database with a couple of forms and views. I'm finding this is typical across all databases. Is there something I need to install/configure etc.? I'm not new to Notes, but I'm new to 8.5 Thanks Aidan Description Resource Path Location Type Cannot resolve plug-in: org.eclipse.core.runtime plugin.xml TestAgent.nsf line 9 Plug-in Problem Cannot resolve plug-in: org.eclipse.ui plugin.xml TestAgent.nsf line 8 Plug-in Problem Cannot resolve plug-in: com.ibm.commons plugin.xml TestAgent.nsf line 10 Plug-in Problem Cannot resolve plug-in: com.ibm.commons.vfs plugin.xml TestAgent.nsf line 12 Plug-in Problem Cannot resolve plug-in: com.ibm.commons.xml plugin.xml TestAgent.nsf line 11 Plug-in Problem Cannot resolve plug-in: com.ibm.designer.runtime plugin.xml TestAgent.nsf line 15 Plug-in Problem Cannot resolve plug-in: com.ibm.designer.runtime.directory plugin.xml TestAgent.nsf line 14 Plug-in Problem Cannot resolve plug-in: com.ibm.jscript plugin.xml TestAgent.nsf line 13 Plug-in Problem Cannot resolve plug-in: com.ibm.notes.java.api plugin.xml TestAgent.nsf line 20 Plug-in Problem Cannot resolve plug-in: com.ibm.xsp.core plugin.xml TestAgent.nsf line 16 Plug-in Problem Cannot resolve plug-in: com.ibm.xsp.core plugin.xml TestAgent.nsf line 21 Plug-in Problem Cannot resolve plug-in: com.ibm.xsp.designer plugin.xml TestAgent.nsf line 18 Plug-in Problem Cannot resolve plug-in: com.ibm.xsp.designer plugin.xml TestAgent.nsf line 22 Plug-in Problem Cannot resolve plug-in: com.ibm.xsp.domino plugin.xml TestAgent.nsf line 19 Plug-in Problem Cannot resolve plug-in: com.ibm.xsp.domino plugin.xml TestAgent.nsf line 23 Plug-in Problem Cannot resolve plug-in: com.ibm.xsp.extsn plugin.xml TestAgent.nsf line 17 Plug-in Problem Cannot resolve plug-in: com.ibm.xsp.extsn plugin.xml TestAgent.nsf line 24 Plug-in Problem Cannot resolve plug-in: com.ibm.xsp.rcp plugin.xml TestAgent.nsf line 25 Plug-in Problem

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• Full-text search error during full-text index population : Error Code '0x80092003'

  - by user360074

  Dear All, I have problem with Full-Text Search service in production environment. Each time I rebuild full-text catalog, there is no error in User Interface, but there is no data in Full-Text Catalog Item Count : 0 Catalog size : 0 MB OS : Windows Server 2003 R2 Standard Edition Service Pack2 SQL Server Version : Microsoft SQL Server 2005 - 9.00.1399.06 (Intel X86) Oct 14 2005 00:33:37 Copyright (c) 1988-2005 Microsoft Corporation Standard Edition on Windows NT 5.2 (Build 3790: Service Pack 2) It work on dev server (windows xp professional version 2002 service pack 3) but error on prod server (Windows Server 2003 R2 Standard Edition Service Pack2) This is error log. Scrawl Log: 2010-06-02 03:51:31.06 spid24s Informational: Full-text Full population initialized for table or indexed view '[test1].[dbo].[test]' (table or indexed view ID '37575172', database ID '9'). Population sub-tasks: 1. 2010-06-02 03:51:31.06 spid24s Error '0x80092003' occurred during full-text index population for table or indexed view '[test1].[dbo].[test]' (table or indexed view ID '37575172', database ID '9'), full-text key value 0x00000006. Attempt will be made to reindex it. 2010-06-02 03:51:31.06 spid24s The component 'MSFTE.DLL' reported error while indexing. Component path 'D:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\Binn\MSFTE.DLL'. 2010-06-02 03:51:31.06 spid24s Error '0x80092003' occurred during full-text index population for table or indexed view '[test1].[dbo].[test]' (table or indexed view ID '37575172', database ID '9'), full-text key value 0x00000005. Attempt will be made to reindex it.

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• SQL Server 2008 alternative for SQL-DMO

  - by alexdelpiero

  Hi! I previously was using SQL-DMO to automatically generate scripts from the database. Now I upgraded to SQL Server 2008 and I don’t want to use this feature anymore since Microsoft will be dropping this feature off. Is there any other alternative I can use to connect to a server and generate scripts automatically from a database? Any answer is welcome. Thanks in advance. This is the procedure i was previously using: CREATE PROC GenerateSP ( @server varchar(30) = null, @uname varchar(30) = null, @pwd varchar(30) = null, @dbname varchar(30) = null, @filename varchar(200) = 'c:\script.sql' ) AS DECLARE @object int DECLARE @hr int DECLARE @return varchar(200) DECLARE @exec_str varchar(2000) DECLARE @spname sysname SET NOCOUNT ON -- Sets the server to the local server IF @server is NULL SELECT @server = @@servername -- Sets the database to the current database IF @dbname is NULL SELECT @dbname = db_name() -- Sets the username to the current user name IF @uname is NULL SELECT @uname = SYSTEM_USER -- Create an object that points to the SQL Server EXEC @hr = sp_OACreate 'SQLDMO.SQLServer', @object OUT IF @hr <> 0 BEGIN PRINT 'error create SQLOLE.SQLServer' RETURN END -- Connect to the SQL Server IF @pwd is NULL BEGIN EXEC @hr = sp_OAMethod @object, 'Connect', NULL, @server, @uname IF @hr <> 0 BEGIN PRINT 'error Connect' RETURN END END ELSE BEGIN EXEC @hr = sp_OAMethod @object, 'Connect', NULL, @server, @uname, @pwd IF @hr <> 0 BEGIN PRINT 'error Connect' RETURN END END --Verify the connection EXEC @hr = sp_OAMethod @object, 'VerifyConnection', @return OUT IF @hr <> 0 BEGIN PRINT 'error VerifyConnection' RETURN END SET @exec_str = 'DECLARE script_cursor CURSOR FOR SELECT name FROM ' + @dbname + '..sysobjects WHERE type = ''P'' ORDER BY Name' EXEC (@exec_str) OPEN script_cursor FETCH NEXT FROM script_cursor INTO @spname WHILE (@@fetch_status <> -1) BEGIN SET @exec_str = 'Databases("'+ @dbname +'").StoredProcedures("'+RTRIM(UPPER(@spname))+'").Script(74077,"'+ @filename +'")' EXEC @hr = sp_OAMethod @object, @exec_str, @return OUT IF @hr <> 0 BEGIN PRINT 'error Script' RETURN END FETCH NEXT FROM script_cursor INTO @spname END CLOSE script_cursor DEALLOCATE script_cursor -- Destroy the object EXEC @hr = sp_OADestroy @object IF @hr <> 0 BEGIN PRINT 'error destroy object' RETURN END GO

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• dynamically horizontal scalable key value store

  - by Zubair

  Hi, Is there a key value store that will give me the following: Allow me to simply add and remove nodes and will redstribute the data automatically Allow me to remove nodes and still have 2 extra data nodes to provide redundancy Allow me to store text or images up to 1GB in size Can store small size data up to 100TB of data Fast (so will allow queries to be performed on top of it) Make all this transparent to the client Works on Ubuntu/FreeBSD or Mac Free or open source I basically want something I can use a "single", and not have to worry about having memcached, a db, and several storage components so yes, I do want a database "silver bullet" you could say. Thanks Zubair Answers so far: MogileFS on top of BackBlaze - As far as I can see this is just a filesystem, and after some research it only seems to be appropriate for large image files Tokyo Tyrant - Needs lightcloud. This doesn't auto scale as you add new nodes. I did look into this and it seems it is very fast for queries which fit onto a single node though Riak - This is one I am looking into myself, but I don't have any results yet Amazon S3 - Is anyone using this as their sole persistance layer in production? From what I have seen it seems to be used for storage of images as complex queries are too expensive @shaman suggested Cassandra - definitely one I am looking into So far it seems that there is no database or key value store that fulfills the criteria I mentioned, not even after offering a bounty of 100 points did the question get answered!

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• The "first past the post election" query problem

  - by MPelletier

  This problem may seem like school work, but it isn't. At best it is self-imposed school work. I encourage any teachers to take is as an example if they wish. "First past the post" elections are single-round, meaning that whoever gets the most votes win, no second rounds. Suppose a table for an election. CREATE TABLE ElectionResults ( DistrictHnd INTEGER NOT NULL, PartyHnd INTEGER NOT NULL, CandidateName VARCHAR2(100) NOT NULL, TotalVotes INTEGER NOT NULL, PRIMARY KEY DistrictHnd, PartyHnd); The table has two foreign keys: DistrictHnd points to a District table (lists all the different electoral districts) and PartyHnd points to a Party table (lists all the different political parties). I won't bother with other tables here, joining them is trivial. This is just a wee bit of context. The question: What SQL query will return a table listing the DistrictHnd, PartyHnd, CandidateName and TotalVotes of the winners (max votes) in each District? This does not suppose any particular database system. If you wish to stick to a particular implementation of SQL, go the way of SQLite and MySQL. If you can devise a better schema (or an easier one), that is acceptable too. Criteria: simplicity, portability to other databases.

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• Installing mongrel service on Windows 2008

  - by akirekadu

  We use InstallAnywhere to install our product. One of the components that it needs to install is mongrel. IA invokes the following command line during installation: mongrel_rails service::install -N service-1 -D "Service 1" -c "C:\app_dir\\rails\rails_apps\service-1" -p 19000 -e production Apprently under the hoods "sc create..." is used. The installation works great on Windows 2003. On Windows 2008 though this operation requires elevated privileges. When I login as local administrator (ie 'local-machine\administrator' user), the installation works just fine. However, when I login as a domain user that is part of local administrators group, the services fails to install with error "access is denied". How can I make it possible to install the product without having to login as local administrator? Thanks! Couple of notes I would like to add. One solution I tried is to execute the installer as administrator. The service does get installed. However, it creates another problem. An embedded 3rd party product and its files get installed with admin only rights. So we do need to run the installer as logged in user.

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• IIS 6 forces AppRoot/Starting Point to upper case when Virtual Directory is imported from a file

  - by user276464

  I have searched the web for this and couldn't find anything (well one remotely relevant post), so here I am. We have multiple ASP.NET apps in IIS 6 using Forms Authentication with dedicated path for each app. Since path is case sensitive it must match URL's path section exactly. However, because of an incorrect casing in IIS 6 Metabase for AppRoot (or Starting Point in IIS UI) bowser doesn't send Form cookie to the server whenever URL is previously resolved on the server and sent to client in incorrect case. Example: App URL = "https://Test.net/Application1" Cookie path = /Application1 Metabase AppRoot = /LM/W3SVC/1393818691/ROOT/APPLICATIONPATH1 Resolved URL = "https://Test.net/APPLICATIONPATH1" Now to the root cause... We create virtual directories on test server manually in a specific case (matches Path for each application). We then export virtual directory using UI to an XML file, which is then imported to another server (let's say production), at which point IIS decides to uppercase AppRoot element of the metabase. Can anyone shed some light on this? Is there a setting on IIS I am not aware of? I am trying to avoid manual edit of metabase after the import. Is that a bug?

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• Database migration pattern for Java?

  - by Eno

  Im working on some database migration code in Java. Im also using a factory pattern so I can use different kinds of databases. And each kind of database im using implements a common interface. What I would like to do is have a migration check that is internal to the class and runs some database schema update code automatically. The actual update is pretty straight forward (I check schema version in a table and compare against a constant in my app to decide whether to migrate or not and between which versions of schema). To make this automatic I was thinking the test should live inside (or be called from) the constructor. OK, fair enough, that's simple enough. My problem is that I dont want the test to run every single time I instantiate a database object (it runs a query so having it run on every construction is not efficient). So maybe this should be a class static method? I guess my question is, what is a good design pattern for this type of problem? There ought to be a clean way to ensure the migration test runs only once OR is super-efficient.

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• Regressing panel data in SAS.

  - by John

  Hey Guys, thanks to your help I succesfully managed all my databases! I am now looking at a panel data set on which I have to regress. Since I only started my Phd this semester together with the econometrics courses I am still new to many statistic applications and regression methods. I want to do a simple regression as in Y = x1 x2 x3 etc, now I already browsed through some literature and found that for panel data it's common to do a fixed effects regression. Also, my Y variable only has positive values so I was thinking in the direction of a Tobit model? I'm doing some research concerning the coverage of analysts in the financial business. My independent variable is the coverage of analysts on a certain firm, so per observation i have 1 analyst and 1 firm, together with different characteristics(market cap and betas etc) of the firm. All this data is monthly. As coverage cannot become negative (only 0) I was thinking of a Tobit model? Do you guys have any ideas what would be a good regression method? Or have some good sources (e books, written books, through university I have access to almost anything concerning my field of work) of information (cause I do have to learn these things for future research)? Thanks!

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• Why is the Clojure Hello World program so slow compared to Java and Python?

  - by viksit

  Hi all, I'm reading "Programming Clojure" and I was comparing some languages I use for some simple code. I noticed that the clojure implementations were the slowest in each case. For instance, Python - hello.py def hello_world(name): print "Hello, %s" % name hello_world("world") and result, $ time python hello.py Hello, world real 0m0.027s user 0m0.013s sys 0m0.014s Java - hello.java import java.io.*; public class hello { public static void hello_world(String name) { System.out.println("Hello, " + name); } public static void main(String[] args) { hello_world("world"); } } and result, $ time java hello Hello, world real 0m0.324s user 0m0.296s sys 0m0.065s and finally, Clojure - hellofun.clj (defn hello-world [username] (println (format "Hello, %s" username))) (hello-world "world") and results, $ time clj hellofun.clj Hello, world real 0m1.418s user 0m1.649s sys 0m0.154s Thats a whole, garangutan 1.4 seconds! Does anyone have pointers on what the cause of this could be? Is Clojure really that slow, or are there JVM tricks et al that need to be used in order to speed up execution? More importantly - isn't this huge difference in performance going to be an issue at some point? (I mean, lets say I was using Clojure for a production system - the gain I get in using lisp seems completely offset by the performance issues I can see here). The machine used here is a 2007 Macbook Pro running Snow Leopard, a 2.16Ghz Intel C2D and 2G DDR2 SDRAM. BTW, the clj script I'm using is from here and looks like, #!/bin/bash JAVA=/System/Library/Frameworks/JavaVM.framework/Versions/1.6/Home/bin/java CLJ_DIR=/opt/jars CLOJURE=$CLJ_DIR/clojure.jar CONTRIB=$CLJ_DIR/clojure-contrib.jar JLINE=$CLJ_DIR/jline-0.9.94.jar CP=$PWD:$CLOJURE:$JLINE:$CONTRIB # Add extra jars as specified by `.clojure` file if [ -f .clojure ] then CP=$CP:`cat .clojure` fi if [ -z "$1" ]; then $JAVA -server -cp $CP \ jline.ConsoleRunner clojure.lang.Repl else scriptname=$1 $JAVA -server -cp $CP clojure.main $scriptname -- $* fi

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• Getting SSL to work with Apache/Passenger on OSX

  - by jonnii

  I use apache/passenger on my development machine, but need to add SSL support (something which isn't exposed through the control panel). I've done this before in production, but for some reason I can't seem to get it work on OSX. The steps I've followed so far are from a default apache osx install: Install passenger and passenger preference pane. Add my rails app (this works) Create my ca.key, server.crt and server.key as detailed on the apple website. At this point I need to start editing the apache configs, so I added: # Apache knows to listen on port 443 for ssl requests. Listen 443 Listen 80 I thought I'd try editing the passenger pref pane generated config first to get everything working, when I add: It starts off looking like this <VirtualHost *:80> ServerName myapp.local DocumentRoot "/Users/jonnii/programming/ruby/myapp/public" RailsEnv development <Directory "/Users/jonnii/programming/ruby/myapp/public"> Order allow,deny Allow from all </Directory> </VirtualHost> I then append this: <VirtualHost *:443> ServerName myapp.local DocumentRoot "/Users/jonnii/programming/ruby/myapp/public" RailsEnv development <directory "/Users/jonnii/programming/ruby/myapp/public"> Order allow,deny Allow from all </directory> # SSL Configuration SSLEngine on SSLCipherSuite ALL:!ADH:!EXPORT56:RC4+RSA:+HIGH:+MEDIUM:+LOW:+SSLv2:+EXP SSLOptions +FakeBasicAuth +ExportCertData +StdEnvVars +StrictRequire #Self Signed certificates SSLCertificateFile /private/etc/apache2/ssl.key/server.crt SSLCertificateKeyFile /private/etc/apache2/ssl.key/server.key SSLCertificateChainFile /private/etc/apache2/ssl.key/ca.crt SetEnvIf User-Agent ".*MSIE.*" nokeepalive ssl-unclean-shutdown downgrade-1.0 force-response-1.0 </VirtualHost> The files referenced all exist (I doubled checked that), but now when I restart my apache I can't even get to myapp.local. However apache can still server the default page when I click on it in the sharing preference panel. Any help would be greatly appreciated.

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• Creating Lotus Notes documents with specific created/modified/last accessed dates for testing

  - by Xolstice

  I'm currently writing an application that moves Notes documents between databases based on the amount of days that have elapsed from the creation/modified/last accessed dates. I would just like to get ideas on a simple and convenient way to create documents with specific dates, without having to change the time on the Domino server, so that I could test out my application. The best way I found so far was to create a local replica and change the system clock to the date I want. Unfortunately there are problems associated with this method. It does not work on the modified date - I'm not sure how it is getting the modified date information when the location is set to Island (Disconnected) - and it also changes the modified and last accessed dates when the documents are replicated to the server replica. Someone suggested trying to create a DXL of the document, modify the date time in the DXL file, then import it back into the database as a Notes document; but that does not work. It just takes on the date-time that it was created. Can anyone offer any other suggestions?

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• Why use SQL database?

  - by martinthenext

  I'm not quite sure stackoverflow is a place for such a general question, but let's give it a try. Being exposed to the need of storing application data somewhere, I've always used MySQL or sqlite, just because it's always done like that. As it seems like the whole world is using these databases, most of all software products, frameworks, etc. It is rather hard for a beginning developer like me to ask a question - why? Ok, say we have some object-oriented logic in our application, and objects are related to each other somehow. We need to map this logic to the storage logic, so we need relations between database objects too. This leads us to using relational database and I'm ok with that - to put it simple, our database rows sometimes will need to have references to other tables' rows. But why do use SQL language for interaction with such a database? SQL query is a text message. I can understand this is cool for actually understanding what it does, but isn't it silly to use text table and column names for a part of application that no one ever seen after deploynment? If you had to write a data storage from scratch, you would have never used this kind of solution. Personally, I would have used some 'compiled db query' bytecode, that would be assembled once inside a client application and passed to the database. And it surely would name tables and colons by id numbers, not ascii-strings. In the case of changes in table structure those byte queries could be recompiled according to new db schema, stored in XML or something like that. What are the problems of my idea? Is there any reason for me not to write it myself and to use SQL database instead?

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• Managing lots of callback recursion in Nodejs

  - by Maciek

  In Nodejs, there are virtually no blocking I/O operations. This means that almost all nodejs IO code involves many callbacks. This applies to reading and writing to/from databases, files, processes, etc. A typical example of this is the following: var useFile = function(filename,callback){ posix.stat(filename).addCallback(function (stats) { posix.open(filename, process.O_RDONLY, 0666).addCallback(function (fd) { posix.read(fd, stats.size, 0).addCallback(function(contents){ callback(contents); }); }); }); }; ... useFile("test.data",function(data){ // use data.. }); I am anticipating writing code that will make many IO operations, so I expect to be writing many callbacks. I'm quite comfortable with using callbacks, but I'm worried about all the recursion. Am I in danger of running into too much recursion and blowing through a stack somewhere? If I make thousands of individual writes to my key-value store with thousands of callbacks, will my program eventually crash? Am I misunderstanding or underestimating the impact? If not, is there a way to get around this while still using Nodejs' callback coding style?

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• Glassfish: Defining Custom JNDI Names for Session Beans

  - by Adeel Ansari

  Background: Want to use GF3 in development, where as actual SIT, UAT, and production is using WAS. Problem: With the remote session beans everything is good to go, as GF3 gives a non-standard JNDI name, which is same as what WAS suggests, i.e. an absolute class name. Now for the local session beans WAS use the same absolute class name but with the prefix, i.e. ejblocal:. Whereas GF3 doesn't give any non-standard JNDI name for local session beans. GF3 came up with only portable name, java:global/..I need to find a way so I can use the same names for both. I am using EJB 3.0, WAS 7.9, and Glassfish 3. Don't have any xml confiuration for ejbs. Using Spring to inject the bean in Struts2 actions. With remote interfaces both servers are okay and agreed on a single convention, but for locals they differ. Is there any solution for this? Or just sun-ejb-jar.xml will solve it? Thanks.

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• Beginner SQL question: querying gold and silver tag badges in Stack Exchange Data Explorer

  - by polygenelubricants

  I'm using the Stack Exchange Data Explorer to learn SQL, but I think the fundamentals of the question is applicable to other databases. I'm trying to query the Badges table, which according to Stexdex (that's what I'm going to call it from now on) has the following schema: Badges Id UserId Name Date This works well for badges like [Epic] and [Legendary] which have unique names, but the silver and gold tag-specific badges seems to be mixed in together by having the same exact name. Here's an example query I wrote for [mysql] tag: SELECT UserId as [User Link], Date FROM Badges Where Name = 'mysql' Order By Date ASC The (slightly annotated) output is: as seen on stexdex: User Link Date --------------- ------------------- // all for silver except where noted Bill Karwin 2009-02-20 11:00:25 Quassnoi 2009-06-01 10:00:16 Greg 2009-10-22 10:00:25 Quassnoi 2009-10-31 10:00:24 // for gold Bill Karwin 2009-11-23 11:00:30 // for gold cletus 2010-01-01 11:00:23 OMG Ponies 2010-01-03 11:00:48 Pascal MARTIN 2010-02-17 11:00:29 Mark Byers 2010-04-07 10:00:35 Daniel Vassallo 2010-05-14 10:00:38 This is consistent with the current list of silver and gold earners at the moment of this writing, but to speak in more timeless terms, as of the end of May 2010 only 2 users have earned the gold [mysql] tag: Quassnoi and Bill Karwin, as evidenced in the above result by their names being the only ones that appear twice. So this is the way I understand it: The first time an Id appears (in chronological order) is for the silver badge The second time is for the gold Now, the above result mixes the silver and gold entries together. My questions are: Is this a typical design, or are there much friendlier schema/normalization/whatever you call it? In the current design, how would you query the silver and gold badges separately? GROUP BY Id and picking the min/max or first/second by the Date somehow? How can you write a query that lists all the silver badges first then all the gold badges next? Imagine also that the "real" query may be more complicated, i.e. not just listing by date. How would you write it so that it doesn't have too many repetition between the silver and gold subqueries? Is it perhaps more typical to do two totally separate queries instead? What is this idiom called? A row "partitioning" query to put them into "buckets" or something?

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• What does stdole.dll do?

  - by rc1

  We have a large C# (.net 2.0) app which uses our own C++ COM component and a 3rd party fingerprint scanner library also accessed via COM. We ran into an issue where in production some events from the fingerprint library do not get fired into the C# app, although events from our own C++ COM component fired and were received just fine. Using MSINFO32 to compare the loaded modules on a working system to those on a failing system we determined that this was caused by STDOLE.DLL not being in the GAC and hence not loaded into the faulty process. Dragging this file into the GAC caused events to come back fine from the fingerprint COM library. So what does stdole.dll do? It's 16k in size so it can't be much... is it some sort of link to another library like STDOLE32? How come its absence causes such odd behavior? How do we distribute stdole.dll? This is an XCOPY deploy app and we don't use the GAC. Should we package it as a resource and use the System.EnterpriseServices.Internal.Publish.GacInstall to ensure it's in the GAC?

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• What type of webapp is the sweet spot for Scala's Lift framework?

  - by ajay

  What kind of applications are the sweet spot for Scala's lift web framework. My requirements: Ease of development and maintainability Ready for production purposes. i.e. good active online community, regular patches and updates for security and performance fixes etc. Framework should survive a few years. I don't want to write a app in a framework for which no updates/patches are available after 1 year. Has good UI templating engines Interoperation with Java (Scala satisfies this arleady. Just mentioning here for completeness sake) Good component oriented development. Time required to develop should be proportion to the complexity of web application. Should not be totally configuration based. I hate it when code gets automatically generated for me and does all sorts of magic under the hood. That is a debugging nightmare. Amount of Lift knowledge required to develop a webapp should be proportional to the complexity of the web application. i.e I should't have to spend 10+ hours learning Lift just to develop a simple TODO application. (I have knowledge of Databases, Scala) Does Lift satisfy these requirements?

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• Several Small, Specific, MySQL Query Cache Questions

  - by Robbie

  I've look all over the web and in the questions asked here about MySQL caching and most of them seem very non-specific about a couple of questions that I have about performance and MySQL query caching. Specifically I want answers to these questions, assume for all questions that I have the query cache enabled and it is of type 2, or "DEMAND": Is the query cache per table, per database, or per server? Meaning if I have the cache size set to X and have T tables and D databases will I be caching TX, DX, or X amount of data? If I have table T1 which I regularly use the SQL_CACHE hint on for SELECT queries and table T2 which I never do, when I query T2 with a SELECT query will it check through the cache first before performing the query? *Note: I don't want to use the SQL_NO_CACHE for all T2 queries.* Assume the same situation as in question 2. If I alter (INSERT, DELETE) table T2 will any processing be done on the cache? For answers to 2 and 3, is this processing time negligible if T2 is constantly being altered and is the target of a majority of my SELECT queries?

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• sql exception when transferring project from usb to c:\

  - by jello

  I'm working on a C# windows program with Visual Studio 2008. Usually, I work from school, directly on my usb drive. But when I copy the folder on my hard drive at home, an sql exception is unhandled whenever I try to write to the database. it is unhandled at the conn.Open(); line. here's the exception unhandled Database 'L:\system\project\the_project\the_project\bin\Debug\PatientMonitoringDatabase.mdf' already exists. Choose a different database name. Cannot attach the file 'C:\Documents and Settings\Administrator\My Documents\system\project\the_project\the_project\bin\Debug\PatientMonitoringDatabase.mdf' as database 'PatientMonitoringDatabase'. it's weird, because my connection string says |DataDirectory|, so it should work on any drive... here's my connection string: string connStr = "Data Source=.\\SQLEXPRESS;AttachDbFilename=|DataDirectory|\\PatientMonitoringDatabase.mdf; " + "Initial Catalog=PatientMonitoringDatabase; " + "Integrated Security=True"; Someone told me to: Connect to localhost with SQL Server Management Studio Express, and remove/detach the existing PatientMonitoringDatabase database. Whether it's a persistent database or only active within a running application, you can't have 2 databases with the same name at the same time attached to a SQL Server instance. So I did that, and now it gives me: Directory lookup for the file "C:\Documents and Settings\Administrator\My Documents\system\project\the_project\the_project\bin\Debug\PatientMonitoringDatabase.mdf" failed with the operating system error 5(Access is denied.). Cannot attach the file 'C:\Documents and Settings\Administrator\My Documents\system\project\the_project\the_project\bin\Debug\PatientMonitoringDatabase.mdf' as database 'PatientMonitoringDatabase' I checked the files' properties, and I have allow for everyone. Does anyone know what's going on here?

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