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• VS 2008 created shortcut doesn't show up in "Send To" menu

  - by Brettski

  I have a WinForms application built using Visual Studio 2008. I added a Setup Project to the solution to create an installation MSI file. I need the setup project to create a shortcut pointing to the application's executable in the users Send To Menu. This way when someone right clicks on a file, my application will show in the Send To list and be selected. I figured out under the file system settings of the Setup project how to add a shortcut to the Users Send To Menu. The problem is, the shortcut doesn't show in the Send To menu when you right click on a file. If I manually create a shortcut to my executable the application does show in the Send To menu. I have read many suggestions on the web to required registry entries for this to work. There is a VBS file written by Ramesh Srinivasan which inserts them. On every system I have tried this on the registry values already existed, so this is not the problem. It seems more to be with the shortcut Visual Studio (or the msi anyway) is creating.

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• How to parse large xml files on google app engine?

  - by Alon Carmel

  Hey, I have fairly large xml file 1mb in size that i host on s3. I need to parse that xml file into my app engine datastore entirely. I have written a simple DOM parser that works fine locally but online it reaches the 30sec error and stops. I tried lowering the xml parsing by downloading the xml file into a BLOB at first before the parser then parse the xml file from blob. problem is that blobs are limited to 1mb. so it fails. I have multiple inserts to the datastore which cause it to fail on 30 sec. i saw somewhere that they recommend using the Mapper class and save some exception where the process stopped but as i am a python n00b i cant figure out how to implement it on a DOM parser or an SAX one (please provide an example?) on how to use it. i'm pretty much doing a bad thing right now and i parse the xml using php outside the app engine and push the data via HTTP post to the app engine using a proprietary API which works fine but is stupid and makes me maintain two codes. can you please help me out?

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• Using OUTPUT/INTO within instead of insert trigger invalidates 'inserted' table

  - by Dan

  I have a problem using a table with an instead of insert trigger. The table I created contains an identity column. I need to use an instead of insert trigger on this table. I also need to see the value of the newly inserted identity from within my trigger which requires the use of OUTPUT/INTO within the trigger. The problem is then that clients that perform INSERTs cannot see the inserted values. For example, I create a simple table: CREATE TABLE [MyTable]( [MyID] [int] IDENTITY(1,1) NOT NULL, [MyBit] [bit] NOT NULL, CONSTRAINT [PK_MyTable_MyID] PRIMARY KEY NONCLUSTERED ( [MyID] ASC )) Next I create a simple instead of trigger: create trigger [trMyTableInsert] on [MyTable] instead of insert as BEGIN DECLARE @InsertedRows table( MyID int, MyBit bit); INSERT INTO [MyTable] ([MyBit]) OUTPUT inserted.MyID, inserted.MyBit INTO @InsertedRows SELECT inserted.MyBit FROM inserted; -- LOGIC NOT SHOWN HERE THAT USES @InsertedRows END; Lastly, I attempt to perform an insert and retrieve the inserted values: DECLARE @tbl TABLE (myID INT) insert into MyTable (MyBit) OUTPUT inserted.MyID INTO @tbl VALUES (1) SELECT * from @tbl The issue is all I ever get back is zero. I can see the row was correctly inserted into the table. I also know that if I remove the OUTPUT/INTO from within the trigger this problem goes away. Any thoughts as to what I'm doing wrong? Or is how I want to do things not feasible? Thanks.

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• Database for Python Twisted

  - by Will

  There's an API for Twisted apps to talk to a database in a scalable way: twisted.enterprise.dbapi The confusing thing is, which database to pick? The database will have a Twisted app that is mostly making inserts and updates and relatively few selects, and then other strictly-read-only clients that are accessing the database directly making selects. (The read-only users are not necessarily selecting the data that the Twisted app is inserting; its not as though the database is being used as a message-queue) My understanding - which I'd like corrected/adviced - is that: Postgres is a great DB, but all the Python bindings - and there is a confusing maze of them - are abandonware There is psycopg2, but that makes a lot of noise about doing its own connection-pooling and things; does this co-exist gracefully/usefully/transparently with the Twisted async database connection pooling and such? SQLLite is a great database for little things but if used in a multi-user way it does whole-database locking, so performance would suck in the usage pattern I envisage MySQL - after the Oracle takeover, who'd want to adopt it now or adopt a fork? Is there anything else out there?

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• mysql and trigger usage question

  - by dhruvbird

  I have a situation in which I don't want inserts to take place (the transaction should rollback) if a certain condition is met. I could write this logic in the application code, but say for some reason, it has to be written in MySQL itself (say clients written in different languages will be inserting into this MySQL InnoDB table) [that's a separate discussion]. Table definition: CREATE TABLE table1(x int NOT NULL); The trigger looks something like this: CREATE TRIGGER t1 BEFORE INSERT ON table1 FOR EACH ROW IF (condition) THEN NEW.x = NULL; END IF; END; I am guessing it could also be written as(untested): CREATE TRIGGER t1 BEFORE INSERT ON table1 FOR EACH ROW IF (condition) THEN ROLLBACK; END IF; END; But, this doesn't work: CREATE TRIGGER t1 BEFORE INSERT ON table1 ROLLBACK; You are guaranteed that: Your DB will always be MySQL Table type will always be InnoDB That NOT NULL column will always stay the way it is Question: Do you see anything objectionable in the 1st method?

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• Passing an Ajax variable to a Codeigniter function

  - by Matt

  Hello, I think this is a simple one. I have a Codeigniter function which takes the inputs from a form and inserts them into a database. I want to Ajaxify the process. At the moment the first line of the function gets the id field from the form - I need to change this to get the id field from the Ajax post (which references a hidden field in the form containing the necessary value) instead. How do I do this please? My Codeigniter Controller function function add() { $product = $this->products_model->get($this->input->post('id')); $insert = array( 'id' => $this->input->post('id'), 'qty' => 1, 'price' => $product->price, 'size' => $product->size, 'name' => $product->name ); $this->cart->insert($insert); redirect('home'); } And the jQuery Ajax function $("#form").submit(function(){ var dataString = $("input#id") //alert (dataString);return false; $.ajax({ type: "POST", url: "/home/add", data: dataString, success: function() { } }); return false; }); As always, many thanks in advance.

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• Long running transactions with Spring and Hibernate?

  - by jimbokun

  The underlying problem I want to solve is running a task that generates several temporary tables in MySQL, which need to stay around long enough to fetch results from Java after they are created. Because of the size of the data involved, the task must be completed in batches. Each batch is a call to a stored procedure called through JDBC. The entire process can take half an hour or more for a large data set. To ensure access to the temporary tables, I run the entire task, start to finish, in a single Spring transaction with a TransactionCallbackWithoutResult. Otherwise, I could get a different connection that does not have access to the temporary tables (this would happen occasionally before I wrapped everything in a transaction). This worked fine in my development environment. However, in production I got the following exception: java.sql.SQLException: Lock wait timeout exceeded; try restarting transaction This happened when a different task tried to access some of the same tables during the execution of my long running transaction. What confuses me is that the long running transaction only inserts or updates into temporary tables. All access to non-temporary tables are selects only. From what documentation I can find, the default Spring transaction isolation level should not cause MySQL to block in this case. So my first question, is this the right approach? Can I ensure that I repeatedly get the same connection through a Hibernate template without a long running transaction? If the long running transaction approach is the correct one, what should I check in terms of isolation levels? Is my understanding correct that the default isolation level in Spring/MySQL transactions should not lock tables that are only accessed through selects? What can I do to debug which tables are causing the conflict, and prevent those tables from being locked by the transaction?

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• NetBeans parameter fill after code completion

  - by byte

  This is a particularly annoying problem I'm having, and I can't be the only one to have issue with it. In NetBeans, when you type part of a method, then hit CTRL-SPACE, it displays the code-completion popup, whereupon you can hit tab to finish out the word. This is great, and pretty much how all IDE's operate. Example: Thread.sl < CTRL-SPACE Thread.sleep Yay! Problem is that in this context, once you type in a paren, it auto-fills the parameters for the method with their default names, and inserts a closing paren (regardless of whether you have disabled the option to automatically close them on the preferences page for code completion). This behavior is NOT present if you had manually typed out the full name. How is this helpful to anyone? You've got to type over it your actual variable that you will be passing, and NetBeans gives you no option to prevent the closing paren on code-completion. Does anyone have a way to solve this issue, without having to dive into the netbeans source and build it just for this minor of an issue?

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• What arguments to use to explain why a SQL DB is far better then a flat file

  - by jamone

  The higher ups in my company were told by good friends that flat files are the way to go, and we should switch from MS SQL server to them for everything we do. We have over 300 servers and hundreds of different databases. From just the few I'm involved with we have 10 billion records in quite a few of them with upwards of 100k new records a day and who knows how many updates... Me and a couple others need to come up with a response saying why we shouldn't do this. Most of our stuff is ASP.NET with some legacy ASP. We thought that making a simple console app that tests/times the same interactions between a flat file (stored on the network) and SQL over the network doing large inserts, searches, updates etc along with things like network disconnects randomly. This would show them how bad flat files can be espically when you are dealing with millions of records. What things should I use in my response? What should I do with my demo code to illustrate this? My sort list so far: Security Concurent access Performance with large ammounts of data Ammount of time to do such a massive rewrite/switch Lack of transactions PITA to map relational data to flat files I fear that this will be a great post on the Daily WTF someday if I can't stop it now.

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• SQL: Order randomly when inserting objects to a table

  - by Ekaterina

  I have an UDF that selects top 6 objects from a table (with a union - code below) and inserts it into another table. (btw SQL 2005) So I paste the UDF below and what the code does is: selects objects for a specific city and add a level to those (from table Europe) union that selection with a selection from the same table for objects that are from the same country and add a level to those From the union, selection is made to get top 6 objects, order by level, so the objects from the same city will be first, and if there aren't any available, then objects from the same country will be returned from the selection. And my problem is, that I want to make a random selection to get random objects from table Europe, but because I insert the result of my selection into a table, I can't use order by newid() or rand() function because they are time-dependent, so I get the following errors: Invalid use of side-effecting or time-dependent operator in 'newid' within a function. Invalid use of side-effecting or time-dependent operator in 'rand' within a function. UDF: ALTER FUNCTION [dbo].[Objects] (@id uniqueidentifier) RETURNS @objects TABLE ( ObjectId uniqueidentifier NOT NULL, InternalId uniqueidentifier NOT NULL ) AS BEGIN declare @city varchar(50) declare @country int select @city = city, @country = country from Europe where internalId = @id insert @objects select @id, internalId from ( select distinct top 6 [level], internalId from ( select top 6 1 as [level], internalId from Europe N4 where N4.city = @city and N4.internalId != @id union select top 6 2 as [level], internalId from Europe N5 where N5.countryId = @country and N5.internalId != @id ) as selection_1 order by [level] ) as selection_2 return END If you have fresh ideas, please share them with me. (Just please, don't suggest to order by newid() or to add a column rand() with seed DateTime (by ms or sthg), because that won't work.)

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• LINQ to Sql: Insert instead of Update

  - by Christina Mayers

  I am stuck with this problems for a long time now. Everything I try to do is insert a row in my DB if it's new information - if not update the existing one. I've updated many entities in my life before - but what's wrong with this code is beyond me (probably something pretty basic) I guess I can't see the wood for the trees... private Models.databaseDataContext db = new Models.databaseDataContext(); internal void StoreInformations(IEnumerable<EntityType> iEnumerable) { foreach (EntityType item in iEnumerable) { EntityType type = db.EntityType.Where(t => t.Room == item.Room).FirstOrDefault(); if (type == null) { db.EntityType.InsertOnSubmit(item); } else { type.Date = item.Date; type.LastUpdate = DateTime.Now(); type.End = item.End; } } } internal void Save() { db.SubmitChanges(); } Edit: just checked the ChangeSet, there are no updates only inserts. For now I've settled with foreach (EntityType item in iEnumerable) { EntityType type = db.EntityType.Where(t => t.Room == item.Room).FirstOrDefault(); if (type != null) { db.Exams.DeleteOnSubmit(type); } db.EntityType.InsertOnSubmit(item); } but I'd love to do updates and lose these unnecessary delete statements.

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• Left/Right/Inner joins using C# and LINQ

  - by Keith Barrows

  I am trying to figure out how to do a series of queries to get the updates, deletes and inserts segregated into their own calls. I have 2 tables, one in each of 2 databases. One is a Read Only feeds database and the other is the T-SQL R/W Production source. There are a few key columns in common between the two. What I am doing to setup is this: List<model.AutoWithImage> feedProductList = _dbFeed.AutoWithImage.Where(a => a.ClientID == ClientID).ToList(); List<model.vwCompanyDetails> companyDetailList = _dbRiv.vwCompanyDetails.Where(a => a.ClientID == ClientID).ToList(); foreach (model.vwCompanyDetails companyDetail in companyDetailList) { List<model.Product> productList = _dbRiv.Product.Include("Company").Where(a => a.Company.CompanyId == companyDetail.CompanyId).ToList(); } Now that I have a (source) list of products from the feed, and an existing (target) list of products from my prod DB I'd like to do 3 things: Find all SKUs in the feed that are not in the target Find all SKUs that are in both, that are active feed products and update the target Find all SKUs that are in both, that are inactive and soft delete from the target What are the best practices for doing this without running a double loop? Would prefer a LINQ 4 Objects solution as I already have my objects. EDIT: BTW, I will need to transfer info from feed rows to target rows in the first 2 instances, just set a flag in the last instance. TIA

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• Ruby Design Problem for SQL Bulk Inserter

  - by crunchyt

  This is a Ruby design problem. How can I make a reusable flat file parser that can perform different data scrubbing operations per call, return the emitted results from each scrubbing operation to the caller and perform bulk SQL insertions? Now, before anyone gets narky/concerned, I have written this code already in a very unDRY fashion. Which is why I am asking any Ruby rockstars our there for some assitance. Basically, everytime I want to perform this logic, I create two nested loops, with custom processing in between, buffer each processed line to an array, and output to the DB as a bulk insert when the buffer size limit is reached. Although I have written lots of helpers, the main pattern is being copy pasted everytime. Not very DRY! Here is a Ruby/Pseudo code example of what I am repeating. lines_from_file.each do |line| line.match(/some regex/).each do |sub_str| # Process substring into useful format # EG1: Simple gsub() call # EG2: Custom function call to do complex scrubbing # and matching, emitting results to array # EG3: Loop to match opening/closing/nested brackets # or other delimiters and emit results to array end # Add processed lines to a buffer as SQL insert statement @buffer << PREPARED INSERT STATEMENT # Flush buffer when "buffer size limit reached" or "end of file" if sql_buffer_full || last_line_reached @dbc.insert(SQL INSERTS FROM BUFFER) @buffer = nil end end I am familiar with Proc/Lambda functions. However, because I want to pass two separate procs to the one function, I am not sure how to proceed. I have some idea about how to solve this, but I would really like to see what the real Rubyists suggest? Over to you. Thanks in advance :D

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• What arguments to use to explain why SQL Server is far better then a flat file

  - by jamone

  The higher ups in my company were told by good friends that flat files are the way to go, and we should switch from SQL Server to them for everything we do. We have over 300 servers and hundreds of different databases. From just the few I'm involved with we have 10 billion records in quite a few of them with upwards of 100k new records a day and who knows how many updates... Me and a couple others need to come up with a response saying why we shouldn't do this. Most of our stuff is ASP.NET with some legacy ASP. We thought that making a simple console app that tests/times the same interactions between a flat file (stored on the network) and SQL over the network doing large inserts, searches, updates etc along with things like network disconnects randomly. This would show them how bad flat files can be especially when you are dealing with millions of records. What things should I use in my response? What should I do with my demo code to illustrate this? My sort list so far: Security Concurrent access Performance with large amounts of data Amount of time to do such a massive rewrite/switch Lack of transactions PITA to map relational data to flat files NTFS doesn't support tons of files in a directory well I fear that this will be a great post on the Daily WTF someday if I can't stop it now.

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• How Do I Escape Apostrophes in Field Valued in SQL Server?

  - by Mikecancook

  I asked a question a couple days ago about creating INSERTs by running a SELECT to move data to another server. That worked great until I ran into a table that has full on HTML and apostrophes in it. What's the best way to deal with this? Lucking there aren't too many rows so it is feasible as a last resort to 'copy and paste'. But, eventually I will need to do this and the table by that time will probably be way too big to copy and paste these HTML fields. This is what I have now: select 'Insert into userwidget ([Type],[UserName],[Title],[Description],[Data],[HtmlOutput],[DisplayOrder],[RealTime],[SubDisplayOrder]) VALUES (' + ISNULL('N'''+Convert(varchar(8000),Type)+'''','NULL') + ',' + ISNULL('N'''+Convert(varchar(8000),Username)+'''','NULL') + ',' + ISNULL('N'''+Convert(varchar(8000),Title)+'''','NULL') + ',' + ISNULL('N'''+Convert(varchar(8000),Description)+'''','NULL') + ',' + ISNULL('N'''+Convert(varchar(8000),Data)+'''','NULL') + ',' + ISNULL('N'''+Convert(varchar(8000),HTMLOutput)+'''','NULL') + ',' + ISNULL('N'''+Convert(varchar(8000),DisplayOrder)+'''','NULL') + ',' + ISNULL('N'''+Convert(varchar(8000),RealTime)+'''','NULL') + ',' + ISNULL('N'''+Convert(varchar(8000),SubDisplayOrder)+'''','NULL') + ')' from userwidget Which is works fine except those pesky apostrophes in the HTMLOutput field. Can I escape them by having the query double up on the apostrophes or is there a way of encoding the field result so it won't matter?

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• Same query has nested loops when used with INSERT, but Hash Match without.

  - by AaronLS

  I have two tables, one has about 1500 records and the other has about 300000 child records. About a 1:200 ratio. I stage the parent table to a staging table, SomeParentTable_Staging, and then I stage all of it's child records, but I only want the ones that are related to the records I staged in the parent table. So I use the below query to perform this staging by joining with the parent tables staged data. --Stage child records INSERT INTO [dbo].[SomeChildTable_Staging] ([SomeChildTableId] ,[SomeParentTableId] ,SomeData1 ,SomeData2 ,SomeData3 ,SomeData4 ) SELECT [SomeChildTableId] ,D.[SomeParentTableId] ,SomeData1 ,SomeData2 ,SomeData3 ,SomeData4 FROM [dbo].[SomeChildTable] D INNER JOIN dbo.SomeParentTable_Staging I ON D.SomeParentTableID = I.SomeParentTableID; The execution plan indicates that the tables are being joined with a Nested Loop. When I run just the select portion of the query without the insert, the join is performed with Hash Match. So the select statement is the same, but in the context of an insert it uses the slower nested loop. I have added non-clustered index on the D.SomeParentTableID so that there is an index on both sides of the join. I.SomeParentTableID is a primary key with clustered index. Why does it use a nested loop for inserts that use a join? Is there a way to improve the performance of the join for the insert?

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• Growing user control not updating

  - by user328259

  I am developing in C# and .Net 2.0. I have a user control that draws cells (columnar) depending upon the maximum number of cells. There are some drawing routines that generate the necessary cells. There is a property NumberOfCells that adjust the height of this control; CELLHEIGHT_CONSTANT * NumberOfCells. The OnPaint() method is overridden (code that draws the Number of cells). There is another user control that contains a panel which contains the userControl1 from above. There is a property NumberCells that changes userControl1's NumberOfCells. UserControl2 is then placed on a windows form. On that form there is a NumericUpDown control (only increments from 1). When the user increments by 1, I adjust the VerticalScroll.Maximum by 1 as well. Everything works well and good BUT when I increment once, the panel updates fine (inserts a vertical scrolll when necessary) but cells are not being added! I've tried Invalidating on userControl2 AND on the form but nothing seems to draw the newly added cells. Any assistance is appreciated. Thank you in advance. Lawrence

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• Looking for a very simple file-based CMS

  - by nfm

  I'm building a site for a friend for free, and am trying to work out a good way for her to be able to easily make updates. I haven't used any CMSs before. I was browsing the web today looking at some, and they all seem way too complicated for what I'm after. Basically, all I want is a really simple CMS that pulls together HTML snippets in particular subdirectories, and wraps them in header/footer HTML and inserts them into a template page in the appropriate section. I'm imagining a site layout something like this: / /index.php /blog_template.php /news_template.php /blog/ /blog/header.php /blog/footer.php /blog/my-first-blog.html /blog/blogs-rule.html /blog/... Say index.php contains div#blog. PHP would wrap each /blog/*.html file in /blog/header.php and blog/footer.php, and insert them into the div#blog as div#blog([0-9]*). I haven't been able to find anything this basic, and am one step away from throwing something together myself, but I'm a bit short on time at the moment and figured I'd post here first. Has anyone come across something like this? I don't want any DB, extensions, user accounts, installation, config, updates... just a simple file based solution. Thanks :) Forgot to mention - needs to be FOSS and run on Linux!

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• insert data to table based on another table C#

  - by user1017315

  I wrote a code which takes some values from one table and inserts the other table in these values.(not just these values, but also these values(this values=values from the based on table)) and I get this error: System.Data.OleDb.OleDbException (0x80040E10): value wan't given for one or more of the required parameters.` here's the code. I don't know what i've missed. string selectedItem = comboBox1.SelectedItem.ToString(); Codons cdn = new Codons(selectedItem); string codon1; int index; if (this.i != this.counter) { //take from the DataBase the matching codonsCodon1 to codonsFullName codon1 = cdn.GetCodon1(); //take the serialnumber of the last protein string connectionString = "Provider=Microsoft.ACE.OLEDB.12.0;" + "Data Source=C:\\Projects_2012\\Project_Noam\\Access\\myProject.accdb"; OleDbConnection conn = new OleDbConnection(connectionString); conn.Open(); string last= "SELECT proInfoSerialNum FROM tblProInfo WHERE proInfoScienceName = "+this.name ; OleDbCommand getSerial = new OleDbCommand(last, conn); OleDbDataReader dr = getSerial.ExecuteReader(); dr.Read(); index = dr.GetInt32(0); //add the amino acid to tblOrderAA using (OleDbConnection connection = new OleDbConnection(connectionString)) { string insertCommand = "INSERT INTO tblOrderAA(orderAASerialPro, orderAACodon1) " + " values (?, ?)"; using (OleDbCommand command = new OleDbCommand(insertCommand, connection)) { connection.Open(); command.Parameters.AddWithValue("orderAASerialPro", index); command.Parameters.AddWithValue("orderAACodon1", codon1); command.ExecuteNonQuery(); } } } EDIT:I put a messagebox after that line: index = dr.GetInt32(0); to see where is the problem, and i get the error before that.i don't see the messagebox

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• How to properly set JavaMail timeout setting

  - by user286149

  I am using JavaMail to connect to a POP3 server. Further, I set the following properties, so that JavaMail won't wait to long if an email server doesn't respond: props.setProperty("mail.pop3.connectionpooltimeout", "3000"); props.setProperty("mail.pop3.connectiontimeout", "3000"); props.setProperty("mail.pop3.timeout", "3000"); However, in some cases the timeout works properly but sometimes JavaMail freezes for minutes(!) with the following debug message: DEBUG POP3: connecting to host "pop3.yahoo.com", port 110, isSSL false Changing ports or protocols (SSL, TLS..) has no effect. I assume that the host simply doesn't exist. For example, if I poll pop3.yahoo.com instead of pop.mail.yahoo.com (which would be the right host name), I have to wait very long til a timeout exception occurs. After several minutes, I get the following exception and the application continues to run: java.net.ConnectException: Operation timed out pop3.yahoo.com seems to exist but won't respond: localhost:~ me$ ping pop3.yahoo.com PING pop3.yahoo.com (206.190.46.10): 56 data bytes Request timeout for icmp_seq 0 Request timeout for icmp_seq 1 Request timeout for icmp_seq 2 Request timeout for icmp_seq 3 ^C You might be asking why I use pop3.yahoo.com instead of pop.mail.yahoo.com. Well, I simply wanted to test what happens if the user of my application inserts a wrong host name. I believe that this issue is related to this report http://www.opensubscriber.com/message/[email protected]/180946.html where the poster claims that the problem occurs if the email server closes the connection. JavaMail then seems to wait very long (don't know why). Since the issue wasn't resolved in the link I posted: Does somebody know how to fix or at least debug this? Any help would be really appreciated!

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• Constructor and Destructors in C++ [Not a question] [closed]

  - by Jack

  I am using gcc. Please tell me if I am wrong - Lets say I have two classes A & B class A { public: A(){cout<<"A constructor"<<endl;} ~A(){cout<<"A destructor"<<endl;} }; class B:public A { public: B(){cout<<"B constructor"<<endl;} ~B(){cout<<"B destructor"<<endl;} }; 1) The first line in B's constructor should be a call to A's constructor ( I assume compiler automatically inserts it). Also the last line in B's destructor will be a call to A's destructor (compiler does it again). Why was it built this way? 2) When I say A * a = new B(); compiler creates a new B object and checks to see if A is a base class of B and if it is it allows 'a' to point to the newly created object. I guess that is why we don't need any virtual constructors. ( with help from @Tyler McHenry , @Konrad Rudolph) 3) When I write delete a compiler sees that a is an object of type A so it calls A's destructor leading to a problem which is solved by making A's destructor virtual. As user - Little Bobby Tables pointed out to me all destructors have the same name destroy() in memory so we can implement virtual destructors and now the call is made to B's destructor and all is well in C++ land. Please comment.

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• JUnit test failing - complaining of missing data that was just inserted

  - by Collin Peters

  I have an extremely odd problem in my JUnit tests that I just can't seem to nail down. I have a multi-module java webapp project with a fairly standard structure (DAO's, service clasess, etc...). Within this project I have a 'core' project which contains some abstracted setup code which inserts a test user along with the necessary items for a user (in this case an 'enterprise', so a user must belong to an enterprise and this is enforced at the database level) Fairly simple so far... but here is where the strangeness begins some tests fail to run and throw a database exception where it complains that a user cannot be inserted because an enterprise does not exist. But it just created the enterprise in the preceding line of code! And there was no errors in the insertion of the enterprise. Stranger yet, if this test class is run by itself everything works fine. It is only when the test is run as part of the project that it fails! And the exact same abstracted code was run by 10+ tests before the one that fails! f I have been banging my head against a wall with this for days and haven't really made any progress. I'm not even sure what information to offer up to help diagnose this. Using JUnit 4.4, Spring 2.5.6, iBatis 2.3.0, Postgresql 8.3 Switching to org.springframework.jdbc.datasource.DriverManagerDataSource from org.apache.commons.dbcp.BasicDataSource changed the problem. Using DriverManagerDataSource the tests work for the first time, but now all of a sudden a lot of data isn't rolled back in the database! It leaves everything behind. All with no errors Tests fail when run via Eclipse & Maven Please ask for any info which may help me solve my problem!

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• sqlite3 'database is locked' won't go away with retries

  - by Azarias

  I have a sqlite3 database that is accessed by a few threads (3-4). I am aware of the general limitations of sqlite3 with regards to concurrency as stated http://www.sqlite.org/faq.html#q6 , but I am convinced that is not the problem. All of the threads both read and write from this database. Whenever I do a write, I have the following construct: try: Cursor.execute(q, params) Connection.commit() except sqlite3.IntegrityError: Notify except sqlite3.OperationalError: print sys.exc_info() print("DATABASE LOCKED; sleeping for 3 seconds and trying again") time.sleep(3) Retry On some runs, I won't even hit this block, but when I do, it never comes out of it (keeps retrying, but I keep getting the 'database is locked' error from exc_info. If I understand the reader/writer lock usage correctly, some amount of waiting should help with the contention. What this sounds like is deadlock, but I do not use any transactions in my code, and every SELECT or INSERT is simply a one off. Some threads, however, keep the same connection when they do their operation (which includes a mix of SELECTS and INSERTS and other modifiers). I would appericiate it if you could shade a light on this, and also ways around fixing it (besides using a different database engine.)

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• What if a large number of objects are passed to my SwingWorker.process() method?

  - by Trejkaz

  I just found an interesting situation. Suppose you have some SwingWorker (I've made this one vaguely reminiscent of my own): public class AddressTreeBuildingWorker extends SwingWorker<Void, NodePair> { private DefaultTreeModel model; public AddressTreeBuildingWorker(DefaultTreeModel model) { } @Override protected Void doInBackground() { // Omitted; performs variable processing to build a tree of address nodes. } @Override protected void process(List<NodePair> chunks) { for (NodePair pair : chunks) { // Actually the real thing inserts in order. model.insertNodeInto(parent, child, parent.getChildCount()); } } private static class NodePair { private final DefaultMutableTreeNode parent; private final DefaultMutableTreeNode child; private NodePair(DefaultMutableTreeNode parent, DefaultMutableTreeNode child) { this.parent = parent; this.child = child; } } } If the work done in the background is significant then things work well - process() is called with relatively small lists of objects and everything is happy. Problem is, if the work done in the background is suddenly insignificant for whatever reason, process() receives a huge list of objects (I have seen 1,000,000, for instance) and by the time you process each object, you have spent 20 seconds on the Event Dispatch Thread, exactly what SwingWorker was designed to avoid. In case it isn't clear, both of these occur on the same SwingWorker class for me - it depends on the input data, and the type of processing the caller wanted. Is there a proper way to handle this? Obviously I can intentionally delay or yield the background processing thread so that a smaller number might arrive each time, but this doesn't feel like the right solution to me.

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• mysql_real_escape_string() just makes an empty string?

  - by James P

  I am using a jQuery AJAX request to a page called like.php that connects to my database and inserts a row. This is the like.php code: <?php // Some config stuff define(DB_HOST, 'localhost'); define(DB_USER, 'root'); define(DB_PASS, ''); define(DB_NAME, 'quicklike'); $link = mysql_connect(DB_HOST, DB_USER, DB_PASS) or die('ERROR: ' . mysql_error()); $sel = mysql_select_db(DB_NAME, $link) or die('ERROR: ' . mysql_error()); $likeMsg = mysql_real_escape_string(trim($_POST['likeMsg'])); $timeStamp = time(); if(empty($likeMsg)) die('ERROR: Message is empty'); $sql = "INSERT INTO `likes` (like_message, timestamp) VALUES ('$likeMsg', $timeStamp)"; $result = mysql_query($sql, $link) or die('ERROR: ' . mysql_error()); echo mysql_insert_id(); mysql_close($link); ?> The problematic line is $likeMsg = mysql_real_escape_string(trim($_POST['likeMsg']));. It seems to just return an empty string, and in my database under the like_message column all I see is blank entries. If I remove mysql_real_escape_string() though, it works fine. Here's my jQuery code if it helps. $('#like').bind('keydown', function(e) { if(e.keyCode == 13) { var likeMessage = $('#changer p').html(); if(likeMessage) { $.ajax({ cache: false, url: 'like.php', type: 'POST', data: { likeMsg: likeMessage }, success: function(data) { $('#like').unbind(); writeLikeButton(data); } }); } else { $('#button_container').html(''); } } }); All this jQuery code works fine, I've tested it myself independently. Any help is greatly appreciated, thanks.

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