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• Statistical analysis on large data set to be published on the web

  - by dassouki

  I have a non-computer related data logger, that collects data from the field. This data is stored as text files, and I manually lump the files together and organize them. The current format is through a csv file per year per logger. Each file is around 4,000,000 lines x 7 loggers x 5 years = a lot of data. some of the data is organized as bins item_type, item_class, item_dimension_class, and other data is more unique, such as item_weight, item_color, date_collected, and so on ... Currently, I do statistical analysis on the data using a python/numpy/matplotlib program I wrote. It works fine, but the problem is, I'm the only one who can use it, since it and the data live on my computer. I'd like to publish the data on the web using a postgres db; however, I need to find or implement a statistical tool that'll take a large postgres table, and return statistical results within an adequate time frame. I'm not familiar with python for the web; however, I'm proficient with PHP on the web side, and python on the offline side. users should be allowed to create their own histograms, data analysis. For example, a user can search for all items that are blue shipped between week x and week y, while another user can search for sort the weight distribution of all items by hour for all year long. I was thinking of creating and indexing my own statistical tools, or automate the process somehow to emulate most queries. This seemed inefficient. I'm looking forward to hearing your ideas Thanks

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• Single website multiple connection strings using asp mvc 2 and nhibernate

  - by jjjjj

  Hi In my website i use ASP MVC 2 + Fluent NHibernate as orm, StructureMap for IoC container. There are several databases with identical metadata(and so entities and mappings are the same). On LogOn page user fiils in login, password, rememberme and chooses his server from dropdownlist (in fact he chooses database). Web.config contains all connstrings and we can assume that they won't be changed in run-time. I suppose that it is required to have one session factory per database. Before using multiple databases, i loaded classes to my StructureMap ObjectFactory in Application_Start ObjectFactory.Initialize(init => init.AddRegistry<ObjectRegistry>()); ObjectFactory.Configure(conf => conf.AddRegistry<NhibernateRegistry>()); NhibernateRegistry class: public class NhibernateRegistry : Registry { public NhibernateRegistry() { var sessionFactory = NhibernateConfiguration.Configuration.BuildSessionFactory(); For<Configuration>().Singleton().Use( NhibernateConfiguration.Configuration); For<ISessionFactory>().Singleton().Use(sessionFactory); For<ISession>().HybridHttpOrThreadLocalScoped().Use( ctx => ctx.GetInstance<ISessionFactory>().GetCurrentSession()); } } In Application_BeginRequest i bind opened nhibernate session to asp session(nhibernate session per request) and in EndRequest i unbind them: protected void Application_BeginRequest( object sender, EventArgs e) { CurrentSessionContext.Bind(ObjectFactory.GetInstance<ISessionFactory>().OpenSession()); } Q1: How can i realize what SessionFactory should i use according to authenticated user? is it something like UserData filled with database name (i use simple FormsAuthentication) For logging i use log4net, namely AdoNetAppender which contains connectionString(in xml, of course). Q2: How can i manage multiple connection strings for this database appender, so logs would be written to current database? I have no idea how to do that except changing xml all the time and reseting xml configuration, but its really bad solution.

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• ZeroMQ REQ/REP on ipc:// and concurrency

  - by Metiu

  I implemented a JSON-RPC server using a REQ/REP 0MQ ipc:// socket and I'm experiencing strange behavior which I suspect is due to the fact that the ipc:// underlying unix socket is not a real socket, but rather a single pipe. From the documentation, one has to enforce strict zmq_send()/zmq_recv() alternation, otherwise the out-of-order zmq_send() will return an error. However, I expected the enforcement to be per-client, not per-socket. Of course with a Unix socket there is just one pipeline from multiple clients to the server, so the server won't know who it is talking with. Two clients could zmq_send() simultaneously and the server would see this as an alternation violation. The sequence could be: ClientA: zmq_send() ClientB: zmq_send() : will it block until the other send/receive completes? will it return -1? (I suspect it will with ipc:// due to inherent low-level problems, but with TCP it could distinguish the two clients) ClientA: zmq_recv() ClientB: zmq_recv() so what about tcp:// sockets? Will it work concurrently? Should I use some other locking mechanism to work around this?

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• Json get a parameter can't access on it iOS

  - by Usi Usi

  That's an example { "updated":1350213484, "id":"http://www.google.com/reader/api/0/feed-finder?q\u003dProva\u0026output\u003djson", "title":"Risultati di feed per \"Prova\"", "self":[ { "href":"http://www.google.com/reader/api/0/feed-finder?q\u003dProva\u0026output\u003djson" } ], "items":[ { "title":"Home Page - La prova del cuoco", "id":"http://www.laprovadelcuoco.rai.it/", "updated":1350213485, "feed":[ { "href":"http://www.laprovadelcuoco.rai.it/dl/portali/site/page/Page-ffb545b4-9e72-41e5-866f-a465588c43fa-rss.html" } ], "alternate":[ { "href":"http://www.laprovadelcuoco.rai.it/", "type":"text/html" } ], "content":{ "direction":"ltr", "content":"Diventa un cuoco provetto con “La Prova del Cuoco”: le videoricette in un' applicazione di facile e veloce consultazione per il tuo Iphone. Scopri come acquistare ..." } }, { "title":"Le prove Invalsi di matematica e italiano", "id":"http://online.scuola.zanichelli.it/quartaprova/", "updated":1350213486, "feed":[ { "href":"http://online.scuola.zanichelli.it/quartaprova/feed/" } ], "alternate":[ { "href":"http://online.scuola.zanichelli.it/quartaprova/", "type":"text/html" } ], "content":{ "direction":"ltr", "content":"Un sito Zanichelli dedicato alle prove Invalsi di italiano e matematica: esercitazioni, consigli, informazioni utili, novità, aggiornamenti e blog d'autore sulle prove ..." } }, How can I get the feed URL? That's what I do NSString *daParsare=[reader searchFeed:searchText]; NSArray *items = [[daParsare JSONValue] objectForKey:@"items"]; for (NSDictionary *item in items) { NSString *title = [item objectForKey:@"title"]; NSString *feed = [item valueForKeyPath:@"feed.href"]; } [tab reloadData]; With the title everything is ok but when I try to access to the feed paramater I get the error...

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• When to use @Singleton in a Jersey resource

  - by dexter

  I have a Jersey resource that access the database. Basically it opens a database connection in the initialization of the resource. Performs queries on the resource's methods. I have observed that when I do not use @Singleton, the database is being open at each request. And we know opening a connection is really expensive right? So my question is, should I specify that the resource be singleton or is it really better to keep it at per request especially when the resource is connecting to the database? My resource code looks like this: //Use @Singleton here or not? @Path(/myservice/) public class MyResource { private ResponseGenerator responser; private Log logger = LogFactory.getLog(MyResource.class); public MyResource() { responser = new ResponseGenerator(); } @GET @Path("/clients") public String getClients() { logger.info("GETTING LIST OF CLIENTS"); return responser.returnClients(); } ... // some more methods ... } And I connect to the database using a code similar to this: public class ResponseGenerator { private Connection conn; private PreparedStatement prepStmt; private ResultSet rs; public ResponseGenerator(){ Class.forName("org.h2.Driver"); conn = DriverManager.getConnection("jdbc:h2:testdb"); } public String returnClients(){ String result; try{ prepStmt = conn.prepareStatement("SELECT * FROM hosts"); rs = prepStmt.executeQuery(); ... //do some processing here ... } catch (SQLException se){ logger.warn("Some message"); } finally { rs.close(); prepStmt.close(); // should I also close the connection here (in every method) if I stick to per request // and add getting of connection at the start of every method // conn.close(); } return result } ... // some more methods ... } Some comments on best practices for the code will also be helpful.

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• Gradual memory leak and slowdown in loop

  - by Benji XVI

  I have a simple foundation tool that exports every frame of a movie as a .tiff file. Here is the relevant code: NSString* movieLoc = [NSString stringWithCString:argv[1]]; QTMovie *sourceMovie = [QTMovie movieWithFile:movieLoc error:nil]; int i=0; while (QTTimeCompare([sourceMovie currentTime], [sourceMovie duration]) != NSOrderedSame) { // save image of movie to disk NSAutoreleasePool *arp = [[NSAutoreleasePool alloc] init]; NSString *filePath = [NSString stringWithFormat:@"/somelocation_%d.tiff", i++]; NSData *currentImageData = [[sourceMovie currentFrameImage] TIFFRepresentation]; [currentImageData writeToFile:filePath atomically:NO]; NSLog(@"%@", filePath); [sourceMovie stepForward]; [arp release]; } [pool drain]; return 0; As you can see, in order to prevent very large memory buildups with the various transparently-autoreleased variables in the loop, we create, and flush, an autoreleasepool with every run through the loop. However, over the course of stepping through a movie, the amount of memory used by the program still gradually increases, and the speed at which frames are processed drops precipitously. (From ~0.5 seconds per frame at the start, to ~2 seconds per frame by the 250th frame.) The only thing I can think can be causing the gradual memory leak is a buildup of the NSAutoreleasePool objects themselves. Am I right in thinking they will only be deallocated when the outer pool is released? If so, is there a better memory management solution here? Creating a pool every run through the loop seems a little hacky. And if not, what is causing the slow memory leak? (It is not NSStrings, and much too slow to be NSImages or NSDatas.) And what could be causing the slowdown?

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• How do I refer to a windows form control by name (C# / VB)

  - by Alex

  Suppose I have a label control on a windows form called "UserName". How can I refer to that label programmatically using the label name? For example I can do: For each ctrl as Control in TabPage.Controls If ctrl.Name = "UserName" Then ' Do something End If Next This seems quite inefficient. I would like to do something like: TabPage.Controls("UserName").Text = "Something" I did some googling but couldn't find a satisfactory answer. Most suggested looping, some said .NET 2005 doesn't support direct refenece using string name, and FindControl method was asp.net only... EDIT Thanks for the response so far. Here is a bit more detail. I have a windows form with three tabpages, all of which a very similar in design and function i.e. same drop down menus, labels, react in simlar way to events etc. Rather than write code for each event per tabpage I have built a class that controls the events etc. per tabpage. For example, on each tabpage there is a Label called "RecordCounter" that simply shows the number of rows in the datagridview when it is populated by selection of a variable in a drop down menu. So what I want to be able to do is, upon selection of a variable in the drop down menu, the datagridview populates itself with data, and then I simply want to display the number of rows in a label ("RecordCounter"). This is exactly the same process on each tabpage so what I am doing is passing the tabpage to the class and then I want to be able to refer to the "RecordCounter" and then update it. In my class I set the ActivePage property to be the TabPage that the user has selected and then want to be able to do something like: ActivePage.RecordCounter.Text = GetNumberOfRows()

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• "Too many indexes on table" error when creating relationships in Microsoft Access 2010.

  - by avianattackarmada

  I have tblUsers which has a primary key of UserID. UserID is used as a foreign key in many tables. Within a table, it is used as a foreign key for multiple fields (e.g. ObserverID, RecorderID, CheckerID). I have successfully added relationships (with in the the MS Access 'Relationship' view), where I have table aliases to do the multiple relationships per table: *tblUser.UserID - 1 to many - tblResight.ObserverID *tblUser_1.UserID - 1 to many - tblResight.CheckerID After creating about 25 relationships with enforcement of referential integrity, when I try to add an additional one, I get the following error: "The operation failed. There are too many indexes on table 'tblUsers.' Delete some of the indexes on the table and try the operation again." I ran the code I found here and it returned that I have 6 indexes on tblUsers. I know there is a limit of 32 indexes per table. Am I using the relationship GUI wrong? Does access create an index for the enforcement of referential integrity any time I create a relationship (especially indexes that wouldn't turn up when I ran the script)? I'm kind of baffled, any help would be appreciated.

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• How to write a JOIN statement to combine data from disparate tables

  - by Amarundo

  I have the following 2 procedures that I use as my source for a report. As of now, I'm presenting 2 different tables in my SQL Server Reporting Services 2008 R2 report, because it doesn't let me put them together as they belong to 2 different data sets. I want to present them in a single table, but I have not been successful trying to use JOIN here. How do I do that? NOTE: cName in IAgentQueueStats corresponds to UserId in AgentActivityLog. /*** Aggregate values for Call Center Agents for calls, talk and hold time ***/ /*** The detail/row values is per 30-minute interval ***/ ALTER PROCEDURE [dbo].[sp_IAgentQueueStats_OnlyCalls_Grouped] @p_StartDate datetime, @p_EndDate datetime, @p_Agents varchar(8000) AS SELECT [cName] ,sum([nAnswered]) SumNAnswered ,sum([nAnsweredAcd]) SumNAnsweredAcd ,sum([tTalkAcd]) SumTTalkAcd ,sum([nHoldAcd]) SumNHoldAcd ,sum([tHoldAcd]) SumTHoldAcd ,sum([tAcw]) SumTAcw FROM [I3_IC].[dbo].[IAgentQueueStats] WHERE dIntervalStart between @p_StartDate and DATEADD(s, 86400-1, @p_EndDate) AND CHARINDEX ( cName ,@p_Agents)> 0 AND cReportGroup <> '*' AND cHKey3 = '*' and cHKey4 ='*' AND nEnteredAcd > 0 AND cReportGroup <> 'CCFax Email' GROUP BY cName And here is the second one: /*** Aggregate values for Call Center Agents for status/activity time ***/ /*** The detail/row values is per start-time/end-time ***/ ALTER PROCEDURE [dbo].[sp_AgentActivity_Grouped] @p_StartDate datetime, @p_EndDate datetime, @p_Agents varchar(8000) AS SELECT [UserId],[StatusCategory],SUM([StateDuration]) [StatusDuration] FROM ( SELECT [UserId] ,[StatusGroup] ,[StatusKey] , CASE [StatusKey] WHEN 'Available' THEN 'Productive' WHEN 'Follow Up' THEN 'Productive' WHEN 'Campaign Call' THEN 'Productive' WHEN 'Awaiting Callback' THEN 'Productive' WHEN 'In a Meeting' THEN 'Not Your Fault' WHEN 'Project Work' THEN 'Not Your Fault' WHEN 'At a Training Session'THEN 'Not Your Fault' WHEN 'System Issues' THEN 'Not Your Fault' WHEN 'Test' THEN 'Not Your Fault' WHEN 'At Lunch' THEN 'Non Productive' WHEN 'Available, Forward' THEN 'Non Productive' WHEN 'Available, Follow-Me' THEN 'Non Productive' WHEN 'At Play' THEN 'Non Productive' WHEN 'AcdAgentNotAnswering' THEN 'Non Productive' WHEN 'Do Not Disturb' THEN 'Non Productive' WHEN 'Available, No ACD' THEN 'Non Productive' WHEN 'Away from desk' THEN 'Non Productive' ELSE [StatusKey] END StatusCategory ,stateduration FROM [I3_IC].[dbo].[AgentActivityLog] WHERE [StatusDateTime] between @p_StartDate and DATEADD(s, 86400-1, @p_EndDate) AND CHARINDEX ( [UserId] ,@p_Agents)> 0 AND [StatusKey] not in ('Gone Home','Out of the Office','On Vacation','Out of Town') ) a GROUP BY [UserId],[StatusCategory] ORDER BY [UserId], [StatusCategory] desc BTW, if I take some time to comment/reply on your posts, it's not lack of interest, but of understanding...

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• Concrete examples of state sharing between multiple viewmodels (WPF MVVM)

  - by JohnMetta

  I have a WPF/Entity Framework (4.0) project with many objects. I'd like to build the application so that that I can have object selection state shared across viewmodels. For Example: We have Cars, Drivers, Passengers, and Cargo classes. We also have UserControls for CarList, DriverList, etc. and editor windows for CarEditor, DriverEditor, etc. Furthermore, we have viewmodels for all of these (CarListViewModel, DriverListViewModel, CargoEditorViewModel, etc). This all composes a dockable interface where the user can have multiple object lists, editors, and viewers open. What I want is a concrete code example of how to wireup multiple viewmodels so that selecting a car in the CarList will cause that car to go live in the CarEditorView, but also be selected in any other view for which the context is valid (such as a DriverByCarView- or just DriverList if there is a filter predicate). There are a number of suggestions and discussions based on this question. The two methods that seem to dominate are: 3018307: Discusses state sharing by mentioning a messaging subsystem 1159035: Discusses state sharing by using an enclosing viewmodel Is one of these approaches better than the other? Does anyone have a concrete example of either/both of these methods in the form of a write-up or small code project? I'm still learning WPF, so pointers to entry points for reading API fundamentals are appreciated, but looking at code examples is where I usually go. Thanks In case anyone is interested, here are some other similar discussions: 3816961: Discusses returning multiple viewmodels depending on object type (i.e. a collection of arbitrary types adhering to a specific interface) 1928130: Discusses whether it is a good idea to aggregate viewmodels as properties of other viewmodels (e.g. a MainWindow viewmodel composed of panel viewmodels) 1120061: Essentially discusses whether to have use a viewmodel-per-model strategy or a viewmodel-per-view-element strategy. 4244222: Discusses whether or not to nest the viewmodels when using a nested object hierarchy. 4429708: Discusses sharing collections between viewmodels directly, but doesn't go into detail. List item: Discusses managing multiple selections within a single viewmodel.

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• how can you have the same form handle by javascript multiple times on the same page?

  - by DeChamp

  I have a thumb gallery where I am using ajax/javascript to submit a form per image to report the image as broken seamlessly along with php. The form and script is templated so the script is in the header and then the form is printed multiple times on the same page with a hidden field with a different id for the value per thumb. So basically this is what i have. javascript in header just a quick idea of the forms i have. Just a quick idea not what I actually have. image1 followed by the form image2 followed by the form So when you hit the button it basically submits all of the forms at the same time. I am sure it can be fixed with a (this) or something like that so it only submits a single form at a time. Let me know please. $(function() { $(".submit").click(function() { var imgId = $("#imgId").val(); var dataString = 'imgId='+ imgId; if(imgId==''){ $('.success').fadeOut(200).hide(); $('.error').fadeIn(200).show(); $('.error').fadeOut(200).hide(); }else{ $.ajax({ type: "POST", url: "inc/brokenImgReport.php", data: dataString, success: function(){ }); $('.error').fadeOut(200).hide(); $('.success').fadeIn(200).show(); setTimeout(function() { $('.success').fadeOut(200); }, 2000); } return false; }); });

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• MySQL: Limit rows linked to each joined row

  - by SolidSnakeGTI

  Hello, Specifications: MySQL 4.1+ I've certain situation that requires certain result set from MySQL query, let's see the current query first & then ask my question: SELECT thread.dateline AS tdateline, post.dateline AS pdateline, MIN(post.dateline) FROM thread AS thread LEFT JOIN post AS post ON(thread.threadid = post.threadid) LEFT JOIN forum AS forum ON(thread.forumid = forum.forumid) WHERE post.postid != thread.firstpostid AND thread.open = 1 AND thread.visible = 1 AND thread.replycount >= 1 AND post.visible = 1 AND (forum.options & 1) AND (forum.options & 2) AND (forum.options & 4) AND forum.forumid IN(1,2,3) GROUP BY post.threadid ORDER BY tdateline DESC, pdateline ASC As you can see, mainly I need to select dateline of threads from 'thread' table, in addition to dateline of the second post of each thread, that's all under the conditions you see in the WHERE CLAUSE. Since each thread has many posts, and I need only one result per thread, I've used GROUP BY CLAUSE for that purpose. This query will return only one post's dateline with it's related unique thread. My questions are: How to limit returned threads per each forum!? Suppose I need only 5 threads -as a maximum- to be returned for each forum declared in the WHERE CLAUSE 'forum.forumid IN(1,2,3)', how can this be achieved. Is there any recommendations for optimizing this query (of course after solving the first point)? Notes: I prefer not to use sub-queries, but if it's the only solution available I'll accept it. Double queries not recommended. I'm sure there's a smart solution for this situation. Appreciated advice in advance :)

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• Cocoa memory management - object going nil on me

  - by SirRatty

  Hi all, Mac OS X 10.6, Cocoa project, with retain/release gc I've got a function which: iterates over a specific directory, scans it for subfolders (included nested ones), builds an NSMutableArray of strings (one string per found subfolder path), and returns that array. e.g. (error handling removed for brevity). NSMutableArray * ListAllSubFoldersForFolderPath(NSString *folderPath) { NSMutableArray *a = [NSMutableArray arrayWithCapacity:100]; NSString *itemName = nil; NSFileManager *fm = [NSFileManager defaultManager]; NSDirectoryEnumerator *e = [fm enumeratorAtPath:folderPath]; while (itemName = [e nextObject]) { NSString *fullPath = [folderPath stringByAppendingPathComponent:itemName]; BOOL isDirectory; if ([fm fileExistsAtPath:fullPath isDirectory:&isDirectory]) { if (isDirectory is_eq YES) { [a addObject: fullPath]; } } } return a; } The calling function takes the array just once per session, keeps it around for later processing: static NSMutableArray *gFolderPaths = nil; ... gFolderPaths = ListAllSubFoldersForFolderPath(myPath); [gFolderPaths retain]; All appears good at this stage. [gFolderPaths count] returns the correct number of paths found, and [gFolderPaths description] prints out all the correct path names. The problem: When I go to use gFolderPaths later (say, the next run through my event loop) my assertion code (and gdb in Xcode) tells me that it is nil. I am not modifying gFolderPaths in any way after that initial grab, so I am presuming that my memory management is screwed and that gFolderPaths is being released by the runtime. My assumptions/presumptions I do not have to retain each string as I add it to the mutable array because that is done automatically, but I do have to retain the the array once it is handed over to me from the function, because I won't be using it immediately. Is this correct? Any help is appreciated.

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• I need a fast runtime expression parser

  - by Chris Lively

  I need to locate a fast, lightweight expression parser. Ideally I want to pass it a list of name/value pairs (e.g. variables) and a string containing the expression to evaluate. All I need back from it is a true/false value. The types of expressions should be along the lines of: varA == "xyz" and varB==123 Basically, just a simple logic engine whose expression is provided at runtime. UPDATE At minimum it needs to support ==, !=, , =, <, <= Regarding speed, I expect roughly 5 expressions to be executed per request. We'll see somewhere in the vicinity of 100/requests a second. Our current pages tend to execute in under 50ms. Usually there will only be 2 or 3 variables involved in any expression. However, I'll need to load approximately 30 into the parser prior to execution. UPDATE 2012/11/5 Update about performance. We implemented nCalc nearly 2 years ago. Since then we've expanded it's use such that we average 40+ expressions covering 300+ variables on post backs. There are now thousands of post backs occurring per second with absolutely zero performance degradation. We've also extended it to include a handful of additional functions, again with no performance loss. In short, nCalc met all of our needs and exceeded our expectations.

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• Twitter friends timeline not returning full history

  - by twofivesevenzero

  I am using twitter4J to get a user's friends timeline, but it is not returning the full available history. I know there are pagination limits (200 per request and 3200 total as per http://bit.ly/ck8ysq) and I am well within those. I make a request like so: private static final int MAX_COUNT = 200; private List<Status> getAllStatuses(long sinceID) throws TwitterException { Twitter twitter = new Twitter(username, password); List<Status> friendsTimelineList = new ArrayList<Status>(); List<Status> tempList; int page = 0; do { page++; tempList = twitter.getFriendsTimeline( new Paging(page, MAX_COUNT, sinceID)); if(tempList == null ) break; friendsTimelineList.addAll(tempList); } while(true); return friendsTimelineList; } This results in only 423 statuses being returned across 3 pages. Any idea why this might be happening?

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• Concurrent usage of table causing issues

  - by Sven

  Hello In our current project we are interfacing with a third party data provider. They need to insert data in a table of ours. This inserting can be frequent every 1 min, every 5min, every 30, depends on the amount of new data they need to provide. The use the isolation level read committed. On our end we have an application, windows service, that calls a webservice every 2 minutes to see if there is new data in this table. Our isolation level is repeatable read. We retrieve the records and update a column on these rows. Now the problem is that sometimes this third party provider needs to insert a lot of data, let's say 5000 records. They do this per transaction (5rows per transaction), but they don't close the connection. They do one transaction and then the next untill all records are inserted. This caused issues for our process, we receive a timeout. If this goes on for a long time the database get's completely unstable. For instance, they maybe stopped, but the table somehow still stays unavailable. When I try to do a select on the table, I get several records but at a certain moment I don't get any response anymore. It just says retrieving data but nothing comes anymore until I get a timeout exception. Only solution is to restart the database and then I see the other records. How can we solve this. What is the ideal isolation level setting in this scenario?

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• Low Throughput on Windows Named Pipe Over WAN

  - by MichaelB76

  I'm having problems with low performance using a Windows named pipe. The throughput drops off rapidly as the network latency increases. There is a roughly linear relationship between messages sent per second and round trip time. It seems that the client must ack each message before the server will send the next one. This leads to very poor performance, I can only send 5 (~100 byte) messages per second over a link with an RTT of 200 ms. The pipe is asynchronous, using multiple overlapped write operations (and multiple overlapped reads at the client end), but this is not improving throughput. Is it possible to send messages in parallel over a named pipe? The pipe is created using PIPE_TYPE_MESSAGE, would PIPE_READMODE_BYTE work better? Is there any other way I can improve performance? This is a deployed solution, so I can't simply replace the pipe with a socket connection (I've read that Windows named pipe aren't recommended for use over a WAN, and I'm wondering if this is why). I'd be grateful for any help with this matter.

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• Refactoring. Your way to reduce code complexity of big class with big methods

  - by Andrew Florko

  I have a legacy class that is rahter complex to maintain: class OldClass { method1(arg1, arg2) { ... 200 lines of code ... } method2(arg1) { ... 200 lines of code ... } ... method20(arg1, arg2, arg3) { ... 200 lines of code ... } } methods are huge, unstructured and repetitive (developer loved copy/paste aprroach). I want to split each method into 3-5 small functions, whith one pulic method and several helpers. What will you suggest? Several ideas come to my mind: Add several private helper methods to each method and join them in #region (straight-forward refactoring) Use Command pattern (one command class per OldClass method in a separate file). Create helper static class per method with one public method & several private helper methods. OldClass methods delegate implementation to appropriate static class (very similiar to commands). ? Thank you in advance!

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• multiple inheritance

  - by hitech

  when we say "a member declated as protected is accessible to any class imediately derived from it" what does this mean. in the follwing example get_number function can be accessible by the result class , as per the statement it sould only be accessile to test class. class student { protected: int roll_number; public: void get_number(int){ cout<< "hello"; } void put_number(void) {cout<< "hello"; } }; class test : public student { protected : float sub1; float sub2; public: void get_marks(float, float) {cout<< "hello"; roll_number = 10; } void put_marks(void) {cout<< "hello"; cout << "roll_number = " << roll_number ; } }; class result :public test { float total; public: void display(){cout<< "hello"; roll_number = 10; } }; int main() { result student; student.get_marks(2.2, 2.2); student.put_marks(); return 0; } i changed the code as per the first statement the protected variable roll_number not be accessible upto the result class ?

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• Custom API requirement

  - by Jonathan.Peppers

  We are currently working on an API for an existing system. It basically wraps some web-requests as an easy-to-use library that 3rd party companies should be able to use with our product. As part of the API, there is an event mechanism where the server can call back to the client via a constantly-running socket connection. To minimize load on the server, we want to only have one connection per computer. Currently there is a socket open per process, and that could eventually cause load problems if you had multiple applications using the API. So my question is: if we want to deploy our API as a single standalone assembly, what is the best way to fix our problem? A couple options we thought of: Write an out of process COM object (don't know if that works in .Net) Include a second exe file that would be required for events, it would have to single-instance itself, and open a named pipe or something to communicate through multiple processes Extract this exe file from an embedded resource and execute it None of those really seem ideal. Any better ideas?

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• Excel, Pivot Calculated formula: SUM(Field1)/AVG(Field2)

  - by Bas

  I've a simple table with some amount and interval in sec by date and product name. Month | Product | Amount | Interval in sec ------------------------------------------ 05-'12| Prod A | 10 | 5 05-'12| Prod A | 3 | 5 05-'12| Prod B | 4 | 5 05-'12| Prod C | 13 | 5 05-'12| Prod C | 5 | 5 From this table I've derived a Pivot table with SUM(Amount), AVERAGE(Interval in sec) by Month and Product. Month | Product | SUM of Amount | AVG of Interval in sec -------------------------------------------------------- 05-'12| Prod A | 13 | 5 05-'12| Prod B | 4 | 5 05-'12| Prod C | 18 | 5 So far So good... Now i want to add and extra column to my Pivot table with gives me the outcome of SUM of Amount / AVG of Interval in sec Adding a calculated value =SUM(Amount)/AVERAGE(Interval) is not giving me the right values. Exel gives me. Month | Product | SUM of Amount | AVG of Interval in sec | Amount per sec ------------------------------------------------------------------------- 05-'12| Prod A | 13 | 5 | 1.3 05-'12| Prod B | 4 | 5 | 0.8 05-'12| Prod C | 18 | 5 | 1.8 What it actually is doing is =SUM(Amount)/SUM(Interval in sec) for every Month and Product based on the values in the first table... But I'm looking for Month | Product | SUM of Amount | AVG of Interval in sec | Amount per sec ------------------------------------------------------------------------- 05-'12| Prod A | 13 | 5 | 2.6 05-'12| Prod B | 4 | 5 | 0.8 05-'12| Prod C | 18 | 5 | 3.6 So litterly devide pivot field 'Sum of Amount' by pivot field 'AVG of Interval in sec' How to achieve this? Thank you in advanced

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• What's the jquery CSS3 selector for excluding nested descendents?

  - by Danjah

  Per my SO question here, which has turned to jquery to solve this, but which may be worked back into YUI if I get my thinking straight, I need a selector to exclude descendents. The solution proposed says something like this: $( '.revealer:not(.revealer > .revealer)' ); To fit more accurately with my situation, because I have multiple HTML chunks to perform the same test on, I have updated it be: $( '#_revealerEl_0 .handle:not(#_revealerEl_0 .reveal .handle)' ); The HTML its selecting on (image there are numerous copies of this same chunk on a page, each needing to be treated alone - an id attribute is assigned to each 'revealer'): <div class="revealer"> <div class="hotspot"> <a class="handle" href="javascript:;">A</a> <div class="reveal"> <p>Content A.</p> </div> <div class="reveal"> <p>Content B.</p> <!-- nested revealer --> <div class="revealer"> <div class="hotspot"> <a class="handle" href="javascript:;">A</a> <div class="reveal"> <p>Sub-content A.</p> </div> <div class="reveal"> <p>Sub-content B.</p> </div> </div> </div> </div> </div> </div> In a nutshell: I need to target 'top level' handles within a 'hotspot', per revealer - and no nested descendents with the same class names. thanks, d

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• Need help optimizing this Django aggregate query

  - by Chris Lawlor

  I have the following model class Plugin(models.Model): name = models.CharField(max_length=50) # more fields which represents a plugin that can be downloaded from my site. To track downloads, I have class Download(models.Model): plugin = models.ForiegnKey(Plugin) timestamp = models.DateTimeField(auto_now=True) So to build a view showing plugins sorted by downloads, I have the following query: # pbd is plugins by download - commented here to prevent scrolling pbd = Plugin.objects.annotate(dl_total=Count('download')).order_by('-dl_total') Which works, but is very slow. With only 1,000 plugins, the avg. response is 3.6 - 3.9 seconds (devserver with local PostgreSQL db), where a similar view with a much simpler query (sorting by plugin release date) takes 160 ms or so. I'm looking for suggestions on how to optimize this query. I'd really prefer that the query return Plugin objects (as opposed to using values) since I'm sharing the same template for the other views (Plugins by rating, Plugins by release date, etc.), so the template is expecting Plugin objects - plus I'm not sure how I would get things like the absolute_url without a reference to the plugin object. Or, is my whole approach doomed to failure? Is there a better way to track downloads? I ultimately want to provide users some nice download statistics for the plugins they've uploaded - like downloads per day/week/month. Will I have to calculate and cache Downloads at some point? EDIT: In my test dataset, there are somewhere between 10-20 Download instances per Plugin - in production I expect this number would be much higher for many of the plugins.

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• Rails nested association issue

  - by Ben Langfeld

  Ok, so I'm new to both Ruby and Rails and I'm trying to do what I believe is called a nested association (please correct me if this is the wrong terminology). I currently have a User model and a Domains model and I have many to many associations setup (using has_many :through) between the two, and this works fine. I now want to extend this to allow for a single role per domain per user (eg User1 is a member of Domain1 and has the role "Admin"). I have setup a Roles model with a single field (name:string) and have created three roles. I have also added a role_id column to the join table (memberships). I expected (and this is probably the issue) to be able to just use user1 = User.find(1) user1.domains.first => <some domain object> user1.domains.first.role => <some role object> but this returns a method not defined error. Can anyone tell me what I'm failing to grasp here? My model classes can be seen at http://gist.github.com/388200

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• Creating a join based on data from other tables...

  - by Workshop Alex

  I'm dealing with a database structure that can be defined as "illogical". It has about 100 different schema's with all different table structures per schema. Only one common factor is a "Version" table in each schema containing about 4 fields. (Thus, there are about 100 Version tables in the database.) There's also another table (view, actually) containing a list of all the schema's in the database that have a version table. I need a stored procedure that walks through all the schema's and selects all data from the Version table, adding the schema name as a fifth field to the result. Basically, this stored procedure is to return a list of all version records per schema. My idea: first walk through the schema list to create one new SQL statements that will JOIN all the schema.version tables into one SQL statement. Then I return the result of that query. How to do this? Or does anyone have a better suggestion? (No, redesigning the structure is NOT an option.)

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