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  • Hibernate Query - Get latest versions by timestamp?

    - by Slim
    I have a database that is being used as a sort of version control system. That is, instead of ever updating any rows, I add a new row with the same information. Each row also contains a version column that is a date timestamp, so the only difference is the new row will have a more recent timestamp. What I'm having trouble with is writing an efficient hibernate query to return the latest version of these rows. For the sake of example, these are rows in a table called Product, the timestamped column is version. There are multiple versions of multiple products in the table. So there may be multiple versions (rows) of ProductA, multiple versions of ProductB, etc. And I would like to grab the latest version of each. Can I do this in just a single hibernate query? session.createQuery("select product from Product product where...?"); Or would this require some intermediate steps?

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  • Effective way of String splitting C#

    - by openidsujoy
    I have a completed string like this N:Pay in Cash++RGI:40++R:200++T:Purchase++IP:N++IS:N++PD:PC++UCP:598.80++UPP:0.00++TCP:598.80++TPP:0.00++QE:1++QS:1++CPC:USD++PPC:Points++D:Y++E:Y++IFE:Y++AD:Y++IR:++MV:++CP:~ ~N:ERedemption++RGI:42++R:200++T:Purchase++IP:N++IS:N++PD:PC++UCP:598.80++UPP:0.00++TCP:598.80++TPP:0.00++QE:1++QS:1++CPC:USD++PPC:Points++D:Y++E:Y++IFE:Y++AD:Y++IR:++MV:++CP: this string is like this It's list of PO's(Payment Options) which are separated by ~~ this list may contains one or more PO contains only Key-Value Pairs which separated by : spaces are denoted by ++ I need to extract the values for Key "RGI" and "N". I can do it via for loop , I want a efficient way to do this. any help on this.

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  • Collection type generated by for with yield

    - by Jesper
    When I evaluate a for in Scala, I get an immutable IndexedSeq (a collection with array-like performance characteristics, such as efficient random access): scala> val s = for (i <- 0 to 9) yield math.random + i s: scala.collection.immutable.IndexedSeq[Double] = Vector(0.6127056766832756, 1.7137598183155291, ... Does a for with a yield always return an IndexedSeq, or can it also return some other type of collection class (a LinearSeq, for example)? If it can also return something else, then what determines the return type, and how can I influence it? I'm using Scala 2.8.0.RC3.

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  • Python - Create a list with initial capacity

    - by Claudiu
    Code like this often happens: l = [] while foo: #baz l.append(bar) #qux This is really slow if you're about to append thousands of elements to your list, as the list will have to constantly be re-initialized to grow. (I understand that lists aren't just wrappers around some array-type-thing, but something more complicated. I think this still applies, though; let me know if not). In Java, you can create an ArrayList with an initial capacity. If you have some idea how big your list will be, this will be a lot more efficient. I understand that code like this can often be re-factored into a list comprehension. If the for/while loop is very complicated, though, this is unfeasible. Is there any equivalent for us python programmers?

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  • Efficiently draw a grid in Windows Forms

    - by Joel
    I'm writing an implementation of Conway's Game of Life in C#. This is the code I'm using to draw the grid, it's in my panel_Paint event. g is the graphics context. for (int y = 0; y < numOfCells * cellSize; y += cellSize) { for (int x = 0; x < numOfCells * cellSize; x += cellSize) { g.DrawLine(p, x, 0, x, y + numOfCells * cellSize); g.DrawLine(p, 0, x, y + size * drawnGrid, x); } } When I run my program, it is unresponsive until it finishes drawing the grid, which takes a few seconds at numOfCells = 100 & cellSize = 10. Removing all the multiplication makes it faster, but not by very much. Is there a better/more efficient way to draw my grid? Thanks

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  • Is there a single query that can update a "sequence number" across multiple groups?

    - by Drarok
    Given a table like below, is there a single-query way to update the table from this: | id | type_id | created_at | sequence | |----|---------|------------|----------| | 1 | 1 | 2010-04-26 | NULL | | 2 | 1 | 2010-04-27 | NULL | | 3 | 2 | 2010-04-28 | NULL | | 4 | 3 | 2010-04-28 | NULL | To this (note that created_at is used for ordering, and sequence is "grouped" by type_id): | id | type_id | created_at | sequence | |----|---------|------------|----------| | 1 | 1 | 2010-04-26 | 1 | | 2 | 1 | 2010-04-27 | 2 | | 3 | 2 | 2010-04-28 | 1 | | 4 | 3 | 2010-04-28 | 1 | I've seen some code before that used an @ variable like the following, that I thought might work: SET @seq = 0; UPDATE `log` SET `sequence` = @seq := @seq + 1 ORDER BY `created_at`; But that obviously doesn't reset the sequence to 1 for each type_id. If there's no single-query way to do this, what's the most efficient way? Data in this table may be deleted, so I'm planning to run a stored procedure after the user is done editing to re-sequence the table.

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  • Generate custom marker (icon) out of two images in Leaflet

    - by Rmatt
    In Javascript/CoffeeScript, using Leaflet to display a map, I would like to have custom markers out of a two custom images, and also featuring a shadow for the pin : I want to have a "background" image with a color (or shape) to identify the category On top, I want to have inside this image a specific image (logo) for each pin I didn't find out how I could do that... Setting one image is quite easy but I don't know how to overlay them. I could also consider using a tool to superpose/group/overlay these images (locally ?) before in order to send only one to the Icon Leaflet Class, but also there, I wouldn't know which tool to use. Nevertheless, I still think that a double overlay would be more efficient and that my case could be useful for several people.

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  • Ruby on Rails: Best way to save search queries in a database

    - by Adam Templeton
    For a RoR app I'm helping develop, I need to save all search queries in a database so I can analyze them later. My plan right now is to create a Result model and table, and just save each search query's text in that table, along with a user's ID, the time, etc. However, the app has about 15,000 users, so I'm afraid the single table approach won't be super efficient when it comes time to parse that data. (The database is setup via MySQL, if that factors in at all.) Am I just being paranoid? Is there a Ruby gem that handles this sort of thing, or a better approach I could take? Any input would be appreciated.

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  • what good orm api will work well with scala or erlang

    - by Emotu Balogun
    I'm considering taking up scala programming but i'm really concerned about what will become of my ORM based applications. I currently use hibernate as my ORM and i find it a really reliable tool. I'd like to know if there's any ORM tool as efficient but written in scala, or will hibernate work seamlessly with it. i don't want to have to start writing endless sql queries again (like the days of JDBC). I also have the same thought about erlang. is there a good orm out there for erlang?? and can i use erlang with other DBMS like oracle and mysql with ORM

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  • Javascript find if english alphabets only

    - by Alec Smart
    Hello, Am trying to find some text only if it contains english letters and numbers using Javascript/jQuery. Am wondering what is the most efficient way to do this? Since there could be thousands of words, it should be as fast as possible and I don't want to use regex. var names[0] = 'test'; var names[1] = '???'; var names[2] = '??????'; for (i=0;i<names.length;i++) { if (names[i] == ENGLISHMATCHCODEHERE) { // do something here } } Thank you for your time.

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  • Image expire time

    - by Jens
    The google page speed tool recommends me to set 'Expires' headers for images etc. But what is the most efficient way to set an Expires header for an image? In now redirect all image requests to an imagehandler.php using htaccess: /* HTTP/1.1 404 Not Found, HTTP/1.1 400 Bad Request and content type detection stuff ... */ header( "Content-Type: " . $content_type ); header( "Cache-Control: public" ); header( "Last-Modified: ".gmdate("D, d M Y H:i:s", filemtime($path))." GMT"); header( "Expires: ". date("r",time() + (60*60*24*30))); readfile( $path ); But of course this adds extra loading time for my images on first request, and I was wondering if there was a better solution for this.

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  • best method for creating a universal extention/plugin

    - by rashcroft44
    Hi, I'm looking to create an extension for the leading browsers (firefox, safari and ie). Its rather simple, and I'm looking for the most efficient way to go about this. I need to get the hostname of the current site the user is on, and if it matches a certain parameter(eg, mysite.org), I'll need to append to the link some extra data and refresh to the new link. What is the simplest way to go about this? (I don't want to go in the direction of a bookmarklet - since this would require the user to click. I'd like this to happen automatically) sort of something like this: if(window.location.hostname == 'mysite.org') { location.replace(document.location.href + '/&mystuff=xyz'); } Thanks!

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  • Sorting 2 arrays that have been added together

    - by tyler
    In my app, users can create galleries that their work may or may not be in. Users have and belong to many Galleries, and each gallery has a 'creator' that is designated by the gallery's user_id field. So to get the 5 latest galleries a user is in, I can do something like: included_in = @user.galleries.order('created_at DESC').uniq.first(5) # SELECT DISTINCT "galleries".* FROM "galleries" INNER JOIN "galleries_users" ON "galleries"."id" = "galleries_users"."gallery_id" WHERE "galleries_users"."user_id" = 10 ORDER BY created_at DESC LIMIT 5 and to get the 5 latest galleries they've created, I can do: created = Gallery.where(user_id: id).order('created_at DESC').uniq.first(5) # SELECT DISTINCT "galleries".* FROM "galleries" WHERE "galleries"."user_id" = 10 ORDER BY created_at DESC LIMIT 5 I want to display these two together, so that it's the 5 latest galleries that they've created OR they're in. Something like the equivalent of: (included_in + created).order('created_at DESC').uniq.first(5) Does anyone know how to construct an efficient query or post-query loop that does this?

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  • Mysql search design

    - by neil
    I'm designing a mysql database, and i'd like some input on an efficient way to store blog/article data for searching. Right now, I've made a separate column that stores the content to be searched - no duplicate words, no words shorter than four letters, and no words that are too common. So, essentially, it's a list of keywords from the original article. Also searched would be a list of tags, and the title field. I'm not quite sure how mysql indexes fulltext columns, so would storing the data like that be ineffective, or redundant somehow? A lot of the articles are on the same topic, so would the score be hurt by so many of the rows having similar keywords? Also, for this project, solutions like sphinx, lucene or google custom seach can't be used -- only php & mysql. Thanks!

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  • solutions for rapid front-end development?

    - by fayer
    im using mvc framework and i have learned some techniques that help me with different parts of RAD. models: doctrine/visual paradigm controllers/libraries: various design patterns now i only need to know what technique/solution i should use for the views so that i can create views more rapidly. cause i don't think it's efficient to code css/html manually, even though i understand it. its the same principle when using visual paradigm to create both my mysql database tables and doctrine model classes. i believe in using right tools will boost up development speed. so what could i use for the views to save time and energy and don't reinvent the wheel all the time? dreamweaver? any css generation tools? 960/blueprint for layout? suggestions? thanks

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  • Is scala functional programming slower than traditional coding?

    - by Fred Haslam
    In one of my first attempts to create functional code, I ran into a performance issue. I started with a common task - multiply the elements of two arrays and sum up the results: var first:Array[Float] ... var second:Array[Float] ... var sum=0f; for(ix<-0 until first.length) sum += first(ix) * second(ix); Here is how I reformed the work: sum = first.zip(second).map{ case (a,b) => a*b }.reduceLeft(_+_) When I benchmarked the two approaches, the second method takes 40 times as long to complete! Why does the second method take so much longer? How can I reform the work to be both speed efficient and use functional programming style?

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  • C# GroupJoin effectiveness

    - by bsnote
    without using GroupJoin: var playersDictionary = players.ToDictionary(player => player.Id, element => new PlayerDto { Rounds = new List<RoundDto>() }); foreach (var round in rounds) { PlayerDto playerDto; playersDictionary.TryGetValue(round.PlayerId, out playerDto); if (playerDto != null) { playerDto.Rounds.Add(new RoundDto { }); } } var playerDtoItems = playersDictionary.Values; using GroupJoin: var playerDtoItems = from player in players join round in rounds on player.Id equals round.PlayerId into playerRounds select new PlayerDto { Rounds = playerRounds.Select(playerRound => new RoundDto {}) }; Which of these two pieces is more efficient?

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  • C# GroupJoin efficiency

    - by bsnote
    without using GroupJoin: var playersDictionary = players.ToDictionary(player => player.Id, element => new PlayerDto { Rounds = new List<RoundDto>() }); foreach (var round in rounds) { PlayerDto playerDto; playersDictionary.TryGetValue(round.PlayerId, out playerDto); if (playerDto != null) { playerDto.Rounds.Add(new RoundDto { }); } } var playerDtoItems = playersDictionary.Values; using GroupJoin: var playerDtoItems = from player in players join round in rounds on player.Id equals round.PlayerId into playerRounds select new PlayerDto { Rounds = playerRounds.Select(playerRound => new RoundDto {}) }; Which of these two pieces is more efficient?

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  • C#. Struct design. Why 16 byte is recommended size?

    - by maxima120
    I read Cwalina book (recommendations on development and design of .NET apps). He says that good designed struct has to be less than 16 bytes in size (for performance purpose). My questions is - why exactly is this? And (more important) can I have larger struct with same efficiency if I run my .NET 3.5 (soon to be .NET 4.0) 64-bit application on i7 under Win7 x64 (is this limitation CPU / OS based)? Just to stress again - I need as efficient struct as it is possible. I try to keep it in stack all the time, the application is heavily multi-threaded and runs on sub-millisecond intervals, the current size of the struct is 64 byte.

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  • Some exam questions about C++ vectors and arrays...

    - by xbonez
    Hey guys, I have a CS exam tomorrow. Just want to get a few questions cleared up. Thanks a lot, and I really appreciate the help. Que 1. What are parallel vectors? Vectors of the same length that contain data that is meant to be processed together Vectors that are all of the same data type Vectors that are of the same length Any vector of data type parallel Que 2. Arrays are faster and more efficient than vectors. True False Que 3. Arrays can be a return type of a function call. True False Que 4. Vectors can be a return type of a function call. True False

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  • How can I call an executable to run on a separate machine within a program on my own machine (win xp

    - by Mr. H.
    My objective is to write a program which will call another executable on a separate computer(all with win xp) with parameters determined at run-time, then repeat for several more computers, and then collect the results. In short, I'm working on a grid-computing project. The algorithm itself being used is already coded in FORTRAN, but we are looking for an efficient way to run it on many computers at once. I suppose one way to accomplish this would be to upload a script to each computer and then run said script on each computer, all automatically and dependent on my own parameters. But how can I write a program which will write to, upload, and run a script on a separate computer? I had considered GridGain, but the algorithm is already coded and in a different language, so that is ruled out. My current guess at accomplishing this task is using Expect (wiki/Expect), but I have no knowledge of the tool. Any advice appreciated.

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  • which is time consuming construct in following program?

    - by user388338
    while submitting a solution for practise problem 6(odd) i got TLE error but while using using print and scanf in place cin and cout my sol was submitted successfully with 0.77s time..i want to know how can i make it more efficient link to problem is codechef problem 6 #include<iostream> #include<cstdio> using namespace std; int main() {int n,N; scanf("%d",&n); for(int l=0;l<n;l++) { scanf("%d",&N); int i=0,x; if(N<=0) continue; for(;N>=(x=(2<<i));i++); printf("%d",x/2); cout<<"\n"; } }

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  • How to very efficiently assign lat/long to city boundary described by shape ?

    - by watcherFR
    I have a huge shapefile of 36.000 non-overlapping polygones (city boundaries). I want to easily determine the polygone into which a given lat/long falls. What would the best way given that it must be extremely computationaly efficient ? I was thinking of creating a lookup table (tilex,tiley,polygone_id) where tilex and tiley are tile identifiers at zoom levels 21 or 22. Yes, the lack of precision of using tile numbers and a planar projection is acceptable in my application. I would rather not use postgres's GIS extension and am fine with a program that will run for 2 days to generate all the INSERT statements.

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  • Query with multiple IN-statements but without the cartesian product

    - by Janne
    How could I make this kind of query e.g. in MySQL SELECT * FROM Table t WHERE t.a IN (1,2,3) AND t.b IN (4,5,6) AND t.c IN (7,8,9) ... so that the result would contain only the three rows: t.a|t.b|t.c ---+---+--- 1 | 4 | 7 2 | 5 | 8 3 | 6 | 9 The above query of course returns all the combinations of the values in the IN clauses but I would like to get just the ones where the first elements of each tuple match, second elements of each tuple match and so on. Is there any efficient way to do this? By the way is there some common term for this kind of query or concept? I'm having hard time coming up with the question's title because I can't put this into words..

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