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  • How can I improve the performance of LinqToSql queries that use EntitySet properties?

    - by DanM
    I'm using LinqToSql to query a small, simple SQL Server CE database. I've noticed that any operations involving sub-properties are disappointingly slow. For example, if I have a Customer table that is referenced by an Order table, LinqToSql will automatically create an EntitySet<Order> property. This is a nice convenience, allowing me to do things like Customer.Order.Where(o => o.ProductName = "Stopwatch"), but for some reason, SQL Server CE hangs up pretty bad when I try to do stuff like this. One of my queries, which isn't really that complicated takes 3-4 seconds to complete. I can get the speed up to acceptable, even fast, if I just grab the two tables individually and convert them to List<Customer> and List<Order>, then join then manually with my own query, but this is throwing out a lot of what makes LinqToSql so appealing. So, I'm wondering if I can somehow get the whole database into RAM and just query that way, then occasionally save it. Is this possible? How? If not, is there anything else I can do to boost the performance besides resorting to doing all the joins manually? Note: My database in its initial state is about 250K and I don't expect it to grow to more than 1-2Mb. So, loading the data into RAM certainly wouldn't be a problem from a memory point of view. Update Here are the table definitions for the example I used in my question: create table Order ( Id int identity(1, 1) primary key, ProductName ntext null ) create table Customer ( Id int identity(1, 1) primary key, OrderId int null references Order (Id) )

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  • HTTP Compression problems on IIS7

    - by Jonathan Wood
    I've spent quite a bit of time on this but seem to be going nowhere. I have a large page that I really want to speed up. The obvious place to start seems to be HTTP compression, but I just can't seem to get it to work for me. After considerable searching, I've tried several variations of the code below. It kind of works, but after refreshing the browser, the results seem to fall apart. They were turning to garbage when the page used caching. If I turn off caching, then the page seems right but I lose my CSS formatting (stored in a separate file) and get an error that an included JS file contains invalid characters. Most of the resources I've found on the Web were either very old or focused on accessing IIS directly. My page is running on a shared hosting account and I do not have direct access to IIS7, which it's running on. protected void Application_BeginRequest(object sender, EventArgs e) { // Implement HTTP compression if (Request["HTTP_X_MICROSOFTAJAX"] == null) // Avoid compressing AJAX calls { // Retrieve accepted encodings string encodings = Request.Headers.Get("Accept-Encoding"); if (encodings != null) { // Verify support for or gzip (deflate takes preference) encodings = encodings.ToLower(); if (encodings.Contains("gzip") || encodings == "*") { Response.Filter = new GZipStream(Response.Filter, CompressionMode.Compress); Response.AppendHeader("Content-Encoding", "gzip"); Response.Cache.VaryByHeaders["Accept-encoding"] = true; } else if (encodings.Contains("deflate")) { Response.Filter = new DeflateStream(Response.Filter, CompressionMode.Compress); Response.AppendHeader("Content-Encoding", "deflate"); Response.Cache.VaryByHeaders["Accept-encoding"] = true; } } } } Is anyone having better success with this?

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  • What is the fastest way for reading huge files in Delphi?

    - by dummzeuch
    My program needs to read chunks from a huge binary file with random access. I have got a list of offsets and lengths which may have several thousand entries. The user selects an entry and the program seeks to the offset and reads length bytes. The program internally uses a TMemoryStream to store and process the chunks read from the file. Reading the data is done via a TFileStream like this: FileStream.Position := Offset; MemoryStream.CopyFrom(FileStream, Size); This works fine but unfortunately it becomes increasingly slower as the files get larger. The file size starts at a few megabytes but frequently reaches several tens of gigabytes. The chunks read are around 100 kbytes in size. The file's content is only read by my program. It is the only program accessing the file at the time. Also the files are stored locally so this is not a network issue. I am using Delphi 2007 on a Windows XP box. What can I do to speed up this file access?

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  • Mercurial CLI is slow in C#?

    - by pATCheS
    I'm writing a utility in C# that will make managing multiple Mercurial repositories easier for the way my team is using it. However, it seems that there is always about a 300 to 400 millisecond delay before I get anything back from hg.exe. I'm using the code below to run hg.exe and hgtk.exe (TortoiseHg's GUI). The code currently includes a Stopwatch and some variables for timing purposes. The delay is roughly the same on multiple runs within the same session. I have also tried specifying the exact path of hg.exe, and got the same result. static string RunCommand(string executable, string path, string arguments) { var psi = new ProcessStartInfo() { FileName = executable, Arguments = arguments, WorkingDirectory = path, UseShellExecute = false, RedirectStandardError = true, RedirectStandardInput = true, RedirectStandardOutput = true, WindowStyle = ProcessWindowStyle.Maximized, CreateNoWindow = true }; var sbOut = new StringBuilder(); var sbErr = new StringBuilder(); var sw = new Stopwatch(); sw.Start(); var process = Process.Start(psi); TimeSpan firstRead = TimeSpan.Zero; process.OutputDataReceived += (s, e) => { if (firstRead == TimeSpan.Zero) { firstRead = sw.Elapsed; } sbOut.Append(e.Data); }; process.ErrorDataReceived += (s, e) => sbErr.Append(e.Data); process.BeginOutputReadLine(); process.BeginErrorReadLine(); var eventsStarted = sw.Elapsed; process.WaitForExit(); var processExited = sw.Elapsed; sw.Reset(); if (process.ExitCode != 0 || sbErr.Length > 0) { Error.Mercurial(process.ExitCode, sbOut.ToString(), sbErr.ToString()); } return sbOut.ToString(); } Any ideas on how I can speed things up? As it is, I'm going to have to do a lot of caching in addition to threading to keep the UI snappy.

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  • What is an efficient strategy for multiple threads posting jobs and waiting for response from a single thread?

    - by jakewins
    In java, what is an efficient solution to the following problem: I have multiple threads (10-20 or so) generating jobs ("Job Creators"), and a single thread capable of performing them ("The worker"). Once a job creator has posted a job, it should wait for the job to finish, yielding no result other than "it's done", before it keeps going. For sending the jobs to the worker thread, I think a ring buffer or similar standard fan-in setup would perhaps be a good approach? But for a Job Creator to find out that her job has been done, I'm not so sure.. The job creators could sleep, and the worker interrupt them when done.. Or each job creator could have an atomic boolean that it checks, and that the worker sets. I dunno, neither of those feel very nice. I'd like to do it with as few (none, if possible) locks as absolutely possible. So to be clear: What I'm looking for is speed, not necessarily simplicity. Does anyone have any suggestions? Links to reading about concurrency strategies would also be very welcome!

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  • Node.js, Cygwin and Socket.io walk into a bar... Node.js throws ENOBUFS and everyone dies...

    - by A Wizard Did It
    I'm hoping someone here can help me out, I'm not having much luck figuring this out myself. I'm running node.js version 0.3.1 on Cygwin. I'm using Connect and Socket.io. I seem to be having some random problems with DNS or something, I haven't quite figured it out. The end result is that I the server is running fine, but when a browser attempts to connect to it the initial HTTP Request works, Socket.io connects, and then the server dies (output below). I don't think it has anything to do with the HTTP request because the server gets a lot data posted to it, and it was receiving requests and responding up until my connection that killed it. I've googled around and the closest thing I've found is DNS being set improperly. It's a network program meant to run only on an internal network, so I've set the nameserver x.x.x.x in my /etc/resolv.conf to the internal DNS. I've also added nameserver 8.8.8.8 in addition. I'm not sure what else to check, but would be grateful of any help. In node.exe.stackdump Exception: STATUS_ACCESS_VIOLATION at eip=610C51B9 eax=00000000 ebx=00000001 ecx=00000000 edx=00000308 esi=00000000 edi=010FCCB0 ebp=010FCAEC esp=010FCAC4 program=\\?\E:\cygwin\usr\local\bin\node.exe, pid 3296, thread unknown (0xBEC) cs=0023 ds=002B es=002B fs=0053 gs=002B ss=002B Stack trace: Frame Function Args 010FCAEC 610C51B9 (00000000, 00000000, 00000000, 00000000) 010FCBFC 610C5B55 (00000000, 00000000, 00000000, 00000000) 010FCCBC 610C693A (FFFFFFFF, FFFFFFFF, 750334F3, FFFFFFFE) 010FCD0C 61027CB2 (00000002, F4B994D5, 010FCE64, 00000002) 010FCD98 76306B59 (00000002, 010FCDD4, 763069A4, 00000002) End of stack trace Node Output: node.js:50 throw e; // process.nextTick error, or 'error' event on first tick ^ Error: ENOBUFS, No buffer space available at doConnect (net.js:642:19) at net.js:803:9 at dns.js:166:30 at IOWatcher.callback (dns.js:48:15) EDIT I'm hitting an LDAP server using http.createClient immediately after a client connects to get information, and that seems to be where the problem is that is causing ENOBUFS. I've edited the source to include && errno != ENOBUFS which now prevents the server from dying, however now the LDAP request isn't working. I'm not sure what the problem is that would cause that though. As I mentioned this is an internal only application, so I set the DNS servers in /etc/resolv.conf to the DNS servers that are being applied to the host machine. Not sure if this is part of the issue? EDIT 2 Here's some output from gdb --args ./node_g --debug ../myscript.js. I'm not sure if this is related to ENOBUFS, however, as it seems to be disconnecting immediately after connection with Socket.io [New thread 672.0x100] Error: dll starting at 0x76e30000 not found. Error: dll starting at 0x76250000 not found. Error: dll starting at 0x76e30000 not found. Error: dll starting at 0x76f50000 not found. [New thread 672.0xc90] [New thread 672.0x448] debugger listening on port 5858 [New thread 672.0xbf4] 14 Jan 18:48:57 - socket.io ready - accepting connections [New thread 672.0xed4] [New thread 672.0xd68] [New thread 672.0x1244] [New thread 672.0xf14] 14 Jan 18:49:02 - Initializing client with transport "websocket" assertion "b[1] == 0" failed: file "../src/node.cc", line 933, function: ssize_t node::DecodeWrite(char*, size_t, v8::Handle<v8::Value>, node::encoding) Program received signal SIGABRT, Aborted. 0x7724f861 in ntdll!RtlUpdateClonedSRWLock () from /cygdrive/c/Windows/system32/ntdll.dll (gdb) backtrace #0 0x7724f861 in ntdll!RtlUpdateClonedSRWLock () from /cygdrive/c/Windows/system32/ntdll.dll #1 0x7724f861 in ntdll!RtlUpdateClonedSRWLock () from /cygdrive/c/Windows/system32/ntdll.dll #2 0x75030816 in WaitForSingleObjectEx () from /cygdrive/c/Windows/syswow64/KernelBase.dll #3 0x0000035c in ?? () #4 0x00000000 in ?? () (gdb)

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  • Programming exercises in Java inheritance for intern

    - by Tenner
    I work for a small software development team, working primarily in Java, for a very large company. Our new intern showed up sight-unseen (not uncommon in my company). He has some C++ experience but no Java. Worse, he's never worked with inheritance in C++. Our code has a great deal of abstraction and a heavy reliance on inheritance. We need to get him up to speed as quickly as possible. Of course the rest of the team is busy, and so we can't take the time out of our day to teach a one-student 200-level CS course. Instead, I'd like to give him an actual programming project to work on which highlights how classes, interfaces, method overrides, etc. work. I've had him look at Project Euler, but most of the solutions end up being procedural, and not object-oriented programs. Do any of you have any somewhat-straightforward (and relatively quick) projects which you would give to an intern in this situation? Or, any recent (or current) students have a school project they'd be willing to share? Anyone else had this experience?

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  • What hash algorithms are paralellizable? Optimizing the hashing of large files utilizing on mult-co

    - by DanO
    I'm interested in optimizing the hashing of some large files (optimizing wall clock time). The I/O has been optimized well enough already and the I/O device (local SSD) is only tapped at about 25% of capacity, while one of the CPU cores is completely maxed-out. I have more cores available, and in the future will likely have even more cores. So far I've only been able to tap into more cores if I happen to need multiple hashes of the same file, say an MD5 AND a SHA256 at the same time. I can use the same I/O stream to feed two or more hash algorithms, and I get the faster algorithms done for free (as far as wall clock time). As I understand most hash algorithms, each new bit changes the entire result, and it is inherently challenging/impossible to do in parallel. Are any of the mainstream hash algorithms parallelizable? Are there any non-mainstream hashes that are parallelizable (and that have at least a sample implementation available)? As future CPUs will trend toward more cores and a leveling off in clock speed, is there any way to improve the performance of file hashing? (other than liquid nitrogen cooled overclocking?) or is it inherently non-parallelizable?

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  • listview and datalist not updating,inserting

    - by raging_boner
    Data entered in textboxes is not getting updated in database. In debug mode I see that text1 and text2 in ItemUpdating event contain the same values as they had before calling ItemUpdating. Here's my listview control: <asp:ListView ID="ListView1" runat="server" onitemediting="ListView1_ItemEditing" onitemupdating="ListView1_ItemUpdating" oniteminserting="ListView1_ItemInserting"> //LayoutTemplate removed <ItemTemplate> <asp:Label ID="Label2" runat="server" Text='<%#Eval("id")%>'></asp:Label> <asp:Label ID="Label3" runat="server" Text='<%#Eval("text1")%>'></asp:Label> <asp:LinkButton ID="LinkButton2" CommandName="Edit" runat="server">Edit</asp:LinkButton> <asp:LinkButton ID="LinkButton4" CommandName="Delete" runat="server">Delete</asp:LinkButton> </ItemTemplate> <EditItemTemplate> <asp:Label ID="Label1" runat="server" Text='<%#Eval("id")%>'></asp:Label> <asp:TextBox ID="TextBox1" runat="server" Text='<%#Eval("text1")%>' TextMode="MultiLine" /> <asp:TextBox ID="TextBox2" runat="server" Text='<%#Eval("text2")%>' Height="100" TextMode="MultiLine" /> <asp:LinkButton ID="LinkButton1" CommandName="Update" CommandArgument='<%# Eval("id")%>' runat="server">Update</asp:LinkButton> <asp:LinkButton ID="LinkButton5" CommandName="Cancel" runat="server">Cancel</asp:LinkButton> </EditItemTemplate> <InsertItemTemplate> <asp:TextBox ID="TextBox3" runat="server" TextMode="MultiLine" Height="100"></asp:TextBox> <asp:TextBox ID="TextBox4" runat="server" Height="100" TextMode="MultiLine"></asp:TextBox> <asp:LinkButton ID="LinkButton3" runat="server">Insert</asp:LinkButton> </InsertItemTemplate> </asp:ListView> Codebehind file: protected void ListView1_ItemEditing(object sender, ListViewEditEventArgs e) { ListView1.EditIndex = e.NewEditIndex; BindList(); } protected void ListView1_ItemUpdating(object sender, ListViewUpdateEventArgs e) { ListViewItem myItem = ListView1.Items[ListView1.EditIndex]; Label id = (Label)myItem.FindControl("Label1"); int dbid = int.Parse(id.Text); TextBox text1 = (TextBox)myItem.FindControl("Textbox1"); TextBox text2 = (TextBox)myItem.FindControl("Textbox2"); //tried to work withNewValues below, but they don't work, "null reference" error is being thrown //text1.Text = e.NewValues["text1"].ToString(); //text2.Text = e.NewValues["text2"].ToString(); //odbc connection routine removed. //i know that there should be odbc parameteres: comm = new OdbcCommand("UPDATE table SET text1 = '" + text1.Text + "', text2 = '" + text2.Text + "' WHERE id = '" + dbid + "'", connection); comm.ExecuteNonQuery(); conn.Close(); ListView1.EditIndex = -1; //here I databind ListView1 } What's wrong with updating of text1.Text, text2.Text in ItemUpdating event? Should I use e.NewValues property? If so, how to use it? Thanks in advance for any help.

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  • Stopping cookies being set from a domain (aka "cookieless domain") to increase site performance

    - by Django Reinhardt
    I was reading in Google's documentation about improving site speed. One of their recommendations is serving static content (images, css, js, etc.) from a "cookieless domain": Static content, such as images, JS and CSS files, don't need to be accompanied by cookies, as there is no user interaction with these resources. You can decrease request latency by serving static resources from a domain that doesn't serve cookies. Google then says that the best way to do this is to buy a new domain and set it to point to your current one: To reserve a cookieless domain for serving static content, register a new domain name and configure your DNS database with a CNAME record that points the new domain to your existing domain A record. Configure your web server to serve static resources from the new domain, and do not allow any cookies to be set anywhere on this domain. In your web pages, reference the domain name in the URLs for the static resources. This is pretty straight forward stuff, except for the bit where it says to "configure your web server to serve static resources from the new domain, and do not allow any cookies to be set anywhere on this domain". From what I've read, there's no setting in IIS that allows you to say "serve static resources", so how do I prevent ASP.NET from setting cookies on this new domain? At present, even if I'm just requesting a .jpg from the new domain, it sets a cookie on my browser, even though our application's cookies are set to our old domain. For example, ASP.NET sets an ".ASPXANONYMOUS" cookie that (as far as I'm aware) we're not telling it to do. Apologies if this is a real newb question, I'm new at this! Thanks.

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  • Jquery cycle plugin and image tag from code behind

    - by Geetha
    Hi All, I am using cycle plugin to show images. I am binding the html code for image from code behind. Problem: Images are not getting displayed. If i hard coded the image tag it is working. Code: $(window).load(function() { $.ajax({ type: "POST", contentType: "application/json; charset=utf-8", data: "{}", url: "Default.aspx/GetImage", dataType: "json", success: function(data) { alert(data.d); $("#sample").html(data.d); $('#sample').cycle({ fx: 'fade', continuous: true, speed: 7500, timeout: 55000, pause: 1, sync: 1 }); } }); }); Data.d will give: <img src="Images/Frontbanner/s0.jpg" width="664" height="428" border="0" /> <img src="Images/Frontbanner/s111.jpg" width="664" height="428" border="0" /> <img src="Images/Frontbanner/s112.jpg" width="664" height="428" border="0" /> <img src="Images/Frontbanner/s113.jpg" width="664" height="428" border="0" /> <img src="Images/Frontbanner/s114.jpg" width="664" height="428" border="0" /> <img src="Images/Frontbanner/s115.jpg" width="664" height="428" border="0" /> <img src="Images/Frontbanner/s116.jpg" width="664" height="428" border="0" />

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  • Program structure in long running data processing python script

    - by fmark
    For my current job I am writing some long-running (think hours to days) scripts that do CPU intensive data-processing. The program flow is very simple - it proceeds into the main loop, completes the main loop, saves output and terminates: The basic structure of my programs tends to be like so: <import statements> <constant declarations> <misc function declarations> def main(): for blah in blahs(): <lots of local variables> <lots of tightly coupled computation> for something in somethings(): <lots more local variables> <lots more computation> <etc., etc.> <save results> if __name__ == "__main__": main() This gets unmanageable quickly, so I want to refactor it into something more manageable. I want to make this more maintainable, without sacrificing execution speed. Each chuck of code relies on a large number of variables however, so refactoring parts of the computation out to functions would make parameters list grow out of hand very quickly. Should I put this sort of code into a python class, and change the local variables into class variables? It doesn't make a great deal of sense tp me conceptually to turn the program into a class, as the class would never be reused, and only one instance would ever be created per instance. What is the best practice structure for this kind of program? I am using python but the question is relatively language-agnostic, assuming a modern object-oriented language features.

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  • Animation management in COCOS2D iphone.

    - by shreya
    Hi All, I have near about 255 image frames for background animation, 99 frames of enemy sprite and 125 frames of player sprite. All animations are running simultaneously on the screen. That is background animation is running and 4-5 enemies are on the screen are present at a time, also player is there at the same time. Take a look at the code below, CCAnimation *_enemyAnimation = [CCAnimation animationWithName:@"Enemy" delay:0.1f]; for (int i = 1; i<99; i++) { [_enemyAnimation addFrameWithFilename:[NSString stringWithFormat:@"enemy %02d.jpg",i]]; } id action1 = [CCAnimate actionWithAnimation: _enemyAnimation]; [_enemySprite runAction:[CCRepeatForever actionWithAction: action1]]; [self schedule:@selector(BackToGameLogic:) interval:5.0]; This makes my game too slower and consumes memory about 65MB in the allocations. How should I manage my animations so there will be improvement in speed and memory consumption will be reduced?. Please suggest me the way. Thanks.

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  • Unable to edit a database row from JSF

    - by user1924104
    Hi guys i have a data table in JSF which displays all of the contents of my database table, it displays it fine, i also have a delete function that can successfully delete from the database fine and updates the data table fine however when i try to update the database i get the error java.lang.IllegalArgumentException: Cannot convert richard.test.User@129d62a7 of type class richard.test.User to long below is the code that i have been using to delete the rows in the database that is working fine : public void delete(long userID) { PreparedStatement ps = null; Connection con = null; if (userID != 0) { try { Class.forName("com.mysql.jdbc.Driver"); con = DriverManager.getConnection("jdbc:mysql://localhost:3306/test", "root", "root"); String sql = "DELETE FROM user1 WHERE userId=" + userID; ps = con.prepareStatement(sql); int i = ps.executeUpdate(); if (i > 0) { System.out.println("Row deleted successfully"); } } catch (Exception e) { e.printStackTrace(); } finally { try { con.close(); ps.close(); } catch (Exception e) { e.printStackTrace(); } } } } i simply wanted to edit the above code so it would update the records instead of deleting them so i edited it to look like : public void editData(long userID) { PreparedStatement ps = null; Connection con = null; if (userID != 0) { try { Class.forName("com.mysql.jdbc.Driver"); con = DriverManager.getConnection("jdbc:mysql://localhost:3306/test", "root", "root"); String sql = "UPDATE user1 set name = '"+name+"', email = '"+ email +"', address = '"+address+"' WHERE userId=" + userID; ps = con.prepareStatement(sql); int i = ps.executeUpdate(); if (i > 0) { System.out.println("Row updated successfully"); } } catch (Exception e) { e.printStackTrace(); } finally { try { con.close(); ps.close(); } catch (Exception e) { e.printStackTrace(); } } } } and the xhmtl is : <p:dataTable id="dataTable" var="u" value="#{userBean.getUserList()}" paginator="true" rows="10" editable="true" paginatorTemplate="{CurrentPageReport} {FirstPageLink} {PreviousPageLink} {PageLinks} {NextPageLink} {LastPageLink} {RowsPerPageDropdown}" rowsPerPageTemplate="5,10,15"> <p:column> <f:facet name="header"> User ID </f:facet> #{u.userID} </p:column> <p:column> <f:facet name="header"> Name </f:facet> #{u.name} </p:column> <p:column> <f:facet name="header"> Email </f:facet> #{u.email} </p:column> <p:column> <f:facet name="header"> Address </f:facet> #{u.address} </p:column> <p:column> <f:facet name="header"> Created Date </f:facet> #{u.created_date} </p:column> <p:column> <f:facet name="header"> Delete </f:facet> <h:commandButton value="Delete" action="#{user.delete(u.userID)}" /> </p:column> <p:column> <f:facet name="header"> Delete </f:facet> <h:commandButton value="Edit" action="#{user.editData(u)}" /> </p:column> currently when you press the edit button it will only update it with the same values as i haven't yet managed to get the datatable to be editable with the database, i have seen a few examples with an array list where the data table gets its values from but never a database so if you have any advice on this too it would be great thanks

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  • Calculating and saving space in Postgresql

    - by punkish
    I have a table in Pg like so CREATE TABLE t ( a BIGSERIAL NOT NULL, -- 8 b b SMALLINT, -- 2 b c SMALLINT, -- 2 b d REAL, -- 4 b e REAL, -- 4 b f REAL, -- 4 b g INTEGER, -- 4 b h REAL, -- 4 b i REAL, -- 4 b j SMALLINT, -- 2 b k INTEGER, -- 4 b l INTEGER, -- 4 b m REAL, -- 4 b CONSTRAINT a_pkey PRIMARY KEY (a) ) The above adds up to 50 bytes per row. My experience is that I need another 40% to 50% for system overhead, without even any user-created indexes to the above. So, about 75 bytes per row. I will have many, many rows in the table, potentially upward of 145 billion rows, so the table is going to be pushing 13-14 Terabytes. What tricks, if any, could I use to compact this table? My possible ideas below -- Convert the REAL values to INTEGERs. If they can stored as SMALLINT, that is a saving of 2 bytes per field. Convert the columns b .. m into an array. I don't need to search on those columns, but I do need to be able to return one column's value at a time. So, if I need column g, I could do something like SELECT a, arr[5] FROM t; Would I save space with the array option? Would there be a speed penalty? Any other ideas?

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  • Good way to identify similar images?

    - by Nick
    I've developed a simple and fast algorithm in PHP to compare images for similarity. Its fast (~40 per second for 800x600 images) to hash and a unoptimised search algorithm can go through 3,000 images in 22 mins comparing each one against the others (3/sec). The basic overview is you get a image, rescale it to 8x8 and then convert those pixels for HSV. The Hue, Saturation and Value are then truncated to 4 bits and it becomes one big hex string. Comparing images basically walks along two strings, and then adds the differences it finds. If the total number is below 64 then its the same image. Different images are usually around 600 - 800. Below 20 and extremely similar. Are there any improvements upon this model I can use? I havent looked at how relevant the different components (hue, saturation and value) are to the comparison. Hue is probably quite important but the others? To speed up searches I could probably split the 4 bits from each part in half, and put the most significant bits first so if they fail the check then the lsb doesnt need to be checked at all. I dont know a efficient way to store bits like that yet still allow them to be searched and compared easily. I've been using a dataset of 3,000 photos (mostly unique) and there havent been any false positives. Its completely immune to resizes and fairly resistant to brightness and contrast changes.

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  • How to improve Visual C++ compilation times?

    - by dtrosset
    I am compiling 2 C++ projects in a buildbot, on each commit. Both are around 1000 files, one is 100 kloc, the other 170 kloc. Compilation times are very different from gcc (4.4) to Visual C++ (2008). Visual C++ compilations for one project take in the 20 minutes. They cannot take advantage of the multiple cores because a project depend on the other. In the end, a full compilation of both projects in Debug and Release, in 32 and 64 bits takes more than 2 1/2 hours. gcc compilations for one project take in the 4 minutes. It can be parallelized on the 4 cores and takes around 1 min 10 secs. All 8 builds for 4 versions (Debug/Release, 32/64 bits) of the 2 projects are compiled in less than 10 minutes. What is happening with Visual C++ compilation times? They are basically 5 times slower. What is the average time that can be expected to compile a C++ kloc? Mine are 7 s/kloc with vc++ and 1.4 s/kloc with gcc. Can anything be done to speed-up compilation times on Visual C++?

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  • Fast, Unicode-capable, cross-platform programmer's text editor that shows invisibles like ZWSP?

    - by Roger_S
    Our publishing workflow includes Windows and Linux machines (there are some Macs too, but not in the critical-path workflow). Many texts include both English and Khmer and are marked-up in XML. XML Copy Editor is the best cross-platform open-source XML editor I've discovered. It utilizes the Scintilla editing component, which is generally good with Unicode but which does not enable non-printing or invisible characters like U+200B (zero-width space) and U+200C (zero-width non-joiner) to be displayed. Khmer does not separate words with a space character as Western languages do, so ZWSP is used in electronic texts to enable applications to break lines easily. Ideally I'd edit the markup and the content in a single editor, but XML awareness is less important at times than being able to display invisibles. (OpenOffice.org Writer and Microsoft Word are the only two apps I know that will display ZWSP. They are not suitable for the markup and text manipulations that need to be done to prepare manuscripts for publication, unfortunately, although I guess they're fine for authoring.) I tried out a promising editor last week, but a search-and-replace regex operation that took under a second in TextPad 4.7.3 lasted over twenty seconds. So I want to mention that speed and the ability to handle large (up to 150mb) files is also a concern. Is there a good, fast, free or not too expensive text editor, with versions on Windows and Linux and maybe mac too, Unicode-aware and capable of displaying invisibles like ZWSP? That has syntax highlighting, can handle large files and is customizable enough that I won't tear my hair out in frustration? Thanks, Roger_S

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  • What is the fastest way to filter a list of strings when making an Intellisense/Autocomplete list?

    - by user559548
    Hello everyone, I'm writing an Intellisense/Autocomplete like the one you find in Visual Studio. It's all fine up until when the list contains probably 2000+ items. I'm using a simple LINQ statement for doing the filtering: var filterCollection = from s in listCollection where s.FilterValue.IndexOf(currentWord, StringComparison.OrdinalIgnoreCase) >= 0 orderby s.FilterValue select s; I then assign this collection to a WPF Listbox's ItemSource, and that's the end of it, works fine. Noting that, the Listbox is also virtualised as well, so there will only be at most 7-8 visual elements in memory and in the visual tree. However the caveat right now is that, when the user types extremely fast in the richtextbox, and on every key up I execute the filtering + binding, there's this semi-race condition, or out of sync filtering, like the first key stroke's filtering could still be doing it's filtering or binding work, while the fourth key stroke is also doing the same. I know I could put in a delay before applying the filter, but I'm trying to achieve a seamless filtering much like the one in Visual Studio. I'm not sure where my problem exactly lies, so I'm also attributing it to IndexOf's string operation, or perhaps my list of string's could be optimised in some kind of index, that could speed up searching. Any suggestions of code samples are much welcomed. Thanks.

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  • What is the fastest way to find duplicates in multiple BIG txt files?

    - by user2950750
    I am really in deep water here and I need a lifeline. I have 10 txt files. Each file has up to 100.000.000 lines of data. Each line is simply a number representing something else. Numbers go up to 9 digits. I need to (somehow) scan these 10 files and find the numbers that appear in all 10 files. And here comes the tricky part. I have to do it in less than 2 seconds. I am not a developer, so I need an explanation for dummies. I have done enough research to learn that hash tables and map reduce might be something that I can make use of. But can it really be used to make it this fast, or do I need more advanced solutions? I have also been thinking about cutting up the files into smaller files. To that 1 file with 100.000.000 lines is transformed into 100 files with 1.000.000 lines. But I do not know what is best: 10 files with 100 million lines or 1000 files with 1 million lines? When I try to open the 100 million line file, it takes forever. So I think, maybe, it is just too big to be used. But I don't know if you can write code that will scan it without opening. Speed is the most important factor in this, and I need to know if it can be done as fast as I need it, or if I have to store my data in another way, for example, in a database like mysql or something. Thank you in advance to anybody that can give some good feedback.

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  • How slow are bit fields in C++

    - by Shane MacLaughlin
    I have a C++ application that includes a number of structures with manually controlled bit fields, something like #define FLAG1 0x0001 #define FLAG2 0x0002 #define FLAG3 0x0004 class MyClass { ' ' unsigned Flags; int IsFlag1Set() { return Flags & FLAG1; } void SetFlag1Set() { Flags |= FLAG1; } void ResetFlag1() { Flags &= 0xffffffff ^ FLAG1; } ' ' }; For obvious reasons I'd like to change this to use bit fields, something like class MyClass { ' ' struct Flags { unsigned Flag1:1; unsigned Flag2:1; unsigned Flag3:1; }; ' ' }; The one concern I have with making this switch is that I've come across a number of references on this site stating how slow bit fields are in C++. My assumption is that they are still faster than the manual code shown above, but is there any hard reference material covering the speed implications of using bit fields on various platforms, specifically 32bit and 64bit windows. The application deals with huge amounts of data in memory and must be both fast and memory efficient, which could well be why it was written this way in the first place.

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  • can a python script know that another instance of the same script is running... and then talk to it?

    - by Justin Grant
    I'd like to prevent multiple instances of the same long-running python command-line script from running at the same time, and I'd like the new instance to be able to send data to the original insance before the new instance commits suicide. How can I do this in a cross-platform way? Specifically, I'd like to enable the following behavior: "foo.py" is launched from the command line, and it will stay running for a long time-- days or weeks until the machine is rebooted or the parent process kills it. every few minutes the same script is launched again, but with different command-line parameters when launched, the script should see if any other instances are running. if other instances are running, then instance #2 should send its command-line parameters to instance #1, and then instance #2 should exit. instance #1, if it receives command-line parameters from another script, should spin up a new thread and (using the command-line parameters sent in the step above) start performing the work that instance #2 was going to perform. So I'm looking for two things: how can a python program know another instance of itself is running, and then how can one python command-line program communicate with another? Making this more complicated, the same script needs to run on both Windows and Linux, so ideally the solution would use only the Python standard library and not any OS-specific calls. Although if I need to have a Windows codepath and an *nix codepath (and a big if statement in my code to choose one or the other), that's OK if a "same code" solution isn't possible. I realize I could probably work out a file-based approach (e.g. instance #1 watches a directory for changes and each instance drops a file into that directory when it wants to do work) but I'm a little concerned about cleaning up those files after a non-graceful machine shutdown. I'd ideally be able to use an in-memory solution. But again I'm flexible, if a persistent-file-based approach is the only way to do it, I'm open to that option. More details: I'm trying to do this because our servers are using a monitoring tool which supports running python scripts to collect monitoring data (e.g. results of a database query or web service call) which the monitoring tool then indexes for later use. Some of these scripts are very expensive to start up but cheap to run after startup (e.g. making a DB connection vs. running a query). So we've chosen to keep them running in an infinite loop until the parent process kills them. This works great, but on larger servers 100 instances of the same script may be running, even if they're only gathering data every 20 minutes each. This wreaks havoc with RAM, DB connection limits, etc. We want to switch from 100 processes with 1 thread to one process with 100 threads, each executing the work that, previously, one script was doing. But changing how the scripts are invoked by the monitoring tool is not possible. We need to keep invocation the same (launch a process with different command-line parameters) but but change the scripts to recognize that another one is active, and have the "new" script send its work instructions (from the command line params) over to the "old" script.

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  • How can I accelerate the generation of the an MD5 Checksum within vb.net?

    - by Richard
    I'm working with some very large files residing on P2 (Panasonic) cards. Part of the process we employ is to first generate a checksum of the file we are going to copy, then copy the file, then run a checksum on the file to confirm that it copied OK. The problem is, is that files are large (70 GB+) and take a long time to complete. It's an issue since we will eventually be dealing with thousands of these files. I would like to find a faster way to generate the checksum other than using the System.Security.Cryptography.MD5CryptoServiceProvider I don't care if this means using a specialized hardware card, provided it works and is not to ungodly expensive. I would prefer to have a method of encoding that provided some feedback as to how far the process has gone along so I can display it like I do now. The application is written in vb.net. I would prefer to be able to use it as component, library, reference within my application, but I'm willing to call an outside application if there is enough improvement in the speed of generating the checksum. Needless to say, the checksum must be consistent and correct. :-) Thank you in advance for your time and efforts, Richard

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  • php curl http 405 error mind body online api

    - by K_G
    I am trying to connect to the Mind Body Online API (their forum is down currently, so I came here). Below is the code I am using. I am receiving this: SERVER ERROR 405 - HTTP verb used to access this page is not allowed. The page you are looking for cannot be displayed because an invalid method (HTTP verb) was used to attempt to access. code: //Data, connection, auth $soapUrl = "http://clients.mindbodyonline.com/api/0_5"; // xml post structure $xml_post_string = '<?xml version="1.0" encoding="utf-8"?> <soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns="http://clients.mindbodyonline.com/api/0_5"> <soapenv:Header/> <soapenv:Body> <GetClasses> <Request> <SourceCredentials> <SourceName>username</SourceName> <Password>password</Password> <SiteIDs> <int>site id</int> </SiteIDs> </SourceCredentials> <UserCredentials> <Username>username</Username> <Password>password</Password> <SiteIDs> <int></int> </SiteIDs> </UserCredentials> <Fields> <string>Classes.Resource</string> </Fields> <XMLDetail>Basic</XMLDetail> <PageSize>10</PageSize> <CurrentPageIndex>0</CurrentPageIndex> </Request> </GetClasses> </soapenv:Body> </soapenv:Envelope>'; $headers = array( "Content-type: text/xml;charset=\"utf-8\"", "Accept: text/xml", "Cache-Control: no-cache", "Pragma: no-cache", "SOAPAction: http://clients.mindbodyonline.com/api/0_5", "Content-length: ".strlen($xml_post_string), ); //SOAPAction: your op URL $url = $soapUrl; // PHP cURL for https connection with auth $ch = curl_init(); curl_setopt($ch, CURLOPT_URL, $url); curl_setopt($ch, CURLOPT_RETURNTRANSFER, true); curl_setopt($ch, CURLOPT_HTTPAUTH, CURLAUTH_ANY); curl_setopt($ch, CURLOPT_TIMEOUT, 10); curl_setopt($ch, CURLOPT_POST, true); curl_setopt($ch, CURLOPT_POSTFIELDS, $xml_post_string); // the SOAP request curl_setopt($ch, CURLOPT_HTTPHEADER, $headers); // converting $response = curl_exec($ch); curl_close($ch); var_dump($response); // converting //$response1 = str_replace("<soap:Body>","",$response); //$response2 = str_replace("</soap:Body>","",$response1); // convertingc to XML //$parser = simplexml_load_string($response2); // user $parser to get your data out of XML response and to display it. Any help would be great and if anyone has any experience working with their API, my first time ;) Here is the post on stack I am going off of: SOAP request in PHP

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  • Parallel.For Batching

    - by chibacity
    Is there built-in support in the TPL for batching operations? I was recently playing with a routine to carry out character replacement on a character array which required a lookup table i.e. transliteration: for (int i = 0; i < chars.Length; i++) { char replaceChar; if (lookup.TryGetValue(chars[i], out replaceChar)) { chars[i] = replaceChar; } } I could see that this could be trivially parallelized, so jumped in with a first stab which I knew would perform worse as the tasks were too fine-grained: Parallel.For(0, chars.Length, i => { char replaceChar; if (lookup.TryGetValue(chars[i], out replaceChar)) { chars[i] = replaceChar; } }); I then reworked the algorithm to use batching so that the work could be chunked onto different threads in less fine-grained batches. This made use of threads as expected and I got some near linear speed up. I'm sure that there must be built-in support for batching in the TPL. What is the syntax, and how do I use it? const int CharBatch = 100; int charLen = chars.Length; Parallel.For(0, ((charLen / CharBatch) + 1), i => { int batchUpper = ((i + 1) * CharBatch); for (int j = i * CharBatch; j < batchUpper && j < charLen; j++) { char replaceChar; if (lookup.TryGetValue(chars[j], out replaceChar)) { chars[j] = replaceChar; } } });

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