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• SQL query performance optimization (TimesTen)

  - by Sergey Mikhanov

  Hi community, I need some help with TimesTen DB query optimization. I made some measures with Java profiler and found the code section that takes most of the time (this code section executes the SQL query). What is strange that this query becomes expensive only for some specific input data. Here’s the example. We have two tables that we are querying, one represents the objects we want to fetch (T_PROFILEGROUP), another represents the many-to-many link from some other table (T_PROFILECONTEXT_PROFILEGROUPS). We are not querying linked table. These are the queries that I executed with DB profiler running (they are the same except for the ID): Command> select G.M_ID from T_PROFILECONTEXT_PROFILEGROUPS CG, T_PROFILEGROUP G where CG.M_ID_EID = G.M_ID and CG.M_ID_OID = 1464837998949302272; < 1169655247309537280 > < 1169655249792565248 > < 1464837997699399681 > 3 rows found. Command> select G.M_ID from T_PROFILECONTEXT_PROFILEGROUPS CG, T_PROFILEGROUP G where CG.M_ID_EID = G.M_ID and CG.M_ID_OID = 1466585677823868928; < 1169655247309537280 > 1 row found. This is what I have in the profiler: 12:14:31.147 1 SQL 2L 6C 10825P Preparing: select G.M_ID from T_PROFILECONTEXT_PROFILEGROUPS CG, T_PROFILEGROUP G where CG.M_ID_EID = G.M_ID and CG.M_ID_OID = 1464837998949302272 12:14:31.147 2 SQL 4L 6C 10825P sbSqlCmdCompile ()(E): (Found already compiled version: refCount:01, bucket:47) cmdType:100, cmdNum:1146695. 12:14:31.147 3 SQL 4L 6C 10825P Opening: select G.M_ID from T_PROFILECONTEXT_PROFILEGROUPS CG, T_PROFILEGROUP G where CG.M_ID_EID = G.M_ID and CG.M_ID_OID = 1464837998949302272; 12:14:31.147 4 SQL 4L 6C 10825P Fetching: select G.M_ID from T_PROFILECONTEXT_PROFILEGROUPS CG, T_PROFILEGROUP G where CG.M_ID_EID = G.M_ID and CG.M_ID_OID = 1464837998949302272; 12:14:31.148 5 SQL 4L 6C 10825P Fetching: select G.M_ID from T_PROFILECONTEXT_PROFILEGROUPS CG, T_PROFILEGROUP G where CG.M_ID_EID = G.M_ID and CG.M_ID_OID = 1464837998949302272; 12:14:31.148 6 SQL 4L 6C 10825P Fetching: select G.M_ID from T_PROFILECONTEXT_PROFILEGROUPS CG, T_PROFILEGROUP G where CG.M_ID_EID = G.M_ID and CG.M_ID_OID = 1464837998949302272; 12:14:31.228 7 SQL 4L 6C 10825P Fetching: select G.M_ID from T_PROFILECONTEXT_PROFILEGROUPS CG, T_PROFILEGROUP G where CG.M_ID_EID = G.M_ID and CG.M_ID_OID = 1464837998949302272; 12:14:31.228 8 SQL 4L 6C 10825P Closing: select G.M_ID from T_PROFILECONTEXT_PROFILEGROUPS CG, T_PROFILEGROUP G where CG.M_ID_EID = G.M_ID and CG.M_ID_OID = 1464837998949302272; 12:14:35.243 9 SQL 2L 6C 10825P Preparing: select G.M_ID from T_PROFILECONTEXT_PROFILEGROUPS CG, T_PROFILEGROUP G where CG.M_ID_EID = G.M_ID and CG.M_ID_OID = 1466585677823868928 12:14:35.243 10 SQL 4L 6C 10825P sbSqlCmdCompile ()(E): (Found already compiled version: refCount:01, bucket:44) cmdType:100, cmdNum:1146697. 12:14:35.243 11 SQL 4L 6C 10825P Opening: select G.M_ID from T_PROFILECONTEXT_PROFILEGROUPS CG, T_PROFILEGROUP G where CG.M_ID_EID = G.M_ID and CG.M_ID_OID = 1466585677823868928; 12:14:35.243 12 SQL 4L 6C 10825P Fetching: select G.M_ID from T_PROFILECONTEXT_PROFILEGROUPS CG, T_PROFILEGROUP G where CG.M_ID_EID = G.M_ID and CG.M_ID_OID = 1466585677823868928; 12:14:35.243 13 SQL 4L 6C 10825P Fetching: select G.M_ID from T_PROFILECONTEXT_PROFILEGROUPS CG, T_PROFILEGROUP G where CG.M_ID_EID = G.M_ID and CG.M_ID_OID = 1466585677823868928; 12:14:35.243 14 SQL 4L 6C 10825P Closing: select G.M_ID from T_PROFILECONTEXT_PROFILEGROUPS CG, T_PROFILEGROUP G where CG.M_ID_EID = G.M_ID and CG.M_ID_OID = 1466585677823868928; It’s clear that the first query took almost 100ms, while the second was executed instantly. It’s not about queries precompilation (the first one is precompiled too, as same queries happened earlier). We have DB indices for all columns used here: T_PROFILEGROUP.M_ID, T_PROFILECONTEXT_PROFILEGROUPS.M_ID_OID and T_PROFILECONTEXT_PROFILEGROUPS.M_ID_EID. My questions are: Why querying the same set of tables yields such a different performance for different parameters? Which indices are involved here? Is there any way to improve this simple query and/or the DB to make it faster? UPDATE: to give the feeling of size: Command> select count(*) from T_PROFILEGROUP; < 183840 > 1 row found. Command> select count(*) from T_PROFILECONTEXT_PROFILEGROUPS; < 2279104 > 1 row found.

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• Socket ping-pong performance

  - by Kamil_H

  I have written two simple programs (tried it in C++ and C#). This is pseudo code: -------- Client --------------- for(int i = 0; i < 200.000; i++) { socket_send("ping") socket_receive(buff) } --------- Server ------------- while(1) { socket_receive(buff) socket_send("pong") } I tried it on Windows. Execution time of client is about 45 seconds. Can somebody explain me why this takes so long? I understand that if there were real network connection between client and server the time of one 'ping-pong' would be: generate_ping + send_via_network + generate_pong + send_via_network but here everything is done in 'local' mode. Is there any way to make this inter process ping-pong faster using network sockets (I'm not asking about shared memory for example :) )

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• Performance problem loading lots of user controls

  - by codymanix

  My application is loading a bunch of the same user control into a ScrollPanel. The problem is, this is very slow. The profiler show that the method Application.LoadComponent(), which is called internally by in the designer code in the constructor of my user control, is the bottleneck. The documentation of this method says, that this method load XAML files. I alway though the compiler compiles XAML to BAML and embedds it into the assembly. So the question is, how can I use BAML instead of XAML? Is there another way to make loading my user controls faster?

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• JDBC batch insert performance

  - by wo_shi_ni_ba_ba

  I need to insert a couple hundreds of millions of records into the mysql db. I'm batch inserting it 1 million at a time. Please see my code below. It seems to be slow. Is there any way to optimize it? try { // Disable auto-commit connection.setAutoCommit(false); // Create a prepared statement String sql = "INSERT INTO mytable (xxx), VALUES(?)"; PreparedStatement pstmt = connection.prepareStatement(sql); Object[] vals=set.toArray(); for (int i=0; i

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• QR Codes for Files on Google Code

  - by Synetech inc.

  Hi, When you download files from Google Code now (example), in addition to the text version of the SHA1 hash, it includes a QR code of it. The device that the file was downloaded to is the one that has to hash the file. But, if it can download the file (ie, has access to the webpage), it also has access to the text version of the hash, so the QR code seems completely useless—and more work to decode when the raw text is available. How would reading the hash into a mobile phone allow you to verify the file you download to the computer? Or if you download the file to the phone, how would you use the phone to take a picture of the QR code displayed on the webpage on its own screen? Does anyone know what the point to the QR code is or how you would use it to verify the downloaded file (I don’t mean QR codes in general, but specifically in this context).

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• Performance experiences for running Windows 7 on a Thin-Client?

  - by Peter Bernier

  Has anyone else tried installing Windows 7 on thin-client hardware? I'd be very interested to hear about other people's experiences and what sort of hardware tweaks they had to do to get it to work. (Yes, I realize this is completely unsupported.. half the fun of playing with machines and beta/RC versions is trying out unsupported scenarios. :) ) I managed to get Windows 7 installed on a modified Wyse 9450 Thin-Client and while the performance isn't great, it is usable, particularly as an RDP workstation. Before installing 7, I added another 256Mb of ram (512 total), a 60G laptop hard-drive and a PCI videocard to the 9450 (this was in order to increase the supported screen resolution). I basically did this in order to see whether or not it was possible to get 7 installed on such minimal hardware, and see what the performance would be. For a 550Mhz processor, I was reasonably impressed. I've been using the machine for RDP for the last couple of days and it actually seems slightly snappier than the default Windows XP embedded install (although this is more likely the result of the extra hardware). I'll be running some more tests later on as I'm curious to see particularl whether the streaming video performance will improve. I'd love to hear about anyone's experiences getting 7 to work on extremely low-powered hardware. Particularly any sort of tweaks that you've discovered in order to increase performance..

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• To what extent is size a factor in SSD performance?

  - by artif

  To what extent is the size of an SSD a factor in its performance? In my mind, correct me if I'm wrong, a bigger SSD should be, everything else being equal, faster than a smaller one. A bigger SSD would have more erase blocks and thus more leeway for the FTL (flash translation layer) to do garbage collection optimization. Also there would be more time before TRIM became necessary. I see on Wikipedia that it remarks that "The performance of the SSD can scale with the number of parallel NAND flash chips used in the device" so it seems throughput also increases significantly. Also many SSDs contain internal caches of some sort and presumably those caches are larger for correspondingly large SSDs. But supposing this effect exists, I would like a quantitative analysis. Does throughput increase linearly? How much is garbage collection impacted, if at all? Does latency stay the same? And so on. Would the performance of a 8 GB SSD be significantly different from, for example, an 80 GB SSD assuming both used high quality chips, controllers, etc? Are there any resources (webpages, research papers, presentations, books, etc) that discuss correlations between SSD performance (4 KB random write speed, latency, maximum sequential throughput, etc) and size? I realize this does not really sound like a programming question but it is relevant for what I'm working on (using flash for caching hard drive data) which does involve programming. If there is a better place to ask this question, eg a more hardware oriented site, what would that be? Something like the equivalent of stack overflow (or perhaps a forum) for in-depth questions on hardware interfaces, internals, etc would be appreciated.

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• Performance experiences for running Windows 7 on a Thin-Client?

  - by Peter Bernier

  Has anyone else tried installing Windows 7 on thin-client hardware? I'd be very interested to hear about other people's experiences and what sort of hardware tweaks they had to do to get it to work. (Yes, I realize this is completely unsupported.. half the fun of playing with machines and beta/RC versions is trying out unsupported scenarios. :) ) I managed to get Windows 7 installed on a modified Wyse 9450 Thin-Client and while the performance isn't great, it is usable, particularly as an RDP workstation. Before installing 7, I added another 256Mb of ram (512 total), a 60G laptop hard-drive and a PCI videocard to the 9450 (this was in order to increase the supported screen resolution). I basically did this in order to see whether or not it was possible to get 7 installed on such minimal hardware, and see what the performance would be. For a 550Mhz processor, I was reasonably impressed. I've been using the machine for RDP for the last couple of days and it actually seems slightly snappier than the default Windows XP embedded install (although this is more likely the result of the extra hardware). I'll be running some more tests later on as I'm curious to see particularl whether the streaming video performance will improve. I'd love to hear about anyone's experiences getting 7 to work on extremely low-powered hardware. Particularly any sort of tweaks that you've discovered in order to increase performance..

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• What to watch out for when writing code at an Interview?

  - by Philip

  Hi, I have read that at a lot of companies you have to write code at an interview. On the one hand I see that it makes sense to ask for a work sample. On the other hand: What kind of code do you expect to be written in 5 minutes? And what if they tell me "Write an algorithm that does this and that" but I cannot think of a smart solution or even write code that doesn't semantically work? I am particularly interested in that question because I do not have that much commercial programming experience, 2 years part-time, one year full-time. (But I am interested in programming languages since nearly 15 years though usually I was more concentrated in playing with the language rather than writing large applications...) And actually I consider my debugging and problem solving skills much better than my coding skills. I sometimes see myself not writing the most beautiful code when looking back, but on the other hand I often come up with solutions for hard problems. And I think I am very good at optimizing, fixing, restructuring existing code, but I have problems with writing new applications from scratch. The software design sucks... ;-) Therefore I don't feel comfortable when thinking about this code writing situation at an interview... So what do the interviewers expect? What kind of information about my code writing are they interested in? Philip

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• Rawr Code Clone Analysis&ndash;Part 0

  - by Dylan Smith

  Code Clone Analysis is a cool new feature in Visual Studio 11 (vNext).  It analyzes all the code in your solution and attempts to identify blocks of code that are similar, and thus candidates for refactoring to eliminate the duplication.  The power lies in the fact that the blocks of code don't need to be identical for Code Clone to identify them, it will report Exact, Strong, Medium and Weak matches indicating how similar the blocks of code in question are.   People that know me know that I'm anal enthusiastic about both writing clean code, and taking old crappy code and making it suck less. So the possibilities for this feature have me pretty excited if it works well - and thats a big if that I'm hoping to explore over the next few blog posts. I'm going to grab the Rawr source code from CodePlex (a World Of Warcraft gear calculator engine program), run Code Clone Analysis against it, then go through the results one-by-one and refactor where appropriate blogging along the way.  My goals with this blog series are twofold: Evaluate and demonstrate Code Clone Analysis Provide some concrete examples of refactoring code to eliminate duplication and improve the code-base Here are the initial results:   Code Clone Analysis has found: 129 Exact Matches 201 Strong Matches 300 Medium Matches 193 Weak Matches Also indicated is that there was a total of 45,181 potentially duplicated lines of code that could be eliminated through refactoring.  Considering the entire solution only has 109,763 lines of code, if true, the duplicates lines of code number is pretty significant. In the next post we’ll start examining some of the individual results and determine if they really do indicate a potential refactoring.

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• How do you stay productive when dealing with extremely badly written code?

  - by gaearon

  I don't have much experience in working in software industry, being self-taught and having participated in open source before deciding to take a job. Now that I work for money, I also have to deal with some unpleasant stuff, which is normal of course. Recently I was assigned to add logging to a large SharePoint project which is written by some programmer who obviously was learning to code on the job. After 2 years of collaboration, the client switched to our company, but the damage was done, and now somehow I need to maintain this code. Not that the code was too hard to read. Despite problems - each project has one class with several copy-pasted methods, enormous if nestings, Systems Hungarian, undisposed connections — it's still readable. However, I found myself absolutely unproductive despite working on something as simple as adding logging. Basically, I just need to go through the code step by step and add some trace calls. However, the idiocy of the code is so annoying that I get tired within 10 minutes of starting. In the beginning, I used to add using constructs, reduce nesting by reversing if's, rename the variables to readable names—but the project is large, and eventually I gave up. I know this is not the task I should be doing, but at least reducing the mess gave me some kind of psychological reward so I could keep going. Now the trick stopped working, and I still have 60% of my work to do. I started having headaches after work, and I no longer get the feeling of satisfaction I used to get - which would usually allow me to code for 10 hours straight and still feel fresh. This is not just one big rant, for I really do have an actual question: Is there a way to stay productive and not to fight the windmills? Is there some kind of psychological trick to stay focused on the task, instead of thinking “How stupid is that?” each time I see another clever trick by the previous programmer? The problem with adding logging is that I actually have to understand what the code does, and doing so hurts my brain in an unpleasant fashion.

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• Which reference provides your definition of "elegant" or "beautiful" code?

  - by Donnied

  This question is phrased in a very specific way - it asks for references. There was a similar question posted which was closed because it was considered a duplicate to a good code question. The Programmers FAQ points out that answers should have references - or its just an unproductive sharing of (seemingly) baseless opinions. There is a difference between shortest code and most elegant code. This becomes clear in several seminal texts: Dijkstra, E. W. (1972). The humble programmer. Communications of the ACM, 15(10), 859–866. Kernighan, B. W., & Plauger, P. J. (1974). Programming style: Examples and counterexamples. ACM Comput. Surv., 6(4), 303–319. Knuth, D. E. (1984). Literate programming. The Computer Journal, 27(2), 97–111. doi:10.1093/comjnl/27.2.97 They all note the importance of clarity over brevity. Kernighan & Plauger (1974) provide descriptions of "good" code, but "good code" is certainly not synonymous with "elegant". Knuth (1984) describes the impo rtance of exposition and "excellence of style" to elegant programs. He cites Hoare - who describes that code should be self documenting. Dijkstra (1972) indicates that beautiful programs optimize efficiency but are not opaque. This sort of conversation is qulaitatively different than a random sharing of opinions. Therefore, the question - Which reference provides your definition of "elegant" or "beautiful" code? "Which *reference*" is not subjective - anything else will most likely shut the thread down, so please supply *references* not opinions.

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• Copy-and-Pasted Test Code: How Bad is This?

  - by joshin4colours

  My current job is mostly writing GUI test code for various applications that we work on. However, I find that I tend to copy and paste a lot of code within tests. The reason for this is that the areas I'm testing tend to be similar enough to need repetition but not quite similar enough to encapsulate code into methods or objects. I find that when I try to use classes or methods more extensively, tests become more cumbersome to maintain and sometimes outright difficult to write in the first place. Instead, I usually copy a big chunk of test code from one section and paste it to another, and make any minor changes I need. I don't use more structured ways of coding, such as using more OO-principles or functions. Do other coders feel this way when writing test code? Obviously I want to follow DRY and YAGNI principles, but I find that test code (automated test code for GUI testing anyway) can make these principles tough to follow. Or do I just need more coding practice and a better overall system of doing things? EDIT: The tool I'm using is SilkTest, which is in a proprietary language called 4Test. As well, these tests are mostly for Windows desktop applications, but I also have tested web apps using this setup as well.

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• How would you react if someone told you your code is a mess?

  - by newbie

  I am a good programmer, or so I thought before. I always love to program. And I want to learn many things about programming to make me a better programmer. I studied programming for 1 year and now I am working as a programmer for almost 2 years. So in short, I have almost 3 years programming experience. Our team is composed of 5 programmers, and 4 of us are new, 1 has more than 3 year experience. We've been working for a program for almost a year now and nobody ever review my code and I was given a page to work with. We never had a code review and we are all new so we don't know what is a clean code looks like. I think programmers learn by themselves? We deployed our program to the program without thorough testing. Now it is tight and we need an approval and code review first before we make changes with the code. For the first time, someone reviews my code and he says it is a mess. I feel so sad and hurt. I really love programming and making them say something like that really hurts me. I really want to improve myself. But it seems like I'm not a genius programmer like in the movies. Can you give me advise on how to be better? Have you ever experience something criticizing your code and you feel really hurt? What do you do on those events.. Thank you

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• Improving long-polling Ajax performance

  - by Bears will eat you

  I'm writing a webapp (Firefox-compatible only) which uses long polling (via jQuery's ajax abilities) to send more-or-less constant updates from the server to the client. I'm concerned about the effects of leaving this running for long periods of time, say, all day or overnight. The basic code skeleton is this: function processResults(xml) { // do stuff with the xml from the server } function fetch() { setTimeout(function () { $.ajax({ type: 'GET', url: 'foo/bar/baz', dataType: 'xml', success: function (xml) { processResults(xml); fetch(); }, error: function (xhr, type, exception) { if (xhr.status === 0) { console.log('XMLHttpRequest cancelled'); } else { console.debug(xhr); fetch(); } } }); }, 500); } (The half-second "sleep" is so that the client doesn't hammer the server if the updates are coming back to the client quickly - which they usually are.) After leaving this running overnight, it tends to make Firefox crawl. I'd been thinking that this could be partially caused by a large stack depth since I've basically written an infinitely recursive function. However, if I use Firebug and throw a breakpoint into fetch, it looks like this is not the case. The stack that Firebug shows me is only about 4 or 5 frames deep, even after an hour. One of the solutions I'm considering is changing my recursive function to an iterative one, but I can't figure out how I would insert the delay in between Ajax requests without spinning. I've looked at the JS 1.7 "yield" keyword but I can't quite wrap my head around it, to figure out if it's what I need here. Is the best solution just to do a hard refresh on the page periodically, say, once every hour? Is there a better/leaner long-polling design pattern that won't put a hurt on the browser even after running for 8 or 12 hours? Or should I just skip the long polling altogether and use a different "constant update" pattern since I usually know how frequently the server will have a response for me?

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• high performance hibernate insert

  - by luke

  I am working on a latency sensitive part of an application, basically i will receive a network event transform the data and then insert all the data into the DB. After profiling i see that basically all my time is spent trying to save the data. here is the code private void insertAllData(Collection<Data> dataItems) { long start_time = System.currentTimeMillis(); long save_time = 0; long commit_time = 0; Transaction tx = null; try { Session s = HibernateSessionFactory.getSession(); s.setCacheMode(CacheMode.IGNORE); s.setFlushMode(FlushMode.NEVER); tx = s.beginTransaction(); for(Data data : dataItems) { s.saveOrUpdate(data); } save_time = System.currentTimeMillis(); tx.commit(); s.flush(); s.clear(); } catch(HibernateException ex) { if(tx != null) tx.rollback(); } commit_time = System.currentTimeMillis(); System.out.println("Save: " + (save_time - start_time)); System.out.println("Commit: " + (commit_time - save_time)); System.out.println(); } The size of the collection is always less than 20. here is the timing data that i see: Save: 27 Commit: 9 Save: 27 Commit: 9 Save: 26 Commit: 9 Save: 36 Commit: 9 Save: 44 Commit: 0 This is confusing to me. I figure that the save should be quick and all the time should be spent on commit. but clearly I'm wrong. I have also tried removing the transaction (its not really necessary) but i saw worse times... I have set hibernate.jdbc.batch_size=20... i need this operation to be as fast as possible, ideally there would only be one roundtrip to the database. How can i do this?

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• Oracle performance problems with large batch of XSL operations

  - by FrustratedWithFormsDesigner

  I have a system that is performing many XSL transformations on XMLType objects. The problem is that the system gradually slows down over time, and sometimes crashes when it runs out of memory. It seems that the slow down (and possibly memory crash) is around the dbms_xslprocessor.processXSL function call, which gradually takes longer and longer to complete. The code looks like this: v_doc dbms_xmldom.DOMDocument; v_transformer dbms_xmldom.DOMDocument; v_XSLprocessor dbms_xslprocessor.Processor; v_stylesheet dbms_xslprocessor.Stylesheet; v_clob clob; ... transformer := PKG_STUFF.getXSL(); v_transformer := dbms_xmldom.newDOMDocument(transformer); v_XSLprocessor := Dbms_Xslprocessor.newProcessor; v_stylesheet := dbms_xslprocessor.newStylesheet(v_transformer, ''); ... for source_data in (select id in source_tbl) loop begin v_doc := PKG_CONVERT.convert(in_id => source_data.id); --start time of operation v_begin_op_time := dbms_utility.get_time; --reset the CLOB v_clob := ' '; --Apply XSL Transform dbms_xslprocessor.processXSL(p => v_XSLprocessor, ss => v_stylesheet, xmldoc => v_Doc, cl => v_clob); v_doc := dbms_xmldom.newDOMDocument(XMLType(v_clob)); --end time v_end_op_time := dbms_utility.get_time; --calculate duration v_time_taken := (((v_end_op_time - v_begin_op_time))); --log the duration PKG_LOG.log_message('Time taken to transform XML: '||v_time_taken); ... ... DBMS_XMLDOM.freeDocument(v_Doc); DBMS_LOB.freetemporary(lob_loc => v_clob); end loop; The time taken to transform the XML is slowly creeping up (I suppose it might also be the call to dbms_xmldom.newDOMDocument, but I had thought that to be fairly straightforward). I have no idea why.... :( (Oracle 10g)

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• GXT Performance Issues

  - by pearl

  Hi All, We are working on a rather complex system using GXT. While everything works great on FF, IE (especially IE6) is a different story (looking at more than 10 seconds until the browser renders the page). I understand that one of the main reasons is DOM manipulation which is a disaster under IE6 (See http://www.quirksmode.org/dom/innerhtml.html). This can be thought to be a generic problem of a front-end Javascript framework (i.e. GWT) but a simple code (see below) that executes the same functionality proofs otherwise. In fact, under IE6 - getSomeGWT() takes 400ms while getSomeGXT() takes 4 seconds. That's a x10 factor which makes a huge different for the user experience !!! private HorizontalPanel getSomeGWT() { HorizontalPanel pointsLogoPanel = new HorizontalPanel(); for (int i=0; i<350; i++) { HorizontalPanel innerContainer = new HorizontalPanel(); innerContainer.add(new Label("some GWT text")); pointsLogoPanel.add(innerContainer); } return pointsLogoPanel; } private LayoutContainer getSomeGXT() { LayoutContainer pointsLogoPanel = new LayoutContainer(); pointsLogoPanel.setLayoutOnChange(true); for (int i=0; i<350; i++) { LayoutContainer innerContainer = new LayoutContainer(); innerContainer.add(new Text("just some text")); pointsLogoPanel.add(innerContainer); } return pointsLogoPanel; } So to solve/mitigate the issue one would need to - a. Reduce the number of DOM manipulations; or b. Replace them with innerHTML. AFAIK, (a) is simply a side effect of using GXT and (b) is only possible with UiBinder which isn't supported yet by GXT. Any ideas? Thanks in advance!

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• Performance problem with System.Net.Mail

  - by Saif Khan

  I have this unusual problem with mailing from my app. At first it wasn't working (getting unable to relay error crap) anyways I added the proper authentication and it works. My problem now is, if I try to send around 300 emails (each with a 500k attachment) the app starts hanging around 95% thru the process. Here is some of my code which is called for each mail to be sent Using mail As New MailMessage() With mail .From = New MailAddress(My.Resources.EmailFrom) For Each contact As Contact In Contacts .To.Add(contact.Email) Next .Subject = "Accounting" .Body = My.Resources.EmailBody 'Back the stream up to the beginning orelse the attachment 'will be sent as a zero (0) byte file. attachment.Seek(0, SeekOrigin.Begin) .Attachments.Add(New Attachment(attachment, String.Concat(Item.Year, Item.AttachmentType.Extension))) End With Dim smtp As New SmtpClient("192.168.1.2") With smtp .DeliveryMethod = SmtpDeliveryMethod.Network .UseDefaultCredentials = False .Credentials = New NetworkCredential("username", "password") .Send(mail) End With End Using With item .SentStatus = True .DateSent = DateTime.Now.Date .Save() End With Return I was thinking, can I just prepare all the mails and add them to a collection then open one SMTP conenction and just iterate the collection, calling the send like this Using mail As New MailMessage() ... MailCollection.Add(mail) End Using ... Dim smtp As New SmtpClient("192.168.1.2") With smtp .DeliveryMethod = SmtpDeliveryMethod.Network .UseDefaultCredentials = False .Credentials = New NetworkCredential("username", "password") For Each mail in MainCollection .Send(mail) Next End With

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• Sharing large objects between ruby processes without a performance hit

  - by Gdeglin

  I have a Ruby hash that reaches approximately 10 megabytes if written to a file using Marshal.dump. After gzip compression it is approximately 500 kilobytes. Iterating through and altering this hash is very fast in ruby (fractions of a millisecond). Even copying it is extremely fast. The problem is that I need to share the data in this hash between Ruby on Rails processes. In order to do this using the Rails cache (file_store or memcached) I need to Marshal.dump the file first, however this incurs a 1000 millisecond delay when serializing the file and a 400 millisecond delay when serializing it. Ideally I would want to be able to save and load this hash from each process in under 100 milliseconds. One idea is to spawn a new Ruby process to hold this hash that provides an API to the other processes to modify or process the data within it, but I want to avoid doing this unless I'm certain that there are no other ways to share this object quickly. Is there a way I can more directly share this hash between processes without needing to serialize or deserialize it? Here is the code I'm using to generate a hash similar to the one I'm working with: @a = [] 0.upto(500) do |r| @a[r] = [] 0.upto(10_000) do |c| if rand(10) == 0 @a[r][c] = 1 # 10% chance of being 1 else @a[r][c] = 0 end end end @c = Marshal.dump(@a) # 1000 milliseconds Marshal.load(@c) # 400 milliseconds

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• Performance issue on Android's MapView Navigation-App

  - by poeschlorn

  Hey Guys, I've got a question on making an navigation app more faster and more stable. The basic layer of my app is a simple mapview, covered with several overlays (2 markers for start and destination and one for the route). My idea is to implement a thread to display the route, so that the app won't hang up during the calculation of a more complex route (like it does right now). After implementing the thread there are no updates shows any more, maybe you can help me with a short glance at an excerpt of my code below: private class MyLocationListener implements LocationListener { @Override public void onLocationChanged(Location loc) { posUser = new GeoPoint((int) (loc.getLatitude() * 1E6), (int) (loc .getLongitude() * 1E6)); new Thread(){ public void run(){ mapView.invalidate(); // Erase old overlays mapView.getOverlays().clear(); // Draw updated overlay elements and adjust basic map settings updateText(); if(firstRefresh){ adjustMap(); firstRefresh = false; } getAndPaintRoute(); drawMarkers(); } }; } Some features have been summarized to a method like "drawMarkers()" or "updateText()"...(they don't need any more attention ;-))

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• Need advice on comparing the performance of 2 equivalent linq to sql queries

  - by uvita

  I am working on tool to optimize linq to sql queries. Basically it intercepts the linq execution pipeline and makes some optimizations like for example removing a redundant join from a query. Of course, there is an overhead in the execution time before the query gets executed in the dbms, but then, the query should be processed faster. I don't want to use a sql profiler because I know that the generated query will be perform better in the dbms than the original one, I am looking for a correct way of measuring the global time between the creation of the query in linq and the end of its execution. Currently, I am using the Stopwatch class and my code looks something like this: var sw = new Stopwatch(); sw.Start(); const int amount = 100; for (var i = 0; i < amount; i++) { ExecuteNonOptimizedQuery(); } sw.Stop(); Console.Writeline("Executing the query {2} times took: {0}ms. On average, each query took: {1}ms", sw.ElapsedMilliseconds, sw.ElapsedMilliseconds / amount, amount); Basically the ExecutenNonOptimizedQuery() method creates a new DataContext, creates a query and then iterates over the results. I did this for both versions of the query, the normal one and the optimized one. I took the idea from this post from Frans Bouma. Is there any other approach/considerations I should take? Thanks in advance!

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• Mysql select - improve performance

  - by realshadow

  Hey, I am working on an e-shop which sells products only via loans. I display 10 products per page in any category, each product has 3 different price tags - 3 different loan types. Everything went pretty well during testing time, query execution time was perfect, but today when transfered the changes to the production server, the site "collapsed" in about 2 minutes. The query that is used to select loan types sometimes hangs for ~10 seconds and it happens frequently and thus it cant keep up and its hella slow. The table that is used to store the data has approximately 2 milion records and each select looks like this: SELECT * FROM products_loans WHERE KOD IN("X17/Q30-10", "X17/12", "X17/5-24") AND 369.27 BETWEEN CENA_OD AND CENA_DO; 3 loan types and the price that needs to be in range between CENA_OD and CENA_DO, thus 3 rows are returned. But since I need to display 10 products per page, I need to run it trough a modified select using OR, since I didnt find any other solution to this. I have asked about it here, but got no answer. As mentioned in the referencing post, this has to be done separately since there is no column that could be used in a join (except of course price and code, but that ended very, very badly). Here is the show create table, kod and CENA_OD/CENA_DO very indexed via INDEX. CREATE TABLE `products_loans` ( `KOEF_ID` bigint(20) NOT NULL, `KOD` varchar(30) NOT NULL, `AKONTACIA` int(11) NOT NULL, `POCET_SPLATOK` int(11) NOT NULL, `koeficient` decimal(10,2) NOT NULL default '0.00', `CENA_OD` decimal(10,2) default NULL, `CENA_DO` decimal(10,2) default NULL, `PREDAJNA_CENA` decimal(10,2) default NULL, `AKONTACIA_SUMA` decimal(10,2) default NULL, `TYP_VYHODY` varchar(4) default NULL, `stage` smallint(6) NOT NULL default '1', PRIMARY KEY (`KOEF_ID`), KEY `CENA_OD` (`CENA_OD`), KEY `CENA_DO` (`CENA_DO`), KEY `KOD` (`KOD`), KEY `stage` (`stage`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 And also selecting all loan types and later filtering them trough php doesnt work good, since each type has over 50k records and the select takes too much time as well... Any ides about improving the speed are appreciated.

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• SQL Server Express performance issue

  - by Developer IT

  Hi folks ! I know my questions will sound silly and probably nobody will have perfect answer but since I am in a complete dead-end with the situation it will make me feel better to post it here. So... I have a SQL Server Express database that's 500 Mb. It contains 5 tables and maybe 30 stored procedure. This database is use to store articles and is use for the Developer It web site. Normally the web pages load quickly, let's say 2 ou 3 sec. BUT, sqlserver process uses 100% of the processor for those 2 or 3 sec. I try to find which stored procedure was the problem and I could not find one. It seems like every read into the table dans contains the articles (there are about 155,000 of them and 20 or so gets added every 15 minutes). I added few index but without luck... It is because the table is full text indexed ? Should I have order with the primary key instead of date ? I never had any problems with ordering by dates.... Should I use dynamic SQL ? Should I add the primary key into the url of the articles ? Should I use mutiple indexes for seperate columns or one big index ? I you want more details or code bits, just ask for it. Basicly, every little hint is much apreciated. Thanks.

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• Performance: float to int cast and clipping result to range

  - by durandai

  I'm doing some audio processing with float. The result needs to be converted back to PCM samples, and I noticed that the cast from float to int is surprisingly expensive. Whats furthermore frustrating that I need to clip the result to the range of a short (-32768 to 32767). While I would normally instictively assume that this could be assured by simply casting float to short, this fails miserably in Java, since on the bytecode level it results in F2I followed by I2S. So instead of a simple: int sample = (short) flotVal; I needed to resort to this ugly sequence: int sample = (int) floatVal; if (sample > 32767) { sample = 32767; } else if (sample < -32768) { sample = -32768; } Is there a faster way to do this? (about ~6% of the total runtime seems to be spent on casting, while 6% seem to be not that much at first glance, its astounding when I consider that the processing part involves a good chunk of matrix multiplications and IDCT) EDIT The cast/clipping code above is (not surprisingly) in the body of a loop that reads float values from a float[] and puts them into a byte[]. I have a test suite that measures total runtime on several test cases (processing about 200MB of raw audio data). The 6% were concluded from the runtime difference when the cast assignment "int sample = (int) floatVal" was replaced by assigning the loop index to sample. EDIT @leopoldkot: I'm aware of the truncation in Java, as stated in the original question (F2I, I2S bytecode sequence). I only tried the cast to short because I assumed that Java had an F2S bytecode, which it unfortunately does not (comming originally from an 68K assembly background, where a simple "fmove.w FP0, D0" would have done exactly what I wanted).

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