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  • Which database should I use for best performance

    - by _simon_
    Hello, I am working in Visual Studio 2005, .NET 2.0. I need to write an application, which listens on COM port and saves incoming data to a database. Main feature: save incoming data (series of 13-digits numbers), if this number allready exists, then mark it as double. For example, there could be these records in database: 0000000000001 OK 0000000000002 OK 0000000000002 Double 0000000000003 OK 0000000000004 OK I could use SQL database, but I don't know if it is fast enough... Database should be able to store up to 10.000.000 records and write up to 100 records per minute (so it needs to check 100 times per minute if this record allready exists). Which database should I use? Maybe the whole database would need to be in RAM. Where could I learn more about this? Thanks

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  • MySQL Data Truncation: Out of range value in Performance test

    - by Khaledez
    on a test for Java-MySQL-Restlet application, I write to database at 4reqs/second for 120 seconds. In this write I insert a row that has foreign key which has the same value for all rows, and this exception occurs: Could not recover transaction. Original exception follows. com.mysql.jdbc.MysqlDataTruncation: Data truncation: Out of range value for column 'idPxxx' at row 1 Only 5% of requests fails to this exceptions, others works. Regards

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  • Google App Engine, Java, and HTTP Performance

    - by polyclef
    A friend and I are currently working on a turn-based game with chat with both desktop browser and Android clients, with Google App Engine as the server. We're using the Java API for GAE and using HTTP for communication with the server. We've implemented simple chat functionality, and we're getting undesirable latencies 1-3 seconds from both the browser and Android clients while just posting simple one-word chat messages. My friend thought it would be best to use XMPP instead of HTTP, but we want to use a Google Accounts cookie for authentication from the Android client, and according to the GAE documentation, XMPP clients cannot use a Google Accounts cookie and must use the user's password. Does anyone have any suggestions as to where the latency might be coming from, how to troubleshoot it, and/or what to do about it? Also, is anyone aware of any opensource implementations of chat (or something similar) on GAE done in Java? Can't seem to find any.

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  • High performance distributed asynchronous RPC in java

    - by unludo
    I would like to do RPC to a list of clients with the following requirements: the server does not know the clients (implies a kind of broker?) and the cleints do not know the server there may be several clients - they share the load to treat the RPC The RPC is asynchronous very fast (round-trip < 1ms) optional : offers a fail-over mechanism. It can be done with underlying tools which are not really intended for that (Hazelcast is an example). What would you use for such requirements? Thanks!

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  • SQL Server insert performance with and without primary key

    - by Eric
    Summary: I have a table populated via the following: insert into the_table (...) select ... from some_other_table Running the above query with no primary key on the_table is ~15x faster than running it with a primary key, and I don't understand why. The details: I think this is best explained through code examples. I have a table: create table the_table ( a int not null, b smallint not null, c tinyint not null ); If I add a primary key, this insert query is terribly slow: alter table the_table add constraint PK_the_table primary key(a, b); -- Inserting ~880,000 rows insert into the_table (a,b,c) select a,b,c from some_view; Without the primary key, the same insert query is about 15x faster. However, after populating the_table without a primary key, I can add the primary key constraint and that only takes a few seconds. This one really makes no sense to me. More info: The estimated execution plan shows 0% total query time spent on the clustered index insert SQL Server 2008 R2 Developer edition, 10.50.1600 Any ideas?

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  • What is wrong with the performance ?

    - by Innovative
    I created an application ( Creating up to 1,00,000 files in a folder ) with 2 different languages ( C#.Net & JAva ) with file concepts and its best methods. The Application that I created with .NET takes just 3 seconds to create all the files. At the same time, with Java, it takes 15 seconds. Why is it so ?

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  • Why Swift is 100 times slower than C in this image processing test?

    - by xiaobai
    Like many other developers I have been very excited at the new Swift language from Apple. Apple has boasted its speed is faster than Objective C and can be used to write operating system. And from what I learned so far, it's a very type-safe language and able to have precisely control over the exact data type (like integer length). So it does look like having good potential handling performance critical tasks, like image processing, right? That's what I thought before I carried out a quick test. The result really surprised me. Here is a much simplified image alpha blending code snippet in C: test.c: #include <stdio.h> #include <stdint.h> #include <string.h> uint8_t pixels[640*480]; uint8_t alpha[640*480]; uint8_t blended[640*480]; void blend(uint8_t* px, uint8_t* al, uint8_t* result, int size) { for(int i=0; i<size; i++) { result[i] = (uint8_t)(((uint16_t)px[i]) *al[i] /255); } } int main(void) { memset(pixels, 128, 640*480); memset(alpha, 128, 640*480); memset(blended, 255, 640*480); // Test 10 frames for(int i=0; i<10; i++) { blend(pixels, alpha, blended, 640*480); } return 0; } I compiled it on my Macbook Air 2011 with the following command: gcc -O3 test.c -o test The 10 frame processing time is about 0.01s. In other words, it takes the C code 1ms to process one frame: $ time ./test real 0m0.010s user 0m0.006s sys 0m0.003s Then I have a Swift version of the same code: test.swift: let pixels = UInt8[](count: 640*480, repeatedValue: 128) let alpha = UInt8[](count: 640*480, repeatedValue: 128) let blended = UInt8[](count: 640*480, repeatedValue: 255) func blend(px: UInt8[], al: UInt8[], result: UInt8[], size: Int) { for(var i=0; i<size; i++) { var b = (UInt16)(px[i]) * (UInt16)(al[i]) result[i] = (UInt8)(b/255) } } for i in 0..10 { blend(pixels, alpha, blended, 640*480) } The build command line is: xcrun swift -O3 test.swift -o test Here I use the same O3 level optimization flag to make the comparison hopefully fair. However, the resulting speed is 100 time slower: $ time ./test real 0m1.172s user 0m1.146s sys 0m0.006s In other words, it takes Swift ~120ms to processing one frame which takes C just 1 ms. I also verified the memory initialization time in both test code are very small compared to the blend processing function time. What happened?

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  • Performance implications of using a variable versus a magic number

    - by Nathan
    I'm often confused by this. I've always been taught to name numbers I use often using variables or constants, but if it reduces the efficiency of the program, should I still do it? Heres an example: private int CenterText(Font font, PrintPageEventArgs e, string text) { int recieptCenter = 125; int stringLength = Convert.ToInt32(e.Graphics.MeasureString(text, font)); return recieptCenter - stringLength / 2; } The above code is using named variables, but runs slower then this code: private int CenterText(Font font, PrintPageEventArgs e, string text) { return 125 - Convert.ToInt32(e.Graphics.MeasureString(text, font) / 2); } In this example, the difference in execution time is minimal, but what about in larger blocks of code?

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  • Improve SQL query performance

    - by Anax
    I have three tables where I store actual person data (person), teams (team) and entries (athlete). The schema of the three tables is: In each team there might be two or more athletes. I'm trying to create a query to produce the most frequent pairs, meaning people who play in teams of two. I came up with the following query: SELECT p1.surname, p1.name, p2.surname, p2.name, COUNT(*) AS freq FROM person p1, athlete a1, person p2, athlete a2 WHERE p1.id = a1.person_id AND p2.id = a2.person_id AND a1.team_id = a2.team_id AND a1.team_id IN ( SELECT id FROM team, athlete WHERE team.id = athlete.team_id GROUP BY team.id HAVING COUNT(*) = 2 ) GROUP BY p1.id ORDER BY freq DESC Obviously this is a resource consuming query. Is there a way to improve it?

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  • Performance issue between builds

    - by DeadMG
    I've been developing a small indie game in my spare time and have run across an inexplicable issue. Some builds of the game will randomly run several hundred frames per second slower than other builds. For example, when rendering some text and no 3D scene, I can achieve 1800FPS on my own hardware. Add one 3D sphere (10k verts, pixel shaded), achieve 1700 FPS. Add two more spheres, achieve 800 FPS. Remove all spheres, achieve 1100FPS- even though the code now renders the same scene as I previously achieved at 1800FPS, which is just the FPS counter being rendered. I've tried rebuilding and cleaning the project and rebooting the compiler. This is in Release mode and I turned on all the optimizations I could find. Any suggestions as to the cause? I ran a quick profile, and Visual Studio seems to think that over 90% of my time was spent in D3D9_43.dll, suggesting that it's not a bug in my app, which doesn't explain why it manifests in only some builds. I rebooted my machine and it's back up to 1800FPS. I think it's a bug in the DirectX SDK tools (amongst many others). Going to delete this question.

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  • Sql Server query performance

    - by Macros
    I have a stored procedure on a busy database which constantly come out top in the list of expensive queries (by some way). The query is very simple, it takes a single parameter (@ID, int) which is the primary key of the table, and selects the record that matches that ID. The primary key is an identity field with a clustered index, so I am stumped as to how to optimise this any further? The query is as follows CREATE PROCEDURE [dbo].[P_Call_Get] @ID int = null AS select ID, AppID, AgentID, AgentLogin, Ext, VDN, VDNName, Skill, SkillName, CallFrom, TelNoFrom, ParentCallID, CallStart, ACWStart, CallEnd, Outcome, StageID, TxTo, TxSuccess, ServiceID, DiallerID, CRC, TSCallID, CallDirection, [Manual], CallBackAgent, CallBackDateTime, Notes from P_Call where (ID = @ID or @ID is null) Not sure the best way to post the execution plan - all it shows is that 100% of the operation is taken up by the clustered index scan

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  • Database with great read performance

    - by mscava
    I have 10 tables from which 4 contain each up to million rows. All values are inserted at once, and afterwards I only read the data many times. I am searching for a database that would perform greatly when it comes to selecting, joining or other reading etc. What is the most recommended option?

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  • Eclipse plugin to measure programmer performance/stats

    - by trenki
    Does anyone know of an Eclipse plugin that can give me some stats about my behavior/usage of the Eclipse IDE? There are quite a few things I would like to know: How often/when do I invoke the "Build All" command (through Ctrl+B) How often does compilation fail/succeed (+ number of errors/warnings) How often do I hit Backspace? (I do that way to often; If pressing that key would give a nasty sound I would in time learn to type correctly in the first place) How many characters/lines of code that I typed do I delete (possibly quite immediately) How (effective/efficient/...) is my Mouse/Keyboard/IDE usage? (Kinda like measuring APM in StarCraft; this could be fun) If there is no such Eclipse plugin around, how complex and time consuming would It be to write a plugin that can accomplish the above?

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  • MySQL TEXT field performance

    - by Jonathon
    I have several TEXT and/or MEDIUMTEXT fields in each of our 1000 MySQL tables. I now know that TEXT fields are written to disk rather than in memory when queried. Is that also true even if that field is not called in the query? For example, if I have a table (tbExam) with 2 fields (id int(11) and comment text) and I run SELECT id FROM tbExam, does MySQL still have to write that to disk before returning results or will it run that query in memory? I am trying to figure out if I need to reconfigure our actual db tables to switch to varchar(xxxx) or keep the text fields and reconfigure the queries.

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  • Are UIView's in TableViewCells cause for performance problems?

    - by iFloh
    Hi, I have a UITableView of UITableViewCells that so far performed well. I now aded a simple UIView to my UITableViewCell as a color indicator (backgroundColor only, no other content or attributes). Running the tableview again I realise scrolling is not as smooth as it used to be. The tableView suddenly also takes long time (~1+ secs) to come back again when returning from a subview (e.g. return from the view that gets pushed upon selection of a cell). Any ideas why the added UIView would be problematic? Why are the labels (being a subclass of UIView) not cause for similar issues?

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  • Improve C function performance with cache locality?

    - by Christoper Hans
    I have to find a diagonal difference in a matrix represented as 2d array and the function prototype is int diagonal_diff(int x[512][512]) I have to use a 2d array, and the data is 512x512. This is tested on a SPARC machine: my current timing is 6ms but I need to be under 2ms. Sample data: [3][4][5][9] [2][8][9][4] [6][9][7][3] [5][8][8][2] The difference is: |4-2| + |5-6| + |9-5| + |9-9| + |4-8| + |3-8| = 2 + 1 + 4 + 0 + 4 + 5 = 16 In order to do that, I use the following algorithm: int i,j,result=0; for(i=0; i<4; i++) for(j=0; j<4; j++) result+=abs(array[i][j]-[j][i]); return result; But this algorithm keeps accessing the column, row, column, row, etc which make inefficient use of cache. Is there a way to improve my function?

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  • SQL Server dilemma, performance

    - by Woland
    Hello I am creating app where user can save options witch one is better? to save into user table varchar feeld smthing like ('1,23,4354,34,3') query for this is select * from data where CHARINDEX ( 'L', Providers , 0 ) 0 create other table where user options are and just add rows select * from data where Providers in (select Providers from userdata where userid=100) thanks for help

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  • Why fill() and copy() of Collections in java is implemented this way

    - by Priyank Doshi
    According to javadoc... Collections.fill() is written as below : public static <T> void fill(List<? super T> list, T obj) { int size = list.size(); if (size < FILL_THRESHOLD || list instanceof RandomAccess) { for (int i=0; i<size; i++) list.set(i, obj); } else { ListIterator<? super T> itr = list.listIterator(); for (int i=0; i<size; i++) { itr.next(); itr.set(obj); } } } Its easy to understand why they didn't use listIterator for if (size < FILL_THRESHOLD || list instanceof RandomAccess) condition as of RandomAccess. But whats the use of size < FILL_THRESHOLD in above? I mean is there any significant performance benefit over using iterator for size>=FILL_THRESHOLD and not for size < FILL_THRESHOLD ? I see the same approach for Collections.copy() also : public static <T> void copy(List<? super T> dest, List<? extends T> src) { int srcSize = src.size(); if (srcSize > dest.size()) throw new IndexOutOfBoundsException("Source does not fit in dest"); if (srcSize < COPY_THRESHOLD || (src instanceof RandomAccess && dest instanceof RandomAccess)) { for (int i=0; i<srcSize; i++) dest.set(i, src.get(i)); } else { ListIterator<? super T> di=dest.listIterator(); ListIterator<? extends T> si=src.listIterator(); for (int i=0; i<srcSize; i++) { di.next(); di.set(si.next()); } } } FYI: private static final int FILL_THRESHOLD = 25; private static final int COPY_THRESHOLD = 10;

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  • Hibernate Performance Best Practice?

    - by user829237
    Im writing a Web application using Hibernate 3. So, after a while i noticed that something was slow. So i tested hibernate profiler and found that hibernate will make unreasonably many db-calls for simple operation. The reason is ofcourse that i load an Object (this object has several "parents") and these "parents" have other "parents". So basicly hibernate loads them all, even though i just need the basic object. Ok, so i looked into lazy-loading. Which lead me into the Lazyloading-exception, because i have a MVC webapp. So now i'm a bit confused as to what is my best approach to this. Basicly all I need is to update a single field on an object. I already have the object-key. Should I: 1. Dig into Lazy-loading. And then rewrite my app for a open-session-view? 2. Dig into lazy-loading. And then rewrite my dao's to be more specific. E.g. writing DAO-methods that will return objects instanciated with only whats necessary for each use-case? Could be a lot of extra methods... 3. Scratch hibernate and do it myself? 4. Cant really think of other solutions right now. Any suggestions? What is the best practice?

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  • High performance SSL client with connection pooling session caching etch on Windows

    - by Yucong Sun
    Hi there, I'm looking for a fast SSL socket client basically talks SSL with remote service and I need features like connection pooling/limiting so that my other client calling this ssl socket can basically issue as many as requests and it will handle it peacefully. I looked into openssl s_client, but it says it's only for testing purpose, is there a handy tool avaiable? STunnel seems to be okay, but don't have that connection limiting option I need. Cheers.

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  • Perf4j Not Logging Correctly

    - by Jehud
    I setup some stop watch calls in my code to measure some code blocks and all the messages are going into my primary log and not into the timing log. The perfStats.log file gets created just fine but all the messages go to the root log which I didn't think was supposed to happen according to the docs I've read. Is there something obvious I'm missing here? perf4j tutorial link: http://perf4j.codehaus.org/devguide.html#Using_the_log4j_Appenders_to_Generate_Real-Time_Performance_Information Example code import org.apache.log4j.Logger; import org.perf4j.LoggingStopWatch; import org.perf4j.StopWatch; public class PerfLogger { /** * @param args */ public static void main(String[] args) { Logger logger = Logger.getLogger(PerfLogger.class.getName()); logger.info("Starting perf log test"); StopWatch stopWatch = new LoggingStopWatch("test time"); try { Thread.sleep(1000); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } stopWatch.stop(); } } Example log4j.xml <log4j:configuration xmlns:log4j='http://jakarta.apache.org/log4j/'> <appender name="STDOUT-DEBUG" class="org.apache.log4j.ConsoleAppender"> <layout class="org.apache.log4j.PatternLayout"> <param name="ConversionPattern" value="%d %-5p [%t]%x %M (%F:%L) - %m%n"/> </layout> </appender> <!-- Perf4J appenders --> <!-- This AsyncCoalescingStatisticsAppender groups StopWatch log messages into GroupedTimingStatistics messages which it sends on the file appender defined below --> <appender name="CoalescingStatistics" class="org.perf4j.log4j.AsyncCoalescingStatisticsAppender"> <!-- The TimeSlice option is used to determine the time window for which all received StopWatch logs are aggregated to create a single GroupedTimingStatistics log. Here we set it to 10 seconds, overriding the default of 30000 ms --> <param name="TimeSlice" value="10000"/> <appender-ref ref="fileAppender"/> </appender> <!-- This file appender is used to output aggregated performance statistics --> <appender name="fileAppender" class="org.apache.log4j.FileAppender"> <param name="File" value="perfStats.log"/> <layout class="org.apache.log4j.PatternLayout"> <param name="ConversionPattern" value="%m%n"/> </layout> </appender> <!-- Loggers --> <!-- The Perf4J logger. Note that org.perf4j.TimingLogger is the value of the org.perf4j.StopWatch.DEFAULT_LOGGER_NAME constant. Also, note that additivity is set to false, which is usually what is desired - this means that timing statements will only be sent to this logger and NOT to upstream loggers. --> <logger name="org.perf4j.TimingLogger" additivity="false"> <level value="INFO"/> <appender-ref ref="CoalescingStatistics"/> </logger> <root> <priority value="info"/> <appender-ref ref="STDOUT-DEBUG"/> </root> </log4j:configuration>

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