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  • Scalable Database Tagging Schema

    - by Longpoke
    EDIT: To people building tagging systems. Don't read this. It is not what you are looking for. I asked this when I wasn't aware that RDBMS all have their own optimization methods, just use a simple many to many scheme. I have a posting system that has millions of posts. Each post can have an infinite number of tags associated with it. Users can create tags which have notes, date created, owner, etc. A tag is almost like a post itself, because people can post notes about the tag. Each tag association has an owner and date, so we can see who added the tag and when. My question is how can I implement this? It has to be fast searching posts by tag, or tags by post. Also, users can add tags to posts by typing the name into a field, kind of like the google search bar, it has to fill in the rest of the tag name for you. I have 3 solutions at the moment, but not sure which is the best, or if there is a better way. Note that I'm not showing the layout of notes since it will be trivial once I get a proper solution for tags. Method 1. Linked list tagId in post points to a linked list in tag_assoc, the application must traverse the list until flink=0 post: id, content, ownerId, date, tagId, notesId tag_assoc: id, tagId, ownerId, flink tag: id, name, notesId Method 2. Denormalization tags is simply a VARCHAR or TEXT field containing a tab delimited array of tagId:ownerId. It cannot be a fixed size. post: id, content, ownerId, date, tags, notesId tag: id, name, notesId Method 3. Toxi (from: http://www.pui.ch/phred/archives/2005/04/tags-database-schemas.html, also same thing here: http://stackoverflow.com/questions/20856/how-do-you-recommend-implementing-tags-or-tagging) post: id, content, ownerId, date, notesId tag_assoc: ownerId, tagId, postId tag: id, name, notesId Method 3 raises the question, how fast will it be to iterate through every single row in tag_assoc? Methods 1 and 2 should be fast for returning tags by post, but for posts by tag, another lookup table must be made. The last thing I have to worry about is optimizing searching tags by name, I have not worked that out yet. I made an ASCII diagram here: http://pastebin.com/f1c4e0e53

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  • Access Creates new file every time I Compact & Repair

    - by NickSentowski
    It didn't always do this, but ever since I split my database and made the front-end an ACCDE file, any time I try to compact and repair either file, a new file called "Database 1" is generated and my original file size doesn't change. Is this normal? My ACCDB is roughly 20MB, and my ACCDE is just over 1M after being used the first time. Before opening, the ACCDE was only 600k (I have lots of forms and queries, and regularly store PDF attachments.

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  • How I can Optimize this mySQL transaction within java code?

    - by worldpython
    Dear All, I am new to MySql database. I've large table(ID,...). I select ID frequently with java code and.And that make a heavy load on transaction select from tableName where ID=someID notes: 1.Database could be 100,000 records 2.I can't cache result 3.ID is a primary key 4.I try to optimize time needed to return result from query. Any ideas for optimization ? thanks in advance

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  • Inbreeding-immune database structure

    - by Nick Savage
    I have an application that requires a "simple" family tree. I would like to be able to perform queries that will give me data for an entire family given one id from a member in the family. I say simple because it does not need to take into account adoption or any other obscurities. The requirements for the application are as follows: Any two people will not be able to breed if they're from the same genetic line Needs to allow for the addition of new family lines (new people with no previous family) Need to be able to pull siblings, parents separately through queries I'm having trouble coming up with the proper structure for the database. So far I've come up with two solutions but they're not very reliable and will probably get out of hand quite quickly. Solution 1 involves placing a family_ids field on the people table and storing a list of unique family ids. Each time two people breed the lists are checked against each other to make sure no ids match and if everything checks out will merge the two lists and set that as the child's family_ids field. Example: Father (family_ids: (null)) breeds with Mother (family_ids: (213, 519)) -> Child (family_ids: (213, 519)) breeds with Random Person (family_ids: (813, 712, 122, 767)) -> Grandchild (family_ids: (213, 519, 813, 712, 122, 767)) And so on and so forth... The problem I see with this is the lists becoming unreasonably large as time goes on. Solution 2 uses cakephp's associations to declare: public $belongsTo = array( 'Father' => array( 'className' => 'User', 'foreignKey' => 'father_id' ), 'Mother' => array( 'className' => 'User', 'foreignKey' => 'mother_id' ) ); Now setting recursive to 2 will fetch the results of the mother and father, along with their mother and father, and so on and so forth all the way down the line. The problem with this route is that the data is in nested arrays and I'm unsure of how to efficiently work through the code. If anyone would be able to steer me in the direction of the most efficient way to handle what I want to achieve that would be tremendously helpful. Any and all help is greatly appreciated and I'll gladly answer any questions anyone has. Thanks a lot.

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  • Help Desk Database Design

    - by user237244
    The company I work at has very specific and unique needs for a help desk system, so none of the open source systems will work for us. That being the case, I created a custom system using PHP and MySQL. It's far from perfect, but it's infinitely better than the last system they were using; trust me! It meets most of our needs quite nicely, but I have a question about the way I have the database set up. Here are the main tables: ClosedTickets ClosedTicketSolutions Locations OpenTickets OpenTicketSolutions Statuses Technicians When a user submits a help request, it goes in the "OpenTickets" table. As the technicians work on the problem, they submit entries with a description of what they've done. These entries go in the "OpenTicketSolutions" table. When the problem has been resolved, the last technician to work on the problem closes the ticket and it gets moved to the "ClosedTickets" table. All of the solution entries get moved to the "ClosedTicketSolutions" table as well. The other tables (Locations, Statuses, and Technicians) exist as a means of normalization (each location, status, and technician has an ID which is referenced). The problem I'm having now is this: When I want to view a list of all the open tickets, the SQL statement is somewhat complicated because I have to left join the "Locations", "Statuses", and "Technicians" tables. Fields from various tables need to be searchable as well. Check out how complicated the SQL statement is to search closed tickets for tickets submitted by anybody with a first name containing "John": SELECT ClosedTickets.*, date_format(ClosedTickets.EntryDate, '%c/%e/%y %l:%i %p') AS Formatted_Date, date_format(ClosedDate, '%c/%e/%y %l:%i %p') AS Formatted_ClosedDate, Concat(Technicians.LastName, ', ', Technicians.FirstName) AS TechFullName, Locations.LocationName, date_format(ClosedTicketSolutions.EntryDate, '%c/%e/%y') AS Formatted_Solution_EntryDate, ClosedTicketSolutions.HoursSpent AS SolutionHoursSpent, ClosedTicketSolutions.Tech_ID AS SolutionTech_ID, ClosedTicketSolutions.EntryText FROM ClosedTickets LEFT JOIN Technicians ON ClosedTickets.Tech_ID = Technicians.Tech_ID LEFT JOIN Locations ON ClosedTickets.Location_ID = Locations.Location_ID LEFT JOIN ClosedTicketSolutions ON ClosedTickets.TicketNum = ClosedTicketSolutions.TicketNum WHERE (ClosedTickets.FirstName LIKE '%John%') ORDER BY ClosedDate Desc, ClosedTicketSolutions.EntryDate, ClosedTicketSolutions.Entry_ID One thing that I'm not able to do right now is search both open and closed tickets at the same time. I don't think a union would work in my case. So I'm wondering if I should store the open and closed tickets in the same table and just have a field indicating whether or not the ticket is closed. The only problem I can forsee is that we have so many closed tickets already (nearly 30,000) so the whole system might perform slowly. Would it be a bad idea to combine the open and closed tickets?

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  • SQLAuthority News – MS Access Database is the Way to Go – April 1st Humor

    - by pinaldave
    First of all, today is April 1- April Fool’s Day, so I have written this post for some light entertainment. My friend has just sent me an email about why a person should go for Access Database. For a short background, I used to be an MS Access user once (I will not call myself MS Access DBA), and I must say I had a good time with Database at that time. As time passed by, I moved from MS Access to SQL Server. Well, as for my friend’s email, his reasons considering MS Access usage really made me laugh. MS Access may have a few points where it totally makes sense to use it. However, in the email that I received, there was not a single reason which was valid.  In fact, I thought it is an April 1st joke- just delivered a little earlier. Let us see some of the reasons from that email. Thanks to Mahesh Bhesania for sending this email to me. MS Access comes with lots of free stuff, e.g. MS Excel MS Access is the most preferred desktop database system MS Access can import data from MS Excel and SQL Server MS Access provides a real time database MS Access has a free IDE-to-VB Script MS Access fits well in your hard drive I actually think that the above points are either incorrect beliefs of some users, or someone just wrote them to give some laughter with such inaccurate data. And, for the same reason I decided to browse the Internet and do some research on MS Access database to verify my thoughts. While searching on this subject, I found the following two interesting statements from the site: Microsoft Access Database, Why Choose It? Other software manufacturers are more likely to provide interfaces to MS Access than any other desktop database system Microsoft Access consulting rates are typically lower for Access consultants compared to Oracle or SQL Server consultants The second one is may be the worst reason for you to switch to MS Access if you are already an SQL Server consultant. With this cartoon, have you ever felt like you were one of these chickens at some point in time? I guess that the moment might have just happened before the minute we say “I guess we were on the same page?” Does this mean we are IN the same table, or ON the same table?! (I accept bad joke!) It is All Fools’ Day after all, so just laugh! If you have something funny but non-offensive to share, just  leave your comment here. Reference: Pinal Dave (http://blog.SQLAuthority.com), Cartoon source unknown. Filed under: Software Development, SQL, SQL Authority, SQL Humor, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority News, T SQL, Technology Tagged: MS ACCESS

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  • Perfect Your MySQL Database Administrators Skills

    - by Antoinette O'Sullivan
    With its proven ease-of-use, performance, and scalability, MySQL has become the leading database choice for web-based applications, used by high profile web properties including Google, Yahoo!, Facebook, YouTube, Wikipedia and thousands of mid-sized companies. Many organizations deploy both Oracle Database and MySQL side by side to serve different needs, and as a database professional you can find training courses on both topics at Oracle University! Check out the upcoming Oracle Database training courses and MySQL training courses. Even if you're only managing Oracle Databases at this point of time, getting familiar with MySQL Database will broaden your career path with growing job demand. Hone your skills as a MySQL Database Administrator by taking the MySQL for Database Administrators course which teaches you how to secure privileges, set resource limitations, access controls and describe backup and recovery basics. You also learn how to create and use stored procedures, triggers and views. You can take this 5 day course through three delivery methods: Training-on-Demand: Take this course at your own pace and at a time that suits you through this high-quality streaming video delivery. You also get to schedule time on a classroom environment to perform the hands-on exercises. Live-Virtual: Attend a live instructor led event from your own desk. 100s of events already of the calendar in many timezones. In-Class: Travel to an education center to attend this class. A sample of events is shown below:  Location  Date  Delivery Language  Budapest, Hungary  26 November 2012  Hungarian  Prague, Czech Republic  19 November 2012  Czech  Warsaw, Poland  10 December 2012  Polish  Belfast, Northern Ireland  26 November, 2012  English  London, England  26 November, 2012  English  Rome, Italy  19 November, 2012  Italian  Lisbon, Portugal  12 November, 2012  European Portugese  Porto, Portugal  21 January, 2013  European Portugese  Amsterdam, Netherlands  19 November, 2012  Dutch  Nieuwegein, Netherlands  8 April, 2013  Dutch  Barcelona, Spain  4 February, 2013  Spanish  Madrid, Spain  19 November, 2012  Spanish  Mechelen, Belgium  25 February, 2013  English  Windhof, Luxembourg  19 November, 2012  English  Johannesburg, South Africa  9 December, 2012  English  Cairo, Egypt  20 October, 2012  English  Nairobi, Kenya  26 November, 2012  English  Petaling Jaya, Malaysia  29 October, 2012  English  Auckland, New Zealand  5 November, 2012  English  Wellington, New Zealand  23 October, 2012  English  Brisbane, Australia  19 November, 2012  English  Edmonton, Canada  7 January, 2013  English  Vancouver, Canada  7 January, 2013  English  Ottawa, Canada  22 October, 2012  English  Toronto, Canada  22 October, 2012  English  Montreal, Canada  22 October, 2012  English  Mexico City, Mexico  10 December, 2012  Spanish  Sao Paulo, Brazil  10 December, 2012  Brazilian Portugese For more information on this course or any aspect of the MySQL curriculum, visit http://oracle.com/education/mysql.

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  • But what version is the database now?

    - by BuckWoody
    When you upgrade your system to SQL Server 2008 R2, you’ll know that the instance is at that version by using the standard commands like SELECT @@VERSION or EXEC xp_msver. My system came back with this info when I typed those: Microsoft SQL Server 2008 R2 (RTM) - 10.50.1600.1 (Intel X86)   Apr  2 2010 15:53:02   Copyright (c) Microsoft Corporation  Developer Edition on Windows NT 6.0 <X86> (Build 6002: Service Pack 2) (Hypervisor) Index Name Internal_Value Character_Value 1 ProductName NULL Microsoft SQL Server 2 ProductVersion 655410 10.50.1600.1 3 Language 1033 English (United States) 4 Platform NULL NT INTEL X86 5 Comments NULL SQL 6 CompanyName NULL Microsoft Corporation 7 FileDescription NULL SQL Server Windows NT 8 FileVersion NULL 2009.0100.1600.01 ((KJ_RTM).100402-1540 ) 9 InternalName NULL SQLSERVR 10 LegalCopyright NULL Microsoft Corp. All rights reserved. 11 LegalTrademarks NULL Microsoft SQL Server is a registered trademark of Microsoft Corporation. 12 OriginalFilename NULL SQLSERVR.EXE 13 PrivateBuild NULL NULL 14 SpecialBuild 104857601 NULL 15 WindowsVersion 393347078 6.0 (6002) 16 ProcessorCount 1 1 17 ProcessorActiveMask 1 1 18 ProcessorType 586 PROCESSOR_INTEL_PENTIUM 19 PhysicalMemory 2047 2047 (2146934784) 20 Product ID NULL NULL   But a database properties are separate from the Instance. After an upgrade, you always want to make sure that the compatibility options (which have much to do with how NULLs and other objects are treated) is at what you expect. For the most part, as long as the application can handle it, I set my compatibility levels to the latest version. For SQL Server 2008, that was “10.0” or “10”. You can do this with the ALTER DATABASE command or you can just right-click the database and select “Properties” and then “Database Options” in SQL Server Management Studio. To check the database compatibility level, I use this query: SELECT name, cmptlevel FROM sys.sysdatabases When I did that this morning I saw that the databases (all of them) were at 10.0 – not 10.5 like the Instance. That’s expected – we didn’t revise the database format up with the Instance for this particular release. Didn’t want to catch you by surprise on that. While your databases should be at the “proper” level for your situation, you can’t rely on the compatibility level to indicate the Instance level. More info on the ALTER DATABASE command in SQL Server 2008 R2 is here: http://technet.microsoft.com/en-us/library/bb510680(SQL.105).aspx Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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  • 8GB, but have to run Windows Xp (32 Bit). Anything I can do with the additional memory?

    - by user12889
    I ordered a new computer with 8GB RAM with the plan to run Windows 7, 64Bit. Turns out now, that I need to run a 32Bit OS (XP or 7) due to some software which does not run on 64Bit yet (not even with any of the available compatibility settings / modes). Is there anything I can do with the memory above 4GB in this scenario? I'm willing to consider creative solutions like running a hypervisor under XP that offers the memory as a RAM-Disk for swapping etc. ? The software that does not run on 64Bit is CISCO VPN (there seems to be a half-working solution for that) and CISCO IP phone / webcam integration "CISCO Unified Video Advantage" (there is apparently no solution for that).

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  • 8GB, but have to run Windows Xp (32 Bit). Anything I can do with the additional memory?

    - by user12889
    I ordered a new computer with 8GB RAM with the plan to run Windows 7, 64Bit. Turns out now, that I need to run a 32Bit OS (XP or 7) due to some software which does not run on 64Bit yet (not even with any of the available compatibility settings / modes). Is there anything I can do with the memory above 4GB in this scenario? I'm willing to consider creative solutions like running a hypervisor under XP that offers the memory as a RAM-Disk for swapping etc. ? The software that does not run on 64Bit is CISCO VPN (there seems to be a half-working solution for that) and CISCO IP phone / webcam integration "CISCO Unified Video Advantage" (there is apparently no solution for that).

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  • Silverlight 4. Activator.CreateInstance uses a huge amount of memory

    - by Marco
    Hi, I have been playing a bit with Silverlight and try to port my Silverlight 3.0 application to Silverlight 4.0. My application loads different XAP files and upon a user request create an instance of a Xaml user control and adds it to the main container, in a sort of MEF approach in order I can have an extensible and pluggable application. The application is pretty huge and to keep acceptable the performances and the initial loading I have built up some helper classes to load in the background all pages and user controls that might be used later on. On Silverlight 3.0 everything was running smoothly without any problem so far. Switching to SL 4.0 I have noticed that when the process approaches to create the instances of the user controls using Activator.CreateInstance, the layout freezes unexpectedly for a minute and sometimes for more. Looking at the task manager the memory usage of IE jumps from 50MB to 400MB and sometimes to 1.5 GB. If the process won't take that much the layout is rendered properly and the memory falls back to 50 MB. Otherwise everything crashes due to out of memory exeption. Does anybody encountered the same problem? Or has anybody a solution about this tricky issue? Thans in advance Marco

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  • Get JVM to grow memory demand as needed up to size of VM limit?

    - by Ira Baxter
    We ship a Java application whose memory demand can vary quite a lot depending on the size of the data it is processing. If you don't set the max VM (virtual memory) size, quite often the JVM quits with an GC failure on big data. What we'd like to see, is the JVM requesting more memory, as GC fails to provide enough, until the total available VM is exhausted. e.g., start with 128Mb, and increase geometrically (or some other step) whenever the GC failed. The JVM ("Java") command line allows explicit setting of max VM sizes (various -Xm* commands), and you'd think that would be designed to be adequate. We try to do this in a .cmd file that we ship with the application. But if you pick any specific number, you get one of two bad behaviors: 1) if your number is small enough to work on most target systems (e.g., 1Gb), it isn't big enough for big data, or 2) if you make it very large, the JVM refuses to run on those systems whose actual VM is smaller than specified. How does one set up Java to use the available VM when needed, without knowing that number in advance, and without grabbing it all on startup?

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  • Java runs out of memory, even though I give it plenty!

    - by spitzanator
    Hey, folks. So, I'm running a java server (specifically Winstone: http://winstone.sourceforge.net/ ) Like this: java -server -Xmx12288M -jar /usr/share/java/winstone-0.9.10.jar --useSavedSessions=false --webappsDir=/var/servlets --commonLibFolder=/usr/share/java This has worked fine in the past, but now it needs to load a bunch more stuff into memory than it has before. The odd part is that, according to 'top', it has 15.0g of VIRT(ual memory) and it's RES(ident set) is 8.4g. Once it hits 8.4g, the CPU hangs at 100% (even though it's loading from disk), and eventually, I get Java's OutOfMemoryError. Presumably, the CPU hanging at 100% is Java doing garbage collection. So, my question is, what gives? I gave it 12 gigs of memory! And it's only using 8.2 gigs before it throws in the towel. What am I doing wrong? Oh, and I'm using java version "1.6.0_07" Java(TM) SE Runtime Environment (build 1.6.0_07-b06) Java HotSpot(TM) 64-Bit Server VM (build 10.0-b23, mixed mode) on Linux. Thanks, Matt

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  • Chrome is leaking memory, when jQuery is used on events?

    - by user269386
    Hi, I'm experiencing an increase of memory usage, when I use the jQuery-eventhandling in Chrome. I've tested it with IE and FF as well, but there I couldn't see a suspicious rise of memory-usage, compared to Chrome. I'm using Chrome version 4.0.223.16 (unfortunately I'm forced to use this version, here) Simple example here. Just scroll with the mousewheel in the red box and open the Chrome-taskmanager and you will see an increase of memory which won't be released anymore: <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <script type="text/javascript" src="js/libs/jquery-1.4.2.min.js"></script> <script type="text/javascript"> jQuery(function () { jQuery("#div1").bind("mousewheel", function (event) { event.preventDefault(); }); }); </script> </head> <body> <div id="div1" style="width: 100px; height: 100px; background-color: red;"></div> </body> </html> Does anyone have experienced the same problem (or is it maybe solvend with a different version of chrome)? And does anyone have a fix for it? thanks

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  • Is there a safe / standard way to manage unstructured memory in C++?

    - by andand
    I'm building a toy VM that requires a block of memory for storing and accessing data elements of different types and of different sizes. I've done this by writing a wrapper class around a uint8_t[] data block of the needed size. That class has some template methods to write / read typed data elements to / from arbitrary locations in the memory block, both of which check to make certain the bounds aren't violated. These methods use memmove in what I hope is a more or less safe manner. That said, while I am willing to press on in this direction, I've got to believe that other with more expertise have been here before and might be willing to share their wisdom. In particular: 1) Is there a class in one of the C++ standards (past, present, future) that has been defined to perform a function similar to what I have outlined above? 2) If not, is there a (preferably free as in beer) library out there that does? 3) Short of that, besides bounds checking and the inevitable issue of writing one type to a memory location and reading a different from that location, are there other issues I should be aware of? Thanks.-&&

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  • Can shared memory be read and validated without mutexes?

    - by Bribles
    On Linux I'm using shmget and shmat to setup a shared memory segment that one process will write to and one or more processes will read from. The data that is being shared is a few megabytes in size and when updated is completely rewritten; it's never partially updated. I have my shared memory segment laid out as follows: ------------------------- | t0 | actual data | t1 | ------------------------- where t0 and t1 are copies of the time when the writer began its update (with enough precision such that successive updates are guaranteed to have differing times). The writer first writes to t1, then copies in the data, then writes to t0. The reader on the other hand reads t0, then the data, then t1. If the reader gets the same value for t0 and t1 then it considers the data consistent and valid, if not, it tries again. Does this procedure ensure that if the reader thinks the data is valid then it actually is? Do I need to worry about out-of-order execution (OOE)? If so, would the reader using memcpy to get the entire shared memory segment overcome the OOE issues on the reader side? (This assumes that memcpy performs it's copy linearly and ascending through the address space. Is that assumption valid?)

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  • Advantage database throws an exception when attempting to delete a record with a like statement used

    - by ChrisR
    The code below shows that a record is deleted when the sql statement is: select * from test where qty between 50 and 59 but the sql statement: select * from test where partno like 'PART/005%' throws the exception: Advantage.Data.Provider.AdsException: Error 5072: Action requires read-write access to the table How can you reliably delete a record with a where clause applied? Note: I'm using Advantage Database v9.10.1.9, VS2008, .Net Framework 3.5 and WinXP 32 bit using System.IO; using Advantage.Data.Provider; using AdvantageClientEngine; using NUnit.Framework; namespace NetworkEidetics.Core.Tests.Dbf { [TestFixture] public class AdvantageDatabaseTests { private const string DefaultConnectionString = @"data source={0};ServerType=local;TableType=ADS_CDX;LockMode=COMPATIBLE;TrimTrailingSpaces=TRUE;ShowDeleted=FALSE"; private const string TestFilesDirectory = "./TestFiles"; [SetUp] public void Setup() { const string createSql = @"CREATE TABLE [{0}] (ITEM_NO char(4), PARTNO char(20), QTY numeric(6,0), QUOTE numeric(12,4)) "; const string insertSql = @"INSERT INTO [{0}] (ITEM_NO, PARTNO, QTY, QUOTE) VALUES('{1}', '{2}', {3}, {4})"; const string filename = "test.dbf"; var connectionString = string.Format(DefaultConnectionString, TestFilesDirectory); using (var connection = new AdsConnection(connectionString)) { connection.Open(); using (var transaction = connection.BeginTransaction()) { using (var command = connection.CreateCommand()) { command.CommandText = string.Format(createSql, filename); command.Transaction = transaction; command.ExecuteNonQuery(); } transaction.Commit(); } using (var transaction = connection.BeginTransaction()) { for (var i = 0; i < 1000; ++i) { using (var command = connection.CreateCommand()) { var itemNo = string.Format("{0}", i); var partNumber = string.Format("PART/{0:d4}", i); var quantity = i; var quote = i * 10; command.CommandText = string.Format(insertSql, filename, itemNo, partNumber, quantity, quote); command.Transaction = transaction; command.ExecuteNonQuery(); } } transaction.Commit(); } connection.Close(); } } [TearDown] public void TearDown() { File.Delete("./TestFiles/test.dbf"); } [Test] public void CanDeleteRecord() { const string sqlStatement = @"select * from test"; Assert.AreEqual(1000, GetRecordCount(sqlStatement)); DeleteRecord(sqlStatement, 3); Assert.AreEqual(999, GetRecordCount(sqlStatement)); } [Test] public void CanDeleteRecordBetween() { const string sqlStatement = @"select * from test where qty between 50 and 59"; Assert.AreEqual(10, GetRecordCount(sqlStatement)); DeleteRecord(sqlStatement, 3); Assert.AreEqual(9, GetRecordCount(sqlStatement)); } [Test] public void CanDeleteRecordWithLike() { const string sqlStatement = @"select * from test where partno like 'PART/005%'"; Assert.AreEqual(10, GetRecordCount(sqlStatement)); DeleteRecord(sqlStatement, 3); Assert.AreEqual(9, GetRecordCount(sqlStatement)); } public int GetRecordCount(string sqlStatement) { var connectionString = string.Format(DefaultConnectionString, TestFilesDirectory); using (var connection = new AdsConnection(connectionString)) { connection.Open(); using (var command = connection.CreateCommand()) { command.CommandText = sqlStatement; var reader = command.ExecuteExtendedReader(); return reader.GetRecordCount(AdsExtendedReader.FilterOption.RespectFilters); } } } public void DeleteRecord(string sqlStatement, int rowIndex) { var connectionString = string.Format(DefaultConnectionString, TestFilesDirectory); using (var connection = new AdsConnection(connectionString)) { connection.Open(); using (var command = connection.CreateCommand()) { command.CommandText = sqlStatement; var reader = command.ExecuteExtendedReader(); reader.GotoBOF(); reader.Read(); if (rowIndex != 0) { ACE.AdsSkip(reader.AdsActiveHandle, rowIndex); } reader.DeleteRecord(); } connection.Close(); } } } }

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  • Objective-C / Cocoa: Uploading Images, Working Memory, And Storage.

    - by Finley Still
    Hello. I'm in the process of porting an application originally in java to cocoa, but I'm rewriting it to make it much better, since I prefer cocoa a lot anyway. One of the problems I had in the application, was that when you uploaded images to it, I had the images created, (as say an NSImage object) and then I just had them sitting in memory, the more I uploaded the more memory they took up, and I ended up running out of memory. My question is this: if I am going to have users upload images to this application in cocoa, how should I go about storing them? I don't just want to copy the file paths, because I want what is saved to contain the images, etc. Is there any way to upload an image and copy it into a different place only for my application? Then load that image with the new path name as needed? Only I would like it all to be consolidated. I'm going to implement saving by archiving one "master" object into an NSData*- so I'd like the images to be saved with that. Is there a temporary location maybe where I could write the images to disk for my application, and then when I saved, they would all be archived into a single file? Also, how do I do this? Thanks.

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  • Why does this program take up so much memory?

    - by Adrian
    I am learning Objective-C. I am trying to release all of the memory that I use. So, I wrote a program to test if I am doing it right: #import <Foundation/Foundation.h> #define DEFAULT_NAME @"Unknown" @interface Person : NSObject { NSString *name; } @property (copy) NSString * name; @end @implementation Person @synthesize name; - (void) dealloc { [name release]; [super dealloc]; } - (id) init { if (self = [super init]) { name = DEFAULT_NAME; } return self; } @end int main (int argc, const char * argv[]) { NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init]; Person *person = [[Person alloc] init]; NSString *str; int i; for (i = 0; i < 1e9; i++) { str = [NSString stringWithCString: "Name" encoding: NSUTF8StringEncoding]; person.name = str; [str release]; } [person release]; [pool drain]; return 0; } I am using a mac with snow leopard. To test how much memory this is using, I open Activity Monitor at the same time that it is running. After a couple of seconds, it is using gigabytes of memory. What can I do to make it not use so much?

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  • Why does this code sample produce a memory leak?

    - by citronas
    In the university we were given the following code sample and we were being told, that there is a memory leak when running this code. The sample should demonstrate that this is a situation where the garbage collector can't work. As far as my object oriented programming goes, the only codeline able to create a memory leak would be items=Arrays.copyOf(items,2 * size+1); The documentation says, that the elements are copied. Does that mean the reference is copied (and therefore another entry on the heap is created) or the object itself is being copied? As far as I know, Object and therefore Object[] are implemented as a reference type. So assigning a new value to 'items' would allow the garbage collector to find that the old 'item' is no longer referenced and can therefore be collected. In my eyes, this the codesample does not produce a memory leak. Could somebody prove me wrong? =) import java.util.Arrays; public class Foo { private Object[] items; private int size=0; private static final int ISIZE=10; public Foo() { items= new Object[ISIZE]; } public void push(final Object o){ checkSize(); items[size++]=o; } public Object pop(){ if (size==0) throw new ///... return items[--size]; } private void checkSize(){ if (items.length==size){ items=Arrays.copyOf(items,2 * size+1); } } }

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  • What is the point of having a key_t if what will be the key to access shared memory is the return value of shmget()?

    - by devoured elysium
    When using shared memory, why should we care about creating a key key_t ftok(const char *path, int id); in the following bit of code? key_t key; int shmid; key = ftok("/home/beej/somefile3", 'R'); shmid = shmget(key, 1024, 0644 | IPC_CREAT); From what I've come to understand, what is needed to access a given shared memory is the shmid, not the key. Or am I wrong? If what we need is the shmid, what is the point in not just creating a random key every time? Edit @link text one can read: What about this key nonsense? How do we create one? Well, since the type key_t is actually just a long, you can use any number you want. But what if you hard-code the number and some other unrelated program hardcodes the same number but wants another queue? The solution is to use the ftok() function which generates a key from two arguments. Reading this, it gives me the impression that what one needs to attach to a shared-memory block is the key. But this isn't true, is it? Thanks

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  • Can I use all my RAM for application data?

    - by gsedej
    Hi! I have yet another question about "where is my Linux memory" Question goes: can I use cache for application data? On my laptop I have 1GB ram. Situation after some time of work: browser takes 400MB and all other apps caa 300MB (quickly summed in system monitor). System monitor says I use 90% of RAM and I have already 200MB on swap. Laptop is getting slower when I start new things (e.g. open new tab in browser or open new Nautilus window). probably putting memory on swap So there should be 1200MB (ram+swap) used but all app I see uses only 600MB. Where are other 600MB? Out of this 600MB there is 400MB real RAM. I am not copying or any other massive IO activity. I read about Linux smartly uses all ram it has using buffers and cache. So, kernel (cache) uses 300MB. What if I don't want to have disk mirrored and I want to use memory for application data (e.g. new browser tab)? I don't need 200MB of mirrored disk data, because I (for example) won't use open the same photos on data partition I just seen. So can I use all my RAM for application data? (including browser, desktop, xorg, other services). How?

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  • Why Are Minimized Programs Often Slow to Open Again?

    - by Jason Fitzpatrick
    It seems particularly counterintuitive: you minimize an application because you plan on returning to it later and wish to skip shutting the application down and restarting it later, but sometimes maximizing it takes even longer than launching it fresh. What gives? Today’s Question & Answer session comes to us courtesy of SuperUser—a subdivision of Stack Exchange, a community-driven grouping of Q&A web sites. The Question SuperUser reader Bart wants to know why he’s not saving any time with application minimization: I’m working in Photoshop CS6 and multiple browsers a lot. I’m not using them all at once, so sometimes some applications are minimized to taskbar for hours or days. The problem is, when I try to maximize them from the taskbar – it sometimes takes longer than starting them! Especially Photoshop feels really weird for many seconds after finally showing up, it’s slow, unresponsive and even sometimes totally freezes for minute or two. It’s not a hardware problem as it’s been like that since always on all on my PCs. Would I also notice it after upgrading my HDD to SDD and adding RAM (my main PC holds 4 GB currently)? Could guys with powerful pcs / macs tell me – does it also happen to you? I guess OSes somehow “focus” on active software and move all the resources away from the ones that run, but are not used. Is it possible to somehow set RAM / CPU / HDD priorities or something, for let’s say, Photoshop, so it won’t slow down after long period of inactivity? So what is the deal? Why does he find himself waiting to maximize a minimized app? The Answer SuperUser contributor Allquixotic explains why: Summary The immediate problem is that the programs that you have minimized are being paged out to the “page file” on your hard disk. This symptom can be improved by installing a Solid State Disk (SSD), adding more RAM to your system, reducing the number of programs you have open, or upgrading to a newer system architecture (for instance, Ivy Bridge or Haswell). Out of these options, adding more RAM is generally the most effective solution. Explanation The default behavior of Windows is to give active applications priority over inactive applications for having a spot in RAM. When there’s significant memory pressure (meaning the system doesn’t have a lot of free RAM if it were to let every program have all the RAM it wants), it starts putting minimized programs into the page file, which means it writes out their contents from RAM to disk, and then makes that area of RAM free. That free RAM helps programs you’re actively using — say, your web browser — run faster, because if they need to claim a new segment of RAM (like when you open a new tab), they can do so. This “free” RAM is also used as page cache, which means that when active programs attempt to read data on your hard disk, that data might be cached in RAM, which prevents your hard disk from being accessed to get that data. By using the majority of your RAM for page cache, and swapping out unused programs to disk, Windows is trying to improve responsiveness of the program(s) you are actively using, by making RAM available to them, and caching the files they access in RAM instead of the hard disk. The downside of this behavior is that minimized programs can take a while to have their contents copied from the page file, on disk, back into RAM. The time increases the larger the program’s footprint in memory. This is why you experience that delay when maximizing Photoshop. RAM is many times faster than a hard disk (depending on the specific hardware, it can be up to several orders of magnitude). An SSD is considerably faster than a hard disk, but it is still slower than RAM by orders of magnitude. Having your page file on an SSD will help, but it will also wear out the SSD more quickly than usual if your page file is heavily utilized due to RAM pressure. Remedies Here is an explanation of the available remedies, and their general effectiveness: Installing more RAM: This is the recommended path. If your system does not support more RAM than you already have installed, you will need to upgrade more of your system: possibly your motherboard, CPU, chassis, power supply, etc. depending on how old it is. If it’s a laptop, chances are you’ll have to buy an entire new laptop that supports more installed RAM. When you install more RAM, you reduce memory pressure, which reduces use of the page file, which is a good thing all around. You also make available more RAM for page cache, which will make all programs that access the hard disk run faster. As of Q4 2013, my personal recommendation is that you have at least 8 GB of RAM for a desktop or laptop whose purpose is anything more complex than web browsing and email. That means photo editing, video editing/viewing, playing computer games, audio editing or recording, programming / development, etc. all should have at least 8 GB of RAM, if not more. Run fewer programs at a time: This will only work if the programs you are running do not use a lot of memory on their own. Unfortunately, Adobe Creative Suite products such as Photoshop CS6 are known for using an enormous amount of memory. This also limits your multitasking ability. It’s a temporary, free remedy, but it can be an inconvenience to close down your web browser or Word every time you start Photoshop, for instance. This also wouldn’t stop Photoshop from being swapped when minimizing it, so it really isn’t a very effective solution. It only helps in some specific situations. Install an SSD: If your page file is on an SSD, the SSD’s improved speed compared to a hard disk will result in generally improved performance when the page file has to be read from or written to. Be aware that SSDs are not designed to withstand a very frequent and constant random stream of writes; they can only be written over a limited number of times before they start to break down. Heavy use of a page file is not a particularly good workload for an SSD. You should install an SSD in combination with a large amount of RAM if you want maximum performance while preserving the longevity of the SSD. Use a newer system architecture: Depending on the age of your system, you may be using an out of date system architecture. The “system architecture” is generally defined as the “generation” (think generations like children, parents, grandparents, etc.) of the motherboard and CPU. Newer generations generally support faster I/O (input/output), better memory bandwidth, lower latency, and less contention over shared resources, instead providing dedicated links between components. For example, starting with the “Nehalem” generation (around 2009), the Front-Side Bus (FSB) was eliminated, which removed a common bottleneck, because almost all system components had to share the same FSB for transmitting data. This was replaced with a “point to point” architecture, meaning that each component gets its own dedicated “lane” to the CPU, which continues to be improved every few years with new generations. You will generally see a more significant improvement in overall system performance depending on the “gap” between your computer’s architecture and the latest one available. For example, a Pentium 4 architecture from 2004 is going to see a much more significant improvement upgrading to “Haswell” (the latest as of Q4 2013) than a “Sandy Bridge” architecture from ~2010. Links Related questions: How to reduce disk thrashing (paging)? Windows Swap (Page File): Enable or Disable? Also, just in case you’re considering it, you really shouldn’t disable the page file, as this will only make matters worse; see here. And, in case you needed extra convincing to leave the Windows Page File alone, see here and here. Have something to add to the explanation? Sound off in the the comments. Want to read more answers from other tech-savvy Stack Exchange users? Check out the full discussion thread here.     

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  • The World of SQL Database Deployment

    - by GGBlogger
    In my early development days, I used Microsoft Access for building databases. It made things easy since I only needed to package the database with the installation package so my clients would have access to it. When we began the development of a new package in Visual Studio .NET I decided to use SQL Server Express. It was free and provided good tools - also free. I thought it was a tremendous idea until it came time to distribute our new software! What a surprise. The nightmare Ah, the choices! Detach the database and have the client reattach it to a newly installed – oh wait. FIRST my new client needs to download and install SQL Server Express with SQL Server Management Studio. That’s not a great thing, but it is one more nightmare step for users who may have other versions of SQL installed. Then the question became – do we detach and reattach or do we do a backup. It was too late (bad planning) to revert to Microsoft Access but we badly needed a simple way to package and distribute both the database AND sample contents. Red Gate to the rescue It took me a while to find an answer but I did find it in a package called SQL Packager sold by a relatively unpublicized company in England called Red Gate. They call their products “ingeniously simple” and I must agree with that description. With SQL Packager you point to the database (more in a minute) you want to distribute. A few mouse clicks and dialogs and you have an executable file that you can ship virtually anywhere and virtually any way which, when run, installs the database on your destination SQL Server instance! It really is that simple. Easier to show than tell Let’s explore a hypothetical case. Let’s say you have a local SQL database of customers and you have decided you want to share it with your subsidiaries or partners. Here is the underlying screen you will see on starting SQL Packager. There are a bunch of possibilities here but I’m going to keep this relatively simple. At this point I simply want to illustrate the simplicity of generating an executable to deliver your database. You will notice that you can set up a new package, edit an existing package or change a bunch of options. Start SQL packager And the following is the default dialog you get on startup. In the next dialog, I’ve selected the Server and Database. I’ve also selected Windows Authentication. Pressing Next causes SQL Packager to run a number of checks and produce a report. Now you’re given a comprehensive list of what is going to be packaged and you’re allowed to change it if you desire. I’ve never made any changes here so I can’t really make any suggestions. The just illustrates the comprehensive nature of so many Red Gate products including this one. Clicking Next gives you still further options. SQL Packager then works its magic and shows you a dialog with the results. Packager then gives you a dialog of the scripts it has generated. The capture above only shows 1 of 4 tabs. Finally pressing Next gives you the option to generate a .NET executable of a C# project. I’ve only generated an executable so I’m not in a position to tell you what the C# project looks like. That may be the subject of further discussions. You can rename the package and tell SQL Packager where to save it. I’ve skipped a lot but this will serve to illustrate the comprehensive (and ingenious) things Red Gate does. All in all, it’s a superb way to distribute populated SQL databases. Oh – we’ll save running the resulting executable for later also but believe me it’s insanely simple.

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  • mod_perl memory leak

    - by marghi
    Hello, I recently discovered that one of our sites has a memory leak in it, it's very strange because it happened all of the sudden. I've used GTop to measure the memory size per process and it tells me that the real value is somewhere around 65 MB (on the server) per request and and additional 5 MB shared. I tried preloading the modules in the startup.pl file a indicated in the performance tuning article for mod_perl. Nothing happened if fact the shared memory decreased down to 3.7 MB, in this situation I thought that my application is leaking memory do before any line of code got executed I measured the memory just to find out that the total value is in fact 64 MB, my questions are: Is there a default preallocation of memory for each process? Is there a configuration issue? Is mod_perl leaking memory ? Thank you very much.

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