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  • Database Design Question: GUID + Natural Numbers

    - by Alan
    For a database I'm building, I've decided to use natural numbers as the primary key. I'm aware of the advantages that GUID's allow, but looking at the data, the bulk of row's data were GUID keys. I want to generate XML records from the database data, and one problem with natural numbers is that I don't want to expose my database key's to the outside world, and allow users to guess "keys." I believe GUID's solve this problem. So, I think the solution is to generate a sparse, unique iD derived from the natural ID (hopefully it would be 2-way), or just add an extra column in the database and store a guid (or some other multibyte id) The derived value is nicer because there is no storage penalty, but it would be easier to reverse and guess compared to a GUID. I'm (buy) curious as to what others on SO have done, and what insights they have.

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  • Losing SQL connections

    - by john pavelka
    sql servr 2005 - Standard; one dedicated sql server (VM); windows server 2003; Small databases; About once a week we lose all sql connections. It seems to fix itself after about 5-10 minutes. System.Web.HttpUnhandledException: Exception of type 'System.Web.HttpUnhandledException' was thrown. --- System.Data.SqlClient.SqlException: Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding. We don't have a fully qualified DBA; it's kind of a joint effort here. Can somebody give me some general ideas for troubleshooting the network side and the application side? We already ran a few tuning profiles and ran through Database Tuning Advisor to apply indexing recommendations. It would sure be nice if there was a way to take a snapshot of what was running on sql server when these 100% cpu spikes occured, but sometimes we're not around. Is it common to throttle CPU for certain processes? Can this be done with Windows server 2003? For example, if security apps were making cpu spike to 100%, is there a way to limit their cpu usage? Any advice is appreciated. thanks,

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  • Existing SQL database android help

    - by basketball4567
    Hey guys, I am new to android programming and i am trying to make an app that will interface with a website i have. It is a movie website with all of its information stored in SQL database. I know how to write the requests and queries in .asp but dont know how to get information from the database in my app. I want the user to be able to enter a movie title, and through a couple of stored procedures that are in my SQL database, return the info on that movie(actor, budget, genre....). I would like to have little info stored on the device, have all of the queries being sent to my SQL server and just have the info being returned. So my question boils down to, how do i link my existing SQL database with an android app. Any help would be great. Thanks Basketball4567

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  • Can I use memcpy in C++ to copy classes that have no pointers or virtual functions

    - by Shane MacLaughlin
    Say I have a class, something like the following; class MyClass { public: MyClass(); int a,b,c; double x,y,z; }; #define PageSize 1000000 MyClass Array1[PageSize],Array2[PageSize]; If my class has not pointers or virtual methods, is it safe to use the following? memcpy(Array1,Array2,PageSize*sizeof(MyClass)); The reason I ask, is that I'm dealing with very large collections of paged data, as decribed here, where performance is critical, and memcpy offers significant performance advantages over iterative assignment. I suspect it should be ok, as the 'this' pointer is an implicit parameter rather than anything stored, but are there any other hidden nasties I should be aware of?

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  • Updating a Database from DataBound Controls

    - by Avatar_Squadron
    Hi. I'm currently creating a WinForm in VB.NET bound to an access database. Basically what i have are two forms: one is a search form used to search the database, and the other is a details form. You run a search on the searchForm and it returns a list of Primary Keys and a few other identifying values. You then double click on the entry you want to view, and it loads the details form. The Details form has a collection of databound controls to display the data: mostly text boxes and checkboxs. The way i've set it up is i used the UI to build the form and then set the DataBindings Property of each control to "TblPropertiesBindingSource - " where value name is one of the values in the table (such as PropertyID or HasWoodFloor). Then, when you double click an entry in the searchform, I handle the event by parsing the Primary Key (PropertyID) out of the selected row and then storing this to the details form: Note: Detail is the details form that is opened to display the info Private Sub propView_CellDoubleClick(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewCellEventArgs) Handles propView.CellDoubleClick Dim detail As frmPropertiesDetail = New frmPropertiesDetail detail.id = propView.Rows(e.RowIndex).Cells(0).Value detail.Show() End Sub Then, upon loading the details form, it set's the filter on the BindSource as such: TblPropertiesBindingSource.Filter() = "PropertyID=" & id This works great so far. All the controls on the details form will display the correct info. The problem is updating changes. Scenario: If i have the user load the details for say, property 10001, it will show a description in a textBox named descriptionBox which is identical to the value of the description value of for that entry in the database. I want the user to then be able to change the text of the text box (which they can currently do) and click the save button (saveBut) and have the form update all the values in the controls to the database. Theorectically, it should do this as the controls are DataBound, thus i can avoid writing code that tells each entry in the database row to take the value of the aligned control. I've tried calleding PropertiesTableAdapter.Update(PropertiesBindingSource.DataSource), but that doesnt seem to do it.

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  • Fluent NHibernate ExportSchema without connexion string

    - by Vince
    Hi all, I want to propose to user a way to generate database table script creation. To do this for now i use NHibernate ExportSchema bases on a NHibernate configuration generated with Fluent NHibernate this way (during my ISessionFactory creation method): FluentConfiguration configuration = Fluently.Configure(); ... Mapping conf ... configuration.Database(fluentDatabaseProvider); this.nhibernateConfiguration = configuration.BuildConfiguration(); returnSF = configuration.BuildSessionFactory(); ... Later new SchemaExport(this.nhibernateConfiguration) .SetOutputFile(filePath) .Execute(false, false, false); fluentDatabaseProvider is a FluentNHibernate IPersistenceConfigurer which is needed to get proper sql dialect for database creation. When factory is created with an existing database, everything works fine. But what i want to do is to create an NHibernate Configuration object on a selected database engine without a real database behind the scene... And i don't manage to do this. If anybody has some idea.

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  • help troubleshooting deadlocks in sql server database

    - by Makach
    I've got two database servers, (1) production (2) test on the production database I get frequent deadlocks and I'm trying to find out what is causing it. I take a backup of the database in production and restore it in test and when I perform the exact same scenario that yields deadlocks on the production server I am unable to reproduce in test. any ideas/tips/hints would be much appreciated.

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  • Would it be simply better to use the system's functions rather than use the language?

    - by Nullw0rm
    There are many scenarios where I've questioned PHP's performance with some of its functions, and whether I should build a complex class to handle specific things using its seemingly slow tools. For example, Complex regular expressions with sed and processing with awk would seemingly be exponential in performance rather than making PHP's regular expression and seemingly excessive functions parse and in time manage to finish it. If I were to do a lot of network tasks such as MX lookups/DIGging/retrieving simultaneously I would rather pass it via system() and let the OS handle it itself. There are simply too many functions in PHP, that are inefficient and result in slow pages or can be handled easier by the OS. What are your opinions? Do you think I should do the hard work with the OS in its own/custom functions?

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  • MySQL Prepared Statements vs Stored Procedures Performance

    - by amardilo
    Hi there, I have an old MySQL 4.1 database with a table that has a few millions rows and an old Java application that connects to this database and returns several thousand rows from this this table on a frequent basis via a simple SQL query (i.e. SELECT * FROM people WHERE first_name = 'Bob'. I think the Java application uses client side prepared statements but was looking at switching this to the server, and in the example mentioned the value for first_name will vary depending on what the user enters). I would like to speed up performance on the select query and was wondering if I should switch to Prepared Statements or Stored Procedures. Is there a general rule of thumb of what is quicker/less resource intensive (or if a combination of both is better)

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  • VS2008 intellisense performance issue with large number of partial static classes

    - by scebula
    My question is a follow-up to the issue posted here regarding the Intellisense performance issue when building a large solution in VS2008 that has many partial static classes. Since Microsoft does not seem to be addressing the issue for VS2008, I would like to know if there are other ways around the problem? Waiting for VS2010 is not an option at this time. The proposed solution in the previous post is not practical as some of the partial classes may be regenerated and this would be a maintenance headache.

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  • Database source control with Oracle

    - by borjab
    I have been looking during hours for a way to check in a database into source control. My first idea was a program for calculating database diffs and ask all the developers to imlement their changes as new diff scripts. Now, I find that if I can dump a database into a file I cound check it in and use it as just antother type of file. The main conditions are: Works for Oracle 9R2 Human readable so we can use diff to see the diferences. (.dmp files doesn't seem readable) All tables in a batch. We have more than 200 tables. It stores BOTH STRUCTURE AND DATA It supports CLOB and RAW Types. It stores Procedures, Packages and its bodies, functions, tables, views, indexes, contraints, Secuences and synonims. It can be turned into an executable script to rebuild the database into a clean machine. Not limitated to really small databases (Supports least 200.000 rows) It is not easy. I have downloaded a lot of demos that does fail in one way or another. EDIT: I wouldn't mind alternatives aproaches provided that they allows us to check a working system against our release DATABASE STRUCTURE AND OBJECTS + DATA in a bath mode. By the way. Our project has been developed for years. Some aproaches can be easily implemented when you make a fresh start but seem hard at this point. EDIT: To understand better the problem let's say that some users can sometimes do changes to the config data in the production eviroment. Or developers might create a new field or alter a view without notice in the realease branch. I need to be aware of this changes or it will be complicated to merge the changes into production.

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  • In what circumstances can large pages produce a speedup ?

    - by timday
    Modern x86 CPUs have the ability to support larger page sizes than the legacy 4K (ie 2MB or 4MB), and there are OS facilities (Linux, Windows) to access this functionality. The Microsoft link above states large pages "increase the efficiency of the translation buffer, which can increase performance for frequently accessed memory". Which isn't very helpful in predicting whether large pages will improve any given situation. I'm interested in concrete, preferably quantified, examples of where moving some program logic (or a whole application) to use huge pages has resulted in some performance improvement. Anyone got any success stories ? There's one particular case I know of myself: using huge pages can dramatically reduce the time needed to fork a large process (presumably as the number of TLB records needing copying is reduced by a factor on the order of 1000). I'm interested in whether huge pages can also benefit more mundane applications though.

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  • Database design question

    - by Lijo
    Hi Team, I have an interesting database design problem that I formulated while travelling by a bus, coming back from my home. Design a normalized database for a bus ticketing system (not reservation system). In each trip, the conductor of the bus will give tickets to its passengers after collecting fare from them. Passengers travel from a various source places to various destination places. The system must be able to give a report of the places for which the number of passengers was more than 2. Suppose the stops for the bus are L1,L2, L3 and L4 Suppose passenger P1 travels from L1 to L4. P2 travels from L2 to L4. P3 travels from L3 to L4. The report should list only (L3-L4) for which it has more than 2 travelers. Can you please help me to solve the following problems 1) Design a normalized database 2) Write a query for the report 3) Is there any site that gives these kinds of interesting database design questions and answers? Thanks Lijo

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  • Inserting asyncronously into Oracle, any benefits?

    - by Karl Trumstedt
    I am using ODP.NET for loading data into Oracle. I am bulking inserts into groups of a 1000 rows each call. Is there any performance benefits in calling my load method asynchronously? So say I want to insert 10000 rows, instead of making 10 calls synchronously I make 10 calls asynchronously. My database is using ASSM right now but otherwise plenty of freelists are used of course. The database server has several cores as well. My initial tests seem to point to a performance increase, but maybe there is something I cannot see? Potential deadlock or contention issues? Of course, there is added complexity in handling transactions and such doing my load this way.

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  • Transforming OLTP Relational Database to Data Warehousing Model

    - by Russ Cam
    What are the common design approaches taken in loading data from a typical Entity-Relationship OLTP database model into a Kimball star schema Data Warehouse/Marts model? Do you use a staging area to perform the transformation and then load into the warehouse? How do you link data between the warehouse and the OLTP database? Where/How do you manage the transformation process - in the database as sprocs, dts/ssis packages, or SQL from application code?

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  • Eclipselink and update trigger on multiple access to the database

    - by Raven
    Hi, in my project I have a database which many clients connect to. Concurrent access and writing works well. The problem now is not to reload the data every second from the database to always have the current status of the data. Does Eclipselink provide a trigger mechanism on (automatically?) reload the data if the database is changed? How would one use this trigger? Thanks!

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  • Store database, good pattern for simultaneous access

    - by dygi
    I am kinda new to database designing so i ask for some advices or some kind of a good pattern. The situation is that, there is one database, few tables and many users. How should i design the database, or / and which types of queries should i use, to make it work, if users can interact with the database simultaneously? I mean, they have access to and can change the same set of data. I was thinking about transactions, but I am not sure, if that is the right / good / the only solution. I will appreciate some google keywords too.

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