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• What arguments to use to explain why a SQL DB is far better then a flat file

  - by jamone

  The higher ups in my company were told by good friends that flat files are the way to go, and we should switch from MS SQL server to them for everything we do. We have over 300 servers and hundreds of different databases. From just the few I'm involved with we have 10 billion records in quite a few of them with upwards of 100k new records a day and who knows how many updates... Me and a couple others need to come up with a response saying why we shouldn't do this. Most of our stuff is ASP.NET with some legacy ASP. We thought that making a simple console app that tests/times the same interactions between a flat file (stored on the network) and SQL over the network doing large inserts, searches, updates etc along with things like network disconnects randomly. This would show them how bad flat files can be espically when you are dealing with millions of records. What things should I use in my response? What should I do with my demo code to illustrate this? My sort list so far: Security Concurent access Performance with large ammounts of data Ammount of time to do such a massive rewrite/switch Lack of transactions PITA to map relational data to flat files I fear that this will be a great post on the Daily WTF someday if I can't stop it now.

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• Core Data: Overkill for simple, static UITableView-based iPhone App?

  - by David Foster

  Hello! I have a rather simple iPhone app consisting of numerous views containing a single, grouped table view. These views are held together in navigation controllers which are grouped in a tab bar. Simple stuff. My table views do little more than list text (like "Dog", "Cat" and "Weasel") and this data is being served from a collection of plists. It's perhaps worth mentioning too that these tables are 'static' in the sense that their data is pre-determined and will only ever be amended—and if so, very rarely indeed—by the developer (in this case, moi). This rudimentary approach has reached its limits though, and I think I'm going to need something a bit more relational. I have worked a tad with Core Data in the past, but only with apps whose data is determined by user input. I have four closely related questions: Is Core Data overkill for an app consisting mainly of a selection of simple table views? Do you recommend using Core Data to manage data which is predetermine and extremely unlikely to ever change? Can one lock Core Data down so that its data can't change, thereby relinquishing my responsibility as the developer to handle the editing and saving of the managed object context? How do I go about giving Core Data my predetermined data, and in a format I know that it can work with? Thanks a bunch guys.

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• Problem with datagridvieew in vb.net

  - by user225269

  I'm trying to add a datagridview in vb.net, but it does not allow me to change the connection string or the database that should be imported to connect to it. The only thing that I'm seeing is the previous ms sql database that I connected with datagridview and everytime I click the new connection, the window closes and it leaves me with the datagridview with the previous connection that I have. And its not applicable because, now I want to connect it with mysql. Not ms sql. Its some sort of a cache like feature in vb.net, how do I get rid of it. so that I can add the new connection for mysql? Do I need to reinstall visual studio 2008?

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• Should an event-sourced aggregate root have access to the event sourcing repository?

  - by JD Courtoy

  I'm working on an event-sourced CQRS implementation, using DDD in the application / domain layer. I have an object model that looks like this: public class Person : AggregateRootBase { private Guid? _bookingId; public Person(Identification identification) { Apply(new PersonCreatedEvent(identification)); } public Booking CreateBooking() { // Enforce Person invariants var booking = new Booking(); Apply(new PersonBookedEvent(booking.Id)); return booking; } public void Release() { // Enforce Person invariants // Should we load the booking here from the aggregate repository? // We need to ensure that booking is released as well. var booking = BookingRepository.Load(_bookingId); booking.Release(); Apply(new PersonReleasedEvent(_bookingId)); } [EventHandler] public void Handle(PersonBookedEvent @event) { _bookingId = @event.BookingId; } [EventHandler] public void Handle(PersonReleasedEvent @event) { _bookingId = null; } } public class Booking : AggregateRootBase { private DateTime _bookingDate; private DateTime? _releaseDate; public Booking() { //Enforce invariants Apply(new BookingCreatedEvent()); } public void Release() { //Enforce invariants Apply(new BookingReleasedEvent()); } [EventHandler] public void Handle(BookingCreatedEvent @event) { _bookingDate = SystemTime.Now(); } [EventHandler] public void Handle(BookingReleasedEvent @event) { _releaseDate = SystemTime.Now(); } // Some other business activities unrelated to a person } With my understanding of DDD so far, both Person and Booking are seperate aggregate roots for two reasons: There are times when business components will pull Booking objects separately from the database. (ie, a person that has been released has a previous booking modified due to incorrect information). There should not be locking contention between Person and Booking whenever a Booking needs to be updated. One other business requirement is that a Booking can never occur for a Person more than once at a time. Due to this, I'm concerned about querying the query database on the read side as there could potentially be some inconsistency there (due to using CQRS and having an eventually consistent read database). Should the aggregate roots be allowed to query the event-sourced backing store by id for objects (lazy-loading them as needed)? Are there any other avenues of implementation that would make more sense?

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• the MVCC effect on migration from oracle to db2

  - by Ryan Fernandes

  I have a simple (actually simplified :) ) scenario that is possibly the cause for the headache I've been having for the last few days... My current application (that serves 100's of users) currently uses Oracle as the database. I have no stored procs (I wish actually). Now, I've been asked if the product will work if I migrate to IBM DB2 as the database. So, after taking Oracle for granted all this while.... and having re-read Tom's article on MVCC (Multiversion Concurrency Control) and going through this post stating that DB2 is not 'on the list' or 'just tip-toeing in the area' as it were... I know I can't be sure that the product will work with DB2 as is. Is there no hope.. or is there a nice disclaimer I could use.. ?

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• how to run foreach loop with ternary condition

  - by I Like PHP

  i have two foreach loop to display some data, but i want to use a single foreach on basis of database result. means if there is any row returns from database then forach($first as $fk=>$fv) should execute otherwise foreach($other as $ok) should execute. i m unsing below ternary operator which gives parse error $n=$db->numRows($taskData); // databsse results <?php ($n) ? foreach ($first as $fk=>$fv) : foreach ($other as $ok) { ?> <table><tr><td>......some data...</td></tr></table> <?php } ?> please suggest me how to handle such condition via ternary operator or any other idea. Thanks

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• Catching constraint violations in JPA 2.0.

  - by Dennetik

  Consider the following entity class, used with, for example, EclipseLink 2.0.2 - where the link attribute is not the primary key, but unique nontheless. @Entity public class Profile { @Id private Long id; @Column(unique = true) private String link; // Some more attributes and getter and setter methods } When I insert records with a duplicate value for the link attribute, EclipseLink does not throw a EntityExistsException, but throws a DatabaseException, with the message explaining that the unique constraint was violated. This doesn't seem very usefull, as there would not be a simple, database independent, way to catch this exception. What would be the advised way to deal with this? A few things that I have considered are: Checking the error code on the DatabaseException - I fear that this error code, though, is the native error code for the database; Checking the existence of a Profile with the specific value for link beforehand - this obviously would result in an enormous amount of superfluous queries.

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• Large ResultSet on postgresql query

  - by tuler

  I'm running a query against a table in a postgresql database. The database is on a remote machine. The table has around 30 sub-tables using postgresql partitioning capability. The query will return a large result set, something around 1.8 million rows. In my code I use spring jdbc support, method JdbcTemplate.query, but my RowCallbackHandler is not being called. My best guess is that the postgresql jdbc driver (I use version 8.3-603.jdbc4) is accumulating the result in memory before calling my code. I thought the fetchSize configuration could control this, but I tried it and nothing changes. I did this as postgresql manual recomended. This query worked fine when I used Oracle XE. But I'm trying to migrate to postgresql because of the partitioning feature, which is not available in Oracle XE. My environment: Postgresql 8.3 Windows Server 2008 Enterprise 64-bit JRE 1.6 64-bit Spring 2.5.6 Postgresql JDBC Driver 8.3-603

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• Should I be concerned about performance with connections to multiple databases?

  - by Josh Ryan

  I have a PHP app that is running on an Apache server with MySQL databases. Based on the subdomain that users access, I am connecting them to a database (sub1.domain.com connects to database_sub1 and sub2.domain.com connects to database_sub2). Right now there are 10 subdomain-database combos, but that number could potentially grow to well over 100. So, is this a bad thing? Considering my situation, is myslq_pconnect a better way to go? Thanks, and please let me know if more info would be helpful. Josh

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• When should I open and close a connection to SQL Server

  - by Martin

  I have a simple static class with a few methods in it. Each of those methods open a SqlConnection, query the database and close the connection. This way, I am sure that I always close the connection to the database, but on the other hand, I don't like to always open and close connection. Below is an example of what my methods look like. public static void AddSomething(string something) { using (SqlConnection connection = new SqlConnection("...")) { connection.Open(); // ... connection.Close(); } } Considering that the methods are inside a static class, should I have a static member containing a single SqlConnection? How and when should I drop it? What are the best practices?

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• Error loading SQL_VARIANT data type using Python

  - by Brett D

  I am using Python and SQLAlchemy to query a database that I did not create. I have run into a problem querying a table that contains the SQL_VARIANT data type. I get the error: sqlalchemy.exc.DBAPIError: (Error) ('ODBC data type -150 is not supported. Cannot read column Value.', 'HY000') I confirmed with the database creator that the "Value" column is of type SQL_VARIANT. Does anyone know a way to load this data type using Python? I am currently using mssql with pyodbc. Thank you for any help you can offer! Versions: Python 2.7, SQLAlchemy 0.7.8

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• How to consolidate multiple LOG files into one .LDF file in SQL2000

  - by John Galt

  Here is what sp_helpfile says about my current database (recovery model is Simple) in SQL2000: name fileid filename size maxsize growth usage MasterScratchPad_Data 1 C:\SQLDATA\MasterScratchPad_Data.MDF 6041600 KB Unlimited 5120000 KB data only MasterScratchPad_Log 2 C:\SQLDATA\MasterScratchPad_Log.LDF 2111304 KB Unlimited 10% log only MasterScratchPad_X1_Log 3 E:\SQLDATA\MasterScratchPad_X1_Log.LDF 191944 KB Unlimited 10% log only I'm trying to prepare this for a detach then an attach to a sql2008 instance but I don't want to have the 2nd .LDF file (I'd like to have just one file for the log). I have backed up the database. I have issued: BACKUP LOG MasterScratchPad WITH TRUNCATE_ONLY. I have run multiple DBCC SHRINKFILE commands on both of the LOG files. How can I accomplish this goal of having just one .LDF? I cannot find anything on how to delete the one with fileid of 3 and/or how to consolidate multiple files into one log file.

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• Shared Variable Among Ruby Processes

  - by Jesse J

  I have a Ruby program that loads up two very large yaml files, so I can get some speed-up by taking advantage of the multiple cores by forking off some processes. I've tried looking, but I'm having trouble figuring how, or even if, I can share variables in different processes. The following code is what I currently have: @proteins = "" @decoyProteins = "" fork do @proteins = YAML.load_file(database) exit end fork do @decoyProteins = YAML.load_file(database) exit end p @proteins["LVDK"] P displays nil though because of the fork. So is it possible to have the forked processes share the variables? And if so, how?

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• How to implement a syndication receiver? (multi-client / single server)

  - by LeonixSolutions

  I have to come up with a system architecture. A few hundred remote devices will be communicating over internet with a central server which will receive data and store it in a database. I could write my own TCP/IP based protocol use SOAP use AJAX use RSS anything else? This is currently seen as one way (telemetry, as opposed to SCADA). Would it make a difference if we make it bi-directional. There are no plans to do so, but Murphy's law makes me wary of a uni-directional solution (on the data plane; I imagine that the control plane is bi-directional in all solutions (?)). I hope that this is not too subjective. I would like a solution which is quick and easy to implement and for others to support and where the general "communications pipeline" from remote deceives to database server can be re-used as the core of future projects. I have a strong background in telecomms protocols, in C/C++ and PHP.

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• Passing parameters to web service method in c#

  - by wafa.cs1

  Hello I'm developing an android application .. which will send location data to a web service to store in the server database. In Java: I've used REST protocol so the URI is: HttpPost request = new HttpPost("http://trafficmapsa.com/GService.asmx/GPSdata? lon="+Lon+"&Lat="+Lat+"&speed="+speed); In Asp.net (c#) web service will be: [WebMethod] public CountryName GPSdata(Double Lon, Double Lat, Double speed) { after passing the data from android ..nothing return in back .. and there is no data in the database!! Is there any library missing in the CS file!! I cannot figure out what is the problem.

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• Recommend me an architecture for this Facebook application

  - by andybaird

  Firstly, this question is subjective. There is not a right answer for this question and it really depends on what works for you. I'm hoping to use this thread as a breeding ground for ideas. I hope this is acceptable in this medium. I'm working on building a Facebook app that will be replacing an already popular app that gets ~50k hits a day. The original app is using a very typical LAMP setup with help from some Zend libraries for database layer extraction. For the most part the app worked well, except to solve a lot of issues I ended up fragmenting tables to speed things up. As a result, I couldn't do a lot of things with the app that I wanted to (namely any processing using aggregate data that needed to be returned quickly) So I'm starting to design plans for the next version of this application, and I have a whole bunch of new and cool features that I know would choke my current setup. I'm looking for technological recommendations of data storage methods that scale well. The database does not necessarily need to be relational, simple key/value storage would suffice (although at present time I know little to nothing about KV stores) What's your recommendation? How would you tackle this? I'd like to take a completely free approach to this -- although I am most familiar and comfortable using PHP, I want to leave all technical options open.

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• What can I do about a SQL Server ghost FK constraint?

  - by rcook8601

  I'm having some trouble with a SQL Server 2005 database that seems like it's keeping a ghost constraint around. I've got a script that drops the constraint in question, does some work, and then re-adds the same constraint. Normally, it works fine. Now, however, it can't re-add the constraint because the database says that it already exists, even though the drop worked fine! Here are the queries I'm working with: alter table individual drop constraint INDIVIDUAL_EMP_FK ALTER TABLE INDIVIDUAL ADD CONSTRAINT INDIVIDUAL_EMP_FK FOREIGN KEY (EMPLOYEE_ID) REFERENCES EMPLOYEE After the constraint is dropped, I've made sure that the object really is gone by using the following queries: select object_id('INDIVIDUAL_EMP_FK') select * from sys.foreign_keys where name like 'individual%' Both return no results (or null), but when I try to add the query again, I get: The ALTER TABLE statement conflicted with the FOREIGN KEY constraint "INDIVIDUAL_EMP_FK". Trying to drop it gets me a message that it doesn't exist. Any ideas?

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• Flashing and closing PyS60 SIS

  - by Matrich

  I created a py script for S60 2nd Edition FP3 with a background image, database, sound files which are stored in a folder on c drive. After several hours, I have managed to convert it into sis which I sent to my mobile phone. First, I installed the sis on the external memory and it failed to work. I read online that it should be on the same drive as python runtime. So I installed it on phone memory but it just flashes and then closes. I made another sis with a database and it worked so I suspect it could be because it cant find the background image and sound files in the folder. How can I know the cause of this? Also, how can I include the background image and sound files with the sis so that they are automatically installed when installing the sis file?

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• Working with hibernate/DAO problems

  - by Gandalf StormCrow

  Hello everyone here is my DAO class : public class UsersDAO extends HibernateDaoSupport { private static final Log log = LogFactory.getLog(UsersDAO.class); protected void initDao() { //do nothing } public void save(User transientInstance) { log.debug("saving Users instance"); try { getHibernateTemplate().saveOrUpdate(transientInstance); log.debug("save successful"); } catch (RuntimeException re) { log.error("save failed", re); throw re; } } public void update(User transientInstance) { log.debug("updating User instance"); try { getHibernateTemplate().update(transientInstance); log.debug("update successful"); } catch (RuntimeException re) { log.error("update failed", re); throw re; } } public void delete(User persistentInstance) { log.debug("deleting Users instance"); try { getHibernateTemplate().delete(persistentInstance); log.debug("delete successful"); } catch (RuntimeException re) { log.error("delete failed", re); throw re; } } public User findById( java.lang.Integer id) { log.debug("getting Users instance with id: " + id); try { User instance = (User) getHibernateTemplate() .get("project.hibernate.Users", id); return instance; } catch (RuntimeException re) { log.error("get failed", re); throw re; } } } Now I wrote a test class(not a junit test) to test is everything working, my user has these fields in the database : userID which is 5characters long string and unique/primary key, and fields such as address, dob etc(total 15 columns in database table). Now in my test class I intanciated User added the values like : User user = new User; user.setAddress("some address"); and so I did for all 15 fields, than at the end of assigning data to User object I called in DAO to save that to database UsersDao.save(user); and save works just perfectly. My question is how do I update/delete users using the same logic? Fox example I tried this(to delete user from table users): User user = new User; user.setUserID("1s54f"); // which is unique key for users no two keys are the same UsersDao.delete(user); I wanted to delete user with this key but its obviously different can someone explain please how to do these. thank you

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• building a web application in eclipse

  - by Noona

  As a concluding assignment for the technologies taught in a data management course, we have to write a web application using the technologies taught throughout the course, this mostly includes xhtml, css, JSP, servelets, JDBC, AJAX, webservices. the project will eventually be deployed using tomcat. we are given the option of choosing the technologies that we see fit. since this is my first time developing a web application I am having some uncertainties about where to start, so for example now I am writing the object classes that will be used in the database and implementing the operations that will be performed on the database, but I am not sure about how to make these operations available to a client through the website, I mean I think I have to write a servlet through which I can extract the request parameters and set the response accordingly, but I would still like a more specific overview of what I am going to do, so if someone can link me to a tutorial with an example that makes use of these technologies while illustrating the stages of the design so that I can see how all these things are linked together in a web project. thanks

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• Encoding issue with form and HTML Purifier / MySQL

  - by Andrew Heath

  Driving me nuts... Page with form is encoded as Unicode (UTF-8) via: <meta http-equiv="content-type" content="text/html; charset=utf-8"> entry column in database is text utf8_unicode_ci copying text from a Word document with " in it, like this: “1922.” is insta-fail and ends up in the database as â??1922.â?? (typing new data into the form, including " works fine... it's cut and pasting from Word...) PHP steps behind the scenes are: grab value from POST run through HTML Purifier default settings run through mysql_real_escape_string insert query into dbase Help?

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• asp.net webservice user management across pages

  - by nakori

  I'm developing a site that will display confidential readonly information, with data fetched from a WCF service. My question: What is the best approach to user management across different information pages. The service returns a collection with customer info after a secure login. My idea is to have a Customer object class that is stored in session. Is it possible to use things like HttpContext.Current.User.Identity.IsAuthenticated followed by HttpContext.Current.Session["UserId"] without using a database with role-based security? Would I be better off with a combination of local database, Linq to SQL or datasets rather than using just class objects for data fetched from service? thanks, nakori

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• Counting the most tagged tag with MySQL

  - by Jack W-H

  Hi folks My problem is that I'm trying to count which tag has been used most in a table of user-submitted code. But the problem is with the database structure. The current query I'm using is this: SELECT tag1, COUNT(tag1) AS counttag FROM code GROUP BY tag1 ORDER BY counttag DESC LIMIT 1 This is fine, except, it only counts the most often occurence of tag1 - and my database has 5 tags per post - so there's columns tag1, tag2, tag3, tag4, tag5. How do I get the highest occurring tag value from all 5 columns in one query? Jack

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• What arguments to use to explain why SQL Server is far better then a flat file

  - by jamone

  The higher ups in my company were told by good friends that flat files are the way to go, and we should switch from SQL Server to them for everything we do. We have over 300 servers and hundreds of different databases. From just the few I'm involved with we have 10 billion records in quite a few of them with upwards of 100k new records a day and who knows how many updates... Me and a couple others need to come up with a response saying why we shouldn't do this. Most of our stuff is ASP.NET with some legacy ASP. We thought that making a simple console app that tests/times the same interactions between a flat file (stored on the network) and SQL over the network doing large inserts, searches, updates etc along with things like network disconnects randomly. This would show them how bad flat files can be especially when you are dealing with millions of records. What things should I use in my response? What should I do with my demo code to illustrate this? My sort list so far: Security Concurrent access Performance with large amounts of data Amount of time to do such a massive rewrite/switch Lack of transactions PITA to map relational data to flat files NTFS doesn't support tons of files in a directory well I fear that this will be a great post on the Daily WTF someday if I can't stop it now.

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• Upgraded activerecord-sqlserver-adapter from 2.2.22 to 2.3.8 and now getting an ODBC error

  - by stuartc

  I have been using MSSQL 2005 with Rails for quite a while now, and decided to bump my gems up on one of my projects and ran into a problem. I moved from 2.2.22 to 2.3.8 (latest as of writing) and all of a sudden I got this: ODBC::Error: S1090 (0) [unixODBC][Driver Manager]Invalid string or buffer length I'm using a DSN connection with FreeTDS my database.yml looks like this: adapter: sqlserver mode: ODBC dsn: 'DRIVER=FreeTDS;TDSVER=7.0;SERVER=10.0.0.5;DATABASE=db;Port=1433;UID=user;PWD=pwd;' Now in the mean time I moved back to 2.2.22 and there are no deprecation warnings and everything seems fine but obviously for the sake of being up to date, any ideas what could have changed in the adaptor that could cause this?

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