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  • What are the best workarounds for known problems with Hibernate's schema validation of floating poin

    - by Jason Novak
    I have several Java classes with double fields that I am persisting via Hibernate. For example, I have @Entity public class Node ... private double value; When Hibernate's org.hibernate.dialect.Oracle10gDialect creates the DDL for the Node table, it maps the value field to a "double precision" type. create table MDB.Node (... value double precision not null, ... It would appear that in Oracle, "double precision" is an alias for "float". So, when I try to verify the database schema using the org.hibernate.cfg.AnnotationConfiguration.validateSchema() method, Oracle appears to describe the value column as a "float". This causes Hibernate to throw the following Exception org.hibernate.HibernateException: Wrong column type in DBO.ACL_RULE for column value. Found: float, expected: double precision A very similar problem is listed in Hibernate's JIRA database as HHH-1961 (http://opensource.atlassian.com/projects/hibernate/browse/HHH-1961). I'd like to avoid doing anything that will break MySql, Postgres, and Sql Server support so extending the Oracle10gDialect appears to be the most promising of the workarounds mentioned in HHH-1961. But extending a Dialect is something I've never done before and I'm afraid there may be some nasty gotchas. What is the best workaround for this problem that won't break our compatibility with MySql, Postgres, and Sql Server? Thanks for taking the time to look at this!

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  • Copying a subset of data to an empty database with the same schema

    - by user193655
    I would like to export part of a database full of data to an empty database. Both databases has the same schema. I want to maintain referential integrity. To simplify my cases it is like this: MainTable has the following fields: 1) MainID integer PK 2) Description varchar(50) 3) ForeignKey integer FK to MainID of SecondaryTable SecondaryTable has the following fields: 4) MainID integer PK (referenced by (3)) 5) AnotherDescription varchar(50) The goal I'm trying to accomplish is "export all records from MainTable using a WHERE condition", for example all records where MainID < 100. To do it manually I shuold first export all data from SecondaryTable contained in this select: select * from SecondaryTable ST outer join PrimaryTable PT on ST.MainID=PT.MainID then export the needed records from MainTable: select * from MainTable where MainID < 100. This is manual, ok. Of course my case is much much much omre complex, I have 200+ tables, so donig it manually is painful/impossible, I have many cascading FKs. Is there a way to force the copy of main table only "enforcing referntial integrity". so that my query is something like: select * from MainTable where MainID < 100 WITH "COPYING ALL FK sources" In this cases also the field (5) will be copied. ====================================================== Is there a syntax or a tool to do this? Table per table I'd like to insert conditions (like MainID <100 is only for MainTable, but I have also other tables).

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  • Understanding Wordpress database schema - querying from 3rd party app

    - by deceze
    Is there an easy way to grab the latest posts out of a Wordpress wp_posts table using a simple SQL query? I have a Wordpress 2.9.2 installation as part of, but separate from, a larger system. It has a customized theme to look like the rest of the site but has otherwise nothing to do with it. I want to display the latest handful of headlines of posts made using Wordpress on a site of that other system. Preferably I do not want to mess around with importing any of the Wordpress library files. Looking at the database structure I can't see an easy, straight-forward query to simply get the latest revision of the latest posts. The post_status can either be "post" or "inherit", the post_type "post" or "revision" and the parent "0" or the id of the original post of a revision. I can't figure out how to reliably filter different revisions of the same post, drafts, attachments and pages out of this mess and just get the latest revision of the latest posts. I'm aware that the database schema is subject to change in subsequent versions of Wordpress, so shouldn't be relied upon, but that's a minor concern, since it's such a minor feature that could easily be fixed. If I understood how that database is supposed to work, that is.

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  • Schema for element with Attributes and Child nodes

    - by Matthew
    I am trying to write xsd type schema for an element that has a custom type to include addition attributes to extend a base type. I am running into trouble getting the syntax right. <xs:element name="graphs"> <xs:complexType> <xs:sequence> <xs:element name="graph" minOccurs="1" maxOccurs="unbounded" type="graphType"> <!-- child elements --> </xs:element> </xs:sequence> </xs:complexType> </xs:element> <xs:complexType name="graphType"> <xs:simpleContent> <xs:extension base="xs:string"> <xs:attribute name="title" type="xs:string"/> <xs:attribute name="type" type="xs:string"/> </xs:extension> </xs:simpleContent> </xs:complexType> I thought this would be something very common, but having read many tuts and forums, I cant seem to find an answer that works for me.

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  • Large invoice database structure and rendering

    - by user132624
    Our client has a MS SQL database that has 1 million customer invoice records in it. Using the database, our client wants its customers to be able to log into a frontend web site and then be able to view, modify and download their company’s invoices. Given the size of the database and the large number of customers who may log into the web site at any time, we are concerned about data base engine performance and web page invoice rendering performance. The 1 million invoice database is for just 90 days sales, so we will remove invoices over 90 days old from the database. Most of the invoices have multiple line items. We can easily convert our invoices into various data formats so for example it is easy for us to convert to and from SQL to XML with related schema and XSLT. Any data conversion would be done on another server so as not to burden the web interface server. We have tentatively decided to run the web site on a .NET Framework IIS web server using MS SQL on MS Azure. How would you suggest we structure our database for best performance? For example, should we put all the invoices of all customers located within the same 5 digit or 6 digit zip codes into the same table? Or could we set up a separate home directory for each customer on IIS and place each customer’s invoices in each customer’s home directory in XML format? And secondly what would you suggest would be the best method to render customer invoices on a web page and allow customers to modify for best performance? The ADO.net XML Data Set looks intriguing to us as a method, but we have never used it.

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  • Best approach to accessing multiple data source in a web application

    - by ced
    I've a base web application developed with .net technologies (asp.net) used into our LAN by 30 users simultanousley. From this web application I've developed two verticalization used from online users. In future i expect hundreds users simultanousley. Our company has different locations. Each site use its own database. The web application needs to retrieve information from all existing databases. Currently there are 3 database, but it's not excluded in the future expansion of new offices. My question then is: What is the best strategy for a web application to retrieve information from different databases (which have the same schema) whereas the main objective performance data access and high fault tolerance? There are case studies in the literature that I can take as an example? Do you know some good documents to study? Do you have any tips to implement this task so efficient? Intuitively I would say that two possible strategy are: perform queries from different sources in real time and aggregate data on the fly; create a repository that contains the union of the entities of interest and perform queries directly on repository;

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  • More Tables or More Databases?

    - by BuckWoody
    I got an e-mail from someone that has an interesting situation. He has 15,000 customers, and he asks if he should have a database for their data per customer. Without a LOT more data it’s impossible to say, of course, but there are some general concepts to keep in mind. Whenever you’re segmenting data, it’s all about boundary choices. You have not only boundaries around how big the data will get, but things like how many objects (tables, stored procedures and so on) that will be involved, if there are any cross-sections of data (do they share location or product information) and – very important – what are the security requirements? From the answer to these types of questions, you now have the choice of making multiple tables in a single database, or using multiple databases. A database carries some overhead – it needs a certain amount of memory for locking and so on. But it has a very clean boundary – everything from objects to security can be kept apart. Having multiple users in the same database is possible as well, using things like a Schema. But keeping 15,000 schemas can be challenging as well. My recommendation in complex situations like this is similar to a post on decisions that I did earlier – I lay out the choices on a spreadsheet in rows, and then my requirements at the top in the columns. I  give each choice a number based on how well it meets each requirement. At the end, the highest number wins. And many times it’s a mix – perhaps this person could segment customers into larger regions or districts or products, in a database. Within that database might be multiple schemas for the customers. Of course, he needs to query across all customers, that becomes another requirement. Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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  • More Tables or More Databases?

    - by BuckWoody
    I got an e-mail from someone that has an interesting situation. He has 15,000 customers, and he asks if he should have a database for their data per customer. Without a LOT more data it’s impossible to say, of course, but there are some general concepts to keep in mind. Whenever you’re segmenting data, it’s all about boundary choices. You have not only boundaries around how big the data will get, but things like how many objects (tables, stored procedures and so on) that will be involved, if there are any cross-sections of data (do they share location or product information) and – very important – what are the security requirements? From the answer to these types of questions, you now have the choice of making multiple tables in a single database, or using multiple databases. A database carries some overhead – it needs a certain amount of memory for locking and so on. But it has a very clean boundary – everything from objects to security can be kept apart. Having multiple users in the same database is possible as well, using things like a Schema. But keeping 15,000 schemas can be challenging as well. My recommendation in complex situations like this is similar to a post on decisions that I did earlier – I lay out the choices on a spreadsheet in rows, and then my requirements at the top in the columns. I  give each choice a number based on how well it meets each requirement. At the end, the highest number wins. And many times it’s a mix – perhaps this person could segment customers into larger regions or districts or products, in a database. Within that database might be multiple schemas for the customers. Of course, he needs to query across all customers, that becomes another requirement. Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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  • Algorithm design, "randomising" timetable schedule in Python although open to other languages.

    - by S1syphus
    Before I start I should add I am a musician and not a native programmer, this was undertook to make my life easier. Here is the situation, at work I'm given a new csv file each which contains a list of sound files, their length, and the minimum total amount of time they must be played. I create a playlist of exactly 60 minutes, from this excel file. Each sample played the by the minimum number of instances, but spread out from each other; so there will never be a period where for where one sound is played twice in a row or in close proximity to itself. Secondly, if the minimum instances of each song has been used, and there is still time with in the 60 min, it needs to fill the remaining time using sounds till 60 minutes is reached, while adhering to above. The smallest duration possible is 15 seconds, and then multiples of 15 seconds. Here is what I came up with in python and the problems I'm having with it, and as one user said its buggy due to the random library used in it. So I'm guessing a total rethink is on the table, here is where I need your help. Whats is the best way to solve the issue, I have had a brief look at things like knapsack and bin packing algorithms, while both are relevant neither are appropriate and maybe a bit beyond me.

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  • How do you model roles / relationships with Domain Driven Design in mind?

    - by kitsune
    If I have three entities, Project, ProjectRole and Person, where a Person can be a member of different Projects and be in different Project Roles (such as "Project Lead", or "Project Member") - how would you model such a relationship? In the database, I currently have the following tablers: Project, Person, ProjectRole Project_Person with PersonId & ProjectId as PK and a ProjectRoleId as a FK Relationship. I'm really at a loss here since all domain models I come up with seem to break some "DDD" rule. Are there any 'standards' for this problem? I had a look at a Streamlined Object Modeling and there is an example what a Project and ProjectMember would look like, but AddProjectMember() in Project would call ProjectMember.AddProject(). So Project has a List of ProjectMembers, and each ProjectMember in return has a reference to the Project. Looks a bit convoluted to me. update After reading more about this subject, I will try the following: There are distinct roles, or better, model relationships, that are of a certain role type within my domain. For instance, ProjectMember is a distinct role that tells us something about the relationship a Person plays within a Project. It contains a ProjectMembershipType that tells us more about the Role it will play. I do know for certain that persons will have to play roles inside a project, so I will model that relationship. ProjectMembershipTypes can be created and modified. These can be "Project Leader", "Developer", "External Adviser", or something different. A person can have many roles inside a project, and these roles can start and end at a certain date. Such relationships are modeled by the class ProjectMember. public class ProjectMember : IRole { public virtual int ProjectMemberId { get; set; } public virtual ProjectMembershipType ProjectMembershipType { get; set; } public virtual Person Person { get; set; } public virtual Project Project { get; set; } public virtual DateTime From { get; set; } public virtual DateTime Thru { get; set; } // etc... } ProjectMembershipType: ie. "Project Manager", "Developer", "Adviser" public class ProjectMembershipType : IRoleType { public virtual int ProjectMembershipTypeId { get; set; } public virtual string Name { get; set; } public virtual string Description { get; set; } // etc... }

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  • Is it a good object-oriented-design practice to send a pointer to private data to another class?

    - by Denis
    Hello everyone, There is well known recommendation not to include into class interface method that returns a pointer (or a reference) to private data of the class. But what do you think about public method of a class that sends to another class a pointer to the private data of the first one. For example: class A { public: void fA(void) {_b.fB(&_var)}; private: B _b; int _var; }; I think that it is some sort of data hiding damage: the private data define state of their own class, so why should one class delegate changes of its own state to another one? What do you think? Denis

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  • How to design a command line program and keep it open for a future GUI?

    - by systempuntoout
    What are some best practices to keep in mind when developing a script program that could be integrated with a GUI, probably by somebody else, in the future? Example scenario: i develop a fancy python CLI program that scrapes every unicorn images from the web i decide to publish it on github a unicorn fan programmer decide to take the sources and build a GUI on them. he gives up because my code is a mess How do i avoid step 4 and let unicorn fan programmer build his GUI without hassle?

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  • Looking for design/architecture suggestions for a simple HTML game.

    - by z-boss
    Imagine that HTML page is a game surface (see picture). User can have n number of boards (blue divs) on his page. Each board can be moved, re-sized, relabeled, created new and removed. Inside each board there are m number of figures (purple divs). Each of these user can move inside the board or to another board, re-size, change color and label, delete, add new. The goal of the game is not important, but let's say it is to rearrange figures in a certain way so that they disappear. But the goal of the programmer is to save the whole game surface in the database for every user of the site, and to load it later when he returns. So, how do I go about data exchange between client and the database? I'll give my idea in one of the answers.

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  • Design suggestions for creating document management structure using hidden shares.

    - by focus.nz
    I need to add some document management functionality into my software. Documents will be grouped by company name and project name. The folders need to be accessed by the application using the id numbers of clients/projects, but also easily browsed by the end user using windows explorer. Clients and Projects will be stored in a database. I am thinking of having the software create the folders using the friendly name and then using a hidden share with the id number for the software to access the files. The folder structure would be something like this --Company 1 (Company-1234$) -- Project 101 (Project-101$) -- Project 102 (Project-102$) -- Project 103 (Project-103$) -- Company 2 (Company-5678$) -- Project 201 (Project-201$) -- Project 202 (Project-202$) -- Project 203 (Project-203$) So in the example above there would be a company called "Company 1" with a ID of "1234". When browsing the folders using windows explorer the user would see \\ServerName\Documents\Company1 and you could also access the same folder from \\ServerName\Documents\Company-1234$ By using the hidden share, if the company name changes or its renamed for some reason it doesn't break the link in the application because its using the hidden shared based on the ID that never changes. Will having hundreds (maybe thousands) or hidden shares on a server provide a huge performance hit? Does any one have any suggestions or alternatives to provide this feature?

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  • Looking for help with a design for a simple C# calendar app.

    - by Vladislav
    As a personal project, I'm putting together a C# WPF calendar. I'm stuck on coding the calendar screen - specifically, the 5x7 grid of days. I've first tried to code it using elements like Panels, Labels, and Buttons. I've decided that was too cumbersome. I've then decided to use GDI to draw the calendar myself. I now have a wonderful layout - but I'm not sure how to handle interactive regions of the calendar. (Say, Previous/Next month, clicking on any particular day...) After rendering the calendar screen, should I be creating button objects for all those tasks, and assigning onClick handlers to them? Or is there an alternative solution? Thanks in advance. -Vladislav

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  • GUI Design - Roleselection with two lists, selected roles on the right, or left list?

    - by subes
    Hi, image two lists for selecting roles for a new user creation in an administrator frontend. One list has all available roles in it and another has the selected roles in it. Between those lists are buttons to move elements from one list to another. Thus the layout is horizontal with [List] [Buttons] [List]. Now to the question: Should the selected elements be on the left, or the right list? Intuitively some people I asked say, that the selected elements have to be on the right list. But some other people follow some sort of guideline that says, that the more important stuff in a frontend has to be on the left side. Also they think the selected elements are more important than the non-selected and so the selected ones have to be on the left side. Whats your opinion?

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  • How to best integrate HTML/design with C# code in ASP.Net or ASP.Net MVC?

    - by LuftMensch
    We're working on a new ASP.Net site. The last major site we did was in classic ASP--the procedure we used there was to have the HTML completed first, then "bring it to life" with the ASP code. In the ASP.Net world, how does this work? I.e. how do the designers do their work if much of the mark-up is actually being generated by the server controls? We are also looking at ASP.Net MVC as a potential lightweight alternative. Would be very interested to know what was worked best for people in both scenarios in terms of working with the designers and integrating their work with the code.

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  • Policy-based template design: How to access certain policies of the class?

    - by dehmann
    I have a class that uses several policies that are templated. It is called Dish in the following example. I store many of these Dishes in a vector (using a pointer to simple base class), but then I'd like to extract and use them. But I don't know their exact types. Here is the code; it's a bit long, but really simple: #include <iostream> #include <vector> struct DishBase { int id; DishBase(int i) : id(i) {} }; std::ostream& operator<<(std::ostream& out, const DishBase& d) { out << d.id; return out; } // Policy-based class: template<class Appetizer, class Main, class Dessert> class Dish : public DishBase { Appetizer appetizer_; Main main_; Dessert dessert_; public: Dish(int id) : DishBase(id) {} const Appetizer& get_appetizer() { return appetizer_; } const Main& get_main() { return main_; } const Dessert& get_dessert() { return dessert_; } }; struct Storage { typedef DishBase* value_type; typedef std::vector<value_type> Container; typedef Container::const_iterator const_iterator; Container container; Storage() { container.push_back(new Dish<int,double,float>(0)); container.push_back(new Dish<double,int,double>(1)); container.push_back(new Dish<int,int,int>(2)); } ~Storage() { // delete objects } const_iterator begin() { return container.begin(); } const_iterator end() { return container.end(); } }; int main() { Storage s; for(Storage::const_iterator it = s.begin(); it != s.end(); ++it){ std::cout << **it << std::endl; std::cout << "Dessert: " << *it->get_dessert() << std::endl; // ?? } return 0; } The tricky part is here, in the main() function: std::cout << "Dessert: " << *it->get_dessert() << std::endl; // ?? How can I access the dessert? I don't even know the Dessert type (it is templated), let alone the complete type of the object that I'm getting from the storage. This is just a toy example, but I think my code reduces to this. I'd just like to pass those Dish classes around, and different parts of the code will access different parts of it (in the example: its appetizer, main dish, or dessert).

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  • Design pattern for Fat Client - Thin Client to use Common code?

    - by kurozakura
    Windows-based client application and web-client application(consuming the same code which windows-client uses) what is the preferable pattern for this scenario? Is it ok to have the code in the common place where both the projects and refer it as dll i.e one which is a windows app and other which is going consume the same code which windows client will be exposing.

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  • c#: Design advice. Using DataTable or List<MyObject> for a generic rule checker

    - by Andrew White
    Hi, I have about 100,000 lines of generic data. Columns/Properties of this data are user definable and are of the usual data types (string, int, double, date). There will be about 50 columns/properties. I have 2 needs: To be able to calculate new columns/properties using an expression e.g. Column3 = Column1 * Column2. Ultimately I would like to be able to use external data using a callback, e.g. Column3 = Column1 * GetTemperature The expression is relatively simple, maths operations, sum, count & IF are the only necessary functions. To be able to filter/group the data and perform aggregations e.g. Sum(Data.Column1) Where(Data.Column2 == "blah") As far as I can see I have two options: 1. Using a DataTable. = Point 1 above is achieved by using DataColumn.Expression = Point 2 above is acheived by using DataTable.DefaultView.RowFilter & C# code 2. Using a List of generic Objects each with a Dictionary< string, object to store the values. = Point 1 could be achieved by something like NCalc = Point 2 is achieved using LINQ DataTable: Pros: DataColumn.Expression is inbuilt Cons: RowFilter & coding c# is not as "nice" as LINQ, DataColumn.Expression does not support callbacks(?) = workaround could be to get & replace external value when creating the calculated column GenericList: Pros: LINQ syntax, NCalc supports callbacks Cons: Implementing NCalc/generic calc engine Based on the above I would think a GenericList approach would win, but something I have not factored in is the performance which for some reason I think would be better with a datatable. Does anyone have a gut feeling / experience with LINQ vs. DataTable performance? How about NCalc? As I said there are about 100,000 rows of data, with 50 columns, of which maybe 20 are calculated. In total about 50 rules will be run against the data, so in total there will be 5 million row/object scans. Would really appreciate any insights. Thx. ps. Of course using a database + SQL & Views etc. would be the easiest solution, but for various reasons can't be implemented.

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