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• Too many columns to index - use mySQL Partitions?

  - by Christopher Padfield

  We have an application with a table with 20+ columns that are all searchable. Building indexes for all these columns would make write queries very slow; and any really useful index would often have to be across multiple columns increasing the number of indexes needed. However, for 95% of these searches, only a small subset of those rows need to be searched upon, and quite a small number - say 50,000 rows. So, we have considered using mySQL Partition tables - having a column that is basically isActive which is what we divide the two partitions by. Most search queries would be run with isActive=1. Most queries would then be run against the small 50,000 row partition and be quick without other indexes. Only issue is the rows where isActive=1 is not fixed; i.e. it's not based on the date of the row or anything fixed like that; we will need to update isActive based on use of the data in that row. As I understand it that is no problem though; the data would just be moved from one partition to another during the UPDATE query. We do have a PK on id for the row though; and I am not sure if this is a problem; the manual seemed to suggest the partition had to be based on any primary keys. This would be a huge problem for us because the primary key ID has no basis on whether the row isActive.

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• Advice on setting up a central db with master tables for web apps

  - by Dragn1821

  I'm starting to write more and more web applications for work. Many of these web applications need to store the same types of data, such as location. I've been thinking that it may be better to create a central db and store these "master" tables there and have each applicaiton access them. I'm not sure how to go about this. Should I create tables in my application's db to copy the data from the master table and store in the app's table (for linking with other app tables using foreign keys)? Should I use something like a web service to read the data from the master table instead of firing up a new db connection in my app? Should I forget this idea and just store the data within my app's db? I would like to have data such as the location central so I can go to one table and add a new location and the next time someone needs to select a location from one of the apps, the new one would be there. I'm using ASP.NET MVC 1.0 to build the web apps and SQL 2005 as the db. Need some advice... Thanks!

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• Fastest way to do a weighted tag search in SQL Server

  - by Hasan Khan

  My table is as follows ObjectID bigint Tag nvarchar(50) Weight float Type tinyint I want to get search for all objects that has tags 'big' or 'large' I want the objectid in order of sum of weights (so objects having both the tags will be on top) select objectid, row_number() over (order by sum(weight) desc) as rowid from tags where tag in ('big', 'large') and type=0 group by objectid the reason for row_number() is that i want paging over results. The query in its current form is very slow, takes a minute to execute over 16 million tags. What should I do to make it faster? I have a non clustered index (objectid, tag, type) Any suggestions?

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• how to use css 's more style on a object

  - by Richa Media and services

  how i can use more style-sheet on a object (ex:div or span)

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• How can I build a voting system to support multiple types of objects to vote on?

  - by Kyle Hayes

  I'm really looking for something very similar to the way SO is setup where a few different kinds of things can be voted on (questions AND answers). What kind of DB schema, generally, could I use to support voting on many different kinds of objects? Would I have a single Vote table that would have references to other objects in the database? Or do I have to have or should have a separate vote table for each of the objects I would like to vote on.

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• How value objects are saving and loading?

  - by yeraycaballero

  Since there isn't respositories for value objects. How can I load all value objects? Suppose we are modeling a blog application and we have this classes: Post (Entity) Comment (Value object) Tag (Value object) PostsRespository (Respository) I Know that when I save a new post, its tags are saving with it in the same table. But how could I load all tags of all posts. Has PostsRespository got a method to load all tags? I usually do it, but I want to know others opinions

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• How does an operating system accomodate for USB 2.0's inability to provide interrrupts for connected

  - by user354822

  That's it. ffffffffffff

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• How can I handle all my errors/messages in one place on an Asp.Net page?

  - by Atomiton

  Hi all, I'm looking for some guidance here. On my site I put things in Web user controls. For example, I will have a NewsItem Control, an Article Control, a ContactForm control. These will appear in various places on my site. What I'm looking for is a way for these controls to pass messages up to the Page that they exist on. I don't want to tightly couple them, so I think I will have to do this with Events/Delegates. I'm a little unclear as to how I would implement this, though. A couple of examples: 1 A contact form is submitted. After it's submitted, instead of replacing itself with a "Your mail has been sent" which limits the placement of that message, I'd like to just notify the page that the control is on with a Status message and perhaps a suggested behaviour. So, a message would include the text to render as well as an enum like DisplayAs.Popup or DisplayAs.Success 2 An Article Control queries the database for an Article object. Database returns an Exception. Custom Exception is passed to the page along with the DisplayAs.Error enum. The page handles this error and displays it wherever the errors go. I'm trying to accomplish something similar to the ValidationSummary Control, except that I want the page to be able to display the messages as the enum feels fit. Again, I don't want to tightly bind or rely a control existing on the Page. I want the controls to raise these events, but the page can ignore them if it wants. Am I going about this the right way? I'd love a code sample just to get me started. I know this is a more involved question, so I'll wait longer before voting/choosing the answers.

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• OOP: class based and prototype based, are there other alternatives?

  - by Gabriel Šcerbák

  I know of class-based and protype based object oriented programming languages, are there any other alternatives? What are they?

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• SELECT product from subclass: How many queries do I need?

  - by Stefano

  I am building a database similar to the one described here where I have products of different type, each type with its own attributes. I report a short version for convenience product_type ============ product_type_id INT product_type_name VARCHAR product ======= product_id INT product_name VARCHAR product_type_id INT -> Foreign key to product_type.product_type_id ... (common attributes to all product) magazine ======== magazine_id INT title VARCHAR product_id INT -> Foreign key to product.product_id ... (magazine-specific attributes) web_site ======== web_site_id INT name VARCHAR product_id INT -> Foreign key to product.product_id ... (web-site specific attributes) This way I do not need to make a huge table with a column for each attribute of different product types (most of which will then be NULL) How do I SELECT a product by product.product_id and see all its attributes? Do I have to make a query first to know what type of product I am dealing with and then, through some logic, make another query to JOIN the right tables? Or is there a way to join everything together? (if, when I retrieve the information about a product_id there are a lot of NULL, it would be fine at this point). Thank you

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• What Features do you Consider Brilliantly implemented in C++

  - by John

  Following features to remove from c++ and desired features for c++ I thought why not complete the trio... what features are you happy about in C++ and don't want to change at all? What features are elegantly and brilliantly implemented and still look better than other more modern languages

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• Database schema to store AND, OR relation, association

  - by user455387

  Many thanks for your help on this. In order for an entreprise to get a call for tender it must meet certain requirements. For the first example the enterprise must have a minimal class 4, and have qualification 2 in sector 5. Minimal class is always one number. Qualification can be anything (single, or multiple using AND, OR logical operators) I have created tables in order to map each number to it's given name. Now I need to store requirements in the database. minimal class 4 Sector Qualification 5.2 minimal class 2 Sector Qualifications 3.9 and 3.10 minimal class 3 Sector Qualifications 6.1 or 6.3 minimal class 1 Sector Qualifications (3.1 and 3.2) or 5.6 class Domain < ActiveRecord::Base has_many :domain_classes has_many :domain_sectors has_many :sector_qualifications, :through => :domain_sectors end class DomainClass < ActiveRecord::Base belongs_to :domain end class DomainSector < ActiveRecord::Base belongs_to :domain has_many :sector_qualifications end class SectorQualification < ActiveRecord::Base belongs_to :domain_sector end create_table "domains", :force => true do |t| t.string "name" end create_table "domain_classes", :force => true do |t| t.integer "number" t.integer "domain_id" end create_table "domain_sectors", :force => true do |t| t.string "name" t.integer "number" t.integer "domain_id" end create_table "sector_qualifications", :force => true do |t| t.string "name" t.integer "number" t.integer "domain_sector_id" end

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• Entering large amounts of text data in HTML form

  - by MakkyNZ

  Hi I have a web page that has a requirement to allow users to paste large amounts of text data from an Excel spreadsheet directly into the input controls of the page. Typically the user would be pasting anywhere between 150 to 300 spreadsheet cells that are all in one column. What are some good ways i could use to capture this data on the web page? thanks

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• Define "Validation in the Model"

  - by sunwukung

  There have been a couple of discussions regarding the location of user input validation: http://stackoverflow.com/questions/659950/should-validation-be-done-in-form-objects-or-the-model http://stackoverflow.com/questions/134388/where-do-you-do-your-validation-model-controller-or-view These discussions were quite old, so I wanted to ask the question again to see if anyone had any fresh input. If not, I apologise in advance. If you come from the Validation in the Model camp - does Model mean OOP representation of data (i.e. Active Record/Data Mapper) as "Entity" (to borrow the DDD terminology) - in which case you would, I assume, want all Model classes to inherit common validation constraints. Or can these rules simply be part of a Service in the Model - i.e. a Validation service? For example, could you consider Zend_Form and it's validation classes part of the Model? The concept of a Domain Model does not appear to be limited to Entities, and so validation may not necessarily need to be confined to this Entities. It seems that you would require a lot of potentially superfluous handing of values and responses back and forth between forms and "Entities" - and in some instances you may not persist the data recieved from user input, or recieve it from user input at all.

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• O(log n) algorithm for merging lists and computing rank?

  - by Eternal Learner

  Given two sorted lists, each containing n real numbers, is there a O(log?n) time algorithm to compute the element of rank i (where i coresponds to index in increasing order) in the union of the two lists, assuming the elements of the two lists are distinct? I can think of using a Merge procedure to merge the 2 lists and then find the A[i] element in constant time. But the Merge would take O(n) time. How do we solve it in O(log n) time?

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• Rails 3 HABTM Strange Association: Project and Employee in a tree.

  - by Mauricio

  Hi guys I have to adapt an existing model to a new relation. I have this: A Project has many Employees. the Employees of a Project are organized in some kind of hierarchy (nothing fancy, I resolved this adding a parent_id for each employee to build the 'tree') class Employee < AR:Base belongs_to :project belongs_to :parent, :class_name => 'Employee' has_many :childs, :class_name => 'Employee', :foreign_column => 'parent_id' end class Project < AR:Base has_many :employees, end That worked like a charm, now the new requirement is: The Employees can belong to many Projects at the same time, and the hierarchy will be different according to the project. So I though I will need a new table to build the HABTM, and a new class to access the parent_id to build the tree. Something like class ProjectEmployee < AR:Base belongs_to :project belongs_to :employee belongs_to :parent, :class_name => 'Employee' # <--- ?????? end class Project < AR:Base has_many :project_employee has_many :employees, :through => :project_employee end class Employee < AR:Base has_many :project_employee has_many :projects, :through => :project_employee end How can I access the parent and the childs of an employee for a given project? I need to add and remove childs as wish from the employees of a project. Thank you!

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• Best ways to construct Dynamic Search Conditions for Sql

  - by CoolBeans

  I have always wondered what's the best way to achieve this task. In most web based applications you have to provide search options on many different criteria. Based on what criteria is chosen behind the scene you modify your SQL. Generally, this is how I tend to go about it:- Have a base SQL template. In the base template have conditions like this WHERE [#PRE_COND1] AND [#PRE_COND2] .. so on and so forth. So an example SQL might look something like SELECT NAME,AGE FROM PERSONS [,#TABLE2] [,#TABLE3] WHERE [#PRE_COND1] AND [#PRE_COND2] ORDER BY [#ORD_COND1] AND [#ORD_COND2] etc. During run time after figuring out the all the search criteria user has entered, I replace the [#PRE_COND1]s and [#ORD_COND1]s with the appropriate SQLs and then execute the query. I personally do not like this brute force method. However, I never came across a better approach either. How do you accomplish such tasks generally given you are either using native JDBC or Spring JDBC? It is almost like I need a C MACRO like functionality in Java to do this.

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• Java: Friendlier way to get an instance of FontMetrics

  - by Martijn Courteaux

  Hi people, Is there a friendlier way to get an instance of FontMetrics than FontMetrics fm = Graphics.getFontMetrics(Font); I hate this way because of the following example: If you want to create in a game a menu and you want all the menuitems in the center of the screen you need fontmetrics. But, mostly, menuitems are clickable. So I create an array of Rectangles and all the rectangles fits around the items, so when the mouse is pressed, I can simply use for (int i = 0; i < rects.length; i++) if (rects[i].contains(mouseX, mouseY)) { ... } But to create the rects I also need FontMetrics for their coordinates. So this mean that I have to construct all my rectangles in the paint-method of my menu. So I want a way to get the FontMetrics so I can construct the Rectangles in a method called by the constructor. Hope you understand. Thanks in advance.

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• Best practice for near reuse of model components?

  - by Chris Knight

  I have a requirement to use a Fund model in my code. It will contain a fund name and fund code. In the interest of reuse I've poked around the package containing the other models used and found an existing Fund model. However the issue here is that, in addition to fund name and code, it also contains an amount. Amount isn't directly relevant in my context. So, do I: 1) Use the existing Fund model as is, ignoring the setters/getters for fund amount. 2) Put a FundDescription interface onto the existing Fund model for accessing only the information I'm interested in. 3) Make a FundDescription base class from which the existing Fund model could now extend 4) Create a whole new seperate model since the two are slightly contextually different

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• When to define SDD operations System->Actor?

  - by devoured elysium

  I am having some trouble understanding how to make SDDs, as I don't fully grasp why in some cases one should define operations for System - Actor and in others don't. Here is an example: 1) The User tells the System that wants to buy some tickets, stating his client number. 2) The System confirms that the given client number is valid. 3) The User tells the System the movie that wants to see. 4) The System shows the set of available sessions and seats for that movie. 5) The System asks the user which session/seat he wants. 6) The user tells the System the chosen session/seat. This would be converted to: a) -----> tellClientNumber(clientNumber) b) <----- validClientNumber c) -----> tellMovieToSee(movie) d) <----- showsAvailableSeatsHours e) -----> tellSystemChosenSessionSeat(session, seat) I know that when we are dealing with SDD's we are still far away from coding. But I can't help trying to imagine how it how it would have been had I to convert it right away to code: I can understand 1) and 2). It's like if it was a C#/Java method with the following signature: boolean tellClientNumber(clientNumber) so I put both on the SDD. Then, we have the pair 3) 4). I can imagine that as something as: SomeDataStructureThatHoldsAvailableSessionsSeats tellSystemMovieToSee(movie) Now, the problem: From what I've come to understand, my lecturer says that we shouldn't make an operation on the SDD for 5) as we should only show operations from the Actor to the System and when the System is either presenting us data (as in c)) or validating sent data (such as in b)). I find this odd, as if I try to imagine this like a DOS app where you have to put your input sequencially, it makes sense to make an arrow even for 5). Why is this wrong? How should I try to visualize this? Thanks

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• Sybase PowerDesigner Change Many (Find/Replace/Convert) Data Item's Data Types

  - by Andy

  Hello, I have a relatively large Conceptual Data Model in PowerDesigner. After generating a Physical Data Model and seeing the DBMS data types, I need to update all of data types(NUMBER/TEXT) for each data item. I'd like to either do a find/replace within the Conceptual Data Model or somehow map to different data types when creating the Physical Data Model. Ex. Change the auto conversion of Text - Clob, to Text - NVARCHAR(20). Thanks!

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• suggestions on syntax to express mathematical formula concisely

  - by aaa

  hello. I am developing functional domain specific embedded language within C++ to translate formulas into working code as concisely and accurately as possible. I post prototype in the comment, it is about 2 hundred lines long. Right now my language looks something like this (well, actually is going to look like): // implies two nested loops j=0:N, i=0,j (range(i) < j < N)[T(i,j) = (T(i,j) - T(j,i))/e(i+j)]; // implies summation over above expression sum(range(i) < j < N))[(T(i,j) - T(j,i))/e(i+j)]; I am looking for possible syntax improvements/extensions or just different ideas about expressing mathematical formulas as clearly and precisely as possible (in any language, not just C++). Can you give me some syntax examples relating to my question which can be accomplished in your language of choice which consider useful. In particular, if you have some ideas about how to translate the above code segments, I would be happy to hear them. Thank you just to clarify and give actual formula, my short-term goal is to express the following expression concisely where values in <> are already computed as 4-dimensional array

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• How can a language be interpreted by itself (like Rubinius)?

  - by japancheese

  I've been programming in Ruby for a while now with just the standard MRI implementation of Ruby, but I've always been curious about the other implementations I hear so much about. I was reading about Rubinius the other day, a Ruby interpreter written in Ruby. I tried looking it up in various places, but I was having a hard time figuring out exactly how something like this works. I've never had much experience in compilers or language writing but I'm really interested to figure it out. How exactly can a language be interpreted by itself? Is there a basic step in compiling that I don't understand where this makes sense? Can someone explain this to me like I'm an idiot (because that wouldn't be too far off base anyways)

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• How to handle injecting dependencies into rich domain models?

  - by Arne

  In a web server project with a rich domain model (application logic is in the model, not in the services) how do you handle injecting the dependencies into the model objects? What are your experiences? Do you use some form of AOP? Like Springs @Configurable annotation? Load time or build time weawing? Problems you encountered? Do you use manual injection? Then how do you handle different instantiation scenarios (creating of the objects through an library [like Hibernate], creating objects with "new" ...)? Or do you use some other way of injecting the dependencies?

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• HTML columns or rows for form layout?

  - by Valera

  I'm building a bunch of forms that have labels and corresponding fields (input element or more complex elements). Labels go on the left, fields go on the right. Labels in a given form should all be a specific width so that the fields all line up vertically. There are two ways (maybe more?) of achieving this: Rows: Float each label and each field left. Put each label and field in a field-row div/container. Set label width to some specific number. With this approach labels on different forms will have different widths, because they'll depend on the width of the text in the longest label. Columns: Put all labels in one div/container that's floated left, put all fields in another floated left container with padding-left set. This way the labels and even the label container don't need to have their widths set, because the column layout and the padding-left will uniformly take care of vertically lining up all the fields. So approach #2 seems to be easier to implement (because the widths don't need to be set all the time), but I think it's also less object oriented, because a label and a field that goes with that label are not grouped together, as they are in approach #1. Also, if building forms dynamically, approach #2 doesn't work as well with functions like addRow(label, field), since it would have to know about the label and the field containers, instead of just creating/adding one field-row element. Which approach do you think is better? Is there another, better approach than these two?

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