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• How to handle Real Time Data from a database perspective?

  - by balexandre

  I have an idea in mind, but it still confuses me the database area. Imagine that I want to show real time data, and using one of the latest browser technologies (web sockets - even using older browsers) it is very easy to show to all observables (user browser) what everyone is doing. Remy Sharp has an example about the simplicity about this. But I still don't get the database part, how would I feed, let's imagine (using Remy game Tron) that I want to save the path for each connected user in a database and if a client wants to see what is going on with a 5 sec delay, he will see that, not only the 5 sec until that moment but the continuation in time ... how can I query a DB like that? SELECT x, y FROM run WHERE time >= DATEADD(second, -5, rundate); is not the recommended path right? and pulling this x in x time ... this is not real data feed correct? If can someone help me understand the Database point of view, I would greatly appreciate.

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• OpenOffice Calc: How can I count the number of different items with data pilot?

  - by manu

  Hi all, I have a rather long spreadsheet with historical information of issues solved by some user on a colaborative environment. The spreadsheet have the following (relevant) columns date, week no., project, author id, etc... The week no. is calculated from the date, is basically the year concatenated with the week number within that year; for instance, both 2009-02-18 and 2009-02-20 yield the week number 200908 - the 8th week of year 2009; and 2009-02-23 yields 200909 - the 9th week of year 2009. I need to count how many different users (given by author id) contributed to some project, on a weekly basis. I have setup a data pilot with the week as Row Field, the project as the Column Field, and count-author as the Data Field. However, this counts the author id as different instances. This is not what I need. I need to count how many different users contributed to each project on a weekly basis. I expect to get something like: projects week Project1 Project2 Project3 200901 10 2 200902 2 7 Each inner cell containing how many different users contributed. With the count-author configuration, what I get is how many contributions (total) got the project on that week. Is there a way to tell OpenOffice Calc to do what I want?

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• Should I cache the data or hit the database?

  - by JD01

  I have not worked with any caching mechanisms and was wondering what my options are in the .net world for the following scenario. We basically have a a REST Service where the user passes an ID of a Category (think folder) and this category may have lots of sub categories and each of the sub categories could have 1000 of media containers (think file reference objects) which contain information about a file that may be on a NAS or SAN server (files are videos in this case). The relationship between these categories is stored in a database together with some permission rules and meta data about the sub categories. So from a UI perspective we have a lazy loaded tree control which is driven by the user by clicking on each sub folder (think of Windows explorer). Once they come to a URL of the video file, they then can watch the video. The number of users could grow into the 1000s and the sub categories and videos could be in the 10000s as the system grows. The question is should we carry on the way it is currently working where each request hits the database or should we think about caching the data? We are on using IIS 6/7 and Asp.net.

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• Where to put business logic in MVC design?

  - by BriskLabs Pakistan

  I have created a simple MVC java application that adds records through data forms to a database. my app collects data, it also validates it and stores it. This is because the data is being sourced online from different users. the data is mostly numeric in nature. now on the numeric data being stored into database (SQL server) , i wish that my app should be able to perform computations... and display it. the user is not interested in how computations are done so they must be encapsulated. the user must only be able to view the simple computed data which for example A column data - B Column data / C column data etc... and just display it to the user... i know how to write stored procedures for same but i want a 3 tier app I want the data, that I put into the database as a record, worked upon by performing calculations on it. However, the original data should remain unaffected, while the new data, post-calculations, must be stored as a new entity record into the database. Where should I write the code for this background calculation? As it is the rules and business logic... in a new java beans files ?

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• How to deal with data on the model specific to the technology being used?

  - by user1620696

  There are some cases where some of the data on a class of the domain model of an application seems to be dependent on the technology being used. One example of this is the following: suppose we are building one application in .NET such that there's the need of an Employee class. Suppose further that we are going to implement relational database, then the Employee has a primary key right? So that the classe would be something like public class Employee { public int EmployeeID { get; set; } public string Name { get; set; } ... } Now, that EmployeeID is dependent on the technology right? That's something that has to do with the way we've choose to persist our data. Should we write down a class independent of such things? If we do it this way, how should we work? I think I would need to map all the time between domain model and persistence specific types, but I'm not sure.

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• Help parsing long (3.5mil lines) text file, line by line and storing data, need a strategy

  - by Jarrod

  This is a question about solving a particular problem I am struggling with, I am parsing a long list of text data, line by line for a business app in PHP (cron script on the CLI). The file follows the format: HD: Some text here {text here too} DC: A description here DC: the description continues here DC: and it ends here. DT: 2012-08-01 HD: Next header here {supplemental text} ... this repeats over and over for a few hundred megs I have to read each line, parse out the HD: line and grab the text on this line. I then compare this text against data stored in a database. When a match is found, I want to then record the following DC: lines that succeed the matched HD:. Pseudo code: while ( the_file_pointer_isnt_end_of_file) { line = getCurrentLineFromFile title = parseTitleFrom(line) matched = searchForMatchInDB(line) if ( matched ) { recordTheDCLines // <- Best way to do this? } } My problem is that because I am reading line by line, what is the best way to trigger the script to start saving DC lines, and then when they are finished save them to the database? I have a vague idea, but have yet to properly implement it. I would love to hear the communities ideas\suggestions! Thank you.

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• FILESTREAM in SQL Server 2008 R2

  - by CatherineRussell

  Much data is unstructured, such as text documents, images, and videos. This unstructured data is often stored outside the database, separate from its structured data. This separation can cause data management complexities. Or, if the data is associated with structured storage, the file streaming capabilities and performance can be limited. FILESTREAM integrates the SQL Server Database Engine with an NTFS file system by storing varbinary(max) binary large object (BLOB) data as files on the file system. Transact-SQL statements can insert, update, query, search, and back up FILESTREAM data. Win32 file system interfaces provide streaming access to the data. FILESTREAM uses the NT system cache for caching file data. This helps reduce any effect that FILESTREAM data might have on Database Engine performance. The SQL Server buffer pool is not used; therefore, this memory is available for query processing. FILESTREAM data is not encrypted even when transparent data encryption is enabled. To read more, go to: http://technet.microsoft.com/en-us/library/bb933993.aspx

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• What sort of data should be sent for mouse-based movement in a multiplayer game?

  - by Daniel

  I'm new to the Multiplayer Rodeo here so please bear with me... I am just getting started and I'm trying to figure out how to deal with movement. I've looked at the question Best way to implement mouse-based movement in MMOG which gives me a pretty good idea, but I'm still struggling with what kind of data should be sent to the server. If a player is on position [x:0, y:0] and I click with the mouse on [x:40, y:40] to start movement, what information should I send to the server? Should I calculate the position based on velocity on client side and just send the expected location? Or should I send current location and velocity and direction? When the server is updating the clients on the players' whereabouts, should the position be sent only, and the clients expected to interpolate/predict movement, or can the direction sent from the client (instead of just coordinates) be used. My concern(or confusion) is regarding the ping/lag frequency of data update and use of a predictive algorithm, as I'd like the movement to be smooth even with a high latency, and prevent ability to cheat(though that's not the top priority).

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• Algorithms for Data Redundancy and Failover for distributed storage system?

  - by kennetham

  I'm building a distributed storage system that works with different storage sizes. For instance, my storage devices have sizes of 50GB, 70GB, 150GB, 250GB, 1000GB, 5 storage systems in one system. My application will store any files to the storage system. Question: How can I build a distributed storage with the idea of data redundancy and fail-over to store documents, videos, any type of files at the same time ensuring that should one of any storage devices fail, there would be another copy of these files on another storage device. However, the concern is, 50GB of storage can only store this maximum number of files as compared to 70GB, 150GB etc. With one storage in mind, bringing 5 storage systems like a cloud storage, is there any logical way to distribute or store the files through my application? How do I ensure data redundancy through different storage sizes? Is there any algorithm to collate multiple blob files into a single file archive? What is the best solution for one cloud storage with multiple different storage sizes? I open this topic with the objective of discussing the best way to implement this idea, assuming simplicity, what are the issues of this implementation, performance measurements and discussion of the limitations.

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• Architecture Question

  - by katie77

  I am writing a rules/eligibility Module. I have 2 sets of data, one is the customer data and the other is the customer products data. Customer data to Customer products data is one to many. Now I have to go through a set of Eligibility rules for each of this Customer product data. For each customer products data, I can say the customer is eligible for that product or decline the eligibility and should move on to the next product record. So in all the rules, I need to have access to customer and customer product data(the particular record that the rules are being executed against). Since all the rules can either approve a product or decline a product, I created an interface with those 2 methods and is implementing the this interface for all the rules. I am passing the Customer data and one product data for all the rules (because rules should be executed on each row of customer product data). An Ideal situation would be having the customer and customer product data available for the rule instead of passing them to each rule. What is the best way of doing this in-terms of architecture?

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• Architecture for a business objects / database access layer

  - by gregmac

  For various reasons, we are writing a new business objects/data storage library. One of the requirements of this layer is to separate the logic of the business rules, and the actual data storage layer. It is possible to have multiple data storage layers that implement access to the same object - for example, a main "database" data storage source that implements most objects, and another "ldap" source that implements a User object. In this scenario, User can optionally come from an LDAP source, perhaps with slightly different functionality (eg, not possible to save/update the User object), but otherwise it is used by the application the same way. Another data storage type might be a web service, or an external database. There are two main ways we are looking at implementing this, and me and a co-worker disagree on a fundamental level which is correct. I'd like some advice on which one is the best to use. I'll try to keep my descriptions of each as neutral as possible, as I'm looking for some objective view points here. Business objects are base classes, and data storage objects inherit business objects. Client code deals with data storage objects. In this case, common business rules are inherited by each data storage object, and it is the data storage objects that are directly used by the client code. This has the implication that client code determines which data storage method to use for a given object, because it has to explicitly declare an instance to that type of object. Client code needs to explicitly know connection information for each data storage type it is using. If a data storage layer implements different functionality for a given object, client code explicitly knows about it at compile time because the object looks different. If the data storage method is changed, client code has to be updated. Business objects encapsulate data storage objects. In this case, business objects are directly used by client application. Client application passes along base connection information to business layer. Decision about which data storage method a given object uses is made by business object code. Connection information would be a chunk of data taken from a config file (client app does not really know/care about details of it), which may be a single connection string for a database, or several pieces connection strings for various data storage types. Additional data storage connection types could also be read from another spot - eg, a configuration table in a database that specifies URLs to various web services. The benefit here is that if a new data storage method is added to an existing object, a configuration setting can be set at runtime to determine which method to use, and it is completely transparent to the client applications. Client apps do not need to be modified if data storage method for a given object changes. Business objects are base classes, data source objects inherit from business objects. Client code deals primarily with base classes. This is similar to the first method, but client code declares variables of the base business object types, and Load()/Create()/etc static methods on the business objects return the appropriate data source-typed objects. The architecture of this solution is similar to the first method, but the main difference is the decision about which data storage object to use for a given business object is made by the business layer, not the client code. I know there are already existing ORM libraries that provide some of this functionality, but please discount those for now (there is the possibility that a data storage layer is implemented with one of these ORM libraries) - also note I'm deliberately not telling you what language is being used here, other than that it is strongly typed. I'm looking for some general advice here on which method is better to use (or feel free to suggest something else), and why.

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• Survey Data Model - How to avoid EAV and excessive denormalization?

  - by AlexDPC

  Hi everyone, My database skills are mediocre at best and I have to design a data model for survey data. I have spent some thoughts on this and right now I feel that I am stuck between some kind of EAV model and a design involving hundreds of tables, each with hundreds of columns (and thousands of records). There must be a better way to do this and I hope that the wise folks on this forum can help me. I have already searched various forums, but I couldn't really find a solution. If it has already been given elsewhere, please excuse me and provide me with a link so I can read it up. Some assumptions about the data I have to deal with: Each survey consists of 1 to n questionnaires Each questionnaire consists of 100-2,000 questions (please ignore that 2,000 questions really sound like a lot to answer...) Questions can be of various types: multiple-choice, free text, a number (like age, income, percentages, ...) Each survey involves 10-200 countries (These are not the respondents. The respondents are actually people in the countries.) Depending on the type of questionnaire, each questionnaire is answered by 100-20,000 respondents per country. A country can adapt the questionnaires for a survey, i.e. add, remove or edit questions The data for one country is gathered in a separate database in that country. There is no possibility for online integration from the start. The data for all countries has to be integrated later. This means for example, if a country has deleted a question, that data must somehow be derived from what they sent in order to achieve a uniform design across all countries I will have to write the integration and cleaning software, which will need to work with every country's data In the end the data needs to be exported to flat files, one rectangular grid per country and questionnaire. I have already discussed this topic with people from various backgrounds and have not come to a good solution yet. I mainly got two kinds of opinions. The domain experts, who are used to working with flat files (spreadsheet-style) for data processing and analysis vote for a denormalized structure with loads of tables and columns as I described above (1 table per country and questionnaire). This sounds terrible to me, because I learned that wide tables are to be avoided, it will be annoying to determine which columns are actually in a table when working with it, the database will become cluttered with hundreds of tables (or I even need to set up multiple databases, each with a similar yet a bit differetn design), etc. O-O-programmers vote for a strongly "normalized" design, which would effectively lead to a central table containing all the answers from all respondents to all questions. This table would either need to contain a column of type sql_variant type or multiple answer columns with different types to store answers of different types (multiple choice, free text, ..). The former would essentially be a EAV model. I tend to follow Joe Celko here, who strongly discourages its use (he calls it OTLT or "One True Lookup Table"). The latter would imply that each row would contain null cells for the not applicable types by design. Another alternative I could think of would be to create one table per answer type, i.e., one for multiple-choice questions, one for free text questions, etc.. That's not so generic, it would lead to a lot of union joins, I think and I would have to add a table if a new answer type is invented. Sorry for boring you with all this text and thank you for your input! Cheers, Alex PS: I asked the same question here: http://www.eggheadcafe.com/community/aspnet/13/10242616/survey-data-model--how-to-avoid-eav-and-excessive-denormalization.aspx

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• What scalability problems have you solved using a NoSQL data store?

  - by knorv

  NoSQL refers to non-relational data stores that break with the history of relational databases and ACID guarantees. Popular open source NoSQL data stores include: Cassandra (tabular, written in Java, used by Facebook, Twitter, Digg, Rackspace, Mahalo and Reddit) CouchDB (document, written in Erlang, used by Engine Yard and BBC) Dynomite (key-value, written in C++, used by Powerset) HBase (key-value, written in Java, used by Bing) Hypertable (tabular, written in C++, used by Baidu) Kai (key-value, written in Erlang) MemcacheDB (key-value, written in C, used by Reddit) MongoDB (document, written in C++, used by Sourceforge, Github, Electronic Arts and NY Times) Neo4j (graph, written in Java, used by Swedish Universities) Project Voldemort (key-value, written in Java, used by LinkedIn) Redis (key-value, written in C, used by Engine Yard, Github and Craigslist) Riak (key-value, written in Erlang, used by Comcast and Mochi Media) Ringo (key-value, written in Erlang, used by Nokia) Scalaris (key-value, written in Erlang, used by OnScale) ThruDB (document, written in C++, used by JunkDepot.com) Tokyo Cabinet/Tokyo Tyrant (key-value, written in C, used by Mixi.jp (Japanese social networking site)) I'd like to know about specific problems you - the SO reader - have solved using data stores and what NoSQL data store you used. Questions: What scalability problems have you used NoSQL data stores to solve? What NoSQL data store did you use? What database did you use before switching to a NoSQL data store? I'm looking for first-hand experiences, so please do not answer unless you have that.

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• Before data is entered, is there a way to make a grouped table graphic placeholder?

  - by Matt Winters

  I have a grouped table with 3 sections, each section with a title. The 1st and 3rd sections always have only 1 row of information so before any user data is entered, I just put some words like "Enter Data Here..." as placeholder text. This text is edited (replaced) by the user with their own actual data. No problem. The 2nd section however will contain several rows of information entered by user and I'd prefer not to enter placeholder data in row 0, having the user Edit the first row of data then Add subsequent rows. If the numberOfRowsInSection is set to 0, the title for the 3rd section comes close to the title for the 2nd section and it looks ugly. The best that I could come with, and I don't know to do it, is to have a fake graphic placeholder on the striped background (between the 2nd and third titles) that looks like a single row in the 2nd section, put "Enter Data Here..." text in the graphic, and then the first row of actual data entered and all subsequent rows will cover it up. Can anyone tell me how to do this or offer a better suggestion. Thanks.

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• C# .Net Serial DataReceived Event response too slow for high-rate data.

  - by Matthew

  Hi, I have set up a SerialDataReceivedEventHandler, with a forms based program in VS2008 express. My serial port is set up as follows: 115200, 8N1 Dtr and Rts enabled ReceivedBytesThreshold = 1 I have a device I am interfacing with over a BlueTooth, USB to Serial. Hyper terminal receives the data just fine at any data rate. The data is sent regularly in 22 byte long packets. This device has an adjustable rate at which data is sent. At low data rates, 10-20Hz, the code below works great, no problems. However, when I increase the data rate past 25Hz, there starts to recieve mulitple packets on one call. What I mean by this is that there should be a event trigger for every incoming packet. With higher output rates, I have tested the buffer size (BytesToRead command) immediatly when the event is called and there are multiple packets in the buffer then. I think that the event fires slowly and by the time it reaches the code, more packes have hit the buffer. One test I do is see how many time the event is trigger per second. At 10Hz, I get 10 event triggers, awesome. At 100Hz, I get something like 40 event triggers, not good. My goal for data rate is 100HZ is acceptable, 200Hz preferred, and 300Hz optimum. This should work because even at 300Hz, that is only 52800bps, less than half of the set 115200 baud rate. Anything I am over looking? public Form1() { InitializeComponent(); serialPort1.DataReceived += new SerialDataReceivedEventHandler(serialPort1_DataReceived); } private void serialPort1_DataReceived(object sender, SerialDataReceivedEventArgs e) { this.Invoke(new EventHandler(Display_Results)); } private void Display_Results(object s, EventArgs e) { serialPort1.Read(IMU, 0, serial_Port1.BytesToRead); }

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• SQL Server CLR stored procedures in data processing tasks - good or evil?

  - by Gart

  In short - is it a good design solution to implement most of the business logic in CLR stored procedures? I have read much about them recently but I can't figure out when they should be used, what are the best practices, are they good enough or not. For example, my business application needs to parse a large fixed-length text file, extract some numbers from each line in the file, according to these numbers apply some complex business rules (involving regex matching, pattern matching against data from many tables in the database and such), and as a result of this calculation update records in the database. There is also a GUI for the user to select the file, view the results, etc. This application seems to be a good candidate to implement the classic 3-tier architecture: the Data Layer, the Logic Layer, and the GUI layer. The Data Layer would access the database The Logic Layer would run as a WCF service and implement the business rules, interacting with the Data Layer The GUI Layer would be a means of communication between the Logic Layer and the User. Now, thinking of this design, I can see that most of the business rules may be implemented in a SQL CLR and stored in SQL Server. I might store all my raw data in the database, run the processing there, and get the results. I see some advantages and disadvantages of this solution: Pros: The business logic runs close to the data, meaning less network traffic. Process all data at once, possibly utilizing parallelizm and optimal execution plan. Cons: Scattering of the business logic: some part is here, some part is there. Questionable design solution, may encounter unknown problems. Difficult to implement a progress indicator for the processing task. I would like to hear all your opinions about SQL CLR. Does anybody use it in production? Are there any problems with such design? Is it a good thing?

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• Database not updating after UPDATE SQL statement in ASP.net

  - by Ronnie

  I currently have a problem attepting to update a record within my database. I have a webpage that displays in text boxes a users details, these details are taken from the session upon login. The aim is to update the details when the user overwrites the current text in the text boxes. I have a function that runs when the user clicks the 'Save Details' button and it appears to work, as i have tested for number of rows affected and it outputs 1. However, when checking the database, the record has not been updated and I am unsure as to why. I've have checked the SQL statement that is being processed by displaying it as a label and it looks as so: UPDATE [users] SET [email]=@email, [firstname]=@firstname, [lastname]=@lastname, [promo]=@promo WHERE ([users].[user_id] = 16) The function and other relevant code is: Sub Button1_Click(sender As Object, e As EventArgs) changeDetails(emailBox.text, firstBox.text, lastBox.text, promoBox.text) End Sub Function changeDetails(ByVal email As String, ByVal firstname As String, ByVal lastname As String, ByVal promo As String) As Integer Dim connectionString As String = "Provider=Microsoft.Jet.OLEDB.4.0; Ole DB Services=-4; Data Source=C:\Documents an"& _ "d Settings\Paul Jarratt\My Documents\ticketoffice\datab\ticketoffice.mdb" Dim dbConnection As System.Data.IDbConnection = New System.Data.OleDb.OleDbConnection(connectionString) Dim queryString As String = "UPDATE [users] SET [email]=@email, [firstname]=@firstname, [lastname]=@lastname, "& _ "[promo]=@promo WHERE ([users].[user_id] = " + session.contents.item("ID") + ")" Dim dbCommand As System.Data.IDbCommand = New System.Data.OleDb.OleDbCommand dbCommand.CommandText = queryString dbCommand.Connection = dbConnection Dim dbParam_email As System.Data.IDataParameter = New System.Data.OleDb.OleDbParameter dbParam_email.ParameterName = "@email" dbParam_email.Value = email dbParam_email.DbType = System.Data.DbType.[String] dbCommand.Parameters.Add(dbParam_email) Dim dbParam_firstname As System.Data.IDataParameter = New System.Data.OleDb.OleDbParameter dbParam_firstname.ParameterName = "@firstname" dbParam_firstname.Value = firstname dbParam_firstname.DbType = System.Data.DbType.[String] dbCommand.Parameters.Add(dbParam_firstname) Dim dbParam_lastname As System.Data.IDataParameter = New System.Data.OleDb.OleDbParameter dbParam_lastname.ParameterName = "@lastname" dbParam_lastname.Value = lastname dbParam_lastname.DbType = System.Data.DbType.[String] dbCommand.Parameters.Add(dbParam_lastname) Dim dbParam_promo As System.Data.IDataParameter = New System.Data.OleDb.OleDbParameter dbParam_promo.ParameterName = "@promo" dbParam_promo.Value = promo dbParam_promo.DbType = System.Data.DbType.[String] dbCommand.Parameters.Add(dbParam_promo) Dim rowsAffected As Integer = 0 dbConnection.Open Try rowsAffected = dbCommand.ExecuteNonQuery Finally dbConnection.Close End Try labelTest.text = rowsAffected.ToString() if rowsAffected = 1 then labelSuccess.text = "* Your details have been updated and saved" else labelError.text = "* Your details could not be updated" end if End Function Any help would be greatly appreciated.

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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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• Incorporating Devise Authentication into an already existing user structure?

  - by Kevin

  I have a fully functional authentication system with a user table that has over fifty columns. It's simple but it does hash encryption with salt, uses email instead of usernames, and has two separate kinds of users with an admin as well. I'm looking to incorporate Devise authentication into my application to beef up the extra parts like email validation, forgetting passwords, remember me tokens, etc... I just wanted to see if anyone has any advice or problems they've encountered when incorporating Devise into an already existing user structure. The essential fields in my user model are: t.string :first_name, :null => false t.string :last_name, :null => false t.string :email, :null => false t.string :hashed_password t.string :salt t.boolean :is_userA, :default => false t.boolean :is_userB, :default => false t.boolean :is_admin, :default => false t.boolean :active, :default => true t.timestamps For reference sake, here's the Devise fields from the migration: t.database_authenticatable :null => false t.confirmable t.recoverable t.rememberable t.trackable That eventually turn into these actual fields in the schema: t.string "email", :default => "", :null => false t.string "encrypted_password", :limit => 128, :default => "", :null => false t.string "password_salt", :default => "", :null => false t.string "confirmation_token" t.datetime "confirmed_at" t.datetime "confirmation_sent_at" t.string "reset_password_token" t.string "remember_token" t.datetime "remember_created_at" t.integer "sign_in_count", :default => 0 t.datetime "current_sign_in_at" t.datetime "last_sign_in_at" t.string "current_sign_in_ip" t.string "last_sign_in_ip" t.datetime "created_at" t.datetime "updated_at" What do you guys recommend? Do I just remove email, hashed_password, and salt from my migration and put in the 5 Devise migration fields and everything will be OK or do I need to do something else?

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• Ruby on Rails 2.3.5: Populating my prod and devel database with data (migration or fixture?)

  - by randombits

  I need to populate my production database app with data in particular tables. This is before anyone ever even touches the application. This data would also be required in development mode as it's required for testing against. Fixtures are normally the way to go for testing data, but what's the "best practice" for Ruby on Rails to ship this data to the live database also upon db creation? ultimately this is a two part question I suppose. 1) What's the best way to load test data into my database for development, this will be roughly 1,000 items. Is it through a migration or through fixtures? The reason this is a different answer than the question below is that in development, there's certain fields in the tables that I'd like to make random. In production, these fields would all start with the same value of 0. 2) What's the best way to bootstrap a production db with live data I need in it, is this also through a migration or fixture? I think the answer is to seed as described here: http://lptf.blogspot.com/2009/09/seed-data-in-rails-234.html but I need a way to seed for development and seed for production. Also, why bother using Fixtures if seeding is available? When does one seed and when does one use fixtures?

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• How to structure an index for type ahead for extremely large dataset using Lucene or similar?

  - by Pete

  I have a dataset of 200million+ records and am looking to build a dedicated backend to power a type ahead solution. Lucene is of interest given its popularity and license type, but I'm open to other open source suggestions as well. I am looking for advice, tales from the trenches, or even better direct instruction on what I will need as far as amount of hardware and structure of software. Requirements: Must have: The ability to do starts with substring matching (I type in 'st' and it should match 'Stephen') The ability to return results very quickly, I'd say 500ms is an upper bound. Nice to have: The ability to feed relevance information into the indexing process, so that, for example, more popular terms would be returned ahead of others and not just alphabetical, aka Google style. In-word substring matching, so for example ('st' would match 'bestseller') Note: This index will purely be used for type ahead, and does not need to serve standard search queries. I am not worried about getting advice on how to set up the front end or AJAX, as long as the index can be queried as a service or directly via Java code. Up votes for any useful information that allows me to get closer to an enterprise level type ahead solution

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• Adding Data into tables iclueds Foreign Keys but Which New Row created Entity FrameWork ?

  - by programmerist

  Addding Data into kartlar Table (RehberID,KampanyaID,BrimID) is ok. But Which Kart'ID created? i need to learn Which Id created after Adding Data (RehberID,KampanyaID,BrimID) into Kartlar? public static List<Kartlar> SaveKartlar(int RehberID, int KampanyaID, int BrimID, string Notlar) { using (GenSatisModuleEntities genSatisCtx = new GenSatisModuleEntities()) { Kartlar kartlar = new Kartlar(); kartlar.RehberReference.EntityKey = new System.Data.EntityKey("GenSatisModuleEntities.Rehber", "ID", RehberID); kartlar.KampanyaReference.EntityKey = new System.Data.EntityKey("GenSatisModuleEntities.Kampanya", "ID", KampanyaID); kartlar.BirimReference.EntityKey = new System.Data.EntityKey("GenSatisModuleEntities.Birim", "ID", BrimID); kartlar.Notlar = Notlar; genSatisCtx.AddToKartlar(kartlar); genSatisCtx.SaveChanges(); List<Kartlar> kartAddedPatient; kartAddedPatient = (from k in genSatisCtx.Kartlar where k.RehberReference.EntityKey == RehberID && k.KampanyaReference.EntityKey == KampanyaID && k.BirimReference.EntityKey == BrimID select k) return kartAddedPatient ; } } How can i do that? i want to get data from Kartlar which data i added?

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• How to encapsulate a third party complex object structure?

  - by tangens

  Motivation Currently I'm using the java parser japa to create an abstract syntax tree (AST) of a java file. With this AST I'm doing some code generation (e.g.: if there's an annotation on a method, create some other source files, ...) Problem When my code generation becomes more complex, I've to dive deeper into the structure of the AST (e.g. I have to use visitors to extract some type information of method parameters). But I'm not sure if I want to stay with japa or if I will change the parser library later. Because my code generator uses freemarker (which isn't good at automatic refactoring) I want the interface that it uses to access the AST information to be stable, even if I decide to change the java parser. Question What's the best way to encapsulate complex datastructures of third party libraries? I could create my own datatypes and copy the parts of the AST that I need into these. I could create lots of specialized access methods that work with the AST and create exactly the infos I need (e.g. the fully qualified return type of a method as one string, or the first template parameter of a class). I could create wrapper classes for the japa datastructures I currently need and embed the japa types inside, so that I can delegate requests to the japa types and transform the resulting japa types to my wrapper classes again. Which solution should I take? Are there other (better) solutions to this problem?

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• Update database every 30 minutes once

  - by Ravi

  Hi, I am working on C#.Net Windows application with SQL Server 2005. This project i am using ADO.Net Data-service for database maintenance. I am working on industrial automation domain, here data keep on reading more than 8 hours. After reading data from device based on the trigger i have periodically update data to database. for example start reading data on 9.00AM, trigger firing on 9.50AM. Once trigger fire, last 30 minutes(9.20 AM to 9.50AM) data store into data base. After trigger firing keep on reading data from device and store into data base. 10.00AM trigger going to off at time storing data to database has to be stop. Again trigger firing on 11.00AM. Once trigger fire, last 30 minutes(10.30 AM to 11.00AM) data store into data base. After trigger firing keep on reading data from device and store into data base. After 10.00AM trigger not firing means data keep on store locally. Here i don't know until trigger fire keep on reading data where & how to maintain temporarily , After trigger firing, last 30 minutes data how to bring and store into database. I don't know how to achieve it. It would be great if anyone could suggest any idea. Thanks

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• query structure - ignoring entries for the same event from multiple users?

  - by Andrew Heath

  One table in my MySQL database tracks game plays. It has the following structure: SCENARIO_VICTORIES [ID] [scenario_id] [game] [timestamp] [user_id] [winning_side] [play_date] ID is the autoincremented primary key. timestamp records the moment of submission for the record. winning_side has one of three possible values: 1, 2, or 0 (meaning a draw) One of the queries done on this table calculates the victory percentage for each scenario, when that scenario's page is viewed. The output is expressed as: Side 1 win % Side 2 win % Draw % and queried with: SELECT winning_side, COUNT(scenario_id) FROM scenario_victories WHERE scenario_id='$scenID' GROUP BY winning_side ORDER BY winning_side ASC and then processed into the percentages and such. Sorry for the long setup. My problem is this: several of my users play each other, and record their mutual results. So these battles are being doubly represented in the victory percentages and result counts. Though this happens infrequently, the userbase isn't large and the double entries do have a noticeable effect on the data. Given the table and query above - does anyone have any suggestions for how I can "collapse" records that have the same play_date & game & scenario_id & winning_side so that they're only counted once?

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