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• Big Data – ClustrixDB – Extreme Scale SQL Database with Real-time Analytics, Releases Software Download – NewSQL

  - by Pinal Dave

  There are so many things to learn and there is so little time we all have. As we have little time we need to be selective to learn whatever we learn. I believe I know quite a lot of things in SQL but I still do not know what is around SQL. I have started to learn about NewSQL recently. If you wonder what is NewSQL I encourage all of you to read my blog post about NewSQL over here Big Data – Buzz Words: What is NewSQL – Day 10 of 21. NewSQL databases are quickly becoming popular – providing the scale of NoSQL with the SQL features and transactions. As a part of learning NewSQL database, I have recently started to learn about ClustrixDB. ClustrixDB has been the most mature NewSQL database used by some of the largest internet sites in the world for over 3 years, with extensive SQL support. In addition to scale, it provides fast real-time analytics by bringing massively parallel processing (MPP), available only in warehousing databases, to the transactional database. The reason I am more intrigued about learning ClustrixDB is their recent announcement on Oct 31. ClustrixDB was only available as an appliance, but now with their software release on Oct 31, everyone can use it. It is now available as forever free for up to 12 cores with community support, and there is a 45 day trial for unlimited cluster sizes. With the forever free world, I am indeed interested in ClustrixDB now. I know that few of the leading eCommerce sites in the world uses them for their transactional database. Here are few of the details I have quickly noted for ClustrixDB. ClustrixDB allows user to: Scale by simply adding nodes to the cluster with a single command Run billions of transactions a day Run fast real-time analytics Achieve high-availability with recovery from node failure Manages itself Easily migrate from MySQL as it is nearly plug-and-play compatible, use MySQL drivers, tools and replication. While I was going through the documentation I realized that ClustrixDB also has extensive support for SQL features including complex queries involving joins on a dozen or more tables, aggregates, sorts, sub-queries. It also supports stored procedures, triggers, foreign keys, partitioned and temporary tables, and fully online schema changes. It is indeed a very matured product and SQL solution. Indeed Clusterix sound very promising solution, I decided to dig a bit deeper to understand who are current customers of the Clustrix as they exist in the industry for quite a few years. Their client list is indeed very interesting and here is my quick research about them. Twoo.com – Europe’s largest social discovery (dating) site runs 4.4 Billion Transactions a day with table sizes over a Terabyte, on a 168 core cluster. EngageBDR – Top 3 in the online advertising category uses ClustrixDB to serve 6.9 billion ads a day through real-time bidding platform. Their reports went from 4 hours to 15 seconds. NoMoreRack – Top 2 fastest growing e-commerce company in US used ClustrixDB for high availability and fast growth through Amazon cloud. MakeMyTrip – India’s leading travel site runs on ClustrixDB with two clusters running as multi-master in Chennai and Bangalore. Many enterprises such as AOL, CSC, Rakuten, Symantec use ClustrixDB when their applications need scale. I must accept that I am impressed with the information I have learned so far and now is the time to do some hand’s on experience with their product. I want to learn this technology so in future when it is about NewSQL, I know what I am talking about. Read more why Clustrix explains why you ClustrixDB might be the right database for you. Download ClustrixDB with me today and install it on your machine so in future when we discuss the technical aspects of it, we all are on the same page. The software can be downloaded here. Reference : Pinal Dave (http://blog.SQLAuthority.com)Filed under: Big Data, MySQL, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL Tagged: Clustrix

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• Oracle Communications Data Model

  - by jean-pierre.dijcks

  I've mentioned OCDM in previous posts but found the following (see end of the post) podcast on the topic and figured it is worthwhile to spread the news some more. ORetailDM and OCommunicationsDM are the two data models currently available from Oracle. Both are intended to capture: Business best practices and industry knowledge Pre-built advanced analytics intended to predict future events before they happen (like the Churn model shown below) Oracle technology best practices to ensure optimal performance of the model All of this typically comes with a reduced time to implementation, or as the marketing slogan goes, reduced time to value. Here are the links: Podcast on OCDM OTN pages for OCDM and ORDM

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• Importing data from text file to specific columns using BULK INSERT

  - by Dinesh Asanka

  Bulk insert is much faster than using other techniques such as  SSIS. However, when you are using bulk insert you can’t insert to specific columns. If, for example, there are five columns in a table you should have five values for each record in the text file you are importing from. This is an issue when you are expecting default values to be inserted into tables. Let us say you have table as below: In this table, you are expecting ID, Status and CreatedDate to be updated automatically, so your text file may only have   FirstName  LastName  values as below: Dinesh,Asanka Saman,Liyanage Ruwan,Silva Susantha,Bathige Jude,Peires Sanjeewa,Jayawickrama If you use bulk insert to this table like follows, You will be returned an error: Bulk load data conversion error (type mismatch or invalid character for the specified codepage) for row 1, column 1 (ID). To avoid this you will need to create a view with the columns you are expecting to fill and use bulk insert against it. If you check the table now, you will see table with values in the text file and the default values.

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• Javascript: Safely upload a client data file

  - by Jeffrey Sweeney

  I'm (still) working on a template-based XML editing program. It's a GUI-based XML editor that only allows users to add certain tags and attributes based off the requirements. You can see the current version here for an idea. Now, I'd like to allow users to upload their own data templates, but I'm concerned about potential XSS hacks. Currently, the template file is in Javascript object literal notation, which unsurprisingly is a security nightmare if the user can upload their own. I was thinking of using XML instead, but is there an even better alternative?

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• Reuse the data CRUD methods in data access layer, but they are updated too quickly

  - by ValidfroM

  I agree that we should put CRUD methods in a data access layer, However, in my current project I have some issues. It is a legacy system, and there are quite a lot CRUD methods in some concrete manager classes. People including me seem to just add new methods to it, rather than reuse the existing methods. Because We don't know whether the existing method is what we need Even if we have source code, do we really need read other's code then make decision? It is updated too quickly. Do not have time get familiar with the DAO API. Back to the question, how do you solve that in your project? If we say "reuse", it really needs to be reusable rather than just an excuse.

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• Get aggregated view of data for entire website with Google Analytics

  - by crmpicco

  I have a website (www.ayrshireminis.com), which has three main sections under different directories, these are: /forum /galleries /contact I would like to have an aggregated view of the data for the whole website, but also for each section. What is the recommended approach for doing this? I believe I can create a web property that includes a profile for the entire website and duplicated filtered profiles, each section having an include filter. This is my gut instinct, but i'd like to know if there is another (better) way to do it? Maybe by having one account that includes a profile for the whole site and another profile with an include filter for the individual sections?

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• Design: How to model / where to store relational data between classes

  - by Walker

  I'm trying to figure out the best design here, and I can see multiple approaches, but none that seems "right." There are three relevant classes here: Base, TradingPost, and Resource. Each Base has a TradingPost which can offer various Resources depending on the Base's tech level. Where is the right place to store the minimum tech level a base must possess to offer any given resource? A database seems like overkill. Putting it in each subclass of Resource seems wrong--that's not an intrinsic property of the Resource. Do I have a mediating class, and if so, how does it work? It's important that I not be duplicating code; that I have one place where I set the required tech level for a given item. Essentially, where does this data belong? P.S. Feel free to change the title; I struggled to come up with one that fits.

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• Still no detected structured data in Google Webmaster Tools [on hold]

  - by user6211

  Can you give me some suggestions what's wrong with my structured data? Google still cannot read it. It looks like this: <div class="identity"> <div itemscope itemtype="http://schema.org/LocalBusiness"> <a itemprop="url" href="http://MYDOMAIN.co.uk/"><div itemprop="name"><strong>MY_COMPANY</strong></div></a> <div itemprop="address" itemscope itemtype="http://schema.org/PostalAddress"> <span itemprop="streetAddress">MY_ADDRESS</span>, <span itemprop="addressLocality">London</span>, <span itemprop="postalCode">SE5 MY_XYZ</span>, <span itemprop="addressCountry">UK</span> </div> </div> </div>

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• Consolidating hotels data from various booking sites with different IDs or reference

  - by Victor

  In one of my projects, I have data for hotels, and other booking sites are able to book this hotel. For example: Hotel A - Booking (ID = 4002), Expedia (ID = 123), Priceline (ID = 147) The three booking engines each uses their own Id to reference to Hotel A. I would need to check manually and make the right reference to the hotel. If I have 100,000 hotels, I have to check manually 300,000 (considering 3 booking sites) times? They might provide API, then I can cross check the name, address or latitude/longitude, but if they differ a little bit then I might give the wrong reference to the wrong hotel. I'm sure there are better ways to do this. There are many travel sites out there which do hotel price checking on many booking sites, but how do they do to make sure they are checking the right hotel on these booking sites? Anyone has any experience on this?

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• Mount external HD ubuntu 12.10

  - by Luigi Tiburzi

  Although it's an abundantly treated matter, I'm unable to find an answer valid for my needs. I had a 12.04 installation of ubuntu and I decided to install the 12.10. I copied (using GParted) the partition where my system was to an external hd where there is a windows partition. Then I installed the newest ubuntu version and now I want to take back some files (for example my .emacs) from that partition but when I try to mount it, it is not found as sdb and if I mount it from /dev/usb/hddev0 I don't get any output, only a blinking cursor, no errors, no output. I even tried to mount it as an ntfs disk but the result was the same. It's like the hd cannot be detected. So how can I access data to that disk? Could I get them from GParted terminal instead of Ubuntu one? Thanks

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• disk not accessible

  - by user107044

  i formatted my hard drive yesterday and it was working well even after the formatting. But when I restarted my system again , is is showing that the space is alloted to my files but they are inaccessible. I have even tried to unhide the files and folders, if they got hidden somehow. But nothing works. the hard drive is being shown empty but the properties are saying that it still conatins the data : http://imgur.com/ObjTE in the image, it is showing that the directory has only 1 file of size:4.8 kbps but the space being used by the drive is 11.6 GB. do suggest some solution.

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• Using Ubuntu to recover data from a crashed Windows install

  - by user289391

  I was using Windows on my laptop when suddenly the blue screen of death appeared and then laptop restarted and wrote for me this : Intel UNDI, PXE-2.1 (built 083) Copyright (C) 1997-200 Intel Corporation This Product is covered by one or more of the following patents: US5,307459, US5,434,872, US5732,094, US6579,884, US6115,776 and US6,327,625 Realtek PCIe FE Family Controller Series v120 (01/26/10) PXE-M0F: ExitingPXEROM. reboot failed I have Ubuntu on an external disk so I have now booted to that. Two questions: Any theories on what happened? How can I use Ubuntu to recovers my data from Windows install?

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• Defining recursive algebraic data types in XML XSD

  - by Ben Challenor

  Imagine I have a recursive algebraic data type like this (Haskell syntax): data Expr = Zero | One | Add Expr Expr | Mul Expr Expr I'd like to represent this in XML, and I'd like an XSD schema for it. I have figured out how to achieve this syntax: <Expr> <Add> <Expr> <Zero/> </Expr> <Expr> <Mul> <Expr> <One/> </Expr> <Expr> <Add> <Expr> <One/> </Expr> <Expr> <One/> </Expr> </Add> </Expr> </Mul> </Expr> </Add> </Expr> with this schema: <xs:complexType name="Expr"> <xs:choice minOccurs="1" maxOccurs="1"> <xs:element minOccurs="1" maxOccurs="1" name="Zero" type="Zero" /> <xs:element minOccurs="1" maxOccurs="1" name="One" type="One" /> <xs:element minOccurs="1" maxOccurs="1" name="Add" type="Add" /> <xs:element minOccurs="1" maxOccurs="1" name="Mul" type="Mul" /> </xs:choice> </xs:complexType> <xs:complexType name="Zero"> <xs:sequence> </xs:sequence> </xs:complexType> <xs:complexType name="One"> <xs:sequence> </xs:sequence> </xs:complexType> <xs:complexType name="Add"> <xs:sequence> <xs:element minOccurs="2" maxOccurs="2" name="Expr" type="Expr" /> </xs:sequence> </xs:complexType> <xs:complexType name="Mul"> <xs:sequence> <xs:element minOccurs="2" maxOccurs="2" name="Expr" type="Expr" /> </xs:sequence> </xs:complexType> But what I really want is this syntax: <Add> <Zero/> <Mul> <One/> <Add> <One/> <One/> </Add> </Mul> </Add> Is this possible? Thanks!

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• How To - Guide to Importing Data from a MySQL Database to Excel using MySQL for Excel

  - by Javier Treviño

  Fetching data from a database to then get it into an Excel spreadsheet to do analysis, reporting, transforming, sharing, etc. is a very common task among users. There are several ways to extract data from a MySQL database to then import it to Excel; for example you can use the MySQL Connector/ODBC to configure an ODBC connection to a MySQL database, then in Excel use the Data Connection Wizard to select the database and table from which you want to extract data from, then specify what worksheet you want to put the data into.  Another way is to somehow dump a comma delimited text file with the data from a MySQL table (using the MySQL Command Line Client, MySQL Workbench, etc.) to then in Excel open the file using the Text Import Wizard to attempt to correctly split the data in columns. These methods are fine, but involve some degree of technical knowledge to make the magic happen and involve repeating several steps each time data needs to be imported from a MySQL table to an Excel spreadsheet. So, can this be done in an easier and faster way? With MySQL for Excel you can. MySQL for Excel features an Import MySQL Data action where you can import data from a MySQL Table, View or Stored Procedure literally with a few clicks within Excel.  Following is a quick guide describing how to import data using MySQL for Excel. This guide assumes you already have a working MySQL Server instance, Microsoft Office Excel 2007 or 2010 and MySQL for Excel installed. 1. Opening MySQL for Excel Being an Excel Add-In, MySQL for Excel is opened from within Excel, so to use it open Excel, go to the Data tab located in the Ribbon and click MySQL for Excel at the far right of the Ribbon. 2. Creating a MySQL Connection (may be optional) If you have MySQL Workbench installed you will automatically see the same connections that you can see in MySQL Workbench, so you can use any of those and there may be no need to create a new connection. If you want to create a new connection (which normally you will do only once), in the Welcome Panel click New Connection, which opens the Setup New Connection dialog. Here you only need to give your new connection a distinctive Connection Name, specify the Hostname (or IP address) where the MySQL Server instance is running on (if different than localhost), the Port to connect to and the Username for the login. If you wish to test if your setup is good to go, click Test Connection and an information dialog will pop-up stating if the connection is successful or errors were found. 3.Opening a connection to a MySQL Server To open a pre-configured connection to a MySQL Server you just need to double-click it, so the Connection Password dialog is displayed where you enter the password for the login. 4. Selecting a MySQL Schema After opening a connection to a MySQL Server, the Schema Selection Panel is shown, where you can select the Schema that contains the Tables, Views and Stored Procedures you want to work with. To do so, you just need to either double-click the desired Schema or select it and click Next >. 5. Importing data… All previous steps were really the basic minimum needed to drill-down to the DB Object Selection Panel  where you can see the Database Objects (grouped by type: Tables, Views and Procedures in that order) that you want to perform actions against; in the case of this guide, the action of importing data from them. a. From a MySQL Table To import from a Table you just need to select it from the list of Database Objects’ Tables group, after selecting it you will note actions below the list become available; then click Import MySQL Data. The Import Data dialog is displayed; you can see some basic information here like the name of the Excel worksheet the data will be imported to (in the window title), the Table Name, the total Row Count and a 10 row preview of the data meant for the user to see the columns that the table contains and to provide a way to select which columns to import. The Import Data dialog is designed with defaults in place so all data is imported (all rows and all columns) by just clicking Import; this is important to minimize the number of clicks needed to get the job done. After the import is performed you will have the data in the Excel worksheet formatted automatically. If you need to override the defaults in the Import Data dialog to change the columns selected for import or to change the number of imported rows you can easily do so before clicking Import. In the screenshot below the defaults are overridden to import only the first 3 columns and rows 10 – 60 (Limit to 50 Rows and Start with Row 10). If the number of rows to be imported exceeds the maximum number of rows Excel can hold in its worksheet, a warning will be displayed in the dialog, meaning the imported number of rows will be limited by that maximum number (65,535 rows if the worksheet is in Compatibility Mode).  In the screenshot below you can see the Table contains 80,559 rows, but only 65,534 rows will be imported since the first row is used for the column names if the Include Column Names as Headers checkbox is checked. b. From a MySQL View Similar to the way of importing from a Table, to import from a View you just need to select it from the list of Database Objects’ Views group, then click Import MySQL Data. The Import Data dialog is displayed; identically to the way everything looks when importing from a table, the dialog displays the View Name, the total Row Count and the data preview grid. Since Views are really a filtered way to display data from Tables, it is actually as if we are extracting data from a Table; so the Import Data dialog is actually identical for those 2 Database Objects. After the import is performed, the data in the Excel spreadsheet looks like the following screenshot. Note that you can override the defaults in the Import Data dialog in the same way described above for importing data from Tables. Also the Compatibility Mode warning will be displayed if data exceeds the maximum number of rows explained before. c. From a MySQL Procedure Too import from a Procedure you just need to select it from the list of Database Objects’ Procedures group (note you can see Procedures here but not Functions since these return a single value, so by design they are filtered out). After the selection is made, click Import MySQL Data. The Import Data dialog is displayed, but this time you can see it looks different to the one used for Tables and Views.  Given the nature of Store Procedures, they require first that values are supplied for its Parameters and also Procedures can return multiple Result Sets; so the Import Data dialog shows the Procedure Name and the Procedure Parameters in a grid where their values are input. After you supply the Parameter Values click Call. After calling the Procedure, the Result Sets returned by it are displayed at the bottom of the dialog; output parameters and the return value of the Procedure are appended as the last Result Set of the group. You can see each Result Set is displayed as a tab so you can see a preview of the returned data.  You can specify if you want to import the Selected Result Set (default), All Result Sets – Arranged Horizontally or All Result Sets – Arranged Vertically using the Import drop-down list; then click Import. After the import is performed, the data in the Excel spreadsheet looks like the following screenshot.  Note in this example all Result Sets were imported and arranged vertically. As you can see using MySQL for Excel importing data from a MySQL database becomes an easy task that requires very little technical knowledge, so it can be done by any type of user. Hope you enjoyed this guide! Remember that your feedback is very important for us, so drop us a message: MySQL on Windows (this) Blog - https://blogs.oracle.com/MySqlOnWindows/ Forum - http://forums.mysql.com/list.php?172 Facebook - http://www.facebook.com/mysql Cheers!

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• Excel Conditional Formatting Multiple Data Bars and Data Icons in one cell

  - by wbeard52

  I am using Excel 2007 on a windows machine. I am attempting to place one data bar and one data icon into a cell under the conditional formatting. The issue is that I don't really want to have data icons or data bars for cells that have dates in the future and I only want to have data icons for dates in the at least one month in the past. This is what I have: This is what I want: I am using the EOMONTH function to determine the last day of the month for the conditional formatting calculations. For the data bar the formula is =EOMONTH(Now(), 4) and =EOMONTH(Now(), -1). The data icons formulas are =EOMONTH(Now(), -1) and =EOMONTH(Now(), -2) Is there a way in Excel 2007 to get rid of the data icons for all the dates in the future and lose the data bars when the date has past. Thanks

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• Criteria strings, how many different criteria can be entered to retrieve specific data?

  - by Janet

  For our membership database we are currently using an old DOS program "Arclist". The program is old but the one feature we desperately need in a database program is to be able to enter multiple criteria at one time for more of a "one time" extraction of the data meeting all the various criteria entered in what I call a "criteria string". An example may be extracting only those records with zip codes matching (67893, 54235, 54323, 54201, 54302, 54303, 54301, 67894, 67895). Another set of criteria might be to omit records, not equal to, one type of criteria in one field and also extract records matching criteria in another field. So we would want records "not equal to" in one field, but whose information equals requested information in another field.

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• Entity Association Mapping with Code First Part 1 : Mapping Complex Types

  - by mortezam

  Last week the CTP5 build of the new Entity Framework Code First has been released by data team at Microsoft. Entity Framework Code-First provides a pretty powerful code-centric way to work with the databases. When it comes to associations, it brings ultimate flexibility. I’m a big fan of the EF Code First approach and am planning to explain association mapping with code first in a series of blog posts and this one is dedicated to Complex Types. If you are new to Code First approach, you can find a great walkthrough here. In order to build a solid foundation for our discussion, we will start by learning about some of the core concepts around the relationship mapping.   What is Mapping?Mapping is the act of determining how objects and their relationships are persisted in permanent data storage, in our case, relational databases. What is Relationship mapping?A mapping that describes how to persist a relationship (association, aggregation, or composition) between two or more objects. Types of RelationshipsThere are two categories of object relationships that we need to be concerned with when mapping associations. The first category is based on multiplicity and it includes three types: One-to-one relationships: This is a relationship where the maximums of each of its multiplicities is one. One-to-many relationships: Also known as a many-to-one relationship, this occurs when the maximum of one multiplicity is one and the other is greater than one. Many-to-many relationships: This is a relationship where the maximum of both multiplicities is greater than one. The second category is based on directionality and it contains two types: Uni-directional relationships: when an object knows about the object(s) it is related to but the other object(s) do not know of the original object. To put this in EF terminology, when a navigation property exists only on one of the association ends and not on the both. Bi-directional relationships: When the objects on both end of the relationship know of each other (i.e. a navigation property defined on both ends). How Object Relationships Are Implemented in POCO domain models?When the multiplicity is one (e.g. 0..1 or 1) the relationship is implemented by defining a navigation property that reference the other object (e.g. an Address property on User class). When the multiplicity is many (e.g. 0..*, 1..*) the relationship is implemented via an ICollection of the type of other object. How Relational Database Relationships Are Implemented? Relationships in relational databases are maintained through the use of Foreign Keys. A foreign key is a data attribute(s) that appears in one table and must be the primary key or other candidate key in another table. With a one-to-one relationship the foreign key needs to be implemented by one of the tables. To implement a one-to-many relationship we implement a foreign key from the “one table” to the “many table”. We could also choose to implement a one-to-many relationship via an associative table (aka Join table), effectively making it a many-to-many relationship. Introducing the ModelNow, let's review the model that we are going to use in order to implement Complex Type with Code First. It's a simple object model which consist of two classes: User and Address. Each user could have one billing address. The Address information of a User is modeled as a separate class as you can see in the UML model below: In object-modeling terms, this association is a kind of aggregation—a part-of relationship. Aggregation is a strong form of association; it has some additional semantics with regard to the lifecycle of objects. In this case, we have an even stronger form, composition, where the lifecycle of the part is fully dependent upon the lifecycle of the whole. Fine-grained domain models The motivation behind this design was to achieve Fine-grained domain models. In crude terms, fine-grained means “more classes than tables”. For example, a user may have both a billing address and a home address. In the database, you may have a single User table with the columns BillingStreet, BillingCity, and BillingPostalCode along with HomeStreet, HomeCity, and HomePostalCode. There are good reasons to use this somewhat denormalized relational model (performance, for one). In our object model, we can use the same approach, representing the two addresses as six string-valued properties of the User class. But it’s much better to model this using an Address class, where User has the BillingAddress and HomeAddress properties. This object model achieves improved cohesion and greater code reuse and is more understandable. Complex Types: Splitting a Table Across Multiple Types Back to our model, there is no difference between this composition and other weaker styles of association when it comes to the actual C# implementation. But in the context of ORM, there is a big difference: A composed class is often a candidate Complex Type. But C# has no concept of composition—a class or property can’t be marked as a composition. The only difference is the object identifier: a complex type has no individual identity (i.e. no AddressId defined on Address class) which make sense because when it comes to the database everything is going to be saved into one single table. How to implement a Complex Types with Code First Code First has a concept of Complex Type Discovery that works based on a set of Conventions. The convention is that if Code First discovers a class where a primary key cannot be inferred, and no primary key is registered through Data Annotations or the fluent API, then the type will be automatically registered as a complex type. Complex type detection also requires that the type does not have properties that reference entity types (i.e. all the properties must be scalar types) and is not referenced from a collection property on another type. Here is the implementation: public class User{    public int UserId { get; set; }    public string FirstName { get; set; }    public string LastName { get; set; }    public string Username { get; set; }    public Address Address { get; set; }} public class Address {     public string Street { get; set; }     public string City { get; set; }            public string PostalCode { get; set; }        }public class EntityMappingContext : DbContext {     public DbSet<User> Users { get; set; }        } With code first, this is all of the code we need to write to create a complex type, we do not need to configure any additional database schema mapping information through Data Annotations or the fluent API. Database SchemaThe mapping result for this object model is as follows: Limitations of this mappingThere are two important limitations to classes mapped as Complex Types: Shared references is not possible: The Address Complex Type doesn’t have its own database identity (primary key) and so can’t be referred to by any object other than the containing instance of User (e.g. a Shipping class that also needs to reference the same User Address). No elegant way to represent a null reference There is no elegant way to represent a null reference to an Address. When reading from database, EF Code First always initialize Address object even if values in all mapped columns of the complex type are null. This means that if you store a complex type object with all null property values, EF Code First returns a initialized complex type when the owning entity object is retrieved from the database. SummaryIn this post we learned about fine-grained domain models which complex type is just one example of it. Fine-grained is fully supported by EF Code First and is known as the most important requirement for a rich domain model. Complex type is usually the simplest way to represent one-to-one relationships and because the lifecycle is almost always dependent in such a case, it’s either an aggregation or a composition in UML. In the next posts we will revisit the same domain model and will learn about other ways to map a one-to-one association that does not have the limitations of the complex types. References ADO.NET team blog Mapping Objects to Relational Databases Java Persistence with Hibernate

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• Isolating test data in acceptance tests

  - by Matt Phillips

  I'm looking for guidance on how to keep my acceptance tests isolated. Right now the issue I'm having with being able to run the tests in parallel is the database records that are manipulated in the tests. I've written helpers that take care of doing inserts and deletes before tests are executed, to make sure the state is correct. But now I can't run them in parallel against the same database without uniquely generating the test data fields for each test. For example. Testing creating a row i'll delete everything where column A = foo and column B = bar Then I'll navigate through the UI in the test and create a record with column A = foo and column B = bar. Testing that a duplicate row is not allowed to be created. I'll insert a row with column A = foo and column B = bar and then use the UI to try and do the exact same thing. This will display an error message in the UI as expected. These tests work perfectly when ran separately and serially. But I can't run them at the same time for fear that one will create or delete a record the other is expecting. Any tips on how to structure them better so they can be run in parallel?

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• Data Structure for Small Number of Agents in a Relatively Big 2D World

  - by Seçkin Savasçi

  I'm working on a project where we will implement a kind of world simulation where there is a square 2D world. Agents live on this world and make decisions like moving or replicating themselves based on their neighbor cells(world=grid) and some extra parameters(which are not based on the state of the world). I'm looking for a data structure to implement such a project. My concerns are : I will implement this 3 times: sequential, using OpenMP, using MPI. So if I can use the same structure that will be quite good. The first thing comes up is keeping a 2D array for the world and storing agent references in it. And simulate the world for each time slice by checking every cell in each iteration and further processing if an agents is found in the cell. The downside is what if I have 1000x1000 world and only 5 agents in it. It will be an overkill for both sequential and parallel versions to check each cell and look for possible agents in them. I can use quadtree and store agents in it, but then how can I get the information about neighbor cells then? Please let me know if I should elaborate more.

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• Ubuntu Tools for recovering data from damaged USB Flash Drive ~ 10 Gb

  - by PREDA LUCIAN

  I have technical issues with my USB Flash Drive - JetFlash®V15 (TS16GJFV15) It's very critical situation because I can not see the data from it and I should get a way to recover them ASAP. So, in general, I have connected Non-stop that USB Flash Disk at my laptop. Was appear Power surges and when I was coming back, I saw that problem with it. Details regarding JetFlash®V15 (in present): - when I connect it on USP slot, the led is working intermittent and later on remain with constant light. - if I inspect the computer drivers, I found "Generic USB Flash Disk" (when the stick it's connected). - if I inspect "Properties", I can see next details: --- Type: unknown (application/octet-stream) --- Size: unknown --- Volume: unknown --- Accessed: unknown --- Modified: unknown I inspected that stick on 2 different computers (as well in different different USB Ports) and was the same problem, I can not see the content. I was checking with Windows 7 and Ubuntu 10.04 OS, but without success. With both OS was working before this issue. I'll appreciate an answer which will solve the problem, not an answer which will certify the problem. What I have to do, to recover the information form it (nearly 10 Gb)? I'm looking forward to be guided from a technical expert.

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• How much information can you mine out of a name?

  - by Finglas Fjorn

  While not directly related to programming, I figured that the programmers on here would be just as curious as I was about this question. Feel free to close the question if it does not meet with the guidelines. A name: first, possibly a middle, and surname. I'm curious about how much information you can mine out of a name, using publicly available datasets. I know that you can get the following with anywhere between a low-high probability (depending on the input) using US census data: 1) Gender. 2) Race. Facebook for instance, used exactly that to find out, with a decent level of accuracy, the racial distribution of users of their site (https://www.facebook.com/note.php?note_id=205925658858). What else can be mined? I'm not looking for anything specific, this is a very open-ended question to assuage my curiousity. My examples are US specific, so we'll assume that the name is the name of someone located in the US; but, if someone knows of publicly available datasets for other countries, I'm more than open to them too. I hope this is an interesting question!

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• Data structure for grid with negative indeces

  - by The Secret Imbecile

  Sorry if this is an insultingly obvious concept, but it's something I haven't done before and I've been unable to find any material discussing the best way to approach it. I'm wondering what's the best data structure for holding a 2D grid of unknown size. The grid has integer coordinates (x,y), and will have negative indices in both directions. So, what is the best way to hold this grid? I'm programming in c# currently, so I can't have negative array indices. My initial thought was to have class with 4 separate arrays for (+x,+y),(+x,-y),(-x,+y), and (-x,-y). This seems to be a valid way to implement the grid, but it does seem like I'm over-engineering the solution, and array resizing will be a headache. Another idea was to keep track of the center-point of the array and set that as the topological (0,0), however I would have the issue of having to do a shift to every element of the grid when repeatedly adding to the top-left of the grid, which would be similar to grid resizing though in all likelihood more frequent. Thoughts?

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• Data model for unlockable card collection

  - by Karlos Zafra

  My game has a collection of cards (about 64) that are unlocked (one by one) provided that 4 items are collected/gained in the game. Right now the deck of cards is modeled with a plist file, like this: <plist> <dict> <key>card1</key> <dict> <key>available</key> <true/> <key>series</key> <integer>1</integer> <key>model</key> <integer>1</integer> <key>color</key> <integer>1</integer> </dict> <key>card2</key> <dict> <key>available</key> <false/> <key>series</key> <integer>1</integer> <key>model</key> <integer>1</integer> <key>color</key> <integer>2</integer> </dict> The value for the key named "available" marks if the item is locked or not. Right now I have to include the data for the items collected by the user, but including that inside the plist looks like too much hassle. What kind of structure should be more suitable for this? How do you manage a collection of unlockable items like this?

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• Complex data types in WCF?

  - by Hojou

  I've run into a problem trying to return an object that holds a collection of childobjects that again can hold a collection of grandchild objects. I get an error, 'connection forcibly closed by host'. Is there any way to make this work? I currently have a structure resembling this: pseudo code: Person: IEnumerable<Order> Order: IEnumberable<OrderLine> All three objects have the DataContract attribute and all public properties i want exposed (including the IEnumerable's) have the DataMember attribute. I have multiple OperationContract's on my service and all the methods returning a single object OR an IEnumerable of an object works perfectly. It's only when i try to nest IEnumerable that it turns bad. Also in my client service reference i picked the generic list as my collection type. I just want to emphasize, only one of my operations/methods fail with this error - the rest of them work perfectly. EDIT (more detailed error description): [SocketException (0x2746): An existing connection was forcibly closed by the remote host] [IOException: Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host.] [WebException: The underlying connection was closed: An unexpected error occurred on a receive.] [CommunicationException: An error occurred while receiving the HTTP response to http://myservice.mydomain.dk/MyService.svc. This could be due to the service endpoint binding not using the HTTP protocol. This could also be due to an HTTP request context being aborted by the server (possibly due to the service shutting down). See server logs for more details.] I tried looking for logs but i can't find any... also i'm using a WSHttpBinding and an http endpoint.

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• Raw types and subtyping

  - by Dmitrii

  We have generic class SomeClass<T>{ } We can write the line: SomeClass s= new SomeClass<String>(); It's ok, because raw type is supertype for generic type. But SomeClass<String> s= new SomeClass(); is correct to. Why is it correct? I thought that type erasure was before type checking, but it's wrong. From Hacker's Guide to Javac When the Java compiler is invoked with default compile policy it performs the following passes: parse: Reads a set of *.java source files and maps the resulting token sequence into AST-Nodes. enter: Enters symbols for the definitions into the symbol table. process annotations: If Requested, processes annotations found in the specified compilation units. attribute: Attributes the Syntax trees. This step includes name resolution, type checking and constant folding. flow: Performs data ow analysis on the trees from the previous step. This includes checks for assignments and reachability. desugar: Rewrites the AST and translates away some syntactic sugar. generate: Generates Source Files or Class Files. Generic is syntax sugar, hence type erasure invoked at 6 pass, after type checking, which invoked at 4 pass. I'm confused.

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