LINQ to HDFS Data

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HDFS ADO.NET Provider

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LINQ provides general-purpose query facilities in .NET Framework 3.0 and above and provides one easy way to programmatically access data through from CData ADO.NET Data Providers. This example uses LINQ to access information from the HDFS Data Provider.

This article demonstrates how to use LINQ to access HDFS tables through the CData ADO.NET Data Provider for HDFS. To do this you will LINQ to Entity Framework, which is used to generate the connection and can be used with any CData ADO.NET Data Providers to access data via LINQ.

See the help documentation for a guide to setting up an EF 6 project to use the provider.

  1. In a new project in Visual Studio, right-click on the project and choose to add a new item. Add an ADO.NET Entity Data Model.
  2. Choose EF Designer from Database and click Next.
  3. Add a new Data Connection, and change your data source type to "CData HDFS Data Source".
  4. Enter your data source connection information.

    In order to authenticate, set the following connection properties:

    • Host: Set this value to the host of your HDFS installation.
    • Port: Set this value to the port of your HDFS installation. Default port: 50070

    Below is a typical connection string:

    Host=sandbox-hdp.hortonworks.com;Port=50070;Path=/user/root;User=root;
  5. If saving your entity connection to App.Config, set an entity name. In this example we are setting HDFSEntities as our entity connection in App.Config.
  6. Enter a model name and select any tables or views you would like to include in the model.

Using the entity you created, you can now perform select commands. For example:

HDFSEntities context = new HDFSEntities(); var filesQuery = from files in context.Files select files; foreach (var result in filesQuery) { Console.WriteLine("{0} {1} ", result.Id, result.FileId); }

See "LINQ and Entity Framework" chapter in the help documentation for example queries of the supported LINQ.